HCS08
Microcontrollers
freescale.com
MC9S08SG8
MC9S08SG4
Data Sheet
Now Includes High-Temperature (up to 150 °C) Devices!
MC9S08SG8
Rev. 8
1/2014
8-Bit HCS08 Central Processor Unit (CPU)
• 40 MHz HCS08 CPU (central processor unit)
• 36 MHz HCS08 CPU for temperatures greater
than 125 C
• HC08 instruction set with added BGND instruction
• Support for up to 32 interrupt/reset sources
On-Chip Memory
• Flash read/program/erase over full operating
voltage and temperature
• Random-access memory (RAM)
Power-Saving Modes
• Two very low power stop modes
• Reduced power wait mode
• Very low power real time interrupt for use in run,
wait, and stop
Clock Source Options
• Oscillator (XOSC) — Loop-control Pierce
oscillator; Crystal or ceramic resonator range of
31.25 kHz to 38.4 kHz or 1 MHz to 16MHz
• Internal Clock Source (ICS) — Internal clock
source module containing a frequency-locked
loop (FLL) controlled by internal or external
reference; precision trimming of internal reference
allows 0.2% resolution and 1.5% deviation over
temperature –40 to 125 C or 3% deviation for
temperature > 125 C and voltage; supports bus
frequencies from 2 MHz to 20MHz.
System Protection
• Watchdog computer operating properly (COP)
reset with option to run from dedicated 1-kHz
internal clock source or bus clock
• Low-voltage detection with reset or interrupt;
selectable trip points
• Illegal opcode detection with reset
• Illegal address detection with reset
• FLASH block protect
Development Support
• Single-wire background debug interface
• Breakpoint capability to allow single breakpoint
setting during in-circuit debugging (plus two more
breakpoints in on-chip debug module)
• On-chip, in-circuit emulation (ICE) debug module
containing two comparators and nine trigger
modes. Eight deep FIFO for storing
change-of-flow address and event-only data.
Debug module supports both tag and force
breakpoints.
Peripherals
•ADC — 12-channel, 10-bit resolution, 2.5 s
conversion time, automatic compare function,
temperature sensor, internal bandgap reference
channel; runs in stop3
•ACMP — Analog comparator with selectable
interrupt on rising, falling, or either edge of
comparator output; compare option to fixed
internal bandgap reference voltage; output can be
optionally routed to TPM module; runs in stop3
•SCI — Full duplex non-return to zero (NRZ); LIN
master extended break generation; LIN slave
extended break detection; wake up on active edge
•SPI — Full-duplex or single-wire bidirectional;
Double-buffered transmit and receive; Master or
Slave mode; MSB-first or LSB-first shifting
•IIC — Up to 100 kbps with maximum bus loading;
Multi-master operation; Programmable slave
address; Interrupt driven byte-by-byte data
transfer; supports broadcast mode and 10-bit
addressing
•MTIM — 8-bit modulo counter with 8-bit prescaler
and overflow interrupt
•TPMx — Two 2-channel timer pwm modules
(TPM1, TPM2); Selectable input capture, output
compare, or buffered edge- or center-aligned
PWM on each channel
•RTC — (Real-time counter) 8-bit modulus counter
with binary or decimal based prescaler; External
clock source for precise time base, time-of-day,
calendar or task scheduling functions; Free
running on-chip low power oscillator (1 kHz) for
cyclic wake-up without external components, runs
in all MCU modes
Input/Output
• 16 general purpose I/O pins (GPIOs)
• 8 interrupt pins with selectable polarity
• Ganged output option for PTB[5:2] and PTC[3:0];
allows single write to change state of multiple pins
• Hysteresis and configurable pull up device on all
input pins; Configurable slew rate and drive
strength on all output pins.
Package Options
• 20-TSSOP (not available on high-temperature
rated devices)
•16-TSSOP
• 8-SOIC (not available on high-temperature rated
devices)
MC9S08SG8 Features
MC9S08SG8 Data Sheet
Covers MC9S08SG8
MC9S08SG4
MC9S08SG8
Rev. 8
1/2014
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
© Freescale Semiconductor, Inc., 2006-2014. All rights reserved.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
6Freescale Semiconductor
© Freescale Semiconductor, Inc., 2006-2014. All rights reserved.
This product incorporates SuperFlash Technology licensed from SST.
Revision History
To provide the most up-to-date information, the revision of our documents on the World Wide Web will be
the most current. Your printed copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://freescale.com/
The following revision history table summarizes changes contained in this document.
Revision
Number
Revision
Date Description of Changes
0 15 Dec 2006 Initial alpha customer release version; Preliminary
1 June 2007
Samples Draft. Updated book with the latest TPM v3 module. Includes some
minor edits to the IIC module to update the Module Quick Start. Fixed the
SOPT1 bits 1 and 0 to be RESERVED for both READ and WRITE. Changed all
the Reset states of the Slew Rate Enable Registers (PTASE, PTBSE, and
PTCSE) bits from 1 to 0 due to silicon functional change.
2 11/2007 Market Launch. Updated the Electricals and Device Numbering scheme informa-
tion.
3 12/2007
• Fixed typos: Chapter 7 heading corrected version to v2, and Figure 16-1. title
corrected to read ...”TPM Modules Highlighted.”
• Table A-3. Thermal Characteristics row 1, V and M entries were transposed. V
now refers to value -40 to 105C and M now refers to value -40 to 125C. Added
row 2, parameter classification of “D” and row 4 symbol of ”JA.”
• Table A-6. DC Characteristics, row 8 Input Hysteresis, corrected units from mV
to V.
43/2008
• SPI block corrected to be version 3 of the module.
• Temperature Sensor values corrected to reflect the ADC 5V in Section 9.1.4
Temperature Sensor and Table A-12. ADC Characteristics.
• Provided Maximum juncture temperature for C, V, and M Temperature ranges.
• Corrected Table A-6, row 10 separated to two pins: PTB6/SDA/XTAL, RESET
.
• Corrected block diagrams User Flash and User RAM listing typos to be SG8
and SG4 instead of SH8 and SH4.
• Updated the Revision History for Revision Number 1 to include the information
on the Slew Rate Enable Register changes that occurred for that revision.
5 6/2008 • Added ICS over Temperature graph to Electricals appendix.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 7
67/2009
• Revised NV Register 0xFFAE address to have dashes instead of 0s.
• Revised NVOPT register in Table 4-4 and Figure 4-6 so that Reserved is indi-
cated with em dashes (—).
• Changed ICS FLL deviation to 1.5% from 2%.
• Table A-9, Row 1and Table A-6 footnote 10: Removed temperature reference. •
Table A-9, Row 9: Changed Column C to “D” and Max to “1.5%”
• Removed section A.14.2.
• Updated Mechanical drawings to point to the Freescale web.
• Rebuilt book to ensure proper footers and pagination.
• Revised all "Reserved" vector space memory locations in Table 4-1 to read,
"Unused Vector Space (available for user program)."
77/2011
• Revised to include high-temperature (up to 150C) devices for 16-pin TSSOP
package.
•In Table 2-1, added TCLK to row 20 and Alt 3 column.
• Updated “How to Reach Us” information.
81/2014
Changes done in Chapter 3, “Modes of Operation”.
Updated Table 3- 1
Updated PPDC column to “x” from “0” for the specification
STOPE=1,ENBDM=0,LVDE and LVDSE =both bits must be 1.
Changes done in Appendix A, “Electrical Characteristics”
•In Table A - 6 . DC Characteristics for column “Characteristic” moved “Reset”
from parameter “P” to “C”.
•In the Table A- 6 added note 11 and 12 for parameter #18.
Note 11: Device functionality is guaranteed between the LVD threshold VLVD0
and VDD Min.When VDD is below the minimum operating voltage (VDD Min),
the analog parameters for the IO pins, ACMP and ADC, are not guaranteed to
meet data sheet performance parameters.
Note 12: In addition to LVD, it is recommended to also use the LVW feature. LVW
can trigger an interrupt and be used as an indicator to warn that the VDD is drop-
ping,so that the software can take actions accordingly before the VDD drops
below VDD Min.
•Table A-13. Control Timing.
For the parameter “Internal low power oscillator period” changed the “Min”
value from “800” to “700”.
Revision
Number
Revision
Date Description of Changes
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 9
Contents
Section Number Title Page
Chapter 1 Device Overview ...................................................................... 21
Chapter 2 Pins and Connections ............................................................. 25
Chapter 3 Modes of Operation................................................................. 33
Chapter 4 Memory..................................................................................... 39
Chapter 5 Resets, Interrupts, and General System Control..................61
Chapter 6 Parallel Input/Output Control.................................................. 75
Chapter 7 Central Processor Unit (S08CPUV2)...................................... 91
Chapter 8 5-V Analog Comparator (S08ACMPV2)................................ 111
Chapter 9 Analog-to-Digital Converter (S08ADCV1)............................ 119
Chapter 10 Internal Clock Source (S08ICSV2)........................................ 147
Chapter 11 Inter-Integrated Circuit (S08IICV2) ....................................... 161
Chapter 12 Modulo Timer (S08MTIMV1).................................................. 179
Chapter 13 Real-Time Counter (S08RTCV1) ........................................... 189
Chapter 14 Serial Communications Interface (S08SCIV4)..................... 199
Chapter 15 Serial Peripheral Interface (S08SPIV3) ................................ 219
Chapter 16 Timer Pulse-Width Modulator (S08TPMV3) ......................... 235
Chapter 17 Development Support ........................................................... 261
Appendix A Electrical Characteristics...................................................... 283
Appendix B Ordering Information and Mechanical Drawings................ 313
MC9S08SG8 MCU Series Data Sheet, Rev. 8
10 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 11
Contents
Section Number Title Page
Chapter 1
Device Overview
1.1 Devices in the MC9S08SG8 Series .................................................................................................21
1.2 MCU Block Diagram ......................................................................................................................22
1.3 System Clock Distribution ..............................................................................................................24
Chapter 2
Pins and Connections
2.1 Device Pin Assignment ...................................................................................................................25
2.2 Recommended System Connections ...............................................................................................27
2.2.1 Power ................................................................................................................................27
2.2.2 Oscillator (XOSC) ............................................................................................................28
2.2.3 RESET Pin ........................................................................................................................28
2.2.4 Background / Mode Select (BKGD/MS) ..........................................................................29
2.2.5 General-Purpose I/O and Peripheral Ports ........................................................................29
Chapter 3
Modes of Operation
3.1 Introduction .....................................................................................................................................33
3.2 Features ...........................................................................................................................................33
3.3 Run Mode ........................................................................................................................................33
3.4 Active Background Mode ...............................................................................................................33
3.5 Wait Mode .......................................................................................................................................34
3.6 Stop Modes ......................................................................................................................................34
3.6.1 Stop3 Mode .......................................................................................................................35
3.6.2 Stop2 Mode .......................................................................................................................36
3.6.3 On-Chip Peripheral Modules in Stop Modes ....................................................................36
Chapter 4
Memory
4.1 MC9S08SG8 Memory Map ............................................................................................................39
4.2 Reset and Interrupt Vector Assignments .........................................................................................40
4.3 Register Addresses and Bit Assignments ........................................................................................41
4.4 RAM ................................................................................................................................................48
4.5 FLASH ............................................................................................................................................48
4.5.1 Features .............................................................................................................................49
4.5.2 Program and Erase Times .................................................................................................49
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12 Freescale Semiconductor
Section Number Title Page
4.5.3 Program and Erase Command Execution .........................................................................50
4.5.4 Burst Program Execution ..................................................................................................51
4.5.5 Access Errors ....................................................................................................................53
4.5.6 FLASH Block Protection ..................................................................................................53
4.5.7 Vector Redirection ............................................................................................................54
4.6 Security ............................................................................................................................................54
4.7 FLASH Registers and Control Bits .................................................................................................55
4.7.1 FLASH Clock Divider Register (FCDIV) ........................................................................56
4.7.2 FLASH Options Register (FOPT and NVOPT) ................................................................57
4.7.3 FLASH Configuration Register (FCNFG) .......................................................................58
4.7.4 FLASH Protection Register (FPROT and NVPROT) ......................................................58
4.7.5 FLASH Status Register (FSTAT) ......................................................................................59
4.7.6 FLASH Command Register (FCMD) ...............................................................................60
Chapter 5
Resets, Interrupts, and General System Control
5.1 Introduction .....................................................................................................................................61
5.2 Features ...........................................................................................................................................61
5.3 MCU Reset ......................................................................................................................................61
5.4 Computer Operating Properly (COP) Watchdog .............................................................................62
5.5 Interrupts .........................................................................................................................................63
5.5.1 Interrupt Stack Frame .......................................................................................................64
5.5.2 Interrupt Vectors, Sources, and Local Masks ...................................................................65
5.6 Low-Voltage Detect (LVD) System ................................................................................................67
5.6.1 Power-On Reset Operation ...............................................................................................67
5.6.2 Low-Voltage Detection (LVD) Reset Operation ...............................................................67
5.6.3 Low-Voltage Warning (LVW) Interrupt Operation ...........................................................67
5.7 Reset, Interrupt, and System Control Registers and Control Bits ...................................................67
5.7.1 System Reset Status Register (SRS) .................................................................................68
5.7.2 System Background Debug Force Reset Register (SBDFR) ............................................69
5.7.3 System Options Register 1 (SOPT1) ................................................................................70
5.7.4 System Options Register 2 (SOPT2) ................................................................................71
5.7.5 System Device Identification Register (SDIDH, SDIDL) ................................................72
5.7.6 System Power Management Status and Control 1 Register (SPMSC1) ...........................73
5.7.7 System Power Management Status and Control 2 Register (SPMSC2) ...........................74
Chapter 6
Parallel Input/Output Control
6.1 Port Data and Data Direction ..........................................................................................................75
6.2 Pull-up, Slew Rate, and Drive Strength ..........................................................................................76
6.3 Ganged Output ................................................................................................................................77
6.4 Pin Interrupts ...................................................................................................................................78
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 13
Section Number Title Page
6.4.1 Edge Only Sensitivity .......................................................................................................78
6.4.2 Edge and Level Sensitivity ...............................................................................................78
6.4.3 Pull-up/Pull-down Resistors .............................................................................................79
6.4.4 Pin Interrupt Initialization .................................................................................................79
6.5 Pin Behavior in Stop Modes ............................................................................................................79
6.6 Parallel I/O and Pin Control Registers ............................................................................................79
6.6.1 Port A Registers ................................................................................................................80
6.6.2 Port B Registers ................................................................................................................84
6.6.3 Port C Registers ................................................................................................................88
Chapter 7
Central Processor Unit (S08CPUV2)
7.1 Introduction .....................................................................................................................................91
7.1.1 Features .............................................................................................................................91
7.2 Programmer’s Model and CPU Registers .......................................................................................92
7.2.1 Accumulator (A) ...............................................................................................................92
7.2.2 Index Register (H:X) ........................................................................................................92
7.2.3 Stack Pointer (SP) .............................................................................................................93
7.2.4 Program Counter (PC) ......................................................................................................93
7.2.5 Condition Code Register (CCR) .......................................................................................93
7.3 Addressing Modes ...........................................................................................................................94
7.3.1 Inherent Addressing Mode (INH) .....................................................................................95
7.3.2 Relative Addressing Mode (REL) ....................................................................................95
7.3.3 Immediate Addressing Mode (IMM) ................................................................................95
7.3.4 Direct Addressing Mode (DIR) ........................................................................................95
7.3.5 Extended Addressing Mode (EXT) ..................................................................................95
7.3.6 Indexed Addressing Mode ................................................................................................95
7.4 Special Operations ...........................................................................................................................96
7.4.1 Reset Sequence .................................................................................................................97
7.4.2 Interrupt Sequence ............................................................................................................97
7.4.3 Wait Mode Operation ........................................................................................................98
7.4.4 Stop Mode Operation ........................................................................................................98
7.4.5 BGND Instruction .............................................................................................................98
7.5 HCS08 Instruction Set Summary ....................................................................................................99
Chapter 8
5-V Analog Comparator (S08ACMPV2)
8.1 Introduction ...................................................................................................................................111
8.1.1 ACMP Configuration Information ..................................................................................111
8.1.2 ACMP in Stop3 Mode ....................................................................................................111
8.1.3 ACMP/TPM Configuration Information ........................................................................111
8.1.4 Features ...........................................................................................................................113
MC9S08SG8 MCU Series Data Sheet, Rev. 8
14 Freescale Semiconductor
Section Number Title Page
8.1.5 Modes of Operation ........................................................................................................113
8.1.6 Block Diagram ................................................................................................................113
8.2 External Signal Description ..........................................................................................................115
8.3 Memory Map ................................................................................................................................115
8.3.1 Register Descriptions ......................................................................................................115
8.4 Functional Description ..................................................................................................................117
Chapter 9
Analog-to-Digital Converter (S08ADCV1)
9.1 Introduction ...................................................................................................................................119
9.1.1 Channel Assignments .....................................................................................................119
9.1.2 Alternate Clock ...............................................................................................................120
9.1.3 Hardware Trigger ............................................................................................................120
9.1.4 Temperature Sensor ........................................................................................................120
9.1.5 Features ...........................................................................................................................123
9.1.6 Block Diagram ................................................................................................................123
9.2 External Signal Description ..........................................................................................................124
9.2.1 Analog Power (VDDAD) ..................................................................................................125
9.2.2 Analog Ground (VSSAD) .................................................................................................125
9.2.3 Voltage Reference High (VREFH) ...................................................................................125
9.2.4 Voltage Reference Low (VREFL) ....................................................................................125
9.2.5 Analog Channel Inputs (ADx) ........................................................................................125
9.3 Register Definition ........................................................................................................................125
9.3.1 Status and Control Register 1 (ADCSC1) ......................................................................125
9.3.2 Status and Control Register 2 (ADCSC2) ......................................................................127
9.3.3 Data Result High Register (ADCRH) .............................................................................128
9.3.4 Data Result Low Register (ADCRL) ..............................................................................128
9.3.5 Compare Value High Register (ADCCVH) ....................................................................129
9.3.6 Compare Value Low Register (ADCCVL) .....................................................................129
9.3.7 Configuration Register (ADCCFG) ................................................................................129
9.3.8 Pin Control 1 Register (APCTL1) ..................................................................................131
9.3.9 Pin Control 2 Register (APCTL2) ..................................................................................132
9.3.10 Pin Control 3 Register (APCTL3) ..................................................................................133
9.4 Functional Description ..................................................................................................................134
9.4.1 Clock Select and Divide Control ....................................................................................134
9.4.2 Input Select and Pin Control ...........................................................................................135
9.4.3 Hardware Trigger ............................................................................................................135
9.4.4 Conversion Control .........................................................................................................135
9.4.5 Automatic Compare Function .........................................................................................138
9.4.6 MCU Wait Mode Operation ............................................................................................138
9.4.7 MCU Stop3 Mode Operation ..........................................................................................138
9.4.8 MCU Stop1 and Stop2 Mode Operation .........................................................................139
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 15
Section Number Title Page
9.5 Initialization Information ..............................................................................................................139
9.5.1 ADC Module Initialization Example .............................................................................139
9.6 Application Information ................................................................................................................141
9.6.1 External Pins and Routing ..............................................................................................141
9.6.2 Sources of Error ..............................................................................................................143
Chapter 10
Internal Clock Source (S08ICSV2)
10.1 Introduction ...................................................................................................................................147
10.1.1 Module Configuration .....................................................................................................147
10.1.2 Features ...........................................................................................................................149
10.1.3 Block Diagram ................................................................................................................149
10.1.4 Modes of Operation ........................................................................................................150
10.2 External Signal Description ..........................................................................................................151
10.3 Register Definition ........................................................................................................................151
10.3.1 ICS Control Register 1 (ICSC1) .....................................................................................152
10.3.2 ICS Control Register 2 (ICSC2) .....................................................................................153
10.3.3 ICS Trim Register (ICSTRM) .........................................................................................154
10.3.4 ICS Status and Control (ICSSC) .....................................................................................154
10.4 Functional Description ..................................................................................................................155
10.4.1 Operational Modes ..........................................................................................................155
10.4.2 Mode Switching ..............................................................................................................157
10.4.3 Bus Frequency Divider ...................................................................................................158
10.4.4 Low Power Bit Usage .....................................................................................................158
10.4.5 Internal Reference Clock ................................................................................................158
10.4.6 Optional External Reference Clock ................................................................................158
10.4.7 Fixed Frequency Clock ...................................................................................................159
Chapter 11
Inter-Integrated Circuit (S08IICV2)
11.1 Introduction ...................................................................................................................................161
11.1.1 Module Configuration .....................................................................................................161
11.1.2 Features ...........................................................................................................................163
11.1.3 Modes of Operation ........................................................................................................163
11.1.4 Block Diagram ................................................................................................................163
11.2 External Signal Description ..........................................................................................................164
11.2.1 SCL — Serial Clock Line ...............................................................................................164
11.2.2 SDA — Serial Data Line ................................................................................................164
11.3 Register Definition ........................................................................................................................164
11.3.1 IIC Address Register (IICA) ...........................................................................................165
11.3.2 IIC Frequency Divider Register (IICF) ..........................................................................165
11.3.3 IIC Control Register (IICC1) ..........................................................................................168
MC9S08SG8 MCU Series Data Sheet, Rev. 8
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Section Number Title Page
11.3.4 IIC Status Register (IICS) ...............................................................................................168
11.3.5 IIC Data I/O Register (IICD) ..........................................................................................169
11.3.6 IIC Control Register 2 (IICC2) .......................................................................................170
11.4 Functional Description ..................................................................................................................171
11.4.1 IIC Protocol .....................................................................................................................171
11.4.2 10-bit Address .................................................................................................................174
11.4.3 General Call Address ......................................................................................................175
11.5 Resets ............................................................................................................................................175
11.6 Interrupts .......................................................................................................................................175
11.6.1 Byte Transfer Interrupt ....................................................................................................175
11.6.2 Address Detect Interrupt .................................................................................................176
11.6.3 Arbitration Lost Interrupt ................................................................................................176
11.7 Initialization/Application Information ..........................................................................................177
Chapter 12
Modulo Timer (S08MTIMV1)
12.1 Introduction ...................................................................................................................................179
12.1.1 MTIM Configuration Information ..................................................................................179
12.1.2 Features ...........................................................................................................................181
12.1.3 Modes of Operation ........................................................................................................181
12.1.4 Block Diagram ................................................................................................................182
12.2 External Signal Description ..........................................................................................................182
12.3 Register Definition ........................................................................................................................183
12.3.1 MTIM Status and Control Register (MTIMSC) .............................................................184
12.3.2 MTIM Clock Configuration Register (MTIMCLK) .......................................................185
12.3.3 MTIM Counter Register (MTIMCNT) ...........................................................................186
12.3.4 MTIM Modulo Register (MTIMMOD) ..........................................................................186
12.4 Functional Description ..................................................................................................................187
12.4.1 MTIM Operation Example .............................................................................................188
Chapter 13
Real-Time Counter (S08RTCV1)
13.1 Introduction ...................................................................................................................................189
13.1.1 Features ...........................................................................................................................191
13.1.2 Modes of Operation ........................................................................................................191
13.1.3 Block Diagram ................................................................................................................192
13.2 External Signal Description ..........................................................................................................192
13.3 Register Definition ........................................................................................................................192
13.3.1 RTC Status and Control Register (RTCSC) ....................................................................193
13.3.2 RTC Counter Register (RTCCNT) ..................................................................................194
13.3.3 RTC Modulo Register (RTCMOD) ................................................................................194
13.4 Functional Description ..................................................................................................................194
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 17
Section Number Title Page
13.4.1 RTC Operation Example .................................................................................................195
13.5 Initialization/Application Information ..........................................................................................196
Chapter 14
Serial Communications Interface (S08SCIV4)
14.1 Introduction ...................................................................................................................................199
14.1.1 Features ...........................................................................................................................201
14.1.2 Modes of Operation ........................................................................................................201
14.1.3 Block Diagram ................................................................................................................202
14.2 Register Definition ........................................................................................................................204
14.2.1 SCI Baud Rate Registers (SCIBDH, SCIBDL) ..............................................................204
14.2.2 SCI Control Register 1 (SCIC1) .....................................................................................205
14.2.3 SCI Control Register 2 (SCIC2) .....................................................................................206
14.2.4 SCI Status Register 1 (SCIS1) ........................................................................................207
14.2.5 SCI Status Register 2 (SCIS2) ........................................................................................209
14.2.6 SCI Control Register 3 (SCIC3) .....................................................................................210
14.2.7 SCI Data Register (SCID) ...............................................................................................211
14.3 Functional Description ..................................................................................................................211
14.3.1 Baud Rate Generation .....................................................................................................211
14.3.2 Transmitter Functional Description ................................................................................212
14.3.3 Receiver Functional Description ....................................................................................213
14.3.4 Interrupts and Status Flags ..............................................................................................215
14.3.5 Additional SCI Functions ...............................................................................................216
Chapter 15
Serial Peripheral Interface (S08SPIV3)
15.1 Introduction ...................................................................................................................................219
15.1.1 Features ...........................................................................................................................221
15.1.2 Block Diagrams ..............................................................................................................221
15.1.3 SPI Baud Rate Generation ..............................................................................................223
15.2 External Signal Description ..........................................................................................................224
15.2.1 SPSCK — SPI Serial Clock ............................................................................................224
15.2.2 MOSI — Master Data Out, Slave Data In ......................................................................224
15.2.3 MISO — Master Data In, Slave Data Out ......................................................................224
15.2.4 SS — Slave Select ..........................................................................................................224
15.3 Modes of Operation .......................................................................................................................225
15.3.1 SPI in Stop Modes ..........................................................................................................225
15.4 Register Definition ........................................................................................................................225
15.4.1 SPI Control Register 1 (SPIC1) ......................................................................................225
15.4.2 SPI Control Register 2 (SPIC2) ......................................................................................226
15.4.3 SPI Baud Rate Register (SPIBR) ....................................................................................227
15.4.4 SPI Status Register (SPIS) ..............................................................................................228
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Section Number Title Page
15.4.5 SPI Data Register (SPID) ...............................................................................................229
15.5 Functional Description ..................................................................................................................230
15.5.1 SPI Clock Formats ..........................................................................................................230
15.5.2 SPI Interrupts ..................................................................................................................233
15.5.3 Mode Fault Detection .....................................................................................................233
Chapter 16
Timer Pulse-Width Modulator (S08TPMV3)
16.1 Introduction ...................................................................................................................................235
16.1.1 ACMP/TPM Configuration Information ........................................................................235
16.1.2 TPM Configuration Information .....................................................................................235
16.1.3 TPMV3 Differences from Previous Versions .................................................................236
16.1.4 Migrating from TPMV1 ..................................................................................................238
16.1.5 Features ...........................................................................................................................240
16.1.6 Modes of Operation ........................................................................................................240
16.1.7 Block Diagram ................................................................................................................241
16.2 Signal Description .........................................................................................................................243
16.2.1 Detailed Signal Descriptions ..........................................................................................243
16.3 Register Definition ........................................................................................................................247
16.3.1 TPM Status and Control Register (TPMxSC) ................................................................247
16.3.2 TPM-Counter Registers (TPMxCNTH:TPMxCNTL) ....................................................248
16.3.3 TPM Counter Modulo Registers (TPMxMODH:TPMxMODL) ....................................249
16.3.4 TPM Channel n Status and Control Register (TPMxCnSC) ..........................................250
16.3.5 TPM Channel Value Registers (TPMxCnVH:TPMxCnVL) ..........................................251
16.4 Functional Description ..................................................................................................................253
16.4.1 Counter ............................................................................................................................253
16.4.2 Channel Mode Selection .................................................................................................255
16.5 Reset Overview .............................................................................................................................258
16.5.1 General ............................................................................................................................258
16.5.2 Description of Reset Operation .......................................................................................258
16.6 Interrupts .......................................................................................................................................258
16.6.1 General ............................................................................................................................258
16.6.2 Description of Interrupt Operation .................................................................................259
Chapter 17
Development Support
17.1 Introduction ...................................................................................................................................261
17.1.1 Forcing Active Background ............................................................................................261
17.1.2 Features ...........................................................................................................................262
17.2 Background Debug Controller (BDC) ..........................................................................................262
17.2.1 BKGD Pin Description ...................................................................................................263
17.2.2 Communication Details ..................................................................................................264
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 19
Section Number Title Page
17.2.3 BDC Commands .............................................................................................................268
17.2.4 BDC Hardware Breakpoint .............................................................................................270
17.3 On-Chip Debug System (DBG) ....................................................................................................271
17.3.1 Comparators A and B .....................................................................................................271
17.3.2 Bus Capture Information and FIFO Operation ...............................................................271
17.3.3 Change-of-Flow Information ..........................................................................................272
17.3.4 Tag vs. Force Breakpoints and Triggers .........................................................................272
17.3.5 Trigger Modes .................................................................................................................273
17.3.6 Hardware Breakpoints ....................................................................................................275
17.4 Register Definition ........................................................................................................................275
17.4.1 BDC Registers and Control Bits .....................................................................................275
17.4.2 System Background Debug Force Reset Register (SBDFR) ..........................................277
17.4.3 DBG Registers and Control Bits .....................................................................................278
Appendix A
Electrical Characteristics
A.1 Introduction ...................................................................................................................................283
A.2 Parameter Classification ................................................................................................................283
A.3 Absolute Maximum Ratings ..........................................................................................................283
A.4 Thermal Characteristics .................................................................................................................285
A.5 ESD Protection and Latch-Up Immunity ......................................................................................287
A.6 DC Characteristics .........................................................................................................................288
A.7 Supply Current Characteristics ......................................................................................................293
A.8 External Oscillator (XOSC) Characteristics .................................................................................297
A.9 Internal Clock Source (ICS) Characteristics .................................................................................299
A.10 Analog Comparator (ACMP) Electricals ......................................................................................301
A.11 ADC Characteristics ......................................................................................................................302
A.12 AC Characteristics .........................................................................................................................305
A.12.1 Control Timing ...............................................................................................................305
A.12.2 TPM/MTIM Module Timing ..........................................................................................307
A.12.3 SPI ...................................................................................................................................308
A.13 FLASH Specifications ...................................................................................................................311
A.14 EMC Performance .........................................................................................................................312
A.14.1 Radiated Emissions .........................................................................................................312
Appendix B
Ordering Information and Mechanical Drawings
B.1 Ordering Information ....................................................................................................................313
B.1.1 Device Numbering Scheme ............................................................................................313
B.2 Mechanical Drawings ....................................................................................................................314
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 21
Chapter 1
Device Overview
The MC9S08SG8 members of the low-cost, high-performance HCS08 family of 8-bit microcontroller
units (MCUs). All MCUs in the family use the enhanced HCS08 core and are available with a variety of
modules, memory sizes, memory types, and package types. The high-temperature devices have been
qualified to meet or exceed AEC Grade 0 requirements to allow them to operate up to 150 °C TA.
1.1 Devices in the MC9S08SG8 Series
Table 1-1 summarizes the feature set available in the MC9S08SG8 series of MCUs.
t
Table 1-1. MC9S08SG8 Features by MCU and Package
Feature 9S08SG8 9S08SG4
FLASH size (bytes) 8192 4096
RAM size (bytes) 512 256
Pin quantity 20 16 8 20 16 8
ACMP yes
ADC channels 12 8 4 12 8 4
DBG yes
ICS yes yes yes1
1FBE and FEE modes are not available in 8-pin packages.
yes yes yes 1
IIC yes
MTIM yes
Pin Interrupts 884884
Pin I/O 16 12 4 16 12 4
RTC yes
SCI yesyesnoyesyesno
SPI yes yes no yes yes no
TPM1 channels 221221
TPM2 channels 221221
XOSC yes yes no yes yes no
Chapter 1 Device Overview
MC9S08SG8 MCU Series Data Sheet, Rev. 8
22 Freescale Semiconductor
1.2 MCU Block Diagram
The block diagram in Figure 1-1 shows the structure of the MC9S08SG8 MCU.
Figure 1-1. MC9S08SG8 Block Diagram
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Chapter 1 Device Overview
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 23
Table 1-2 provides the functional version of the on-chip modules.
Table 1-2. Module Versions
Module Version
Analog Comparator (5V) (ACMP) 2
Analog-to-Digital Converter (ADC) 1
Central Processor Unit (CPU) 2
Inter-Integrated Circuit (IIC) 2
Internal Clock Source (ICS) 2
Serial Peripheral Interface (SPI) 3
Serial Communications Interface (SCI) 4
Modulo Timer (MTIM) 1
Real-Time Counter (RTC) 1
Timer Pulse Width Modulator (TPM) 3
Chapter 1 Device Overview
MC9S08SG8 MCU Series Data Sheet, Rev. 8
24 Freescale Semiconductor
1.3 System Clock Distribution
Figure 1-2 shows a simplified clock connection diagram. Some modules in the MCU have selectable clock
inputs as shown. The clock inputs to the modules indicate the clock(s) that are used to drive the module
function.
The following defines the clocks used in this MCU:
• BUSCLK — The frequency of the bus is always half of ICSOUT.
• ICSOUT — Primary output of the ICS and is twice the bus frequency.
• ICSLCLK — Development tools can select this clock source to speed up BDC communications in
systems where the bus clock is configured to run at a very slow frequency.
• ICSERCLK — External reference clock can be selected as the RTC clock source and as the
alternate clock for the ADC module.
• ICSIRCLK — Internal reference clock can be selected as the RTC clock source.
• ICSFFCLK — Fixed frequency clock can be selected as clock source for the TPM1, TPM2 and
MTIM modules.
• LPOCLK — Independent 1-kHz clock source that can be selected as the clock source for the COP
and RTC modules.
• TCLK — External input clock source for TPM1, TPM2 and MTIM and is referenced as TPMCLK
in TPM chapters.
Figure 1-2. System Clock Distribution Diagram
TPM1 TPM2 MTIM SCI
BDC
CPU ADC IIC FLASH
ICS
ICSOUT 2 BUSCLK
ICSLCLK
ICSERCLK
COP
* The fixed frequency clock (FFCLK) is internally
synchronized to the bus clock and must not exceed one
half of the bus clock frequency.
FLASH has frequency
requirements for program
and erase operation. See
the electricals appendix
for details.
ADC has min and max
frequency requirements.
See the ADC chapter
and electricals appendix
for details.
XOSC
EXTAL XTAL
SPI
FFCLK*
ICSFFCLK
RTC
1 kHZ
LPO
TCLK
ICSIRCLK
2 SYNC*
LPOCLK
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 25
Chapter 2
Pins and Connections
This section describes signals that connect to package pins. It includes pinout diagrams, recommended
system connections, and detailed discussions of signals.
2.1 Device Pin Assignment
Figure 2-1 - Figure 2-3 shows the pin assignments for the MC9S08SG8 devices.
NOTE
20-pin TSSOP package and 8-pin SOIC package are not available for the
AEC Grade 0 high-temperature rated devices.
Figure 2-1. 20-Pin TSSOP
Figure 2-2. 16-Pin TSSOP
PTB1/PIB1/TxD/ADP5
PTB5/TPM1CH1/SS
PTB6/SDA/XTAL
PTB2/PIB2/SPSCK/ADP6
PTA3/PIA3/SCL/ADP3
PTB4/TPM2CH1/MISO PTB3/PIB3/MOSI/ADP7
PTB0/PIB0/RxD/ADP4
VDD
VSS
PTB7/SCL/EXTAL
1
2
3
4
5
6
7
8
20
19
18
17
16
15
9
10
14
12
11
13
PTC3/ADP11 PTC0/TPM1CH0/ADP8
PTC2/ADP10 PTC1/TPM1CH1/ADP9
BKGD/MS
RESET
PTA2/PIA2/SDA/ADP2/ACMPO
PTA1/PIA1/TPM2CH0/ADP1/ACMP-
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
PTB1/PIB1/TxD/ADP5
PTB5/TPM1CH1/SS
PTB6/SDA/XTAL
PTB2/PIB2/SPSCK/ADP6
PTA3/PIA3/SCL/ADP3
PTB4/TPM2CH1/MISO PTB3/PIB3/MOSI/ADP7
PTB0/PIB0/RxD/ADP4
VDD
VSS
PTB7/SCL/EXTAL
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
BKGD/MS
RESET
PTA2/PIA2/SDA/ADP2/ACMPO
PTA1/PIA1/TPM2CH0/ADP1/ACMP-
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
26 Freescale Semiconductor
Figure 2-3. 8-Pin SOIC
1
2
3
4
8
7
6
5
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
PTA1/PIA1/TPM2CH0/ADP1/ACMP-
PTA2/PIA2/SDA/ADP2/ACMPO
PTA3/PIA3/SCL/ADP3
VSS
VDD
BKGD/MS
RESET
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 27
2.2 Recommended System Connections
Figure 2-4 shows pin connections that are common to MC9S08SG8 application systems.
Figure 2-4. Basic System Connections
2.2.1 Power
VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all
I/O buffer circuitry, ACMP and ADC modules, and to an internal voltage regulator. The internal voltage
regulator provides regulated lower-voltage source to the CPU and other internal circuitry of the MCU.
Typically, application systems have two separate capacitors across the power pins. In this case, there
should be a bulk electrolytic capacitor, such as a 10-F tantalum capacitor, to provide bulk charge storage
BKGD/MS
RESET
OPTIONAL
MANUAL
RESET
V
DD
BACKGROUND HEADER
SYSTEM
POWER
PORT
B
PTB0/PIB0/RxD/ADP4
PTB1/PIB1/TxD/ADP5
PTB2/PIB2/SPSCK/ADP6
PTB3/PIB3/MOSI/ADP7
PTB4/TPM2CH1/MISO
PTB5/TPM1CH1/SS
PTB6/SDA/XTAL
PTB7/SCL/EXTAL
PORT
C
PTC0/TPM1CH0/ADP8
PTC1/TPM1CH1/ADP9
PTC2/ADP10
PTC3/ADP11
MC9S08SG8
VSS
VDD
CBY
0.1 F
CBLK
10 F
+
5 V
+
C2
C1 X1
RFRS
PORT
A
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
PTA1/PIA1/TPM2CH0/ADP1/ACMP-
PTA2/PIA2/SDA/ADP2/ACMPO
PTA3/PIA3/SCL/ADP3
0.1 F
VDD
4.7 k
–10 k
NOTE 1
NOTES:
1. External crystal circuit not required if using the internal clock option.
2. RESET pin can only be used to reset into user mode, you can not enter BDM using RESET
pin. BDM can be entered by holding MS low during POR or writing a 1 to BDFR in SBDFR
with MS low after issuing BDM command.
3. RC filter on RESET pin recommended for noisy environments.
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
28 Freescale Semiconductor
for the overall system and a 0.1-F ceramic bypass capacitor located as near to the MCU power pins as
practical to suppress high-frequency noise. Each pin must have a bypass capacitor for best noise
suppression.
2.2.2 Oscillator (XOSC)
Immediately after reset, the MCU uses an internally generated clock provided by the clock source
generator (ICS) module. For more information on the ICS, see Chapter 10, “Internal Clock Source
(S08ICSV2).”
The oscillator (XOSC) in this MCU is a Pierce oscillator that can accommodate a crystal or ceramic
resonator. Rather than a crystal or ceramic resonator, an external oscillator can be connected to the EXTAL
input pin.
Refer to Figure 2-4 for the following discussion. RS (when used) and RF should be low-inductance
resistors such as carbon composition resistors. Wire-wound resistors, and some metal film resistors, have
too much inductance. C1 and C2 normally should be high-quality ceramic capacitors that are specifically
designed for high-frequency applications.
RF is used to provide a bias path to keep the EXTAL input in its linear range during crystal startup; its value
is not generally critical. Typical systems use 1 M to 10 M. Higher values are sensitive to humidity and
lower values reduce gain and (in extreme cases) could prevent startup.
C1 and C2 are typically in the 5-pF to 25-pF range and are chosen to match the requirements of a specific
crystal or resonator. Be sure to take into account printed circuit board (PCB) capacitance and MCU pin
capacitance when selecting C1 and C2. The crystal manufacturer typically specifies a load capacitance
which is the series combination of C1 and C2 (which are usually the same size). As a first-order
approximation, use 10 pF as an estimate of combined pin and PCB capacitance for each oscillator pin
(EXTAL and XTAL).
2.2.3 RESET Pin
RESET is a dedicated pin with open-drain drive containing an internal pull-up device. Internal power-on
reset and low-voltage reset circuitry typically make external reset circuitry unnecessary. This pin is
normally connected to the standard 6-pin background debug connector so a development system can
directly reset the MCU system. If desired, a manual external reset can be added by supplying a simple
switch to ground (pull reset pin low to force a reset).
Whenever any reset is initiated (whether from an external signal or from an internal system), the RESET
pin is driven low for about 66 bus cycles. The reset circuitry decodes the cause of reset and records it by
setting a corresponding bit in the system reset status register (SRS).
NOTE
This pin does not contain a clamp diode to VDD and should not be driven
above VDD.
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 29
The voltage measured on the internally pulled up RESET pin will not be
pulled to VDD. The internal gates connected to this pin are pulled to VDD. If
the RESET pin is required to drive to a VDD level an external pullup should
be used.
NOTE
In EMC-sensitive applications, an external RC filter is recommended on the
RESET. See Figure 2-4 for an example.
2.2.4 Background / Mode Select (BKGD/MS)
During a power-on-reset (POR) or background debug force reset (see Section 5.7.2, “System Background
Debug Force Reset Register (SBDFR),” for more information), the BKGD/MS pin functions as a mode
select pin. Immediately after any reset, the pin functions as the background pin and can be used for
background debug communication. The BKGD/MS pin contains an internal pullup device.
If nothing is connected to this pin, the MCU will enter normal operating mode at the rising edge of the
internal reset after a POR or force BDC reset. If a debug system is connected to the 6-pin standard
background debug header, it can hold BKGD/MS low during a POR or immediately after issuing a
background debug force reset, which will force the MCU to active background mode.
The BKGD pin is used primarily for background debug controller (BDC) communications using a custom
protocol that uses 16 clock cycles of the target MCU’s BDC clock per bit time. The target MCU’s BDC
clock could be as fast as the maximum bus clock rate, so there must never be any significant capacitance
connected to the BKGD/MS pin that could interfere with background serial communications.
Although the BKGD pin is a pseudo open-drain pin, the background debug communication protocol
provides brief, actively driven, high speedup pulses to ensure fast rise times. Small capacitances from
cables and the absolute value of the internal pullup device play almost no role in determining rise and fall
times on the BKGD pin.
2.2.5 General-Purpose I/O and Peripheral Ports
The MC9S08SG8 series of MCUs support up to 16 general-purpose I/O pins which are shared with
on-chip peripheral functions (timers, serial I/O, ADC, etc.).
When a port pin is configured as a general-purpose output or a peripheral uses the port pin as an output,
software can select one of two drive strengths and enable or disable slew rate control. When a port pin is
configured as a general-purpose input or a peripheral uses the port pin as an input, software can enable a
pull-up device. Immediately after reset, all of these pins are configured as high-impedance
general-purpose inputs with internal pull-up devices disabled.
When an on-chip peripheral system is controlling a pin, data direction control bits still determine what is
read from port data registers even though the peripheral module controls the pin direction by controlling
the enable for the pin’s output buffer. For information about controlling these pins as general-purpose I/O
pins, see Chapter 6, “Parallel Input/Output Control.”
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
30 Freescale Semiconductor
The MC9S08SG8 devices contain a ganged output drive feature that allows a safe and reliable method of
allowing pins to be tied together externally to produce a higher output current drive. See Section 6.3,
“Ganged Output” for more information for configuring the port pins for ganged output drive.
NOTE
To avoid extra current drain from floating input pins, the reset initialization
routine in the application program should either enable on-chip pull-up
devices or change the direction of unused pins to outputs so they do not
float.
When using the 8-pin devices, the user must either enable on-chip pullup
devices or change the direction of non-bonded out port B and port C pins to
outputs so the pins do not float.
When using the 16-pin devices, the user must either enable on-chip pullup
devices or change the direction of non-bonded out port C pins to outputs so
the pins do not float.
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 31
Pin Number
Priority
20-pin 16-pin 8-pin Port Pin Alt 1 Alt 2 Alt 3 Alt 4 Alt5
111 RESET
2 2 2 BKGD MS
333 VDD
444 VSS
55—PTB7SCL
1
1IIC pins can be repositioned using IICPS in SOPT2, default reset locations are on PTA2 and PTA3.
EXTAL
66—PTB6SDA
1XTAL
77—PTB5TPM1CH1
2
2TPM1CHx pins can be repositioned using TPM1PS in SOPT2, default reset locations are on PTA0 and
PTB5.
SS PTC03
3This port pin is part of the ganged output feature. When pin is enabled for ganged output, it will have priority
over all digital modules. The output data, drive strength and slew-rate control of this port pin will follow the
configuration for the PTC0 pin, even in 16-pin packages where PTC0 doesn’t bond out. Ganged output not
available in 8-pin packages.
8 8 — PTB4 TPM2CH1 MISO PTC03
9——PTC3 PTC0
3ADP11
10 — — PTC2 PTC03ADP10
11 — — PTC1 TPM1CH12PTC03ADP9
12 — — PTC0 TPM1CH02PTC03ADP8
13 9 — PTB3 PIB3 MOSI PTC03ADP7
14 10 — PTB2 PIB2 SPSCK PTC03ADP6
15 11 — PTB1 PIB1 TxD ADP5
16 12 — PTB0 PIB0 RxD ADP4
17 13 5 PTA3 PIA3 SCL1ADP3
18 14 6 PTA2 PIA2 SDA1ADP2 ACMPO
19 15 7 PTA1 PIA1 TPM2CH0 ADP14
4If ACMP and ADC are both enabled, both will have access to the pin.
ACMP–4
20 16 8 PTA0 PIA0 TPM1CH02TCLK ADP04ACMP+4
Lowest Highest
Table 2-1. Pin Availability by Package Pin-Count
Chapter 2 Pins and Connections
MC9S08SG8 MCU Series Data Sheet, Rev. 8
32 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 33
Chapter 3
Modes of Operation
3.1 Introduction
The operating modes of the MC9S08SG8 are described in this chapter. Entry into each mode, exit from
each mode, and functionality while in each of the modes are described.
3.2 Features
• Active background mode for code development
• Wait mode — CPU shuts down to conserve power; system clocks are running and full regulation
is maintained
• Stop modes — System clocks are stopped and voltage regulator is in standby
— Stop3 — All internal circuits are powered for fast recovery
— Stop2 — Partial power down of internal circuits, RAM content is retained
3.3 Run Mode
This is the normal operating mode for the MC9S08SG8. This mode is selected upon the MCU exiting reset
if the BKGD/MS pin is high. In this mode, the CPU executes code from internal memory with execution
beginning at the address fetched from memory at 0xFFFE–0xFFFF after reset.
3.4 Active Background Mode
The active background mode functions are managed through the background debug controller (BDC) in
the HCS08 core. The BDC, together with the on-chip debug module (DBG), provide the means for
analyzing MCU operation during software development.
Active background mode is entered in any of the following ways:
• When the BKGD/MS pin is low during POR or immediately after issuing a background debug
force reset (see Section 5.7.2, “System Background Debug Force Reset Register (SBDFR)”)
• When a BACKGROUND command is received through the BKGD/MS pin
• When a BGND instruction is executed
• When encountering a BDC breakpoint
• When encountering a DBG breakpoint
After entering active background mode, the CPU is held in a suspended state waiting for serial background
commands rather than executing instructions from the user application program.
Chapter 3 Modes of Operation
MC9S08SG8 MCU Series Data Sheet, Rev. 8
34 Freescale Semiconductor
Background commands are of two types:
• Non-intrusive commands, defined as commands that can be issued while the user program is
running. Non-intrusive commands can be issued through the BKGD/MS pin while the MCU is in
run mode; non-intrusive commands can also be executed when the MCU is in the active
background mode. Non-intrusive commands include:
— Memory access commands
— Memory-access-with-status commands
— BDC register access commands
— The BACKGROUND command
• Active background commands, which can only be executed while the MCU is in active background
mode. Active background commands include commands to:
— Read or write CPU registers
— Trace one user program instruction at a time
— Leave active background mode to return to the user application program (GO)
The active background mode is used to program a bootloader or user application program into the FLASH
program memory before the MCU is operated in run mode for the first time. When the MC9S08SG8 is
shipped from the Freescale Semiconductor factory, the FLASH program memory is erased by default
unless specifically noted so there is no program that could be executed in run mode until the FLASH
memory is initially programmed. The active background mode can also be used to erase and reprogram
the FLASH memory after it has been previously programmed.
For additional information about the active background mode, refer to the Development Support chapter.
3.5 Wait Mode
Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT instruction, the CPU
enters a low-power state in which it is not clocked. The I bit in CCR is cleared when the CPU enters the
wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits the wait mode and
resumes processing, beginning with the stacking operations leading to the interrupt service routine.
While the MCU is in wait mode, there are some restrictions on which background debug commands can
be used. Only the BACKGROUND command and memory-access-with-status commands are available
when the MCU is in wait mode. The memory-access-with-status commands do not allow memory access,
but they report an error indicating that the MCU is in either stop or wait mode. The BACKGROUND
command can be used to wake the MCU from wait mode and enter active background mode.
3.6 Stop Modes
One of two stop modes is entered upon execution of a STOP instruction when STOPE in SOPT1. In any
stop mode, the bus and CPU clocks are halted. The ICS module can be configured to leave the reference
clocks running. See Chapter 10, “Internal Clock Source (S08ICSV2),” for more information.
Chapter 3 Modes of Operation
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 35
Table 3-1 shows all of the control bits that affect stop mode selection and the mode selected under various
conditions. The selected mode is entered following the execution of a STOP instruction.
3.6.1 Stop3 Mode
Stop3 mode is entered by executing a STOP instruction under the conditions as shown in Table 3-1. The
states of all of the internal registers and logic, RAM contents, and I/O pin states are maintained.
Stop3 can be exited by asserting RESET, or by an interrupt from one of the following sources: the real-time
counter (RTC), LVD system, ACMP, ADC, SCI, or any pin interrupts.
If stop3 is exited by means of the RESET pin, then the MCU is reset and operation will resume after taking
the reset vector. Exit by means of one of the internal interrupt sources results in the MCU taking the
appropriate interrupt vector.
3.6.1.1 LVD Enabled in Stop Mode
The LVD system is capable of generating either an interrupt or a reset when the supply voltage drops below
the LVD voltage. For configuring the LVD system for interrupt or reset, refer to 5.6, “Low-Voltage Detect
(LVD) System”. If the LVD is enabled in stop (LVDE and LVDSE bits in SPMSC1 both set) at the time
the CPU executes a STOP instruction, then the voltage regulator remains active during stop mode.
For the ADC to operate in stop mode, the LVD must be enabled when entering stop3.
For the ACMP to operate in stop mode with compare to internal bandgap option, the LVD must be enabled
when entering stop3.
3.6.1.2 Active BDM Enabled in Stop Mode
Entry into the active background mode from run mode is enabled if ENBDM in BDCSCR is set. This
register is described in Chapter 17, “Development Support.” If ENBDM is set when the CPU executes a
STOP instruction, the system clocks to the background debug logic remain active when the MCU enters
stop mode. Because of this, background debug communication remains possible. In addition, the voltage
regulator does not enter its low-power standby state but maintains full internal regulation.
Table 3-1. Stop Mode Selection
STOPE ENBDM 1
1ENBDM is located in the BDCSCR, which is only accessible through BDC commands, see Section 17.4.1.1, “BDC Status and
Control Register (BDCSCR)”.
LVDE LVDSE PPDC Stop Mo d e
0 x x x Stop modes disabled; illegal opcode reset if STOP instruction executed
1 1 x x Stop3 with BDM enabled 2
2When in Stop3 mode with BDM enabled, The SIDD will be near RIDD levels because internal clocks are enabled.
1 0 Both bits must be 1 x Stop3 with voltage regulator active
1 0 Either bit a 0 0 Stop3
1 0 Either bit a 0 1 Stop2
Chapter 3 Modes of Operation
MC9S08SG8 MCU Series Data Sheet, Rev. 8
36 Freescale Semiconductor
Most background commands are not available in stop mode. The memory-access-with-status commands
do not allow memory access, but they report an error indicating that the MCU is in either stop or wait
mode. The BACKGROUND command can be used to wake the MCU from stop and enter active
background mode if the ENBDM bit is set. After entering background debug mode, all background
commands are available.
3.6.2 Stop2 Mode
Stop2 mode is entered by executing a STOP instruction under the conditions as shown in Table 3-1. Most
of the internal circuitry of the MCU is powered off in stop2 with the exception of the RAM. Upon entering
stop2, all I/O pin control signals are latched so that the pins retain their states during stop2.
Exit from stop2 is performed by asserting the wake-up pin (RESET) on the MCU.
In addition, the real-time counter (RTC) can wake the MCU from stop2, if enabled.
Upon wake-up from stop2 mode, the MCU starts up as from a power-on reset (POR):
• All module control and status registers are reset
• The LVD reset function is enabled and the MCU remains in the reset state if VDD is below the LVD
trip point (low trip point selected due to POR)
• The CPU takes the reset vector
In addition to the above, upon waking up from stop2, the PPDF bit in SPMSC2 is set. This flag is used to
direct user code to go to a stop2 recovery routine. PPDF remains set and the I/O pin states remain latched
until a 1 is written to PPDACK in SPMSC2.
To maintain I/O states for pins that were configured as general-purpose I/O before entering stop2, the user
must restore the contents of the I/O port registers, which have been saved in RAM, to the port registers
before writing to the PPDACK bit. If the port registers are not restored from RAM before writing to
PPDACK, then the pins will switch to their reset states when PPDACK is written.
For pins that were configured as peripheral I/O, the user must reconfigure the peripheral module that
interfaces to the pin before writing to the PPDACK bit. If the peripheral module is not enabled before
writing to PPDACK, the pins will be controlled by their associated port control registers when the I/O
latches are opened.
3.6.3 On-Chip Peripheral Modules in Stop Modes
When the MCU enters any stop mode, system clocks to the internal peripheral modules are stopped. Even
in the exception case (ENBDM = 1), where clocks to the background debug logic continue to operate,
clocks to the peripheral systems are halted to reduce power consumption. Refer to Section 3.6.2, “Stop2
Mode,” and Section 3.6.1, “Stop3 Mode,” for specific information on system behavior in stop modes.
Chapter 3 Modes of Operation
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 37
Table 3-2. Stop Mode Behavior
Peripheral
Mode
Stop2 Stop3
CPU Off Standby
RAM Standby Standby
FLASH Off Standby
Parallel Port Registers Off Standby
ADC Off Optionally On1
1Requires the asynchronous ADC clock and LVD to be enabled, else in
standby.
ACMP Off Optionally On2
2Requires the LVD to be enabled when compare to internal bandgap reference
option is enabled.
BDM Off3
3If ENBDM is set when entering stop2, the MCU will actually enter stop3.
Optionally On
ICS Off Optionally On4
4IRCLKEN and IREFSTEN set in ICSC1, else in standby.
IIC Off Standby
LVD/LV W O f f 5
5If LVDSE is set when entering stop2, the MCU will actually enter stop3.
Optionally On
MTIM Off Standby
RTC Optionally On Optionally On
SCI Off Standby
SPI Off Standby
TPM Off Standby
Voltage Regulator Standby Optionally On6
6Voltage regulator will be on if BDM is enabled or if LVD is enabled when
entering stop3.
XOSC Off Optionally On7
7ERCLKEN and EREFSTEN set in ICSC2, else in standby. For high frequency
range (RANGE in ICSC2 set) requires the LVD to also be enabled in stop3.
I/O Pins States Held States Held
Chapter 3 Modes of Operation
MC9S08SG8 MCU Series Data Sheet, Rev. 8
38 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 39
Chapter 4
Memory
4.1 MC9S08SG8 Memory Map
As shown in Figure 4-1, on-chip memory in the MC9S08SG8 series of MCUs consists of RAM, FLASH
program memory for nonvolatile data storage, and I/O and control/status registers. The registers are
divided into three groups:
• Direct-page registers (0x0000 through 0x007F)
• High-page registers (0x1800 through 0x185F)
• Nonvolatile registers (0xFFB0 through 0xFFBF)
Figure 4-1. MC9S08SG8 Memory Map
DIRECT PAGE REGISTERS
RAM
HIGH PAGE REGISTERS
512 BYTES
0x0000
0x007F
0x0080
0x027F
0x1800
0x17FF
0x185F
0xFFFF
0x0280
MC9S08SG8
FLASH
8192 BYTES
0x1860
MC9S08SG4
UNIMPLEMENTED
51,104 BYTES
0xE000
0xDFFF
DIRECT PAGE REGISTERS
RAM
HIGH PAGE REGISTERS
256 BYTES
0x0000
0x007F
0x0080
0x1800
0x17FF
0x185F
0xFFFF
FLASH
4096 BYTES
0x1860
0x017F
0x0180
0xF000
0xEFFF
UNIMPLEMENTED
5504 BYTES
0x027F
0x0280 UNIMPLEMENTED
5504 BYTES
RESERVED
256 BYTES
UNIMPLEMENTED
51,104 BYTES
0xE000
0xDFFF
RESERVED
4096 BYTES
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
40 Freescale Semiconductor
4.2 Reset and Interrupt Vector Assignments
Table 4-1 shows address assignments for reset and interrupt vectors. The vector names shown in this table
are the labels used in the Freescale Semiconductor provided equate file for the MC9S08SG8.
Table 4-1. Reset and Interrupt Vectors
Address
(High/Low) Vector Vector Name
0xFFC0:0xFFC1 Unused Vector Space (available for user program) —
0xFFC2:0xFFC3 ACMP Vacmp
0xFFC4:0xFFC5 Unused Vector Space (available for user program) —
0xFFC6:0xFFC7 Unused Vector Space (available for user program) —
0xFFC8:0xFFC9 Unused Vector Space (available for user program) —
0xFFCA:0xFFCB MTIM Overflow Vmtim
0xFFCC:0xFFCD RTC Vrtc
0xFFCE:0xFFCF IIC Viic
0xFFD0:0xFFD1 ADC Conversion Vadc
0xFFD2:0xFFD3 Unused Vector Space (available for user program) —
0xFFD4:0xFFD5 Port B Pin Interrupt Vportb
0xFFD6:0xFFD7 Port A Pin Interrupt Vporta
0xFFD8:0xFFD9 Unused Vector Space (available for user program) —
0xFFDA:0xFFDB SCI Transmit Vscitx
0xFFDC:0xFFDD SCI Receive Vscirx
0xFFDE:0xFFDF SCI Error Vscierr
0xFFE0:0xFFE1 SPI Vspi
0xFFE2:0xFFE3 TPM2 Overflow Vtpm2ovf
0xFFE4:0xFFE5 TPM2 Channel 1 Vtpm2ch1
0xFFE6:0xFFE7 TPM2 Channel 0 Vtpm2ch0
0xFFE8:0xFFE9 TPM1 Overflow Vtpm1ovf
0xFFEA:0xFFEB Unused Vector Space (available for user program) —
0xFFEC:0xFFED Unused Vector Space (available for user program) —
0xFFEE:0xFFEF Unused Vector Space (available for user program) —
0xFFF0:0xFFF1 Unused Vector Space (available for user program) —
0xFFF2:0xFFF3 TPM1 Channel 1 Vtpm1ch1
0xFFF4:0xFFF5 TPM1 Channel 0 Vtpm1ch0
0xFFF6:0xFFF7 Unused Vector Space (available for user program) —
0xFFF8:0xFFF9 Low Voltage Detect Vlvd
0xFFFA:0xFFFB Unused Vector Space (available for user program) —
0xFFFC:0xFFFD SWI Vswi
0xFFFE:0xFFFF Reset Vreset
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 41
4.3 Register Addresses and Bit Assignments
The registers in the MC9S08SG8 are divided into these groups:
• Direct-page registers are located in the first 128 locations in the memory map; these are accessible
with efficient direct addressing mode instructions.
• High-page registers are used much less often, so they are located above 0x1800 in the memory
map. This leaves more room in the direct page for more frequently used registers and RAM.
• The nonvolatile register area consists of a block of 16 locations in FLASH memory at
0xFFB0–0xFFBF. Nonvolatile register locations include:
— NVPROT and NVOPT are loaded into working registers at reset
— An 8-byte backdoor comparison key that optionally allows a user to gain controlled access to
secure memory
Because the nonvolatile register locations are FLASH memory, they must be erased and
programmed like other FLASH memory locations.
Direct-page registers can be accessed with efficient direct addressing mode instructions. Bit manipulation
instructions can be used to access any bit in any direct-page register. Table 4-2 is a summary of all
user-accessible direct-page registers and control bits.
The direct page registers in Table 4-2 can use the more efficient direct addressing mode, which requires
only the lower byte of the address. Because of this, the lower byte of the address in column one is shown
in bold text. In Table 4-3 and Table 4-4, the whole address in column one is shown in bold. In Table 4-2,
Table 4-3, and Table 4-4, the register names in column two are shown in bold to set them apart from the
bit names to the right. Cells that are not associated with named bits are shaded. A shaded cell with a 0
indicates this unused bit always reads as a 0. Shaded cells with dashes indicate unused or reserved bit
locations that could read as 1s or 0s.
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
42 Freescale Semiconductor
Table 4-2. Direct-Page Register Summary (Sheet 1 of 3)
Address Register
Name Bit 7654321Bit 0
0x0000 PTAD 0 0 — — PTAD3 PTAD2 PTAD1 PTAD0
0x0001 PTADD 0 0 — — PTADD3 PTADD2 PTADD1 PTADD0
0x0002 PTBD PTBD7 PTBD6 PTBD5 PTBD4 PTBD3 PTBD2 PTBD1 PTBD0
0x0003 PTBDD PTBDD7 PTBDD6 PTBDD5 PTBDD4 PTBDD3 PTBDD2 PTBDD1 PTBDD0
0x0004 PTCD 0000 PTCD3 PTCD2 PTCD1 PTCD0
0x0005 PTCDD 0000 PTCDD3 PTCDD2 PTCDD1 PTCDD0
0x0006–
0x000D Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x000E ACMPSC ACME ACBGS ACF ACIE ACO ACOPE ACMOD1 ACMOD0
0x000F Reserved ————————
0x0010 ADCSC1 COCO AIEN ADCO ADCH
0x0011 ADCSC2 ADACT ADTRG ACFE ACFGT ————
0x0012 ADCRH 000000 ADR9 ADR8
0x0013 ADCRL ADR7 ADR6 ADR5 ADR4 ADR3 ADR2 ADR1 ADR0
0x0014 ADCVH 000000 ADCV9 ADCV8
0x0015 ADCVL ADCV7 ADCV6 ADCV5 ADCV4 ADCV3 ADCV2 ADCV1 ADCV0
0x0016 ADCFG ADLPC ADIV ADLSMP MODE ADICLK
0x0017 APCTL1 ADPC7 ADPC6 ADPC5 ADPC4 ADPC3 ADPC2 ADPC1 ADPC0
0x0018 APCTL2 0000 ADPC11 ADPC10 ADPC9 ADPC8
0x0019–
0x001B Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x001C MTIMSC TOF TOIE TRST TSTP 0 0 0 0
0x001D MTIMCLK 00CLKS PS
0x001E MTIMCNT CNT
0x001F MTIMMOD MOD
0x0020 TPM1SC TOF TOIE CPWMS CLKSB CLKSA PS2 PS1 PS0
0x0021 TPM1CNTH Bit 15 14 13 12 11 10 9 Bit 8
0x0022 TPM1CNTL Bit 7654321Bit 0
0x0023 TPM1MODH Bit 15 14 13 12 11 10 9 Bit 8
0x0024 TPM1MODL Bit 7654321Bit 0
0x0025 TPM1C0SC CH0F CH0IE MS0B MS0A ELS0B ELS0A 0 0
0x0026 TPM1C0VH Bit 15 14 13 12 11 10 9 Bit 8
0x0027 TPM1C0VL Bit 7654321Bit 0
0x0028 TPM1C1SC CH1F CH1IE MS1B MS1A ELS1B ELS1A 0 0
0x0029 TPM1C1VH Bit 15 14 13 12 11 10 9 Bit 8
0x002A TPM1C1VL Bit 7654321Bit 0
0x002B–
0x0037 Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x0038 SCIBDH LBKDIE RXEDGIE 0 SBR12 SBR11 SBR10 SBR9 SBR8
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 43
0x0039 SCIBDL SBR7 SBR6 SBR5 SBR4 SBR3 SBR2 SBR1 SBR0
0x003A SCIC1 LOOPS SCISWAI RSRC M WAKE ILT PE PT
0x003B SCIC2 TIE TCIE RIE ILIE TE RE RWU SBK
0x003C SCIS1 TDRE TC RDRF IDLE OR NF FE PF
0x003D SCIS2 LBKDIF RXEDGIF 0 RXINV RWUID BRK13 LBKDE RAF
0x003E SCIC3 R8 T8 TXDIR TXINV ORIE NEIE FEIE PEIE
0x003F SCID Bit 7654321Bit 0
0x0040–
0x0047 Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x0048 ICSC1 CLKS RDIV IREFS IRCLKEN IREFSTEN
0x0049 ICSC2 BDIV RANGE HGO LP EREFS ERCLKEN EREFSTEN
0x004A ICSTRM TRIM
0x004B ICSSC 000 IREFST CLKST OSCINIT FTRIM
0x004C–
0x004F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x0050 SPIC1 SPIE SPE SPTIE MSTR CPOL CPHA SSOE LSBFE
0x0051 SPIC2 000 MODFEN BIDIROE 0 SPISWAI SPC0
0x0052 SPIBR 0 SPPR2 SPPR1 SPPR0 0 SPR2 SPR1 SPR0
0x0053 SPIS SPRF 0 SPTEF MODF 0 0 0 0
0x0054 Reserved 00000000
0x0055 SPID Bit 7654321Bit 0
0x0056–
0x0057 Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x0058 IICA AD7 AD6 AD5 AD4 AD3 AD2 AD1 0
0x0059 IICF MULT ICR
0x005A IICC1 IICEN IICIE MST TX TXAK RSTA 0 0
0x005B IICS TCF IAAS BUSY ARBL 0 SRW IICIF RXAK
0x005C IICD DATA
0x005D IICC2 GCAEN ADEXT 0 0 0 AD10 AD9 AD8
0x005E–
0x005F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x0060 TPM2SC TOF TOIE CPWMS CLKSB CLKSA PS2 PS1 PS0
0x0061 TPM2CNTH Bit 15 14 13 12 11 10 9 Bit 8
0x0062 TPM2CNTL Bit 7654321Bit 0
0x0063 TPM2MODH Bit 15 14 13 12 11 10 9 Bit 8
0x0064 TPM2MODL Bit 7654321Bit 0
0x0065 TPM2C0SC CH0F CH0IE MS0B MS0A ELS0B ELS0A 0 0
0x0066 TPM2C0VH Bit 15 14 13 12 11 10 9 Bit 8
0x0067 TPM2C0VL Bit 7654321Bit 0
0x0068 TPM2C1SC CH1F CH1IE MS1B MS1A ELS1B ELS1A 0 0
Table 4-2. Direct-Page Register Summary (Sheet 2 of 3)
Address Register
Name Bit 7654321Bit 0
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
44 Freescale Semiconductor
0x0069 TPM2C1VH Bit 15 14 13 12 11 10 9 Bit 8
0x006A TPM2C1VL Bit 7654321Bit 0
0x006B Reserved ————————
0x006C RTCSC RTIF RTCLKS RTIE RTCPS
0x006D RTCCNT RTCCNT
0x006E RTCMOD RTCMOD
0x006F -
0x007F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Table 4-2. Direct-Page Register Summary (Sheet 3 of 3)
Address Register
Name Bit 7654321Bit 0
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 45
High-page registers, shown in Table 4-3, are accessed much less often than other I/O and control registers
so they have been located outside the direct addressable memory space, starting at 0x1800.
Table 4-3. High-Page Register Summary (Sheet 1 of 2)
AddressRegister NameBit 7654321Bit 0
0x1800 SRS POR PIN COP ILOP ILAD 0LVD0
0x1801 SBDFR 0000000BDFR
0x1802 SOPT1 COPT STOPE 00 IICPS 0 0
0x1803 SOPT2 COPCLKS COPW 0ACIC0 0 T1CH1PS T1CH0PS
0x1804 –
0x1805 Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x1806 SDIDH 1 ——— ID11 ID10 ID9 ID8
0x1807 SDIDL ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0
0x1808 Reserved ————————
0x1809 SPMSC1 LVWF LV WAC K LVWIE LVDR E LVDSE LVDE 0BGBE
0x180A SPMSC2 0 0 LVDV LVWV PPDF PPDACK — PPDC
0x180B–
0x180F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x1810 DBGCAH Bit 15 14 13 12 11 10 9 Bit 8
0x1811 DBGCAL Bit 7654321Bit 0
0x1812 DBGCBH Bit 15 14 13 12 11 10 9 Bit 8
0x1813 DBGCBL Bit 7654321Bit 0
0x1814 DBGFH Bit 15 14 13 12 11 10 9 Bit 8
0x1815 DBGFL Bit 7654321Bit 0
0x1816 DBGC DBGEN ARM TAG BRKEN RWA RWAEN RWB RWBEN
0x1817 DBGT TRGSEL BEGIN 00 TRG3 TRG2 TRG1 TRG0
0x1818 DBGS AF BF ARMF 0 CNT3 CNT2 CNT1 CNT0
0x1819–
0x181F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x1820 FCDIV DIVLD PRDIV8 DIV
0x1821 FOPT KEYEN FNORED 0000 SEC
0x1822 Reserved ————————
0x1823 FCNFG 00 KEYACC 00000
0x1824 FPROT FPS FPDIS
0x1825 FSTAT FCBEF FCCF FPVIOL FACCERR 0 FBLANK 0 0
0x1826 FCMD FCMD
0x1827–
0x183F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0x1840 PTAPE 0 0 — — PTAPE3 PTAPE2 PTAPE1 PTAPE0
0x1841 PTASE 0 0 — — PTASE3 PTASE2 PTASE1 PTASE0
0x1842 PTADS 0 0 — — PTA D S 3 PTA D S 2 P TA D S 1 P TA D S 0
0x1843 Reserved ————————
0x1844 PTASC 0000 PTAIF PTAACK PTAIE PTAMOD
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
46 Freescale Semiconductor
0x1845 PTAPS 0000 PTAPS3 PTAPS2 PTAPS1 PTAPS0
0x1846 PTAES 0000 PTAES3 PTAES2 PTAES1 PTAES0
0x1847 Reserved ————————
0x1848 PTBPE PTBPE7 PTBPE6 PTBPE5 PTBPE4 PTBPE3 PTBPE2 PTBPE1 PTBPE0
0x1849 PTBSE PTBSE7 PTBSE6 PTBSE5 PTBSE4 PTBSE3 PTBSE2 PTBSE1 PTBSE0
0x184A PTBDS PTBDS7 PTBDS6 PTBDS5 PTBDS4 PTBDS3 PTBDS2 PTBDS1 PTBDS0
0x184B Reserved ————————
0x184C PTBSC 0000 PTBIF PTBACK PTBIE PTBMOD
0x184D PTBPS 0000 PTBPS3 PTBPS2 PTBPS1 PTBPS0
0x184E PTBES 0000 PTBES3 PTBES2 PTBES1 PTBES0
0x184F Reserved ————————
0x1850 PTCPE 0000 PTCPE3 PTCPE2 PTCPE1 PTCPE0
0x1851 PTCSE 0000 PTCSE3 PTCSE2 PTCSE1 PTCSE0
0x1852 PTCDS 0000 PTCDS3 PTCDS2 PTCDS1 PTCDS0
0x1853 GNGC GNGPS7 GNGPS6 GNGPS5 GNGPS4 GNGPS3 GNGPS2 GNGPS1 GNGEN
0x1854–
0x185F Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Table 4-3. High-Page Register Summary (Sheet 2 of 2)
AddressRegister NameBit 7654321Bit 0
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 47
Nonvolatile FLASH registers, shown in Table 4-4, are located in the FLASH memory. These registers
include an 8-byte backdoor key, NVBACKKEY, which can be used to gain access to secure memory
resources. During reset events, the contents of NVPROT and NVOPT in the nonvolatile register area of
the FLASH memory are transferred into corresponding FPROT and FOPT working registers in the
high-page registers to control security and block protection options.
Provided the key enable (KEYEN) bit is 1, the 8-byte comparison key can be used to temporarily
disengage memory security. This key mechanism can be accessed only through user code running in secure
memory. (A security key cannot be entered directly through background debug commands.) This security
key can be disabled completely by programming the KEYEN bit to 0. If the security key is disabled, the
only way to disengage security is by mass erasing the FLASH if needed (normally through the background
debug interface) and verifying that FLASH is blank. To avoid returning to secure mode after the next reset,
program the security bits (SEC) to the unsecured state (1:0).
Table 4-4. Nonvolatile Register Summary
AddressRegister NameBit 7654321Bit 0
0xFFAE Reserved for
storage of FTRIM ———————FTRIM
0xFFAF Reserved for
storage of ICSTRM TRIM
0xFFB0 –
0xFFB7
NVBACKKEY 8-Byte Comparison Key
0xFFB8 –
0xFFBC
Reserved —
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0xFFBD NVPROT FPS FPDIS
0xFFBE Reserved ————————
0xFFBF NVOPT KEYEN FNORED ———— SEC
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
48 Freescale Semiconductor
4.4 RAM
The MC9S08SG8 includes static RAM. The locations in RAM below 0x0100 can be accessed using the
more efficient direct addressing mode, and any single bit in this area can be accessed with the bit
manipulation instructions (BCLR, BSET, BRCLR, and BRSET). Locating the most frequently accessed
program variables in this area of RAM is preferred.
The RAM retains data when the MCU is in low-power wait, stop2, or stop3 mode. At power-on the
contents of RAM are uninitialized. RAM data is unaffected by any reset provided that the supply voltage
does not drop below the minimum value for RAM retention (VRAM).
For compatibility with M68HC05 MCUs, the HCS08 resets the stack pointer to 0x00FF. In the
MC9S08SG8, it is usually best to reinitialize the stack pointer to the top of the RAM so the direct page
RAM can be used for frequently accessed RAM variables and bit-addressable program variables. Include
the following 2-instruction sequence in your reset initialization routine (where RamLast is equated to the
highest address of the RAM in the Freescale Semiconductor-provided equate file).
LDHX #RamLast+1 ;point one past RAM
TXS ;SP<-(H:X-1)
When security is enabled, the RAM is considered a secure memory resource and is not accessible through
BDM or through code executing from non-secure memory. See Section 4.6, “Security”, for a detailed
description of the security feature.
4.5 FLASH
The FLASH memory is intended primarily for program storage. In-circuit programming allows the
operating program to be loaded into the FLASH memory after final assembly of the application product.
It is possible to program the entire array through the single-wire background debug interface. Because no
special voltages are needed for FLASH erase and programming operations, in-application programming
is also possible through other software-controlled communication paths. For a more detailed discussion of
in-circuit and in-application programming, refer to the HCS08 Family Reference Manual, Volume I,
Freescale Semiconductor document order number HCS08RMv1/D.
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 49
4.5.1 Features
Features of the FLASH memory include:
•FLASH size
— MC9S08SG8: 8,192 bytes (16 pages of 512 bytes each)
— MC9S08SG4: 4,096 bytes (8 pages of 512 bytes each)
• Single power supply program and erase
• Command interface for fast program and erase operation
• Up to 100,000 program/erase cycles at typical voltage and temperature
• Flexible block protection
• Security feature for FLASH and RAM
• Auto power-down for low-frequency read accesses
4.5.2 Program and Erase Times
Before any program or erase command can be accepted, the FLASH clock divider register (FCDIV) must
be written to set the internal clock for the FLASH module to a frequency (fFCLK) between 150 kHz and
200 kHz (see Section 4.7.1, “FLASH Clock Divider Register (FCDIV)”). This register can be written only
once, so normally this write is done during reset initialization. FCDIV cannot be written if the access error
flag, FACCERR in FSTAT, is set. The user must ensure that FACCERR is not set before writing to the
FCDIV register. One period of the resulting clock (1/fFCLK) is used by the command processor to time
program and erase pulses. An integer number of these timing pulses are used by the command processor
to complete a program or erase command.
Table 4-5 shows program and erase times. The bus clock frequency and FCDIV determine the frequency
of FCLK (fFCLK). The time for one cycle of FCLK is tFCLK = 1/fFCLK. The times are shown as a number
of cycles of FCLK and as an absolute time for the case where tFCLK = 5 s. Program and erase times
shown include overhead for the command state machine and enabling and disabling of program and erase
voltages.
Table 4-5. Program and Erase Times
Parameter Cycles of FCLK Time if FCLK = 200 kHz
Byte program 9 45 s
Byte program (burst) 4 20 s1
1Excluding start/end overhead
Page erase 4000 20 ms
Mass erase 20,000 100 ms
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
50 Freescale Semiconductor
4.5.3 Program and Erase Command Execution
The steps for executing any of the commands are listed below. The FCDIV register must be initialized and
any error flags cleared before beginning command execution. The command execution steps are:
1. Write a data value to an address in the FLASH array. The address and data information from this
write is latched into the FLASH interface. This write is a required first step in any command
sequence. For erase and blank check commands, the value of the data is not important. For page
erase commands, the address may be any address in the 512-byte page of FLASH to be erased. For
mass erase and blank check commands, the address can be any address in the FLASH memory.
Whole pages of 512 bytes are the smallest block of FLASH that may be erased.
NOTE
Do not program any byte in the FLASH more than once after a successful
erase operation. Reprogramming bits to a byte that is already programmed
is not allowed without first erasing the page in which the byte resides or
mass erasing the entire FLASH memory. Programming without first erasing
may disturb data stored in the FLASH.
2. Write the command code for the desired command to FCMD. The five valid commands are blank
check (0x05), byte program (0x20), burst program (0x25), page erase (0x40), and mass erase
(0x41). The command code is latched into the command buffer.
3. Write a 1 to the FCBEF bit in FSTAT to clear FCBEF and launch the command (including its
address and data information).
A partial command sequence can be aborted manually by writing a 0 to FCBEF any time after the write to
the memory array and before writing the 1 that clears FCBEF and launches the complete command.
Aborting a command in this way sets the FACCERR access error flag, which must be cleared before
starting a new command.
A strictly monitored procedure must be obeyed or the command will not be accepted. This minimizes the
possibility of any unintended changes to the FLASH memory contents. The command complete flag
(FCCF) indicates when a command is complete. The command sequence must be completed by clearing
FCBEF to launch the command. Figure 4-2 is a flowchart for executing all of the commands except for
burst programming. The FCDIV register must be initialized before using any FLASH commands. This
must be done only once following a reset.
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 51
Figure 4-2. FLASH Program and Erase Flowchart
4.5.4 Burst Program Execution
The burst program command is used to program sequential bytes of data in less time than would be
required using the standard program command. This is possible because the high voltage to the FLASH
array does not need to be disabled between program operations. Ordinarily, when a program or erase
command is issued, an internal charge pump associated with the FLASH memory must be enabled to
supply high voltage to the array. Upon completion of the command, the charge pump is turned off. When
a burst program command is issued, the charge pump is enabled and then remains enabled after completion
of the burst program operation if these two conditions are met:
• The next burst program command has been queued before the current program operation has
completed.
• The next sequential address selects a byte on the same physical row as the current byte being
programmed. A row of FLASH memory consists of 64 bytes. A byte within a row is selected by
addresses A5 through A0. A new row begins when addresses A5 through A0 are all zero.
START
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND TO FCMD
NO
YES
FPVIOL OR
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (Note 2)
1
0FCCF ?
ERROR EXIT
DONE
Note 2: Wait at least four bus cycles
0
FACCERR ?
CLEAR ERROR
FACCERR ?
WRITE TO FCDIV (Note 1) Note 1: Required only once after reset.
1
before checking FCBEF or FCCF.
FLASH PROGRAM AND
ERASE FLOW
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
52 Freescale Semiconductor
The first byte of a series of sequential bytes being programmed in burst mode will take the same amount
of time to program as a byte programmed in standard mode. Subsequent bytes will program in the burst
program time provided that the conditions above are met. In the case the next sequential address is the
beginning of a new row, the program time for that byte will be the standard time instead of the burst time.
This is because the high voltage to the array must be disabled and then enabled again. If a new burst
command has not been queued before the current command completes, then the charge pump will be
disabled and high voltage removed from the array.
Figure 4-3. FLASH Burst Program Flowchart
1
0
FCBEF ?
START
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND (0x25) TO FCMD
NO
YES
FPVIO OR
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (Note 2)
NO
YES NEW BURST COMMAND ?
1
0FCCF ?
ERROR EXIT
DONE
Note 2: Wait at least four bus cycles before
1
0
FACCERR ?
CLEAR ERROR
FACCERR ?
Note 1: Required only once after reset.
WRITE TO FCDIV (Note 1)
checking FCBEF or FCCF.
FLASH BURST
PROGRAM FLOW
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 53
4.5.5 Access Errors
An access error occurs whenever the command execution protocol is violated.
Any of the following specific actions will cause the access error flag (FACCERR) in FSTAT to be set.
FACCERR must be cleared by writing a 1 to FACCERR in FSTAT before any command can be processed.
• Writing to a FLASH address before the internal FLASH clock frequency has been set by writing
to the FCDIV register
• Writing to a FLASH address while FCBEF is not set (A new command cannot be started until the
command buffer is empty.)
• Writing a second time to a FLASH address before launching the previous command (There is only
one write to FLASH for every command.)
• Writing a second time to FCMD before launching the previous command (There is only one write
to FCMD for every command.)
• Writing to any FLASH control register other than FCMD after writing to a FLASH address
• Writing any command code other than the five allowed codes (0x05, 0x20, 0x25, 0x40, or 0x41)
to FCMD
• Writing any FLASH control register other than the write to FSTAT (to clear FCBEF and launch the
command) after writing the command to FCMD
• The MCU enters stop mode while a program or erase command is in progress (The command is
aborted.)
• Writing the byte program, burst program, or page erase command code (0x20, 0x25, or 0x40) with
a background debug command while the MCU is secured (The background debug controller can
only do blank check and mass erase commands when the MCU is secure.)
• Writing 0 to FCBEF to cancel a partial command
4.5.6 FLASH Block Protection
The block protection feature prevents the protected region of FLASH from program or erase changes.
Block protection is controlled through the FLASH protection register (FPROT). When enabled, block
protection begins at any 512 byte boundary below the last address of FLASH, 0xFFFF. (See Section 4.7.4,
“FLASH Protection Register (FPROT and NVPROT)”).
After exit from reset, FPROT is loaded with the contents of the NVPROT location, which is in the
nonvolatile register block of the FLASH memory. FPROT cannot be changed directly from application
software so a runaway program cannot alter the block protection settings. Because NVPROT is within the
last 512 bytes of FLASH, if any amount of memory is protected, NVPROT is itself protected and cannot
be altered (intentionally or unintentionally) by the application software. FPROT can be written through
background debug commands, which allows a way to erase and reprogram a protected FLASH memory.
The block protection mechanism is illustrated in Figure 4-4. The FPS bits are used as the upper bits of the
last address of unprotected memory. This address is formed by concatenating FPS7:FPS1 with logic 1 bits
as shown. For example, to protect the last 1536 bytes of memory (addresses 0xFA00 through 0xFFFF), the
FPS bits must be set to 1111 100, which results in the value 0xF9FF as the last address of unprotected
memory. In addition to programming the FPS bits to the appropriate value, FPDIS (bit 0 of NVPROT)
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
54 Freescale Semiconductor
must be programmed to logic 0 to enable block protection. Therefore the value 0xF8 must be programmed
into NVPROT to protect addresses 0xFA00 through 0xFFFF.
Figure 4-4. Block Protection Mechanism
One use for block protection is to block protect an area of FLASH memory for a bootloader program. This
bootloader program then can be used to erase the rest of the FLASH memory and reprogram it. Because
the bootloader is protected, it remains intact even if MCU power is lost in the middle of an erase and
reprogram operation.
4.5.7 Vector Redirection
Whenever any block protection is enabled, the reset and interrupt vectors will be protected. Vector
redirection allows users to modify interrupt vector information without unprotecting bootloader and reset
vector space. Vector redirection is enabled by programming the FNORED bit in the NVOPT register
located at address 0xFFBF to zero. For redirection to occur, at least some portion but not all of the FLASH
memory must be block protected by programming the NVPROT register located at address 0xFFBD. All
of the interrupt vectors (memory locations 0xFFC0–0xFFFD) are redirected, though the reset vector
(0xFFFE:FFFF) is not.
For example, if 512 bytes of FLASH are protected, the protected address region is from 0xFE00 through
0xFFFF. The interrupt vectors (0xFFC0–0xFFFD) are redirected to the locations 0xFDC0–0xFDFD. Now,
if an SPI interrupt is taken for instance, the values in the locations 0xFDE0:FDE1 are used for the vector
instead of the values in the locations 0xFFE0:FFE1. This allows the user to reprogram the unprotected
portion of the FLASH with new program code including new interrupt vector values while leaving the
protected area, which includes the default vector locations, unchanged.
4.6 Security
The MC9S08SG8 includes circuitry to prevent unauthorized access to the contents of FLASH and RAM
memory. When security is engaged, FLASH and RAM are considered secure resources. Direct-page
registers, high-page registers, and the background debug controller are considered unsecured resources.
Programs executing within secure memory have normal access to any MCU memory locations and
resources. Attempts to access a secure memory location with a program executing from an unsecured
memory space or through the background debug interface are blocked (writes are ignored and reads return
all 0s).
Security is engaged or disengaged based on the state of two nonvolatile register bits (SEC01:SEC00) in
the FOPT register. During reset, the contents of the nonvolatile location NVOPT are copied from FLASH
into the working FOPT register in high-page register space. A user engages security by programming the
NVOPT location which can be done at the same time the FLASH memory is programmed. The 1:0 state
disengages security and the other three combinations engage security. Notice the erased state (1:1) makes
FPS7 FPS6 FPS5 FPS4 FPS3 FPS2 FPS1
A15 A14 A13 A12 A11 A10 A9 A8
1
A7 A6 A5 A4 A3 A2 A1 A0
11111111
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 55
the MCU secure. During development, whenever the FLASH is erased, it is good practice to immediately
program the SEC00 bit to 0 in NVOPT so SEC01:SEC00 = 1:0. This would allow the MCU to remain
unsecured after a subsequent reset.
The on-chip debug module cannot be enabled while the MCU is secure. The separate background debug
controller can still be used for background memory access commands of unsecured resources.
A user can choose to allow or disallow a security unlocking mechanism through an 8-byte backdoor
security key. If the nonvolatile KEYEN bit in NVOPT/FOPT is 0, the backdoor key is disabled and there
is no way to disengage security without completely erasing all FLASH locations. If KEYEN is 1, a secure
user program can temporarily disengage security by:
1. Writing 1 to KEYACC in the FCNFG register. This makes the FLASH module interpret writes to
the backdoor comparison key locations (NVBACKKEY through NVBACKKEY+7) as values to
be compared against the key rather than as the first step in a FLASH program or erase command.
2. Writing the user-entered key values to the NVBACKKEY through NVBACKKEY+7 locations.
These writes must be done in order starting with the value for NVBACKKEY and ending with
NVBACKKEY+7. STHX should not be used for these writes because these writes cannot be done
on adjacent bus cycles. User software normally would get the key codes from outside the MCU
system through a communication interface such as a serial I/O.
3. Writing 0 to KEYACC in the FCNFG register. If the 8-byte key that was just written matches the
key stored in the FLASH locations, SEC01:SEC00 are automatically changed to 1:0 and security
will be disengaged until the next reset.
The security key can be written only from secure memory (either RAM or FLASH), so it cannot be entered
through background commands without the cooperation of a secure user program.
The backdoor comparison key (NVBACKKEY through NVBACKKEY+7) is located in FLASH memory
locations in the nonvolatile register space so users can program these locations exactly as they would
program any other FLASH memory location. The nonvolatile registers are in the same 512-byte block of
FLASH as the reset and interrupt vectors, so block protecting that space also block protects the backdoor
comparison key. Block protects cannot be changed from user application programs, so if the vector space
is block protected, the backdoor security key mechanism cannot permanently change the block protect,
security settings, or the backdoor key.
Security can always be disengaged through the background debug interface by taking these steps:
1. Disable any block protections by writing FPROT. FPROT can be written only with background
debug commands, not from application software.
2. Mass erase FLASH if necessary.
3. Blank check FLASH. Provided FLASH is completely erased, security is disengaged until the next
reset.
To avoid returning to secure mode after the next reset, program NVOPT so SEC01:SEC00 = 1:0.
4.7 FLASH Registers and Control Bits
The FLASH module has nine 8-bit registers in the high-page register space, two locations (NVOPT,
NVPROT) in the nonvolatile register space in FLASH memory are copied into corresponding high-page
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
56 Freescale Semiconductor
control registers (FOPT, FPROT) at reset. There is also an 8-byte comparison key in FLASH memory.
Refer to Table 4-3 and Table 4-4 for the absolute address assignments for all FLASH registers. This
section refers to registers and control bits only by their names. A Freescale Semiconductor-provided
equate or header file normally is used to translate these names into the appropriate absolute addresses.
4.7.1 FLASH Clock Divider Register (FCDIV)
Bit 7 of this register is a read-only flag. Bits 6:0 may be read at any time but can be written only one time.
Before any erase or programming operations are possible, write to this register to set the frequency of the
clock for the nonvolatile memory system within acceptable limits.
if PRDIV8 = 0 — fFCLK = fBus (DIV + 1) Eqn. 4-1
if PRDIV8 = 1 — fFCLK = fBus (8 (DIV + 1)) Eqn. 4-2
Table 4-7 shows the appropriate values for PRDIV8 and DIV for selected bus frequencies.
76543210
RDIVLD
PRDIV8 DIV
W
Reset00000000
= Unimplemented or Reserved
Figure 4-5. FLASH Clock Divider Register (FCDIV)
Table 4-6. FCDIV Register Field Descriptions
Field Description
7
DIVLD
Divisor Loaded Status Flag — When set, this read-only status flag indicates that the FCDIV register has been
written since reset. Reset clears this bit and the first write to this register causes this bit to become set regardless
of the data written.
0 FCDIV has not been written since reset; erase and program operations disabled for FLASH.
1 FCDIV has been written since reset; erase and program operations enabled for FLASH.
6
PRDIV8
Prescale (Divide) FLASH Clock by 8
0 Clock input to the FLASH clock divider is the bus rate clock.
1 Clock input to the FLASH clock divider is the bus rate clock divided by 8.
5:0
DIV
Divisor for FLASH Clock Divider — The FLASH clock divider divides the bus rate clock (or the bus rate clock
divided by 8 if PRDIV8 = 1) by the value in the 6-bit DIV field plus one. The resulting frequency of the internal
FLASH clock must fall within the range of 200 kHz to 150 kHz for proper FLASH operations. Program/Erase
timing pulses are one cycle of this internal FLASH clock which corresponds to a range of 5 s to 6.7 s. The
automated programming logic uses an integer number of these pulses to complete an erase or program
operation. See Equation 4-1 and Equation 4-2.
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 57
4.7.2 FLASH Options Register (FOPT and NVOPT)
During reset, the contents of the nonvolatile location NVOPT are copied from FLASH into FOPT. To
change the value in this register, erase and reprogram the NVOPT location in FLASH memory as usual
and then issue a new MCU reset.
Table 4-7. FLASH Clock Divider Settings
fBus
PRDIV8
(Binary)
DIV
(Decimal) fFCLK
Program/Erase Timing Pulse
(5 s Min, 6.7s Max)
20 MHz 1 12 192.3 kHz 5.2 s
10 MHz 0 49 200 kHz 5 s
8 MHz 0 39 200 kHz 5 s
4 MHz 0 19 200 kHz 5 s
2 MHz 0 9 200 kHz 5 s
1 MHz 0 4 200 kHz 5 s
200 kHz 0 0 200 kHz 5 s
150 kHz 0 0 150 kHz 6.7 s
76543210
R KEYEN FNORED — — — — SEC01 SEC00
W
Reset This register is loaded from nonvolatile location NVOPT during reset.
= Unimplemented or Reserved
Figure 4-6. FLASH Options Register (FOPT)
Table 4-8. FOPT Register Field Descriptions
Field Description
7
KEYEN
Backdoor Key Mechanism Enable — When this bit is 0, the backdoor key mechanism cannot be used to
disengage security. The backdoor key mechanism is accessible only from user (secured) firmware. BDM
commands cannot be used to write key comparison values that would unlock the backdoor key. For more detailed
information about the backdoor key mechanism, refer to Section 4.6, “Security.”
0 No backdoor key access allowed.
1 If user firmware writes an 8-byte value that matches the nonvolatile backdoor key (NVBACKKEY through
NVBACKKEY+7 in that order), security is temporarily disengaged until the next MCU reset.
6
FNORED
Vector Redirection Disable — When this bit is 1, then vector redirection is disabled.
0 Vector redirection enabled.
1 Vector redirection disabled.
1:0
SEC0[1:0]
Security State Code — This 2-bit field determines the security state of the MCU as shown in Table 4-9. When
the MCU is secure, the contents of RAM and FLASH memory cannot be accessed by instructions from any
unsecured source including the background debug interface. SEC01:SEC00 changes to 1:0 after successful
backdoor key entry or a successful blank check of FLASH.
For more detailed information about security, refer to Section 4.6, “Security.”
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
58 Freescale Semiconductor
4.7.3 FLASH Configuration Register (FCNFG)
4.7.4 FLASH Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT is copied from FLASH into FPROT. This
register can be read at any time, but user program writes have no meaning or effect.
Figure 4-8. FLASH Protection Register (FPROT)
Table 4-9. Security States1
1SEC01:SEC00 changes to 1:0 after successful backdoor
key entry or a successful blank check of FLASH.
SEC01:SEC00 Description
0:0 secure
0:1 secure
1:0 unsecured
1:1 secure
76543210
R0 0
KEYACC
00000
W
Reset00000000
= Unimplemented or Reserved
Figure 4-7. FLASH Configuration Register (FCNFG)
Table 4-10. FCNFG Register Field Descriptions
Field Description
5
KEYACC
Enable Writing of Access Key — This bit enables writing of the backdoor comparison key. For more detailed
information about the backdoor key mechanism, refer to Section 4.6, “Security.”
0 Writes to 0xFFB0–0xFFB7 are interpreted as the start of a FLASH programming or erase command.
1 Writes to NVBACKKEY (0xFFB0–0xFFB7) are interpreted as comparison key writes.
76543210
R
FPS(1)
1Background commands can be used to change the contents of these bits in FPROT.
FPDIS(1)
W
Reset This register is loaded from nonvolatile location NVPROT during reset.
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 59
4.7.5 FLASH Status Register (FSTAT)
Table 4-11. FPROT Register Field Descriptions
Field Description
7:1
FPS
FLASH Protect Select Bits — When FPDIS = 0, this 7-bit field determines the ending address of unprotected
FLASH locations at the high address end of the FLASH. Protected FLASH locations cannot be erased or
programmed.
0
FPDIS
FLASH Protection Disable
0 FLASH block specified by FPS7:FPS1 is block protected (program and erase not allowed).
1 No FLASH block is protected.
76543210
R
FCBEF
FCCF
FPVIOL FACCERR
0FBLANK0 0
W
Reset11000000
= Unimplemented or Reserved
Figure 4-9. FLASH Status Register (FSTAT)
Table 4-12. FSTAT Register Field Descriptions
Field Description
7
FCBEF
FLASH Command Buffer Empty Flag — The FCBEF bit is used to launch commands. It also indicates that the
command buffer is empty so that a new command sequence can be executed when performing burst
programming. The FCBEF bit is cleared by writing a 1 to it or when a burst program command is transferred to
the array for programming. Only burst program commands can be buffered.
0 Command buffer is full (not ready for additional commands).
1 A new burst program command can be written to the command buffer.
6
FCCF
FLASH Command Complete Flag — FCCF is set automatically when the command buffer is empty and no
command is being processed. FCCF is cleared automatically when a new command is started (by writing 1 to
FCBEF to register a command). Writing to FCCF has no meaning or effect.
0 Command in progress
1 All commands complete
5
FPVIOL
Protection Violation Flag — FPVIOL is set automatically when a command is written that attempts to erase or
program a location in a protected block (the erroneous command is ignored). FPVIOL is cleared by writing a 1 to
FPVIOL.
0 No protection violation.
1 An attempt was made to erase or program a protected location.
Chapter 4 Memory
MC9S08SG8 MCU Series Data Sheet, Rev. 8
60 Freescale Semiconductor
4.7.6 FLASH Command Register (FCMD)
Only five command codes are recognized in normal user modes as shown in Table 4-13. Refer to Section
4.5.3, “Program and Erase Command Execution,” for a detailed discussion of FLASH programming and
erase operations.
All other command codes are illegal and generate an access error.
It is not necessary to perform a blank check command after a mass erase operation. Only blank check is
required as part of the security unlocking mechanism.
4
FACCERR
Access Error Flag — FACCERR is set automatically when the proper command sequence is not obeyed exactly
(the erroneous command is ignored), if a program or erase operation is attempted before the FCDIV register has
been initialized, or if the MCU enters stop while a command was in progress. For a more detailed discussion of
the exact actions that are considered access errors, see Section 4.5.5, “Access Errors.” FACCERR is cleared by
writing a 1 to FACCERR. Writing a 0 to FACCERR has no meaning or effect.
0 No access error.
1 An access error has occurred.
2
FBLANK
FLASH Verified as All Blank (erased) Flag — FBLANK is set automatically at the conclusion of a blank check
command if the entire FLASH array was verified to be erased. FBLANK is cleared by clearing FCBEF to write a
new valid command. Writing to FBLANK has no meaning or effect.
0 After a blank check command is completed and FCCF = 1, FBLANK = 0 indicates the FLASH array is not
completely erased.
1 After a blank check command is completed and FCCF = 1, FBLANK = 1 indicates the FLASH array is
completely erased (all 0xFF).
76543210
R00000000
WFCMD
Reset00000000
Figure 4-10. FLASH Command Register (FCMD)
Table 4-13. FLASH Commands
Command FCMD Equate File Label
Blank check 0x05 mBlank
Byte program 0x20 mByteProg
Byte program — burst mode 0x25 mBurstProg
Page erase (512 bytes/page) 0x40 mPageErase
Mass erase (all FLASH) 0x41 mMassErase
Table 4-12. FSTAT Register Field Descriptions (continued)
Field Description
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 61
Chapter 5
Resets, Interrupts, and General System Control
5.1 Introduction
This section discusses basic reset and interrupt mechanisms and the various sources of reset and interrupt
in the MC9S08SG8. Some interrupt sources from peripheral modules are discussed in greater detail within
other sections of this data sheet. This section gathers basic information about all reset and interrupt sources
in one place for easy reference. A few reset and interrupt sources, including the computer operating
properly (COP) watchdog are not part of on-chip peripheral systems with their own chapters.
5.2 Features
Reset and interrupt features include:
• Multiple sources of reset for flexible system configuration and reliable operation
• Reset status register (SRS) to indicate source of most recent reset
• Separate interrupt vector for each module (reduces polling overhead) (see Table 5-2)
5.3 MCU Reset
Resetting the MCU provides a way to start processing from a known set of initial conditions. During reset,
most control and status registers are forced to initial values and the program counter is loaded from the
reset vector (0xFFFE:0xFFFF). On-chip peripheral modules are disabled and I/O pins are initially
configured as general-purpose high-impedance inputs with pull-up devices disabled. The I bit in the
condition code register (CCR) is set to block maskable interrupts so the user program has a chance to
initialize the stack pointer (SP) and system control settings. SP is forced to 0x00FF at reset.
The MC9S08SG8 has the following sources for reset:
• Power-on reset (POR)
• External pin reset (PIN)
• Low-voltage detect (LVD)
• Computer operating properly (COP) timer
• Illegal opcode detect (ILOP)
• Illegal address detect (ILAD)
• Background debug forced reset
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status register (SRS).
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
62 Freescale Semiconductor
5.4 Computer Operating Properly (COP) Watchdog
The COP watchdog is intended to force a system reset when the application software fails to execute as
expected. To prevent a system reset from the COP timer (when it is enabled), application software must
reset the COP counter periodically. If the application program gets lost and fails to reset the COP counter
before it times out, a system reset is generated to force the system back to a known starting point.
After any reset, the COP watchdog is enabled (see Section 5.7.3, “System Options Register 1 (SOPT1),”
for additional information). If the COP watchdog is not used in an application, it can be disabled by
clearing COPT bits in SOPT1.
The COP counter is reset by writing 0x0055 and 0x00AA (in this order) to the address of SRS during the
selected timeout period. Writes do not affect the data in the read-only SRS. As soon as the write sequence
is done, the COP timeout period is restarted. If the program fails to do this during the time-out period, the
MCU will reset. Also, if any value other than 0x0055 or 0x00AA is written to SRS, the MCU is
immediately reset.
The COPCLKS bit in SOPT2 (see Section 5.7.4, “System Options Register 2 (SOPT2),” for additional
information) selects the clock source used for the COP timer. The clock source options are either the bus
clock or an internal 1-kHz clock source. With each clock source, there are three associated time-outs
controlled by the COPT bits in SOPT1. Table 5-1 summaries the control functions of the COPCLKS and
COPT bits. The COP watchdog defaults to operation from the 1-kHz clock source and the longest time-out
(210 cycles).
Table 5-1. COP Configuration Options
When the bus clock source is selected, windowed COP operation is available by setting COPW in the
SOPT2 register. In this mode, writes to the SRS register to clear the COP timer must occur in the last 25%
of the selected timeout period. A premature write immediately resets the MCU. When the 1-kHz clock
source is selected, windowed COP operation is not available.
Control Bits
Clock Source COP Window1 Opens
(COPW = 1)
1Windowed COP operation requires the user to clear the COP timer in the last 25% of the selected timeout period. This column
displays the minimum number of clock counts required before the COP timer can be reset hen in windowed COP mode
(COPW = 1).
COP Overflow Count
COPCLKS COPT[1:0]
N/A 0:0 N/A N/A COP is disabled
00:1
1 kHz N/A 25 cycles (32 ms2)
2Values shown in milliseconds based on tLPO = 1 ms. See tLPO in the appendix Section A.12.1, “Control Timing,” for the
tolerance of this value.
01:0
1 kHz N/A 28 cycles (256 ms1)
01:1
1 kHz N/A 210 cycles (1.024 s1)
10:1
Bus 6144 cycles 213 cycles
11:0
Bus 49,152 cycles 216 cycles
11:1
Bus 196,608 cycles 218 cycles
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 63
The COP counter is initialized by the first writes to the SOPT1 and SOPT2 registers after any system reset.
Subsequent writes to SOPT1 and SOPT2 have no effect on COP operation. Even if the application will use
the reset default settings of COPT, COPCLKS, and COPW bits, the user should write to the write-once
SOPT1 and SOPT2 registers during reset initialization to lock in the settings. This will prevent accidental
changes if the application program gets lost.
The write to SRS that services (clears) the COP counter should not be placed in an interrupt service routine
(ISR) because the ISR could continue to be executed periodically even if the main application program
fails.
If the bus clock source is selected, the COP counter does not increment while the MCU is in background
debug mode or while the system is in stop mode. The COP counter resumes when the MCU exits
background debug mode or stop mode.
If the 1-kHz clock source is selected, the COP counter is re-initialized to zero upon entry to either
background debug mode or stop mode and begins from zero upon exit from background debug mode or
stop mode.
5.5 Interrupts
Interrupts provide a way to save the current CPU status and registers, execute an interrupt service routine
(ISR), and then restore the CPU status so processing resumes where it left off before the interrupt. Other
than the software interrupt (SWI), which is a program instruction, interrupts are caused by hardware events
such as an edge on a pin interrupt or a timer-overflow event. The debug module can also generate an SWI
under certain circumstances.
If an event occurs in an enabled interrupt source, an associated read-only status flag will become set. The
CPU will not respond unless the local interrupt enable is a 1 to enable the interrupt and the I bit in the CCR
is 0 to allow interrupts. The global interrupt mask (I bit) in the CCR is initially set after reset which
prevents all maskable interrupt sources. The user program initializes the stack pointer and performs other
system setup before clearing the I bit to allow the CPU to respond to interrupts.
When the CPU receives a qualified interrupt request, it completes the current instruction before responding
to the interrupt. The interrupt sequence obeys the same cycle-by-cycle sequence as the SWI instruction
and consists of:
• Saving the CPU registers on the stack
• Setting the I bit in the CCR to mask further interrupts
• Fetching the interrupt vector for the highest-priority interrupt that is currently pending
• Filling the instruction queue with the first three bytes of program information starting from the
address fetched from the interrupt vector locations
While the CPU is responding to the interrupt, the I bit is automatically set to avoid the possibility of
another interrupt interrupting the ISR itself (this is called nesting of interrupts). Normally, the I bit is
restored to 0 when the CCR is restored from the value stacked on entry to the ISR. In rare cases, the I bit
can be cleared inside an ISR (after clearing the status flag that generated the interrupt) so that other
interrupts can be serviced without waiting for the first service routine to finish. This practice is not
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
64 Freescale Semiconductor
recommended for anyone other than the most experienced programmers because it can lead to subtle
program errors that are difficult to debug.
The interrupt service routine ends with a return-from-interrupt (RTI) instruction which restores the CCR,
A, X, and PC registers to their pre-interrupt values by reading the previously saved information from the
stack.
NOTE
For compatibility with M68HC08 devices, the H register is not
automatically saved and restored. It is good programming practice to push
H onto the stack at the start of the interrupt service routine (ISR) and restore
it immediately before the RTI that is used to return from the ISR.
If more than one interrupt is pending when the I bit is cleared, the highest priority source is serviced first
(see Table 5-2).
5.5.1 Interrupt Stack Frame
Figure 5-1 shows the contents and organization of a stack frame. Before the interrupt, the stack pointer
(SP) points at the next available byte location on the stack. The current values of CPU registers are stored
on the stack starting with the low-order byte of the program counter (PCL) and ending with the CCR. After
stacking, the SP points at the next available location on the stack which is the address that is one less than
the address where the CCR was saved. The PC value that is stacked is the address of the instruction in the
main program that would have executed next if the interrupt had not occurred.
Figure 5-1. Interrupt Stack Frame
When an RTI instruction is executed, these values are recovered from the stack in reverse order. As part
of the RTI sequence, the CPU fills the instruction pipeline by reading three bytes of program information,
starting from the PC address recovered from the stack.
CONDITION CODE REGISTER
ACCUMULATOR
INDEX REGISTER (LOW BYTE X)
PROGRAM COUNTER HIGH
* High byte (H) of index register is not automatically stacked.
*
PROGRAM COUNTER LOW
²
²
²
²
70
UNSTACKING
ORDER
STACKING
ORDER
5
4
3
2
1
1
2
3
4
5
TOWARD LOWER ADDRESSES
TOWARD HIGHER ADDRESSES
SP BEFORE
SP AFTER
INTERRUPT STACKING
THE INTERRUPT
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 65
The status flag corresponding to the interrupt source must be acknowledged (cleared) before returning
from the ISR. Typically, the flag is cleared at the beginning of the ISR so that if another interrupt is
generated by this same source, it will be registered so it can be serviced after completion of the current ISR.
5.5.2 Interrupt Vectors, Sources, and Local Masks
Table 5-2 provides a summary of all interrupt sources. Higher-priority sources are located toward the
bottom of the table. The high-order byte of the address for the interrupt service routine is located at the
first address in the vector address column, and the low-order byte of the address for the interrupt service
routine is located at the next higher address.
When an interrupt condition occurs, an associated flag bit becomes set. If the associated local interrupt
enable is 1, an interrupt request is sent to the CPU. Within the CPU, if the global interrupt mask (I bit in
the CCR) is 0, the CPU will finish the current instruction; stack the PCL, PCH, X, A, and CCR CPU
registers; set the I bit; and then fetch the interrupt vector for the highest priority pending interrupt.
Processing then continues in the interrupt service routine.
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
66 Freescale Semiconductor
Table 5-2. Vector Summary
Vector
Priority
Vector
Number
Address
(High/Low)
Vector
Name Module Source Enable Description
Lowest
Highest
31 0xFFC0/0xFFC1 — — — — —
30 0xFFC2/0xFFC3 Vacmp ACMP ACF ACIE Analog comparator
29 0xFFC4/0xFFC5 — — — — —
28 0xFFC6/0xFFC7 — — — — —
27 0xFFC8/0xFFC9 — — — — —
26 0xFFCA/0xFFCB Vmtim MTIM TOF TOIE MTIM overflow
25 0xFFCC/0xFFCD Vrtc RTC RTIF RTIE Real-time interrupt
24 0xFFCE/0xFFCF Viic IIC IICIF IICIE IIC control
23 0xFFD0/0xFFD1 Vadc ADC COCO AIEN ADC
22 0xFFD2/0xFFD3 — — — — —
21 0xFFD4/0xFFD5 Vportb Port B PTBIF PTBIE Port B Pins
20 0xFFD6/0xFFD7 Vporta Port A PTAIF PTAIE Port A Pins
19 0xFFD8/0xFFD9 — — — — —
18 0xFFDA/0xFFDB Vscitx SCI TDRE, TC TIE, TCIE SCI transmit
17 0xFFDC/0xFFDD Vscirx SCI IDLE, RDRF,
LBKDIF,
RXEDGIF
ILIE, RIE, LBKDIE,
RXEDGIE
SCI receive
16 0xFFDE/0xFFDF Vscierr SCI OR, NF,
FE, PF
ORIE, NFIE,
FEIE, PFIE
SCI error
15 0xFFE0/0xFFE1 Vspi SPI SPIF, MODF,
SPTEF
SPIE, SPIE, SPTIE SPI
14 0xFFE2/0xFFE3 Vtpm2ovf TPM2 TOF TOIE TPM2 overflow
13 0xFFE4/0xFFE5 Vtpm2ch1 TPM2 CH1F CH1IE TPM2 channel 1
12 0xFFE6/0xFFE7 Vtpm2ch0 TPM2 CH0F CH0IE TPM2 channel 0
11 0xFFE8/0xFFE9 Vtpm1ovf TPM1 TOF TOIE TPM1 overflow
10 0xFFEA/0xFFEB — — — — —
9 0xFFEC/0xFFED — — — — —
8 0xFFEE/0xFFEF — — — — —
7 0xFFF0/0xFFF1 — — — — —
6 0xFFF2/0xFFF3 Vtpm1ch1 TPM1 CH1F CH1IE TPM1 channel 1
5 0xFFF4/0xFFF5 Vtpm1ch0 TPM1 CH0F CH0IE TPM1 channel 0
4 0xFFF6/0xFFF7 — — — — —
3 0xFFF8/0xFFF9 Vlvd System
control
LVWF LVWIE Low-voltage warning
2 0xFFFA/0xFFFB — — — — —
1 0xFFFC/0xFFFD Vswi Core SWI Instruction — Software interrupt
0 0xFFFE/0xFFFF Vreset System
control
COP,
LVD,
RESET pin,
Illegal opcode,
Illegal address
COPT
LVDRE
—
—
—
Watchdog timer
Low-voltage detect
External pin
Illegal opcode
Illegal address
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 67
5.6 Low-Voltage Detect (LVD) System
The MC9S08SG8 includes a system to protect against low voltage conditions in order to protect memory
contents and control MCU system states during supply voltage variations. The system is comprised of a
power-on reset (POR) circuit and a LVD circuit with trip voltages for warning and detection. The LVD
circuit is enabled when LVDE in SPMSC1 is set to 1. The LVD is disabled upon entering any of the stop
modes unless LVDSE is set in SPMSC1. If LVDSE and LVDE are both set, then the MCU cannot enter
stop2, and the current consumption in stop3 with the LVD enabled will be higher.
5.6.1 Power-On Reset Operation
When power is initially applied to the MCU, or when the supply voltage drops below the power-on reset
rearm voltage level, VPOR, the POR circuit will cause a reset condition. As the supply voltage rises, the
LVD circuit will hold the MCU in reset until the supply has risen above the low voltage detection low
threshold, VLVDL. Both the POR bit and the LVD bit in SRS are set following a POR.
5.6.2 Low-Voltage Detection (LVD) Reset Operation
The LVD can be configured to generate a reset upon detection of a low voltage condition by setting
LVDRE to 1. The low voltage detection threshold is determined by the LVDV bit. After an LVD reset has
occurred, the LVD system will hold the MCU in reset until the supply voltage has risen above the low
voltage detection threshold. The LVD bit in the SRS register is set following either an LVD reset or POR.
5.6.3 Low-Voltage Warning (LVW) Interrupt Operation
The LVD system has a low voltage warning flag to indicate to the user that the supply voltage is
approaching the low voltage condition. When a low voltage warning condition is detected and is
configured for interrupt operation (LVWIE set to 1), LVWF in SPMSC1 will be set and an LVW interrupt
request will occur.
5.7 Reset, Interrupt, and System Control Registers and Control Bits
One 8-bit register in the direct page register space and eight 8-bit registers in the high-page register space
are related to reset and interrupt systems.
Refer to Table 4-2 and Table 4-3 in Chapter 4, “Memory,” of this data sheet for the absolute address
assignments for all registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
Some control bits in the SOPT1 and SPMSC2 registers are related to modes of operation. Although brief
descriptions of these bits are provided here, the related functions are discussed in greater detail in
Chapter 3, “Modes of Operation.”
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
68 Freescale Semiconductor
5.7.1 System Reset Status Register (SRS)
This high page register includes read-only status flags to indicate the source of the most recent reset. When
a debug host forces reset by writing 1 to BDFR in the SBDFR register, none of the status bits in SRS will
be set. Writing any value to this register address causes a COP reset when the COP is enabled except the
values 0x55 and 0xAA. Writing a 0x55-0xAA sequence to this address clears the COP watchdog timer
without affecting the contents of this register. The reset state of these bits depends on what caused the
MCU to reset.
Figure 5-2. System Reset Status (SRS)
76543210
R POR PIN COP ILOP ILAD 0 LVD 0
W Writing 0x55, 0xAA to SRS address clears COP watchdog timer.
POR: 10000010
LVR: u(1)
1u = unaffected
0000010
Any other
reset: 0Note
(2)
2Any of these reset sources that are active at the time of reset entry will cause the corresponding bit(s) to be set; bits
corresponding to sources that are not active at the time of reset entry will be cleared.
Note(2) Note(2) Note(2) 000
Table 5-3. SRS Register Field Descriptions
Field Description
7
POR
Power-On Reset — Reset was caused by the power-on detection logic. Because the internal supply voltage was
ramping up at the time, the low-voltage reset (LVR) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVR threshold.
0 Reset not caused by POR.
1 POR caused reset.
6
PIN
External Reset Pin — Reset was caused by an active-low level on the external reset pin.
0 Reset not caused by external reset pin.
1 Reset came from external reset pin.
5
COP
Computer Operating Properly (COP) Watchdog — Reset was caused by the COP watchdog timer timing out.
This reset source can be blocked by COPT bits = 0:0.
0 Reset not caused by COP timeout.
1 Reset caused by COP timeout.
4
ILOP
Illegal Opcode — Reset was caused by an attempt to execute an unimplemented or illegal opcode. The STOP
instruction is considered illegal if stop is disabled by STOPE = 0 in the SOPT register. The BGND instruction is
considered illegal if active background mode is disabled by ENBDM = 0 in the BDCSC register.
0 Reset not caused by an illegal opcode.
1 Reset caused by an illegal opcode.
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 69
5.7.2 System Background Debug Force Reset Register (SBDFR)
This high page register contains a single write-only control bit. A serial background command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
Figure 5-3. System Background Debug Force Reset Register (SBDFR)
3
ILAD
Illegal Address — Reset was caused by an attempt to access either data or an instruction at an unimplemented
memory address.
0 Reset not caused by an illegal address
1 Reset caused by an illegal address
1
LVD
Low Voltage Detect — If the LVDRE bit is set and the supply drops below the LVD trip voltage, an LVD reset will
occur. This bit is also set by POR.
0 Reset not caused by LVD trip or POR.
1 Reset caused by LVD trip or POR.
76543210
R00000000
WBDFR1
1BDFR is writable only through serial background debug commands, not from user programs.
Reset:00000000
= Unimplemented or Reserved
Table 5-4. SBDFR Register Field Descriptions
Field Description
0
BDFR
Background Debug Force Reset — A serial background command such as WRITE_BYTE can be used to allow
an external debug host to force a target system reset. Writing 1 to this bit forces an MCU reset. This bit cannot
be written from a user program.
Table 5-3. SRS Register Field Descriptions
Field Description
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
70 Freescale Semiconductor
5.7.3 System Options Register 1 (SOPT1)
This high page register is a write-once register so only the first write after reset is honored. It can be read
at any time. Any subsequent attempt to write to SOPT1 (intentionally or unintentionally) is ignored to
avoid accidental changes to these sensitive settings. SOPT1 should be written during the user’s reset
initialization program to set the desired controls even if the desired settings are the same as the reset
settings.
7654
1
1NOTE: Bit 4 is reserved. Writes change the value, but have no effect on this MCU.
3210
R
COPT STOPE
0
IICPS
00
W
Reset:11000000
= Unimplemented or Reserved
Figure 5-4. System Options Register 1 (SOPT1)
Table 5-5. SOPT1 Register Field Descriptions
Field Description
7:6
COPT[1:0]
COP Watchdog Timeout — These write-once bits select the timeout period of the COP. COPT along with
COPCLKS in SOPT2 defines the COP timeout period. See Ta bl e 5 - 1 .
5
STOPE
Stop Mode Enable — This write-once bit is used to enable stop mode. If stop mode is disabled and a user
program attempts to execute a STOP instruction, an illegal opcode reset is forced.
0 Stop mode disabled.
1 Stop mode enabled.
2
IICPS
IIC Pin Select — This bit selects the location of the SDA and SCL pins of the IIC module.
0 SDA on PTA2, SCL on PTA3.
1 SDA on PTB6, SCL on PTB7.
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 71
5.7.4 System Options Register 2 (SOPT2)
This high page register contains bits to configure MCU specific features on the MC9S08SG8 devices.
76543210
R
COPCLKS1
1This bit can be written only one time after reset. Additional writes are ignored.
COPW10
ACIC
00
T1CH1PS T1CH0PS
W
Reset:00000000
= Unimplemented or Reserved
Figure 5-5. System Options Register 2 (SOPT2)
Table 5-6. SOPT2 Register Field Descriptions
Field Description
7
COPCLKS
COP Watchdog Clock Select — This write-once bit selects the clock source of the COP watchdog.
0 Internal 1-kHz clock is source to COP.
1 Bus clock is source to COP.
6
COPW
COP Window — This write-once bit selects the COP operation mode. When set, the 0x55-0xAA write sequence
to the SRS register must occur in the last 25% of the selected period. Any write to the SRS register during the
first 75% of the selected period will reset the MCU.
0 Normal COP operation
1 Window COP operation (only if COPCLKS = 1)
4
ACIC
Analog Comparator to Input Capture Enable— This bit connects the output of ACMP to TPM1 input channel 0.
0 ACMP output not connected to TPM1 input channel 0.
1 ACMP output connected to TPM1 input channel 0.
1
T1CH1PS
TPM1CH1 Pin Select— This bit selects the location of the TPM1CH1 pin of the TPM1 module.
0 TPM1CH1 on PTB5.
1 TPM1CH1 on PTC1.
0
T1CH0PS
TPM1CH0 Pin Select— This bit selects the location of the TPM1CH0 pin of the TPM1 module.
0 TPM1CH0 on PTA0.
1 TPM1CH0 on PTC0.
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
72 Freescale Semiconductor
5.7.5 System Device Identification Register (SDIDH, SDIDL)
These high page read-only registers are included so host development systems can identify the HCS08
derivative and revision number. This allows the development software to recognize where specific
memory blocks, registers, and control bits are located in a target MCU.
Figure 5-6. System Device Identification Register — High (SDIDH)
76543210
R1 ID11 ID10 ID9 ID8
W
Reset: 11
1- Bit 7 is a mask option tie off that is used internally to determine that the device is a MC9S08SG8.
———0000
= Unimplemented or Reserved
Table 5-7. SDIDH Register Field Descriptions
Field Description
7 Bit 7 will read as a 1 for the MC9S08SG8 devices; writes have no effect.
6:4
Reserved
Bits 6:4 are reserved. Reading these bits will result in an indeterminate value; writes have no effect.
3:0
ID[11:8]
Part Identification Number — Each derivative in the HCS08 Family has a unique identification number. The
MC9S08SG8 is hard coded to the value 0x014. See also ID bits in Table 5-8.
76543210
R ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0
W
Reset:00010100
= Unimplemented or Reserved
Figure 5-7. System Device Identification Register — Low (SDIDL)
Table 5-8. SDIDL Register Field Descriptions
Field Description
7:0
ID[7:0]
Part Identification Number — Each derivative in the HCS08 Family has a unique identification number. The
MC9S08SG8 is hard coded to the value 0x014. See also ID bits in Table 5-7.
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 73
5.7.6 System Power Management Status and Control 1 Register
(SPMSC1)
This high page register contains status and control bits to support the low voltage detect function, and to
enable the bandgap voltage reference for use by the ADC module.
Figure 5-8. System Power Management Status and Control 1 Register (SPMSC1)
76543210
RLVWF
1
1LVWF will be set in the case when VSupply transitions below the trip point or after reset and VSupply is already below VLVW
0
LVWIE LVDRE LVDSE LVDE
0
BGBE
WLVWAC K
Reset:00011100
= Unimplemented or Reserved
Table 5-9. SPMSC1 Register Field Descriptions
Field Description
7
LVWF
Low-Voltage Warning Flag — The LVWF bit indicates the low voltage warning status.
0 Low voltage warning is not present.
1 Low voltage warning is present or was present.
6
LVWACK
Low-Voltage Warning Acknowledge — The LVWF bit indicates the low voltage warning status.Writing a 1 to
LVWACK clears LVWF to a 0 if a low voltage warning is not present.
5
LVWIE
Low-Voltage Warning Interrupt Enable — This bit enables hardware interrupt requests for LVWF.
0 Hardware interrupt disabled (use polling).
1 Request a hardware interrupt when LVWF = 1.
4
LVDRE
Low-Voltage Detect Reset Enable — This write-once bit enables LVD events to generate a hardware reset
(provided LVDE = 1).
0 LVD events do not generate hardware resets.
1 Force an MCU reset when an enabled low-voltage detect event occurs.
3
LVDSE
Low-Voltage Detect Stop Enable — Provided LVDE = 1, this control bit determines whether the low-voltage
detect function operates when the MCU is in stop mode.
0 Low-voltage detect disabled during stop mode.
1 Low-voltage detect enabled during stop mode.
2
LVDE
Low-Voltage Detect Enable — This write-once bit enables low-voltage detect logic and qualifies the operation
of other bits in this register.
0 LVD logic disabled.
1 LVD logic enabled.
0
BGBE
Bandgap Buffer Enable — This bit enables an internal buffer for the bandgap voltage reference for use by the
ADC module on one of its internal channels or ACMP on its ACMP+ input.
0 Bandgap buffer disabled.
1 Bandgap buffer enabled.
Chapter 5 Resets, Interrupts, and General System Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
74 Freescale Semiconductor
5.7.7 System Power Management Status and Control 2 Register
(SPMSC2)
This register is used to report the status of the low voltage warning function, and to configure the stop
mode behavior of the MCU.
Figure 5-9. System Power Management Status and Control 2 Register (SPMSC2)
76543 210
R0 0
LVDV1
1This bit can be written only one time after power-on reset. Additional writes are ignored.
LVWV
PPDF 0 0 PPDC2
2This bit can be written only one time after reset. Additional writes are ignored.
WPPDACK
Power-on Reset:00000 000
LVD Reset:00uu0 000
Any other Reset: 0 0 u u 0 0 0 0
= Unimplemented or Reserved u = Unaffected by reset
Table 5-10. SPMSC2 Register Field Descriptions
Field Description
5
LVDV
Low-Voltage Detect Voltage Select — This write-once bit selects the low voltage detect (LVD) trip point setting.
It also selects the warning voltage range. See Table 5-11.
4
LVWV
Low-Voltage Warning Voltage Select — This bit selects the low voltage warning (LVW) trip point voltage. See
Table 5-11.
3
PPDF
Partial Power Down Flag — This read-only status bit indicates that the MCU has recovered from stop2 mode.
0 MCU has not recovered from stop2 mode.
1 MCU recovered from stop2 mode.
2
PPDACK
Partial Power Down Acknowledge — Writing a 1 to PPDACK clears the PPDF bit
0
PPDC
Partial Power Down Control — This write-once bit controls whether stop2 or stop3 mode is selected.
0 Stop3 mode enabled.
1 Stop2, partial power down, mode enabled.
Table 5-11. LVD and LVW trip point typical values1
1See Electrical Characteristics appendix for minimum and maximum values.
LVDV:LVWV LVW Trip Point LVD Trip Point
0:0 VLVW 0 = 2.74 V VLVD0 = 2.56 V
0:1 VLVW 1 = 2.92 V
1:0 VLVW 2 = 4.3 V VLVD 1 = 4.0 V
1:1 VLVW 3 = 4.6 V
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 75
Chapter 6
Parallel Input/Output Control
This section explains software controls related to parallel input/output (I/O) and pin control. The
MC9S08SG8 has three parallel I/O ports which include a total of 16 I/O pins. See Chapter 2, “Pins and
Connections,” for more information about pin assignments and external hardware considerations of these
pins.
Many of these pins are shared with on-chip peripherals such as timer systems, communication systems, or
pin interrupts as shown in Table 2-1. The peripheral modules have priority over the general-purpose I/O
functions so that when a peripheral is enabled, the I/O functions associated with the shared pins are
disabled.
After reset, the shared peripheral functions are disabled and the pins are configured as inputs
(PTxDDn = 0). The pin control functions for each pin are configured as follows: slew rate disabled
(PTxSEn = 0), low drive strength selected (PTxDSn = 0), and internal pull-ups disabled (PTxPEn = 0).
NOTE
Not all general-purpose I/O pins are available on all packages. To avoid
extra current drain from floating input pins, the user’s reset initialization
routine in the application program must either enable on-chip pull-up
devices or change the direction of unconnected pins to outputs so the pins
do not float.
6.1 Port Data and Data Direction
Reading and writing of parallel I/Os are performed through the port data registers. The direction, either
input or output, is controlled through the port data direction registers. The parallel I/O port function for an
individual pin is illustrated in the block diagram shown in Figure 6-1.
The data direction control bit (PTxDDn) determines whether the output buffer for the associated pin is
enabled, and also controls the source for port data register reads. The input buffer for the associated pin is
always enabled unless the pin is enabled as an analog function or is an output-only pin.
When a shared digital function is enabled for a pin, the output buffer is controlled by the shared function.
However, the data direction register bit will continue to control the source for reads of the port data register.
When a shared analog function is enabled for a pin, both the input and output buffers are disabled. A value
of 0 is read for any port data bit where the bit is an input (PTxDDn = 0) and the input buffer is disabled. In
general, whenever a pin is shared with both an alternate digital function and an analog function, the analog
function has priority such that if both the digital and analog functions are enabled, the analog function
controls the pin.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
76 Freescale Semiconductor
It is a good programming practice to write to the port data register before changing the direction of a port
pin to become an output. This ensures that the pin will not be driven momentarily with an old data value
that happened to be in the port data register.
Figure 6-1. Parallel I/O Block Diagram
6.2 Pull-up, Slew Rate, and Drive Strength
Associated with the parallel I/O ports is a set of registers located in the high page register space that operate
independently of the parallel I/O registers. These registers are used to control pull-ups, slew rate, and drive
strength for the pins.
An internal pull-up device can be enabled for each port pin by setting the corresponding bit in the pull-up
enable register (PTxPEn). The pull-up device is disabled if the pin is configured as an output by the parallel
I/O control logic or any shared peripheral function regardless of the state of the corresponding pull-up
enable register bit. The pull-up device is also disabled if the pin is controlled by an analog function.
Slew rate control can be enabled for each port pin by setting the corresponding bit in the slew rate control
register (PTxSEn). When enabled, slew control limits the rate at which an output can transition in order to
reduce EMC emissions. Slew rate control has no effect on pins that are configured as inputs.
An output pin can be selected to have high output drive strength by setting the corresponding bit in the
drive strength select register (PTxDSn). When high drive is selected, a pin is capable of sourcing and
sinking greater current. Even though every I/O pin can be selected as high drive, the user must ensure that
the total current source and sink limits for the MCU are not exceeded. Drive strength selection is intended
to affect the DC behavior of I/O pins. However, the AC behavior is also affected. High drive allows a pin
to drive a greater load with the same switching speed as a low drive enabled pin into a smaller load.
Because of this, the EMC emissions may be affected by enabling pins as high drive.
QD
QD
1
0
Port Read
PTxDDn
PTxDn
Output Enable
Output Data
Input Data
Synchronizer
Data
BUSCLK
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 77
6.3 Ganged Output
The MC9S08SG8 devices contain a feature that allows for up to eight port pins to be tied together
externally to allow higher output current drive. The ganged output drive control register (GNGC) is a
write-once register that is used to enabled the ganged output feature and select which port pins will be used
as ganged outputs. The GNGEN bit in GNGC enables ganged output. The GNGPS[7:1] bits are used to
select which pin will be part of the ganged output.
When GNGEN is set, any pin that is enabled as a ganged output will be automatically configured as an
output and follow the data, drive strength and slew rate control of PTC0. The ganged output drive pin
mapping is shown in Table 6-1.
NOTE
See the DC characteristics in the electrical section for maximum Port I/O
currents allowed for this MCU.
When a pin is enabled as ganged output, this feature will have priority over
any digital module. An enabled analog function will have priority over the
ganged output pin. See Table 2-1 for information on pin priority.
Table 6-1. Ganged Output Pin Enable
GNGC Register Bits
GNGPS7 GNGPS6 GNGPS5 GNGPS4 GNGPS3 GNGPS2 GNGPS1 GNGEN1
1Ganged output not available on 8-pin packages. PTC3-PTC0 not available on 16-pin packages, however PTC0 control registers
are still used to control ganged output.
Port Pin 2
2When GNGEN = 1, PTC0 is forced to an output, regardless of the value in PTCDD0 in PTCDD.
PTB5 PTB4 PTB3 PTB2 PTC3 PTC2 PTC1 PTC0
Data Direction
Control Pin is automatically configured as output when pin is enabled as ganged output.
Data
Control PTCD0 in PTCD controls data value of output
Drive Strength
Control PTCDS0 in PTCDS controls drive strength of output
Slew Rate
Control PTCSE0 in PTCSE controls slew rate of output
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
78 Freescale Semiconductor
6.4 Pin Interrupts
Port A[3:0] and port B[3:0] pins can be configured as external interrupt inputs and as an external means
of waking the MCU from stop3 or wait low-power modes.
The block diagram for the pin interrupts is shown Figure 6-2.
Figure 6-2. Pin Interrupt Block Diagram
Writing to the PTxPSn bits in the port interrupt pin enable register (PTxPS) independently enables or
disables each port pin interrupt. Each port can be configured as edge sensitive or edge and level sensitive
based on the PTxMOD bit in the port interrupt status and control register (PTxSC). Edge sensitivity can be
software programmed to be either falling or rising; the level can be either low or high. The polarity of the
edge or edge and level sensitivity is selected using the PTxESn bits in the port interrupt edge select register
(PTxES).
Synchronous logic is used to detect edges. Prior to detecting an edge, enabled pin interrupt inputs must be
at the deasserted logic level. A falling edge is detected when an enabled port input signal is seen as a logic
1 (the deasserted level) during one bus cycle and then a logic 0 (the asserted level) during the next cycle.
A rising edge is detected when the input signal is seen as a logic 0 during one bus cycle and then a logic 1
during the next cycle.
6.4.1 Edge Only Sensitivity
A valid edge on an enabled pin interrupt will set PTxIF in PTxSC. If PTxIE in PTxSC is set, an interrupt
request will be presented to the CPU. Clearing of PTxIF is accomplished by writing a 1 to PTxACK in
PTxSC.
6.4.2 Edge and Level Sensitivity
A valid edge or level on an enabled pin interrupt will set PTxIF in PTxSC. If PTxIE in PTxSC is set, an
interrupt request will be presented to the CPU. Clearing of PTxIF is accomplished by writing a 1 to
PTxACK in PTxSC provided all enabled pin interrupt inputs are at their deasserted levels. PTxIF will
remain set if any enabled pin interrupt is asserted while attempting to clear by writing a 1 to PTxACK.
PTxESn
DQ
CK
CLR
V
DD
PTxMOD
PTxIE
PORT
INTERRUPT FF
PTxACK
RESET
SYNCHRONIZER
PTxIF
STOP BYPASS
STOP
BUSCLK
PTxPSn
0
1
S
PTxPS0
0
1
S
PTxES0
PIxn
PIxn
PTx
INTERRUPT
REQUEST
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 79
6.4.3 Pull-up/Pull-down Resistors
The pin interrupts can be configured to use an internal pull-up/pull-down resistor using the associated I/O
port pull-up enable register. If an internal resistor is enabled, the PTxES register is used to select whether
the resistor is a pull-up (PTxESn = 0) or a pull-down (PTxESn = 1).
6.4.4 Pin Interrupt Initialization
When a pin interrupt is first enabled, it is possible to get a false interrupt flag. To prevent a false interrupt
request during pin interrupt initialization, the user should do the following:
1. Mask interrupts by clearing PTxIE in PTxSC.
2. Select the pin polarity by setting the appropriate PTxESn bits in PTxES.
3. If using internal pull-up/pull-down device, configure the associated pull enable bits in PTxPE.
4. Enable the interrupt pins by setting the appropriate PTxPEn bits in PTxPE.
5. Write to PTxACK in PTxSC to clear any false interrupts.
6. Set PTxIE in PTxSC to enable interrupts.
6.5 Pin Behavior in Stop Modes
Pin behavior following execution of a STOP instruction depends on the stop mode that is entered. An
explanation of pin behavior for the various stop modes follows:
• Stop2 mode is a partial power-down mode, whereby I/O latches are maintained in their state as
before the STOP instruction was executed. CPU register status and the state of I/O registers should
be saved in RAM before the STOP instruction is executed to place the MCU in stop2 mode. Upon
recovery from stop2 mode, before accessing any I/O, the user should examine the state of the PPDF
bit in the SPMSC2 register. If the PPDF bit is 0, I/O must be initialized as if a power on reset had
occurred. If the PPDF bit is 1, I/O data previously stored in RAM, before the STOP instruction was
executed, peripherals may require being initialized and restored to their pre-stop condition. The
user must then write a 1 to the PPDACK bit in the SPMSC2 register. Access to I/O is now permitted
again in the user application program.
• In stop3 mode, all I/O is maintained because internal logic circuity stays powered up. Upon
recovery, normal I/O function is available to the user.
6.6 Parallel I/O and Pin Control Registers
This section provides information about the registers associated with the parallel I/O ports. The data and
data direction registers are located in page zero of the memory map. The pull up, slew rate, drive strength,
and interrupt control registers are located in the high page section of the memory map.
Refer to tables in Chapter 4, “Memory,” for the absolute address assignments for all parallel I/O and their
pin control registers. This section refers to registers and control bits only by their names. A Freescale
Semiconductor-provided equate or header file normally is used to translate these names into the
appropriate absolute addresses.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
80 Freescale Semiconductor
6.6.1 Port A Registers
Port A is controlled by the registers listed below.
6.6.1.1 Port A Data Register (PTAD)
6.6.1.2 Port A Data Direction Register (PTADD)
76543210
R00RR PTAD3 PTAD2 PTAD1 PTAD0
W
Reset:00000000
Figure 6-3. Port A Data Register (PTAD)
Table 6-2. PTAD Register Field Descriptions
Field Description
5:4
Reserved
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
3:0
PTAD[3:0]
Port A Data Register Bits — For port A pins that are inputs, reads return the logic level on the pin. For port A
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port A pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTAD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pull-ups/pull-downs disabled.
76543210
R00RR PTADD3 PTADD2 PTADD1 PTADD0
W
Reset:00000000
Figure 6-4. Port A Data Direction Register (PTADD)
Table 6-3. PTADD Register Field Descriptions
Field Description
5:4
Reserved
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
3:0
PTADD[3:0]
Data Direction for Port A Bits — These read/write bits control the direction of port A pins and what is read for
PTAD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port A bit n and PTAD reads return the contents of PTADn.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 81
6.6.1.3 Port A Pull Enable Register (PTAPE)
6.6.1.4 Port A Slew Rate Enable Register (PTASE)
76543210
R00RR PTAPE3 PTAPE2 PTAPE1 PTAPE0
W
Reset:00000000
Figure 6-5. Internal Pull Enable for Port A Register (PTAPE)
Table 6-4. PTAPE Register Field Descriptions
Field Description
5:4
Reserved
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
3:0
PTAPE[3:0]
Internal Pull Enable for Port A Bits — Each of these control bits determines if the internal pull-up or pull-down
device is enabled for the associated PTA pin. For port A pins that are configured as outputs, these bits have no
effect and the internal pull devices are disabled.
0 Internal pull-up/pull-down device disabled for port A bit n.
1 Internal pull-up/pull-down device enabled for port A bit n.
76543210
R00RR PTASE3 PTASE2 PTASE1 PTASE0
W
Reset:00000000
Figure 6-6. Slew Rate Enable for Port A Register (PTASE)
Table 6-5. PTASE Register Field Descriptions
Field Description
5:4
Reserved
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
3:0
PTASE[3:0]
Output Slew Rate Enable for Port A Bits — Each of these control bits determines if the output slew rate control
is enabled for the associated PTA pin. For port A pins that are configured as inputs, these bits have no effect.
0 Output slew rate control disabled for port A bit n.
1 Output slew rate control enabled for port A bit n.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
82 Freescale Semiconductor
6.6.1.5 Port A Drive Strength Selection Register (PTADS)
6.6.1.6 Port A Interrupt Status and Control Register (PTASC)
76543210
R00RR PTADS3 PTADS2 PTADS1 PTADS0
W
Reset:00000000
Figure 6-7. Drive Strength Selection for Port A Register (PTADS)
Table 6-6. PTADS Register Field Descriptions
Field Description
5:4
Reserved
Reserved Bits — These bits are unused on this MCU, writes have no affect and could read as 1s or 0s.
3:0
PTADS[3:0]
Output Drive Strength Selection for Port A Bits — Each of these control bits selects between low and high
output drive for the associated PTA pin. For port A pins that are configured as inputs, these bits have no effect.
0 Low output drive strength selected for port A bit n.
1 High output drive strength selected for port A bit n.
76543210
R0000PTAIF0
PTAIE PTAMOD
WPTAACK
Reset:00000000
Figure 6-8. Port A Interrupt Status and Control Register (PTASC)
Table 6-7. PTASC Register Field Descriptions
Field Description
3
PTAIF
Port A Interrupt Flag — PTAIF indicates when a port A interrupt is detected. Writes have no effect on PTAIF.
0 No port A interrupt detected.
1 Port A interrupt detected.
2
PTAACK
Port A Interrupt Acknowledge — Writing a 1 to PTAACK is part of the flag clearing mechanism. PTAACK always
reads as 0.
1
PTAIE
Port A Interrupt Enable — PTAIE determines whether a port A interrupt is requested.
0 Port A interrupt request not enabled.
1 Port A interrupt request enabled.
0
PTAMOD
Port A Detection Mode — PTAMOD (along with the PTAES bits) controls the detection mode of the port A
interrupt pins.
0 Port A pins detect edges only.
1 Port A pins detect both edges and levels.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 83
6.6.1.7 Port A Interrupt Pin Select Register (PTAPS)
6.6.1.8 Port A Interrupt Edge Select Register (PTAES)
76543210
R0000
PTAPS3 PTAPS2 PTAPS1 PTAPS0
W
Reset:00000000
Figure 6-9. Port A Interrupt Pin Select Register (PTAPS)
Table 6-8. PTAPS Register Field Descriptions
Field Description
3:0
PTAPS[3:0]
Port A Interrupt Pin Selects — Each of the PTAPSn bits enable the corresponding port A interrupt pin.
0 Pin not enabled as interrupt.
1 Pin enabled as interrupt.
76543210
R0000
PTAES3 PTAES2 PTAES1 PTAES0
W
Reset:00000000
Figure 6-10. Port A Edge Select Register (PTAES)
Table 6-9. PTAES Register Field Descriptions
Field Description
3:0
PTAES[3:0]
Port A Edge Selects — Each of the PTAESn bits serves a dual purpose by selecting the polarity of the active
interrupt edge as well as selecting a pull-up or pull-down device if enabled.
0 A pull-up device is connected to the associated pin and detects falling edge/low level for interrupt generation.
1 A pull-down device is connected to the associated pin and detects rising edge/high level for interrupt
generation.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
84 Freescale Semiconductor
6.6.2 Port B Registers
Port B is controlled by the registers listed below.
6.6.2.1 Port B Data Register (PTBD)
6.6.2.2 Port B Data Direction Register (PTBDD)
76543210
R
PTBD7 PTBD6 PTBD5 PTBD4 PTBD3 PTBD2 PTBD1 PTBD0
W
Reset:00000000
Figure 6-11. Port B Data Register (PTBD)
Table 6-10. PTBD Register Field Descriptions
Field Description
7:0
PTBD[7:0]
Port B Data Register Bits — For port B pins that are inputs, reads return the logic level on the pin. For port B
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port B pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTBD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pull-ups/pull-downs disabled.
76543210
R
PTBDD7 PTBDD6 PTBDD5 PTBDD4 PTBDD3 PTBDD2 PTBDD1 PTBDD0
W
Reset:00000000
Figure 6-12. Port B Data Direction Register (PTBDD)
Table 6-11. PTBDD Register Field Descriptions
Field Description
7:0
PTBDD[7:0]
Data Direction for Port B Bits — These read/write bits control the direction of port B pins and what is read for
PTBD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port B bit n and PTBD reads return the contents of PTBDn.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 85
6.6.2.3 Port B Pull Enable Register (PTBPE)
6.6.2.4 Port B Slew Rate Enable Register (PTBSE)
76543210
R
PTBPE7 PTBPE6 PTBPE5 PTBPE4 PTBPE3 PTBPE2 PTBPE1 PTBPE0
W
Reset:00000000
Figure 6-13. Internal Pull Enable for Port B Register (PTBPE)
Table 6-12. PTBPE Register Field Descriptions
Field Description
7:0
PTBPE[7:0]
Internal Pull Enable for Port B Bits — Each of these control bits determines if the internal pull-up or pull-down
device is enabled for the associated PTB pin. For port B pins that are configured as outputs, these bits have no
effect and the internal pull devices are disabled.
0 Internal pull-up/pull-down device disabled for port B bit n.
1 Internal pull-up/pull-down device enabled for port B bit n.
76543210
R
PTBSE7 PTBSE6 PTBSE5 PTBSE4 PTBSE3 PTBSE2 PTBSE1 PTBSE0
W
Reset:00000000
Figure 6-14. Slew Rate Enable for Port B Register (PTBSE)
Table 6-13. PTBSE Register Field Descriptions
Field Description
7:0
PTBSE[7:0]
Output Slew Rate Enable for Port B Bits — Each of these control bits determines if the output slew rate control
is enabled for the associated PTB pin. For port B pins that are configured as inputs, these bits have no effect.
0 Output slew rate control disabled for port B bit n.
1 Output slew rate control enabled for port B bit n.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
86 Freescale Semiconductor
6.6.2.5 Port B Drive Strength Selection Register (PTBDS)
6.6.2.6 Port B Interrupt Status and Control Register (PTBSC)
76543210
R
PTBDS7 PTBDS6 PTBDS5 PTBDS4 PTBDS3 PTBDS2 PTBDS1 PTBDS0
W
Reset:00000000
Figure 6-15. Drive Strength Selection for Port B Register (PTBDS)
Table 6-14. PTBDS Register Field Descriptions
Field Description
7:0
PTBDS[7:0]
Output Drive Strength Selection for Port B Bits — Each of these control bits selects between low and high
output drive for the associated PTB pin. For port B pins that are configured as inputs, these bits have no effect.
0 Low output drive strength selected for port B bit n.
1 High output drive strength selected for port B bit n.
76543210
R0000PTBIF0
PTBIE PTBMOD
WPTBACK
Reset:00000000
Figure 6-16. Port B Interrupt Status and Control Register (PTBSC)
Table 6-15. PTBSC Register Field Descriptions
Field Description
3
PTBIF
Port B Interrupt Flag — PTBIF indicates when a Port B interrupt is detected. Writes have no effect on PTBIF.
0 No Port B interrupt detected.
1 Port B interrupt detected.
2
PTBACK
Port B Interrupt Acknowledge — Writing a 1 to PTBACK is part of the flag clearing mechanism. PTBACK
always reads as 0.
1
PTBIE
Port B Interrupt Enable — PTBIE determines whether a port B interrupt is requested.
0 Port B interrupt request not enabled.
1 Port B interrupt request enabled.
0
PTBMOD
Port B Detection Mode — PTBMOD (along with the PTBES bits) controls the detection mode of the port B
interrupt pins.
0 Port B pins detect edges only.
1 Port B pins detect both edges and levels.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 87
6.6.2.7 Port B Interrupt Pin Select Register (PTBPS)
6.6.2.8 Port B Interrupt Edge Select Register (PTBES)
76543210
R0000
PTBPS3 PTBPS2 PTBPS1 PTBPS0
W
Reset:00000000
Figure 6-17. Port B Interrupt Pin Select Register (PTBPS)
Table 6-16. PTBPS Register Field Descriptions
Field Description
3:0
PTBPS[3:0]
Port B Interrupt Pin Selects — Each of the PTBPSn bits enable the corresponding port B interrupt pin.
0 Pin not enabled as interrupt.
1 Pin enabled as interrupt.
76543210
R0000
PTBES3 PTBES2 PTBES1 PTBES0
W
Reset:00000000
Figure 6-18. Port B Edge Select Register (PTBES)
Table 6-17. PTBES Register Field Descriptions
Field Description
3:0
PTBES[3:0]
Port B Edge Selects — Each of the PTBESn bits serves a dual purpose by selecting the polarity of the active
interrupt edge as well as selecting a pull-up or pull-down device if enabled.
0 A pull-up device is connected to the associated pin and detects falling edge/low level for interrupt generation.
1 A pull-down device is connected to the associated pin and detects rising edge/high level for interrupt
generation.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
88 Freescale Semiconductor
6.6.3 Port C Registers
Port C is controlled by the registers listed below.
6.6.3.1 Port C Data Register (PTCD)
6.6.3.2 Port C Data Direction Register (PTCDD)
76543210
R0000
PTCD3 PTCD2 PTCD1 PTCD0
W
Reset:00000000
Figure 6-19. Port C Data Register (PTCD)
Table 6-18. PTCD Register Field Descriptions
Field Description
3:0
PTCD[3:0]
Port C Data Register Bits — For port C pins that are inputs, reads return the logic level on the pin. For port C
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port C pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTCD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pull-ups disabled.
76543210
R0000
PTCDD3 PTCDD2 PTCDD1 PTCDD0
W
Reset:00000000
Figure 6-20. Port C Data Direction Register (PTCDD)
Table 6-19. PTCDD Register Field Descriptions
Field Description
3:0
PTCDD[3:0]
Data Direction for Port C Bits — These read/write bits control the direction of port C pins and what is read for
PTCD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port C bit n and PTCD reads return the contents of PTCDn.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 89
6.6.3.3 Port C Pull Enable Register (PTCPE)
6.6.3.4 Port C Slew Rate Enable Register (PTCSE)
76543210
R0000
PTCPE3 PTCPE2 PTCPE1 PTCPE0
W
Reset:00000000
Figure 6-21. Internal Pull Enable for Port C Register (PTCPE)
Table 6-20. PTCPE Register Field Descriptions
Field Description
3:0
PTCPE[3:0]
Internal Pull Enable for Port C Bits — Each of these control bits determines if the internal pull-up device is
enabled for the associated PTC pin. For port C pins that are configured as outputs, these bits have no effect and
the internal pull devices are disabled.
0 Internal pull-up device disabled for port C bit n.
1 Internal pull-up device enabled for port C bit n.
76543210
R0000
PTCSE3 PTCSE2 PTCSE1 PTCSE0
W
Reset:00000000
Figure 6-22. Slew Rate Enable for Port C Register (PTCSE)
Table 6-21. PTCSE Register Field Descriptions
Field Description
3:0
PTCSE[3:0]
Output Slew Rate Enable for Port C Bits — Each of these control bits determines if the output slew rate control
is enabled for the associated PTC pin. For port C pins that are configured as inputs, these bits have no effect.
0 Output slew rate control disabled for port C bit n.
1 Output slew rate control enabled for port C bit n.
Chapter 6 Parallel Input/Output Control
MC9S08SG8 MCU Series Data Sheet, Rev. 8
90 Freescale Semiconductor
6.6.3.5 Port C Drive Strength Selection Register (PTCDS)
6.6.3.6 Ganged Output Drive Control Register (GNGC)
76543210
R0000
PTCDS3 PTCDS2 PTCDS1 PTCDS0
W
Reset:00000000
Figure 6-23. Drive Strength Selection for Port C Register (PTCDS)
Table 6-22. PTCDS Register Field Descriptions
Field Description
3:0
PTCDS[3:0]
Output Drive Strength Selection for Port C Bits — Each of these control bits selects between low and high
output drive for the associated PTC pin. For port C pins that are configured as inputs, these bits have no effect.
0 Low output drive strength selected for port C bit n.
1 High output drive strength selected for port C bit n.
76543210
R
GNGPS7 GNGPS6 GNGPS5 GNGPS4 GNGPS3 GNGPS2 GNGPS1 GNGEN
W
Reset:00000000
Figure 6-24. Ganged Output Drive Control Register (GNGC)
Table 6-23. GNGC Register Field Descriptions
Field Description
7:1
GNGP[7:1]
Ganged Output Pin Select Bits— These write-once control bits selects whether the associated pin (see
Ta ble 6 - 1 for pins available) is enabled for ganged output. When GNGEN = 1, all enabled ganged output pins will
be controlled by the data, drive strength and slew rate settings for PTC0.
0 Associated pin is not part of the ganged output drive.
1 Associated pin is part of the ganged output drive. Requires GNGEN = 1.
0
GNGEN
Ganged Output Drive Enable Bit— This write-once control bit selects whether the ganged output drive feature
is enabled.
0 Ganged output drive disabled.
1 Ganged output drive enabled. PTC0 forced to output regardless of the value of PTCDD0 in PTCDD.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 91
Chapter 7
Central Processor Unit (S08CPUV2)
7.1 Introduction
This section provides summary information about the registers, addressing modes, and instruction set of
the CPU of the HCS08 Family. For a more detailed discussion, refer to the HCS08 Family Reference
Manual, volume 1, Freescale Semiconductor document order number HCS08RMV1/D.
The HCS08 CPU is fully source- and object-code-compatible with the M68HC08 CPU. Several
instructions and enhanced addressing modes were added to improve C compiler efficiency and to support
a new background debug system which replaces the monitor mode of earlier M68HC08 microcontrollers
(MCU).
7.1.1 Features
Features of the HCS08 CPU include:
• Object code fully upward-compatible with M68HC05 and M68HC08 Families
• All registers and memory are mapped to a single 64-Kbyte address space
• 16-bit stack pointer (any size stack anywhere in 64-Kbyte address space)
• 16-bit index register (H:X) with powerful indexed addressing modes
• 8-bit accumulator (A)
• Many instructions treat X as a second general-purpose 8-bit register
• Seven addressing modes:
— Inherent — Operands in internal registers
— Relative — 8-bit signed offset to branch destination
— Immediate — Operand in next object code byte(s)
— Direct — Operand in memory at 0x0000–0x00FF
— Extended — Operand anywhere in 64-Kbyte address space
— Indexed relative to H:X — Five submodes including auto increment
— Indexed relative to SP — Improves C efficiency dramatically
• Memory-to-memory data move instructions with four address mode combinations
• Overflow, half-carry, negative, zero, and carry condition codes support conditional branching on
the results of signed, unsigned, and binary-coded decimal (BCD) operations
• Efficient bit manipulation instructions
• Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
• STOP and WAIT instructions to invoke low-power operating modes
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7.2 Programmer’s Model and CPU Registers
Figure 7-1 shows the five CPU registers. CPU registers are not part of the memory map.
Figure 7-1. CPU Registers
7.2.1 Accumulator (A)
The A accumulator is a general-purpose 8-bit register. One operand input to the arithmetic logic unit
(ALU) is connected to the accumulator and the ALU results are often stored into the A accumulator after
arithmetic and logical operations. The accumulator can be loaded from memory using various addressing
modes to specify the address where the loaded data comes from, or the contents of A can be stored to
memory using various addressing modes to specify the address where data from A will be stored.
Reset has no effect on the contents of the A accumulator.
7.2.2 Index Register (H:X)
This 16-bit register is actually two separate 8-bit registers (H and X), which often work together as a 16-bit
address pointer where H holds the upper byte of an address and X holds the lower byte of the address. All
indexed addressing mode instructions use the full 16-bit value in H:X as an index reference pointer;
however, for compatibility with the earlier M68HC05 Family, some instructions operate only on the
low-order 8-bit half (X).
Many instructions treat X as a second general-purpose 8-bit register that can be used to hold 8-bit data
values. X can be cleared, incremented, decremented, complemented, negated, shifted, or rotated. Transfer
instructions allow data to be transferred from A or transferred to A where arithmetic and logical operations
can then be performed.
For compatibility with the earlier M68HC05 Family, H is forced to 0x00 during reset. Reset has no effect
on the contents of X.
SP
PC
CONDITION CODE REGISTER
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
H X
0
0
0
7
15
15
70
ACCUMULATOR A
INDEX REGISTER (LOW)INDEX REGISTER (HIGH)
STACK POINTER
87
PROGRAM COUNTER
16-BIT INDEX REGISTER H:X
CCR
CV11HINZ
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7.2.3 Stack Pointer (SP)
This 16-bit address pointer register points at the next available location on the automatic last-in-first-out
(LIFO) stack. The stack may be located anywhere in the 64-Kbyte address space that has RAM and can
be any size up to the amount of available RAM. The stack is used to automatically save the return address
for subroutine calls, the return address and CPU registers during interrupts, and for local variables. The
AIS (add immediate to stack pointer) instruction adds an 8-bit signed immediate value to SP. This is most
often used to allocate or deallocate space for local variables on the stack.
SP is forced to 0x00FF at reset for compatibility with the earlier M68HC05 Family. HCS08 programs
normally change the value in SP to the address of the last location (highest address) in on-chip RAM
during reset initialization to free up direct-page RAM (from the end of the on-chip registers to 0x00FF).
The RSP (reset stack pointer) instruction was included for compatibility with the M68HC05 Family and
is seldom used in new HCS08 programs because it only affects the low-order half of the stack pointer.
7.2.4 Program Counter (PC)
The program counter is a 16-bit register that contains the address of the next instruction or operand to be
fetched.
During normal program execution, the program counter automatically increments to the next sequential
memory location every time an instruction or operand is fetched. Jump, branch, interrupt, and return
operations load the program counter with an address other than that of the next sequential location. This
is called a change-of-flow.
During reset, the program counter is loaded with the reset vector that is located at $FFFE and $FFFF. The
vector stored there is the address of the first instruction that will be executed after exiting the reset state.
7.2.5 Condition Code Register (CCR)
The 8-bit condition code register contains the interrupt mask (I) and five flags that indicate the results of
the instruction just executed. Bits 6 and 5 are set permanently to 1. The following paragraphs describe the
functions of the condition code bits in general terms. For a more detailed explanation of how each
instruction sets the CCR bits, refer to the HCS08 Family Reference Manual, volume 1, Freescale
Semiconductor document order number HCS08RMv1.
Figure 7-2. Condition Code Register
CONDITION CODE REGISTER
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
70
CCR
CV11HINZ
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7.3 Addressing Modes
Addressing modes define the way the CPU accesses operands and data. In the HCS08, all memory, status
and control registers, and input/output (I/O) ports share a single 64-Kbyte linear address space so a 16-bit
binary address can uniquely identify any memory location. This arrangement means that the same
instructions that access variables in RAM can also be used to access I/O and control registers or nonvolatile
program space.
Some instructions use more than one addressing mode. For instance, move instructions use one addressing
mode to specify the source operand and a second addressing mode to specify the destination address.
Instructions such as BRCLR, BRSET, CBEQ, and DBNZ use one addressing mode to specify the location
Table 7-1. CCR Register Field Descriptions
Field Description
7
V
Two’s Complement Overflow Flag — The CPU sets the overflow flag when a two’s complement overflow occurs.
The signed branch instructions BGT, BGE, BLE, and BLT use the overflow flag.
0 No overflow
1Overflow
4
H
Half-Carry Flag — The CPU sets the half-carry flag when a carry occurs between accumulator bits 3 and 4 during
an add-without-carry (ADD) or add-with-carry (ADC) operation. The half-carry flag is required for binary-coded
decimal (BCD) arithmetic operations. The DAA instruction uses the states of the H and C condition code bits to
automatically add a correction value to the result from a previous ADD or ADC on BCD operands to correct the
result to a valid BCD value.
0 No carry between bits 3 and 4
1 Carry between bits 3 and 4
3
I
Interrupt Mask Bit — When the interrupt mask is set, all maskable CPU interrupts are disabled. CPU interrupts
are enabled when the interrupt mask is cleared. When a CPU interrupt occurs, the interrupt mask is set
automatically after the CPU registers are saved on the stack, but before the first instruction of the interrupt service
routine is executed.
Interrupts are not recognized at the instruction boundary after any instruction that clears I (CLI or TAP). This
ensures that the next instruction after a CLI or TAP will always be executed without the possibility of an intervening
interrupt, provided I was set.
0 Interrupts enabled
1 Interrupts disabled
2
N
Negative Flag — The CPU sets the negative flag when an arithmetic operation, logic operation, or data
manipulation produces a negative result, setting bit 7 of the result. Simply loading or storing an 8-bit or 16-bit value
causes N to be set if the most significant bit of the loaded or stored value was 1.
0 Non-negative result
1 Negative result
1
Z
Zero Flag — The CPU sets the zero flag when an arithmetic operation, logic operation, or data manipulation
produces a result of 0x00 or 0x0000. Simply loading or storing an 8-bit or 16-bit value causes Z to be set if the
loaded or stored value was all 0s.
0 Non-zero result
1Zero result
0
C
Carry/Borrow Flag — The CPU sets the carry/borrow flag when an addition operation produces a carry out of bit
7 of the accumulator or when a subtraction operation requires a borrow. Some instructions — such as bit test and
branch, shift, and rotate — also clear or set the carry/borrow flag.
0 No carry out of bit 7
1 Carry out of bit 7
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of an operand for a test and then use relative addressing mode to specify the branch destination address
when the tested condition is true. For BRCLR, BRSET, CBEQ, and DBNZ, the addressing mode listed in
the instruction set tables is the addressing mode needed to access the operand to be tested, and relative
addressing mode is implied for the branch destination.
7.3.1 Inherent Addressing Mode (INH)
In this addressing mode, operands needed to complete the instruction (if any) are located within CPU
registers so the CPU does not need to access memory to get any operands.
7.3.2 Relative Addressing Mode (REL)
Relative addressing mode is used to specify the destination location for branch instructions. A signed 8-bit
offset value is located in the memory location immediately following the opcode. During execution, if the
branch condition is true, the signed offset is sign-extended to a 16-bit value and is added to the current
contents of the program counter, which causes program execution to continue at the branch destination
address.
7.3.3 Immediate Addressing Mode (IMM)
In immediate addressing mode, the operand needed to complete the instruction is included in the object
code immediately following the instruction opcode in memory. In the case of a 16-bit immediate operand,
the high-order byte is located in the next memory location after the opcode, and the low-order byte is
located in the next memory location after that.
7.3.4 Direct Addressing Mode (DIR)
In direct addressing mode, the instruction includes the low-order eight bits of an address in the direct page
(0x0000–0x00FF). During execution a 16-bit address is formed by concatenating an implied 0x00 for the
high-order half of the address and the direct address from the instruction to get the 16-bit address where
the desired operand is located. This is faster and more memory efficient than specifying a complete 16-bit
address for the operand.
7.3.5 Extended Addressing Mode (EXT)
In extended addressing mode, the full 16-bit address of the operand is located in the next two bytes of
program memory after the opcode (high byte first).
7.3.6 Indexed Addressing Mode
Indexed addressing mode has seven variations including five that use the 16-bit H:X index register pair
and two that use the stack pointer as the base reference.
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7.3.6.1 Indexed, No Offset (IX)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair as the address of
the operand needed to complete the instruction.
7.3.6.2 Indexed, No Offset with Post Increment (IX+)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair as the address of
the operand needed to complete the instruction. The index register pair is then incremented
(H:X = H:X + 0x0001) after the operand has been fetched. This addressing mode is only used for MOV
and CBEQ instructions.
7.3.6.3 Indexed, 8-Bit Offset (IX1)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus an unsigned
8-bit offset included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.4 Indexed, 8-Bit Offset with Post Increment (IX1+)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus an unsigned
8-bit offset included in the instruction as the address of the operand needed to complete the instruction.
The index register pair is then incremented (H:X = H:X + 0x0001) after the operand has been fetched. This
addressing mode is used only for the CBEQ instruction.
7.3.6.5 Indexed, 16-Bit Offset (IX2)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus a 16-bit offset
included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.6 SP-Relative, 8-Bit Offset (SP1)
This variation of indexed addressing uses the 16-bit value in the stack pointer (SP) plus an unsigned 8-bit
offset included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.7 SP-Relative, 16-Bit Offset (SP2)
This variation of indexed addressing uses the 16-bit value in the stack pointer (SP) plus a 16-bit offset
included in the instruction as the address of the operand needed to complete the instruction.
7.4 Special Operations
The CPU performs a few special operations that are similar to instructions but do not have opcodes like
other CPU instructions. In addition, a few instructions such as STOP and WAIT directly affect other MCU
circuitry. This section provides additional information about these operations.
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7.4.1 Reset Sequence
Reset can be caused by a power-on-reset (POR) event, internal conditions such as the COP (computer
operating properly) watchdog, or by assertion of an external active-low reset pin. When a reset event
occurs, the CPU immediately stops whatever it is doing (the MCU does not wait for an instruction
boundary before responding to a reset event). For a more detailed discussion about how the MCU
recognizes resets and determines the source, refer to the Resets, Interrupts, and System Configuration
chapter.
The reset event is considered concluded when the sequence to determine whether the reset came from an
internal source is done and when the reset pin is no longer asserted. At the conclusion of a reset event, the
CPU performs a 6-cycle sequence to fetch the reset vector from 0xFFFE and 0xFFFF and to fill the
instruction queue in preparation for execution of the first program instruction.
7.4.2 Interrupt Sequence
When an interrupt is requested, the CPU completes the current instruction before responding to the
interrupt. At this point, the program counter is pointing at the start of the next instruction, which is where
the CPU should return after servicing the interrupt. The CPU responds to an interrupt by performing the
same sequence of operations as for a software interrupt (SWI) instruction, except the address used for the
vector fetch is determined by the highest priority interrupt that is pending when the interrupt sequence
started.
The CPU sequence for an interrupt is:
1. Store the contents of PCL, PCH, X, A, and CCR on the stack, in that order.
2. Set the I bit in the CCR.
3. Fetch the high-order half of the interrupt vector.
4. Fetch the low-order half of the interrupt vector.
5. Delay for one free bus cycle.
6. Fetch three bytes of program information starting at the address indicated by the interrupt vector
to fill the instruction queue in preparation for execution of the first instruction in the interrupt
service routine.
After the CCR contents are pushed onto the stack, the I bit in the CCR is set to prevent other interrupts
while in the interrupt service routine. Although it is possible to clear the I bit with an instruction in the
interrupt service routine, this would allow nesting of interrupts (which is not recommended because it
leads to programs that are difficult to debug and maintain).
For compatibility with the earlier M68HC05 MCUs, the high-order half of the H:X index register pair (H)
is not saved on the stack as part of the interrupt sequence. The user must use a PSHH instruction at the
beginning of the service routine to save H and then use a PULH instruction just before the RTI that ends
the interrupt service routine. It is not necessary to save H if you are certain that the interrupt service routine
does not use any instructions or auto-increment addressing modes that might change the value of H.
The software interrupt (SWI) instruction is like a hardware interrupt except that it is not masked by the
global I bit in the CCR and it is associated with an instruction opcode within the program so it is not
asynchronous to program execution.
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7.4.3 Wait Mode Operation
The WAIT instruction enables interrupts by clearing the I bit in the CCR. It then halts the clocks to the
CPU to reduce overall power consumption while the CPU is waiting for the interrupt or reset event that
will wake the CPU from wait mode. When an interrupt or reset event occurs, the CPU clocks will resume
and the interrupt or reset event will be processed normally.
If a serial BACKGROUND command is issued to the MCU through the background debug interface while
the CPU is in wait mode, CPU clocks will resume and the CPU will enter active background mode where
other serial background commands can be processed. This ensures that a host development system can still
gain access to a target MCU even if it is in wait mode.
7.4.4 Stop Mode Operation
Usually, all system clocks, including the crystal oscillator (when used), are halted during stop mode to
minimize power consumption. In such systems, external circuitry is needed to control the time spent in
stop mode and to issue a signal to wake the target MCU when it is time to resume processing. Unlike the
earlier M68HC05 and M68HC08 MCUs, the HCS08 can be configured to keep a minimum set of clocks
running in stop mode. This optionally allows an internal periodic signal to wake the target MCU from stop
mode.
When a host debug system is connected to the background debug pin (BKGD) and the ENBDM control
bit has been set by a serial command through the background interface (or because the MCU was reset into
active background mode), the oscillator is forced to remain active when the MCU enters stop mode. In this
case, if a serial BACKGROUND command is issued to the MCU through the background debug interface
while the CPU is in stop mode, CPU clocks will resume and the CPU will enter active background mode
where other serial background commands can be processed. This ensures that a host development system
can still gain access to a target MCU even if it is in stop mode.
Recovery from stop mode depends on the particular HCS08 and whether the oscillator was stopped in stop
mode. Refer to the Modes of Operation chapter for more details.
7.4.5 BGND Instruction
The BGND instruction is new to the HCS08 compared to the M68HC08. BGND would not be used in
normal user programs because it forces the CPU to stop processing user instructions and enter the active
background mode. The only way to resume execution of the user program is through reset or by a host
debug system issuing a GO, TRACE1, or TAGGO serial command through the background debug
interface.
Software-based breakpoints can be set by replacing an opcode at the desired breakpoint address with the
BGND opcode. When the program reaches this breakpoint address, the CPU is forced to active
background mode rather than continuing the user program.
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Freescale Semiconductor 99
7.5 HCS08 Instruction Set Summary
Table 7-2 provides a summary of the HCS08 instruction set in all possible addressing modes. The table
shows operand construction, execution time in internal bus clock cycles, and cycle-by-cycle details for
each addressing mode variation of each instruction.
Table 7-2. Instruction Set Summary (Sheet 1 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
ADC #opr8i
ADC opr8a
ADC opr16a
ADC oprx16,X
ADC oprx8,X
ADC ,X
ADC oprx16,SP
ADC oprx8,SP
Add with Carry
A (A) + (M) + (C)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A9
B9
C9
D9
E9
F9
9E D9
9E E9
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
Þ Þ – Þ Þ Þ
ADD #opr8i
ADD opr8a
ADD opr16a
ADD oprx16,X
ADD oprx8,X
ADD ,X
ADD oprx16,SP
ADD oprx8,SP
Add without Carry
A (A) + (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AB
BB
CB
DB
EB
FB
9E DB
9E EB
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
Þ Þ – Þ Þ Þ
AIS #opr8i
Add Immediate Value (Signed) to
Stack Pointer
SP (SP) + (M)
IMM A7 ii 2pp – – – – – –
AIX #opr8i
Add Immediate Value (Signed) to
Index Register (H:X)
H:X (H:X) + (M)
IMM AF ii 2pp – – – – – –
AND #opr8i
AND opr8a
AND opr16a
AND oprx16,X
AND oprx8,X
AND ,X
AND oprx16,SP
AND oprx8,SP
Logical AND
A (A) & (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A4
B4
C4
D4
E4
F4
9E D4
9E E4
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 – – Þ Þ –
ASL opr8a
ASLA
ASLX
ASL oprx8,X
ASL ,X
ASL oprx8,SP
Arithmetic Shift Left
(Same as LSL)
DIR
INH
INH
IX1
IX
SP1
38
48
58
68
78
9E 68
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ Þ
ASR opr8a
ASRA
ASRX
ASR oprx8,X
ASR ,X
ASR oprx8,SP
Arithmetic Shift Right DIR
INH
INH
IX1
IX
SP1
37
47
57
67
77
9E 67
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ Þ
BCC rel Branch if Carry Bit Clear
(if C = 0) REL 24 rr 3ppp – – – – – –
C
b0
b7
0
b0
b7
C
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BCLR n,opr8a Clear Bit n in Memory
(Mn 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– – – – – –
BCS rel Branch if Carry Bit Set (if C = 1)
(Same as BLO) REL 25 rr 3ppp – – – – – –
BEQ rel Branch if Equal (if Z = 1) REL 27 rr 3ppp – – – – – –
BGE rel Branch if Greater Than or Equal To
(if N V=0) (Signed) REL 90 rr 3ppp – – – – – –
BGND
Enter active background if ENBDM=1
Waits for and processes BDM commands
until GO, TRACE1, or TAGGO
INH 82 5+ fp...ppp – – – – – –
BGT rel Branch if Greater Than (if Z| (N V)=0)
(Signed) REL 92 rr 3ppp – – – – – –
BHCC rel Branch if Half Carry Bit Clear (if H = 0) REL 28 rr 3ppp – –– – – –
BHCS rel Branch if Half Carry Bit Set (if H = 1) REL 29 rr 3ppp – – – – – –
BHI rel Branch if Higher (if C | Z = 0) REL 22 rr 3ppp – – – – – –
BHS rel Branch if Higher or Same (if C = 0)
(Same as BCC) REL 24 rr 3ppp – – – – – –
BIH rel Branch if IRQ Pin High (if IRQ pin = 1) REL 2F rr 3ppp – – – – – –
BIL rel Branch if IRQ Pin Low (if IRQ pin = 0) REL 2E rr 3ppp – – – – – –
BIT #opr8i
BIT opr8a
BIT opr16a
BIT oprx16,X
BIT oprx8,X
BIT ,X
BIT oprx16,SP
BIT oprx8,SP
Bit Test
(A) & (M)
(CCR Updated but Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A5
B5
C5
D5
E5
F5
9E D5
9E E5
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 – – Þ Þ –
BLE rel Branch if Less Than or Equal To
(if Z| (N V) 1) (Signed) REL 93 rr 3ppp – – – – – –
BLO rel Branch if Lower (if C = 1) (Same as BCS) REL 25 rr 3ppp – – – – – –
BLS rel Branch if Lower or Same (if C | Z = 1) REL 23 rr 3ppp – – – – – –
BLT rel Branch if Less Than (if N V1) (Signed) REL 91 rr 3ppp – – – – – –
BMC rel Branch if Interrupt Mask Clear (if I = 0) REL 2C rr 3ppp – – – – – –
BMI rel Branch if Minus (if N = 1) REL 2B rr 3ppp – – – – – –
BMS rel Branch if Interrupt Mask Set (if I = 1) REL 2D rr 3ppp – – – – – –
BNE rel Branch if Not Equal (if Z = 0) REL 26 rr 3ppp – – – – – –
BPL rel Branch if Plus (if N = 0) REL 2A rr 3ppp – – – – – –
Table 7-2. Instruction Set Summary (Sheet 2 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
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BRA rel Branch Always (if I = 1) REL 20 rr 3ppp – – – – – –
BRCLR n,opr8a,rel Branch if Bit n in Memory Clear (if (Mn) = 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– – – – – Þ
BRN rel Branch Never (if I = 0) REL 21 rr 3ppp – – – – – –
BRSET n,opr8a,rel Branch if Bit n in Memory Set (if (Mn) = 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– – – – – Þ
BSET n,opr8a Set Bit n in Memory (Mn 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– – – – – –
BSR rel
Branch to Subroutine
PC (PC) + 0x0002
push (PCL); SP (SP) – 0x0001
push (PCH); SP (SP) – 0x0001
PC (PC) + rel
REL AD rr 5ssppp – – – – – –
CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
Compare and... Branch if (A) = (M)
Branch if (A) = (M)
Branch if (X) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
DIR
IMM
IMM
IX1+
IX+
SP1
31
41
51
61
71
9E 61
dd rr
ii rr
ii rr
ff rr
rr
ff rr
5
4
4
5
5
6
rpppp
pppp
pppp
rpppp
rfppp
prpppp
– – – – – –
CLC Clear Carry Bit (C 0) INH 98 1p– – – – – 0
CLI Clear Interrupt Mask Bit (I 0) INH 9A 1p– – 0 – – –
CLR opr8a
CLRA
CLRX
CLRH
CLR oprx8,X
CLR ,X
CLR oprx8,SP
Clear M 0x00
A 0x00
X 0x00
H 0x00
M 0x00
M 0x00
M 0x00
DIR
INH
INH
INH
IX1
IX
SP1
3F
4F
5F
8C
6F
7F
9E 6F
dd
ff
ff
5
1
1
1
5
4
6
rfwpp
p
p
p
rfwpp
rfwp
prfwpp
0 – – 0 1 –
Table 7-2. Instruction Set Summary (Sheet 3 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
102 Freescale Semiconductor
CMP #opr8i
CMP opr8a
CMP opr16a
CMP oprx16,X
CMP oprx8,X
CMP ,X
CMP oprx16,SP
CMP oprx8,SP
Compare Accumulator with Memory
A – M
(CCR Updated But Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A1
B1
C1
D1
E1
F1
9E D1
9E E1
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
Þ –– Þ Þ Þ
COM opr8a
COMA
COMX
COM oprx8,X
COM ,X
COM oprx8,SP
Complement M (M)= 0xFF – (M)
(One’s Complement) A (A) = 0xFF – (A)
X (X) = 0xFF – (X)
M (M) = 0xFF – (M)
M (M) = 0xFF – (M)
M (M) = 0xFF – (M)
DIR
INH
INH
IX1
IX
SP1
33
43
53
63
73
9E 63
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
0 – – Þ Þ 1
CPHX opr16a
CPHX #opr16i
CPHX opr8a
CPHX oprx8,SP
Compare Index Register (H:X) with Memory
(H:X) – (M:M + 0x0001)
(CCR Updated But Operands Not Changed)
EXT
IMM
DIR
SP1
3E
65
75
9E F3
hh ll
jj kk
dd
ff
6
3
5
6
prrfpp
ppp
rrfpp
prrfpp
Þ –– Þ Þ Þ
CPX #opr8i
CPX opr8a
CPX opr16a
CPX oprx16,X
CPX oprx8,X
CPX ,X
CPX oprx16,SP
CPX oprx8,SP
Compare X (Index Register Low) with
Memory
X – M
(CCR Updated But Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A3
B3
C3
D3
E3
F3
9E D3
9E E3
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
Þ ––
Þ Þ Þ
DAA Decimal Adjust Accumulator
After ADD or ADC of BCD Values INH 72 1pU – – Þ Þ Þ
DBNZ opr8a,rel
DBNZA rel
DBNZX rel
DBNZ oprx8,X,rel
DBNZ ,X,rel
DBNZ oprx8,SP,rel
Decrement A, X, or M and Branch if Not Zero
(if (result) 0)
DBNZX Affects X Not H
DIR
INH
INH
IX1
IX
SP1
3B
4B
5B
6B
7B
9E 6B
dd rr
rr
rr
ff rr
rr
ff rr
7
4
4
7
6
8
rfwpppp
fppp
fppp
rfwpppp
rfwppp
prfwpppp
– – – – – –
DEC opr8a
DECA
DECX
DEC oprx8,X
DEC ,X
DEC oprx8,SP
Decrement M (M) – 0x01
A (A) – 0x01
X (X) – 0x01
M (M) – 0x01
M (M) – 0x01
M (M) – 0x01
DIR
INH
INH
IX1
IX
SP1
3A
4A
5A
6A
7A
9E 6A
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ –
DIV Divide
A (H:A)(X); H Remainder INH 52 6fffffp – – – – Þ Þ
EOR #opr8i
EOR opr8a
EOR opr16a
EOR oprx16,X
EOR oprx8,X
EOR ,X
EOR oprx16,SP
EOR oprx8,SP
Exclusive OR Memory with Accumulator
A (A M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A8
B8
C8
D8
E8
F8
9E D8
9E E8
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 – – Þ Þ –
Table 7-2. Instruction Set Summary (Sheet 4 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 103
INC opr8a
INCA
INCX
INC oprx8,X
INC ,X
INC oprx8,SP
Increment M (M) + 0x01
A (A) + 0x01
X (X) + 0x01
M (M) + 0x01
M (M) + 0x01
M (M) + 0x01
DIR
INH
INH
IX1
IX
SP1
3C
4C
5C
6C
7C
9E 6C
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ –
JMP opr8a
JMP opr16a
JMP oprx16,X
JMP oprx8,X
JMP ,X
Jump
PC Jump Address
DIR
EXT
IX2
IX1
IX
BC
CC
DC
EC
FC
dd
hh ll
ee ff
ff
3
4
4
3
3
ppp
pppp
pppp
ppp
ppp
– – – – – –
JSR opr8a
JSR opr16a
JSR oprx16,X
JSR oprx8,X
JSR ,X
Jump to Subroutine
PC (PC) + n (n = 1, 2, or 3)
Push (PCL); SP (SP) – 0x0001
Push (PCH); SP (SP) – 0x0001
PC Unconditional Address
DIR
EXT
IX2
IX1
IX
BD
CD
DD
ED
FD
dd
hh ll
ee ff
ff
5
6
6
5
5
ssppp
pssppp
pssppp
ssppp
ssppp
– – – – – –
LDA #opr8i
LDA opr8a
LDA opr16a
LDA oprx16,X
LDA oprx8,X
LDA ,X
LDA oprx16,SP
LDA oprx8,SP
Load Accumulator from Memory
A (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A6
B6
C6
D6
E6
F6
9E D6
9E E6
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 – – Þ Þ –
LDHX #opr16i
LDHX opr8a
LDHX opr16a
LDHX ,X
LDHX oprx16,X
LDHX oprx8,X
LDHX
oprx8,SP
Load Index Register (H:X)
H:X M:M+ 0x0001
IMM
DIR
EXT
IX
IX2
IX1
SP1
45
55
32
9E AE
9E BE
9E CE
9E FE
jj kk
dd
hh ll
ee ff
ff
ff
3
4
5
5
6
5
5
ppp
rrpp
prrpp
prrfp
pprrpp
prrpp
prrpp
0 – – Þ Þ –
LDX #opr8i
LDX opr8a
LDX opr16a
LDX oprx16,X
LDX oprx8,X
LDX ,X
LDX oprx16,SP
LDX oprx8,SP
Load X (Index Register Low) from Memory
X (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AE
BE
CE
DE
EE
FE
9E DE
9E EE
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 – – Þ Þ –
LSL opr8a
LSLA
LSLX
LSL oprx8,X
LSL ,X
LSL oprx8,SP
Logical Shift Left
(Same as ASL)
DIR
INH
INH
IX1
IX
SP1
38
48
58
68
78
9E 68
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ Þ
LSR opr8a
LSRA
LSRX
LSR oprx8,X
LSR ,X
LSR oprx8,SP
Logical Shift Right DIR
INH
INH
IX1
IX
SP1
34
44
54
64
74
9E 64
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– 0 Þ Þ
Table 7-2. Instruction Set Summary (Sheet 5 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
C
b0
b7
0
b0
b7
C0
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
104 Freescale Semiconductor
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
Move
(M)destination (M)source
In IX+/DIR and DIR/IX+ Modes,
H:X (H:X) + 0x0001
DIR/DIR
DIR/IX+
IMM/DIR
IX+/DIR
4E
5E
6E
7E
dd dd
dd
ii dd
dd
5
5
4
5
rpwpp
rfwpp
pwpp
rfwpp
0 – – Þ Þ –
MUL Unsigned multiply
X:A (X) (A) INH 42 5ffffp – 0– – – 0
NEG opr8a
NEGA
NEGX
NEG oprx8,X
NEG ,X
NEG oprx8,SP
Negate M – (M) = 0x00 – (M)
(Two’s Complement) A – (A) = 0x00 – (A)
X – (X) = 0x00 – (X)
M – (M) = 0x00 – (M)
M – (M) = 0x00 – (M)
M – (M) = 0x00 – (M)
DIR
INH
INH
IX1
IX
SP1
30
40
50
60
70
9E 60
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ Þ
NOP No Operation — Uses 1 Bus Cycle INH 9D 1p– – – – – –
NSANibble Swap Accumulator
A (A[3:0]:A[7:4]) INH 62 1p– – – – – –
ORA #opr8i
ORA opr8a
ORA opr16a
ORA oprx16,X
ORA oprx8,X
ORA ,X
ORA oprx16,SP
ORA oprx8,SP
Inclusive OR Accumulator and Memory
A (A) | (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AA
BA
CA
DA
EA
FA
9E DA
9E EA
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 – – Þ Þ –
PSHA Push Accumulator onto Stack
Push (A); SP (SP) – 0x0001 INH 87 2sp – – – – – –
PSHH Push H (Index Register High) onto Stack
Push (H); SP (SP) – 0x0001 INH 8B 2sp – – – – – –
PSHX Push X (Index Register Low) onto Stack
Push (X); SP (SP) – 0x0001 INH 89 2sp – – – – – –
PULA Pull Accumulator from Stack
SP (SP + 0x0001); PullAINH86 3ufp – – – – – –
PULH Pull H (Index Register High) from Stack
SP (SP + 0x0001); PullHINH 8A 3ufp – – – – – –
PULX Pull X (Index Register Low) from Stack
SP (SP + 0x0001); PullXINH 88 3ufp – – – – – –
ROL opr8a
ROLA
ROLX
ROL oprx8,X
ROL ,X
ROL oprx8,SP
Rotate Left through Carry DIR
INH
INH
IX1
IX
SP1
39
49
59
69
79
9E 69
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ –– Þ Þ Þ
ROR opr8a
RORA
RORX
ROR oprx8,X
ROR ,X
ROR oprx8,SP
Rotate Right through Carry DIR
INH
INH
IX1
IX
SP1
36
46
56
66
76
9E 66
dd
ff
ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
Þ ––
Þ Þ Þ
Table 7-2. Instruction Set Summary (Sheet 6 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
C
b0
b7
b0
b7
C
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 105
RSP
Reset Stack Pointer (Low Byte)
SPL 0xFF
(High Byte Not Affected)
INH 9C 1p– – – – – –
RTI
Return from Interrupt
SP (SP) + 0x0001; Pull (CCR)
SP (SP) + 0x0001; Pull (A)
SP (SP) + 0x0001; Pull (X)
SP (SP) + 0x0001; Pull (PCH)
SP (SP) + 0x0001; Pull (PCL)
INH 80 9uuuuufppp Þ Þ Þ Þ Þ Þ
RTS
Return from Subroutine
SP SP + 0x0001PullPCH)
SP SP + 0x0001; Pull (PCL)
INH 81 5ufppp – – – – – –
SBC #opr8i
SBC opr8a
SBC opr16a
SBC oprx16,X
SBC oprx8,X
SBC ,X
SBC oprx16,SP
SBC oprx8,SP
Subtract with Carry
A (A) – (M) – (C)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A2
B2
C2
D2
E2
F2
9E D2
9E E2
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
Þ ––
Þ Þ Þ
SEC Set Carry Bit
(C 1) INH 99 1p– – – – – 1
SEI Set Interrupt Mask Bit
(I 1) INH 9B 1p– – 1 – – –
STA opr8a
STA opr16a
STA oprx16,X
STA oprx8,X
STA ,X
STA oprx16,SP
STA oprx8,SP
Store Accumulator in Memory
M (A)
DIR
EXT
IX2
IX1
IX
SP2
SP1
B7
C7
D7
E7
F7
9E D7
9E E7
dd
hh ll
ee ff
ff
ee ff
ff
3
4
4
3
2
5
4
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 – – Þ Þ –
STHX opr8a
STHX opr16a
STHX oprx8,SP
Store H:X (Index Reg.)
(M:M + 0x0001) (H:X)
DIR
EXT
SP1
35
96
9E FF
dd
hh ll
ff
4
5
5
wwpp
pwwpp
pwwpp
0 – – Þ Þ –
STOP
Enable Interrupts: Stop Processing
Refer to MCU Documentation
I bit 0; Stop Processing
INH 8E 2fp... – – 0 – – –
STX opr8a
STX opr16a
STX oprx16,X
STX oprx8,X
STX ,X
STX oprx16,SP
STX oprx8,SP
Store X (Low 8 Bits of Index Register)
in Memory
M (X)
DIR
EXT
IX2
IX1
IX
SP2
SP1
BF
CF
DF
EF
FF
9E DF
9E EF
dd
hh ll
ee ff
ff
ee ff
ff
3
4
4
3
2
5
4
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 – – Þ Þ –
Table 7-2. Instruction Set Summary (Sheet 7 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
106 Freescale Semiconductor
SUB #opr8i
SUB opr8a
SUB opr16a
SUB oprx16,X
SUB oprx8,X
SUB ,X
SUB oprx16,SP
SUB oprx8,SP
Subtract
A (A) – (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A0
B0
C0
D0
E0
F0
9E D0
9E E0
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
Þ –– Þ Þ Þ
SWI
Software Interrupt
PC (PC) + 0x0001
Push (PCL); SP (SP) – 0x0001
Push (PCH); SP (SP) – 0x0001
Push (X); SP (SP) – 0x0001
Push (A); SP (SP) – 0x0001
Push (CCR); SP (SP) – 0x0001
I 1;
PCH Interrupt Vector High Byte
PCL Interrupt Vector Low Byte
INH 83 11 sssssvvfppp – – 1 – – –
TAP Transfer Accumulator to CCR
CCR (A) INH 84 1pÞ Þ Þ Þ Þ Þ
TAX
Transfer Accumulator to X (Index Register
Low)
X (A)
INH97 1p– – – – – –
TPA Transfer CCR to Accumulator
A (CCR) INH 85 1p– – – – – –
TST opr8a
TSTA
TSTX
TST oprx8,X
TST ,X
TST oprx8,SP
Test for Negative or Zero (M) – 0x00
(A) – 0x00
(X) – 0x00
(M) – 0x00
(M) – 0x00
(M) – 0x00
DIR
INH
INH
IX1
IX
SP1
3D
4D
5D
6D
7D
9E 6D
dd
ff
ff
4
1
1
4
3
5
rfpp
p
p
rfpp
rfp
prfpp
0 – – Þ Þ –
TSX Transfer SP to Index Reg.
H:X (SP) + 0x0001 INH 95 2fp – – – – – –
TXA Transfer X (Index Reg. Low) to Accumulator
A (X) INH 9F 1p– – – – – –
Table 7-2. Instruction Set Summary (Sheet 8 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 107
TXS Transfer Index Reg. to SP
SP (H:X) – 0x0001 INH 94 2fp – – – – – –
WAIT Enable Interrupts; Wait for Interrupt
I bit 0; Halt CPU INH 8F 2+ fp... – – 0 – – –
Source Form: Everything in the source forms columns, except expressions in italic characters, is literal information which must appear in
the assembly source file exactly as shown. The initial 3- to 5-letter mnemonic and the characters (# , ( ) and +) are always a literal
characters.
nAny label or expression that evaluates to a single integer in the range 0-7.
opr8i Any label or expression that evaluates to an 8-bit immediate value.
opr16i Any label or expression that evaluates to a 16-bit immediate value.
opr8a Any label or expression that evaluates to an 8-bit direct-page address (0x00xx).
opr16a Any label or expression that evaluates to a 16-bit address.
oprx8 Any label or expression that evaluates to an unsigned 8-bit value, used for indexed addressing.
oprx16 Any label or expression that evaluates to a 16-bit value, used for indexed addressing.
rel Any label or expression that refers to an address that is within –128 to +127 locations from the start of the next instruction.
Operation Symbols:
A Accumulator
CCR Condition code register
H Index register high byte
M Memory location
nAny bit
opr Operand (one or two bytes)
PC Program counter
PCH Program counter high byte
PCL Program counter low byte
rel Relative program counter offset byte
SP Stack pointer
SPL Stack pointer low byte
X Index register low byte
& Logical AND
| Logical OR
Logical EXCLUSIVE OR
( ) Contents of
Add
– Subtract, Negation (two’s complement)
Multiply
Divide
# Immediate value
Loaded with
: Concatenated with
Addressing Modes:
DIR Direct addressing mode
EXT Extended addressing mode
IMM Immediate addressing mode
INH Inherent addressing mode
IX Indexed, no offset addressing mode
IX1 Indexed, 8-bit offset addressing mode
IX2 Indexed, 16-bit offset addressing mode
IX+ Indexed, no offset, post increment addressing mode
IX1+ Indexed, 8-bit offset, post increment addressing mode
REL Relative addressing mode
SP1 Stack pointer, 8-bit offset addressing mode
SP2 Stack pointer 16-bit offset addressing mode
Cycle-by-Cycle Codes:
fFree cycle. This indicates a cycle where the CPU
does not require use of the system buses. An f
cycle is always one cycle of the system bus clock
and is always a read cycle.
pProgryam fetch; read from next consecutive
location in program memory
rRead 8-bit operand
s Push (write) one byte onto stack
uPop (read) one byte from stack
vRead vector from 0xFFxx (high byte first)
wWrite 8-bit operand
CCR Bits:
VOverflow bit
H Half-carry bit
I Interrupt mask
N Negative bit
Z Zero bit
C Carry/borrow bit
CCR Effects:
ÞSet or cleared
– Not affected
U Undefined
Table 7-2. Instruction Set Summary (Sheet 9 of 9)
Source
Form Operation
Address
Mode
Object Code
Cycles
Cyc-by-Cyc
Details
Affect
on CCR
VH I N Z C
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
108 Freescale Semiconductor
Table 7-3. Opcode Map (Sheet 1 of 2)
Bit-Manipulation Branch Read-Modify-Write Control Register/Memory
00 5
BRSET0
3DIR
10 5
BSET0
2DIR
20 3
BRA
2REL
30 5
NEG
2DIR
40 1
NEGA
1INH
50 1
NEGX
1INH
60 5
NEG
2IX1
70 4
NEG
1IX
80 9
RTI
1INH
90 3
BGE
2REL
A0 2
SUB
2IMM
B0 3
SUB
2DIR
C0 4
SUB
3 EXT
D0 4
SUB
3IX2
E0 3
SUB
2IX1
F0 3
SUB
1IX
01 5
BRCLR0
3DIR
11 5
BCLR0
2DIR
21 3
BRN
2REL
31 5
CBEQ
3DIR
41 4
CBEQA
3IMM
51 4
CBEQX
3IMM
61 5
CBEQ
3IX1+
71 5
CBEQ
2IX+
81 6
RTS
1INH
91 3
BLT
2REL
A1 2
CMP
2IMM
B1 3
CMP
2DIR
C1 4
CMP
3 EXT
D1 4
CMP
3IX2
E1 3
CMP
2IX1
F1 3
CMP
1IX
02 5
BRSET1
3DIR
12 5
BSET1
2DIR
22 3
BHI
2REL
32 5
LDHX
3EXT
42 5
MUL
1INH
52 6
DIV
1INH
62 1
NSA
1INH
72 1
DAA
1INH
82 5+
BGND
1INH
92 3
BGT
2REL
A2 2
SBC
2IMM
B2 3
SBC
2DIR
C2 4
SBC
3 EXT
D2 4
SBC
3IX2
E2 3
SBC
2IX1
F2 3
SBC
1IX
03 5
BRCLR1
3DIR
13 5
BCLR1
2DIR
23 3
BLS
2REL
33 5
COM
2DIR
43 1
COMA
1INH
53 1
COMX
1INH
63 5
COM
2IX1
73 4
COM
1IX
83 11
SWI
1INH
93 3
BLE
2REL
A3 2
CPX
2IMM
B3 3
CPX
2DIR
C3 4
CPX
3 EXT
D3 4
CPX
3IX2
E3 3
CPX
2IX1
F3 3
CPX
1IX
04 5
BRSET2
3DIR
14 5
BSET2
2DIR
24 3
BCC
2REL
34 5
LSR
2DIR
44 1
LSRA
1INH
54 1
LSRX
1INH
64 5
LSR
2IX1
74 4
LSR
1IX
84 1
TA P
1INH
94 2
TXS
1INH
A4 2
AND
2IMM
B4 3
AND
2DIR
C4 4
AND
3 EXT
D4 4
AND
3IX2
E4 3
AND
2IX1
F4 3
AND
1IX
05 5
BRCLR2
3DIR
15 5
BCLR2
2DIR
25 3
BCS
2REL
35 4
STHX
2DIR
45 3
LDHX
3IMM
55 4
LDHX
2DIR
65 3
CPHX
3IMM
75 5
CPHX
2DIR
85 1
TPA
1INH
95 2
TSX
1INH
A5 2
BIT
2IMM
B5 3
BIT
2DIR
C5 4
BIT
3 EXT
D5 4
BIT
3IX2
E5 3
BIT
2IX1
F5 3
BIT
1IX
06 5
BRSET3
3DIR
16 5
BSET3
2DIR
26 3
BNE
2REL
36 5
ROR
2DIR
46 1
RORA
1INH
56 1
RORX
1INH
66 5
ROR
2IX1
76 4
ROR
1IX
86 3
PULA
1INH
96 5
STHX
3EXT
A6 2
LDA
2IMM
B6 3
LDA
2DIR
C6 4
LDA
3 EXT
D6 4
LDA
3IX2
E6 3
LDA
2IX1
F6 3
LDA
1IX
07 5
BRCLR3
3DIR
17 5
BCLR3
2DIR
27 3
BEQ
2REL
37 5
ASR
2DIR
47 1
ASRA
1INH
57 1
ASRX
1INH
67 5
ASR
2IX1
77 4
ASR
1IX
87 2
PSHA
1INH
97 1
TA X
1INH
A7 2
AIS
2IMM
B7 3
STA
2DIR
C7 4
STA
3 EXT
D7 4
STA
3IX2
E7 3
STA
2IX1
F7 2
STA
1IX
08 5
BRSET4
3DIR
18 5
BSET4
2DIR
28 3
BHCC
2REL
38 5
LSL
2DIR
48 1
LSLA
1INH
58 1
LSLX
1INH
68 5
LSL
2IX1
78 4
LSL
1IX
88 3
PULX
1INH
98 1
CLC
1INH
A8 2
EOR
2IMM
B8 3
EOR
2DIR
C8 4
EOR
3 EXT
D8 4
EOR
3IX2
E8 3
EOR
2IX1
F8 3
EOR
1IX
09 5
BRCLR4
3DIR
19 5
BCLR4
2DIR
29 3
BHCS
2REL
39 5
ROL
2DIR
49 1
ROLA
1INH
59 1
ROLX
1INH
69 5
ROL
2IX1
79 4
ROL
1IX
89 2
PSHX
1INH
99 1
SEC
1INH
A9 2
ADC
2IMM
B9 3
ADC
2DIR
C9 4
ADC
3 EXT
D9 4
ADC
3IX2
E9 3
ADC
2IX1
F9 3
ADC
1IX
0A 5
BRSET5
3DIR
1A 5
BSET5
2DIR
2A 3
BPL
2REL
3A 5
DEC
2DIR
4A 1
DECA
1INH
5A 1
DECX
1INH
6A 5
DEC
2IX1
7A 4
DEC
1IX
8A 3
PULH
1INH
9A 1
CLI
1INH
AA 2
ORA
2IMM
BA 3
ORA
2DIR
CA 4
ORA
3 EXT
DA 4
ORA
3IX2
EA 3
ORA
2IX1
FA 3
ORA
1IX
0B 5
BRCLR5
3DIR
1B 5
BCLR5
2DIR
2B 3
BMI
2REL
3B 7
DBNZ
3DIR
4B 4
DBNZA
2INH
5B 4
DBNZX
2INH
6B 7
DBNZ
3IX1
7B 6
DBNZ
2IX
8B 2
PSHH
1INH
9B 1
SEI
1INH
AB 2
ADD
2IMM
BB 3
ADD
2DIR
CB 4
ADD
3 EXT
DB 4
ADD
3IX2
EB 3
ADD
2IX1
FB 3
ADD
1IX
0C 5
BRSET6
3DIR
1C 5
BSET6
2DIR
2C 3
BMC
2REL
3C 5
INC
2DIR
4C 1
INCA
1INH
5C 1
INCX
1INH
6C 5
INC
2IX1
7C 4
INC
1IX
8C 1
CLRH
1INH
9C 1
RSP
1INH
BC 3
JMP
2DIR
CC 4
JMP
3 EXT
DC 4
JMP
3IX2
EC 3
JMP
2IX1
FC 3
JMP
1IX
0D 5
BRCLR6
3DIR
1D 5
BCLR6
2DIR
2D 3
BMS
2REL
3D 4
TST
2DIR
4D 1
TSTA
1INH
5D 1
TSTX
1INH
6D 4
TST
2IX1
7D 3
TST
1IX
9D 1
NOP
1INH
AD 5
BSR
2REL
BD 5
JSR
2DIR
CD 6
JSR
3 EXT
DD 6
JSR
3IX2
ED 5
JSR
2IX1
FD 5
JSR
1IX
0E 5
BRSET7
3DIR
1E 5
BSET7
2DIR
2E 3
BIL
2REL
3E 6
CPHX
3EXT
4E 5
MOV
3DD
5E 5
MOV
2DIX+
6E 4
MOV
3IMD
7E 5
MOV
2IX+D
8E 2+
STOP
1INH
9E
Page 2 AE 2
LDX
2IMM
BE 3
LDX
2DIR
CE 4
LDX
3 EXT
DE 4
LDX
3IX2
EE 3
LDX
2IX1
FE 3
LDX
1IX
0F 5
BRCLR7
3DIR
1F 5
BCLR7
2DIR
2F 3
BIH
2REL
3F 5
CLR
2DIR
4F 1
CLRA
1INH
5F 1
CLRX
1INH
6F 5
CLR
2IX1
7F 4
CLR
1IX
8F 2+
WAIT
1INH
9F 1
TXA
1INH
AF 2
AIX
2IMM
BF 3
STX
2DIR
CF 4
STX
3 EXT
DF 4
STX
3IX2
EF 3
STX
2IX1
FF 2
STX
1IX
INH Inherent REL Relative SP1 Stack Pointer, 8-Bit Offset
IMM Immediate IX Indexed, No Offset SP2 Stack Pointer, 16-Bit Offset
DIR Direct IX1 Indexed, 8-Bit Offset IX+ Indexed, No Offset with
EXT Extended IX2 Indexed, 16-Bit Offset Post Increment
DD DIR to DIR IMD IMM to DIR IX1+ Indexed, 1-Byte Offset with
IX+D IX+ to DIR DIX+ DIR to IX+ Post Increment Opcode in
Hexadecimal
Number of Bytes
F0 3
SUB
1IX
HCS08 Cycles
Instruction Mnemonic
Addressing Mode
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 109
Bit-Manipulation Branch Read-Modify-Write Control Register/Memory
9E60 6
NEG
3SP1
9ED0 5
SUB
4SP2
9EE0 4
SUB
3SP1
9E61 6
CBEQ
4SP1
9ED1 5
CMP
4SP2
9EE1 4
CMP
3SP1
9ED2 5
SBC
4SP2
9EE2 4
SBC
3SP1
9E63 6
COM
3SP1
9ED3 5
CPX
4SP2
9EE3 4
CPX
3SP1
9EF3 6
CPHX
3SP1
9E64 6
LSR
3SP1
9ED4 5
AND
4SP2
9EE4 4
AND
3SP1
9ED5 5
BIT
4SP2
9EE5 4
BIT
3SP1
9E66 6
ROR
3SP1
9ED6 5
LDA
4SP2
9EE6 4
LDA
3SP1
9E67 6
ASR
3SP1
9ED7 5
STA
4SP2
9EE7 4
STA
3SP1
9E68 6
LSL
3SP1
9ED8 5
EOR
4SP2
9EE8 4
EOR
3SP1
9E69 6
ROL
3SP1
9ED9 5
ADC
4SP2
9EE9 4
ADC
3SP1
9E6A 6
DEC
3SP1
9EDA 5
ORA
4SP2
9EEA 4
ORA
3SP1
9E6B 8
DBNZ
4SP1
9EDB 5
ADD
4SP2
9EEB 4
ADD
3SP1
9E6C 6
INC
3SP1
9E6D 5
TST
3SP1
9EAE 5
LDHX
2IX
9EBE 6
LDHX
4IX2
9ECE 5
LDHX
3IX1
9EDE 5
LDX
4SP2
9EEE 4
LDX
3SP1
9EFE 5
LDHX
3SP1
9E6F 6
CLR
3SP1
9EDF 5
STX
4SP2
9EEF 4
STX
3SP1
9EFF 5
STHX
3SP1
INH Inherent REL Relative SP1 Stack Pointer, 8-Bit Offset
IMM Immediate IX Indexed, No Offset SP2 Stack Pointer, 16-Bit Offset
DIR Direct IX1 Indexed, 8-Bit Offset IX+ Indexed, No Offset with
EXT Extended IX2 Indexed, 16-Bit Offset Post Increment
DD DIR to DIR IMD IMM to DIR IX1+ Indexed, 1-Byte Offset with
IX+D IX+ to DIR DIX+ DIR to IX+ Post Increment
Note: All Sheet 2 Opcodes are Preceded by the Page 2 Prebyte (9E) Prebyte (9E) and Opcode in
Hexadecimal
Number of Bytes
9E60 6
NEG
3SP1
HCS08 Cycles
Instruction Mnemonic
Addressing Mode
Table 7-3. Opcode Map (Sheet 2 of 2)
Chapter 7 Central Processor Unit (S08CPUV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
110 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 111
Chapter 8
5-V Analog Comparator (S08ACMPV2)
8.1 Introduction
The analog comparator module (ACMP) provides a circuit for comparing two analog input voltages or for
comparing one analog input voltage to an internal reference voltage. The comparator circuit is designed to
operate across the full range of the supply voltage (rail-to-rail operation).
Figure 8-1 shows the MC9S08SG8 block diagram with the ACMP module highlighted.
8.1.1 ACMP Configuration Information
When using the bandgap reference voltage for input to ACMP+, the user must enable the bandgap buffer
by setting BGBE =1 in SPMSC1 see Section 5.7.6, “System Power Management Status and Control 1
Register (SPMSC1)”. For value of bandgap voltage reference see Section A.6, “DC Characteristics”.
8.1.2 ACMP in Stop3 Mode
S08ACMPV2 continues to operate in stop3 mode if enabled. If ACOPE is enabled, comparator output will
operate as in the normal operating mode and will control ACMPO pin. The MCU is brought out of stop
when a compare event occurs and ACIE is enabled; ACF flag sets accordingly.
8.1.3 ACMP/TPM Configuration Information
The ACMP module can be configured to connect the output of the analog comparator to TPM1 input
capture channel 0 by setting ACIC in SOPT2. With ACIC set, the TPM1CH0 pin is not available externally
regardless of the configuration of the TPM1 module for channel 0.
Chapter 8 5-V Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
112 Freescale Semiconductor
Figure 8-1. MC9S08SG8 Block Diagram with ACMP Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1: Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 113
8.1.4 Features
The ACMP has the following features:
• Full rail to rail supply operation.
• Selectable interrupt on rising edge, falling edge, or either rising or falling edges of comparator
output.
• Option to compare to fixed internal bandgap reference voltage.
• Option to allow comparator output to be visible on a pin, ACMPO.
• Can operate in stop3 mode
8.1.5 Modes of Operation
This section defines the ACMP operation in wait, stop and background debug modes.
8.1.5.1 ACMP in Wait Mode
The ACMP continues to run in wait mode if enabled before executing the WAIT instruction. Therefore,
the ACMP can be used to bring the MCU out of wait mode if the ACMP interrupt, ACIE is enabled. For
lowest possible current consumption, the ACMP should be disabled by software if not required as an
interrupt source during wait mode.
8.1.5.2 ACMP in Stop Modes
8.1.5.2.1 Stop3 Mode Operation
The ACMP continues to operate in Stop3 mode if enabled and compare operation remains active. If
ACOPE is enabled, comparator output operates as in the normal operating mode and comparator output is
placed onto the external pin. The MCU is brought out of stop when a compare event occurs and ACIE is
enabled; ACF flag sets accordingly.
If stop is exited with a reset, the ACMP will be put into its reset state.
8.1.5.2.2 Stop2 and Stop1 Mode Operation
During either Stop2 and Stop1 mode, the ACMP module will be fully powered down. Upon wake-up from
Stop2 or Stop1 mode, the ACMP module will be in the reset state.
8.1.5.3 ACMP in Active Background Mode
When the microcontroller is in active background mode, the ACMP will continue to operate normally.
8.1.6 Block Diagram
The block diagram for the Analog Comparator module is shown Figure 8-2.
Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
114 Freescale Semiconductor
Figure 8-2. Analog Comparator 5V (ACMP5) Block Diagram
+
-
Interrupt
Control
Internal
Reference
ACBGS
Internal Bus
Status & Control
Register
ACMOD
set ACF
ACME ACF
ACIE
ACOPE
Comparator
ACMP
INTERRUPT
REQUEST
ACMP+
ACMP-
ACMPO
Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 115
8.2 External Signal Description
The ACMP has two analog input pins, ACMP+ and ACMP- and one digital output pin ACMPO. Each of
these pins can accept an input voltage that varies across the full operating voltage range of the MCU. As
shown in Figure 8-2, the ACMP- pin is connected to the inverting input of the comparator, and the ACMP+
pin is connected to the comparator non-inverting input if ACBGS is a 0. As shown in Figure 8-2, the
ACMPO pin can be enabled to drive an external pin.
The signal properties of ACMP are shown in Table 8-1.
8.3 Memory Map
8.3.1 Register Descriptions
The ACMP includes one register:
• An 8-bit status and control register
Refer to the direct-page register summary in the memory section of this data sheet for the absolute address
assignments for all ACMP registers.This section refers to registers and control bits only by their names .
Some MCUs may have more than one ACMP, so register names include placeholder characters to identify
which ACMP is being referenced.
Table 8-1. Signal Properties
Signal Function I/O
ACMP- Inverting analog input to the ACMP.
(Minus input)
I
ACMP+ Non-inverting analog input to the ACMP.
(Positive input)
I
ACMPO Digital output of the ACMP. O
Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
116 Freescale Semiconductor
8.3.1.1 ACMP Status and Control Register (ACMPSC)
ACMPSC contains the status flag and control bits which are used to enable and configure the ACMP.
76543210
R
ACME ACBGS ACF ACIE
ACO
ACOPE ACMOD
W
Reset:00000000
= Unimplemented
Figure 8-3. ACMP Status and Control Register
Table 8-2. ACMP Status and Control Register Field Descriptions
Field Description
7
ACME
Analog Comparator Module Enable — ACME enables the ACMP module.
0 ACMP not enabled
1 ACMP is enabled
6
ACBGS
Analog Comparator Bandgap Select — ACBGS is used to select between the bandgap reference voltage or
the ACMP+ pin as the input to the non-inverting input of the analog comparatorr.
0 External pin ACMP+ selected as non-inverting input to comparator
1 Internal reference select as non-inverting input to comparator
Note: refer to this chapter introduction to verify if any other config bits are necessary to enable the bandgap
reference in the chip level.
5
ACF
Analog Comparator Flag — ACF is set when a compare event occurs. Compare events are defined by ACMOD.
ACF is cleared by writing a one to ACF.
0 Compare event has not occured
1 Compare event has occured
4
ACIE
Analog Comparator Interrupt Enable — ACIE enables the interrupt from the ACMP. When ACIE is set, an
interupt will be asserted when ACF is set.
0 Interrupt disabled
1 Interrupt enabled
3
ACO
Analog Comparator Output — Reading ACO will return the current value of the analog comparator output. ACO
is reset to a 0 and will read as a 0 when the ACMP is disabled (ACME = 0).
2
ACOPE
Analog Comparator Output Pin Enable — ACOPE is used to enable the comparator output to be placed onto
the external pin, ACMPO.
0 Analog comparator output not available on ACMPO
1 Analog comparator output is driven out on ACMPO
1:0
ACMOD
Analog Comparator Mode — ACMOD selects the type of compare event which sets ACF.
00 Encoding 0 — Comparator output falling edge
01 Encoding 1 — Comparator output rising edge
10 Encoding 2 — Comparator output falling edge
11 Encoding 3 — Comparator output rising or falling edge
Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 117
8.4 Functional Description
The analog comparator can be used to compare two analog input voltages applied to ACMP+ and ACMP-;
or it can be used to compare an analog input voltage applied to ACMP- with an internal bandgap reference
voltage. ACBGS is used to select between the bandgap reference voltage or the ACMP+ pin as the input
to the non-inverting input of the analog comparator. The comparator output is high when the non-inverting
input is greater than the inverting input, and is low when the non-inverting input is less than the inverting
input. ACMOD is used to select the condition which will cause ACF to be set. ACF can be set on a rising
edge of the comparator output, a falling edge of the comparator output, or either a rising or a falling edge
(toggle). The comparator output can be read directly through ACO. The comparator output can be driven
onto the ACMPO pin using ACOPE.
Analog Comparator (S08ACMPV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
118 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 119
Chapter 9
Analog-to-Digital Converter (S08ADCV1)
9.1 Introduction
The 10-bit analog-to-digital converter (ADC) is a successive approximation ADC designed for operation
within an integrated microcontroller system-on-chip.
NOTE
The MC9S08SG8 Family of devices do not include stop1 mode.
The ADC channel assignments, alternate clock function, and hardware trigger function are configured as
described below for the MC9S08SG8 family of devices.
9.1.1 Channel Assignments
The ADC channel assignments for the MC9S08SG8 devices are shown in Table 9-1. Reserved channels
convert to an unknown value.
Table 9-1. ADC Channel Assignment
ADCH Channel Input ADCH Channel Input
00000 AD0 PTA0/ADP0 10000 AD16 VSS
00001 AD1 PTA1/ADP1 10001 AD17 VSS
00010 AD2 PTA2/ADP2 10010 AD18 VSS
00011 AD3 PTA3/ADP3 10011 AD19 VSS
00100 AD4 PTB0/ADP4 10100 AD20 VSS
00101 AD5 PTB1/ADP5 10101 AD21 Reserved
00110 AD6 PTB2/ADP6 10110 AD22 Reserved
00111 AD7 PTB3/ADP7 10111 AD23 Reserved
01000 AD8 PTC0/ADP8 11000 AD24 Reserved
01001 AD9 PTC1/ADP9 11001 AD25 Reserved
01010 AD10 PTC2/ADP10 11010 AD26 Temperature Sensor1
1For information, see Section 9.1.4, “Temperature Sensor”.
01011 AD11 PTC3/ADP11 11011 AD27 Internal Bandgap2
2Requires BGBE =1 in SPMSC1 see Section 5.7.7, “System Power Management Status and Control 2 Register (SPMSC2)”. For
value of bandgap voltage reference see A.6, “DC Characteristics”.
01100 AD12 VSS 11100 - Reserved
01101 AD13 VSS 11101 VREFH VDD
01110 AD14 VSS 11110 VREFL VSS
01111 AD15 VSS 11111 Module Disabled None
Chapter 9 Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
120 Freescale Semiconductor
9.1.2 Alternate Clock
The ADC module is capable of performing conversions using the MCU bus clock, the bus clock divided
by two, the local asynchronous clock (ADACK) within the module, or the alternate clock, ALTCLK. The
alternate clock for the MC9S08SG8 MCU devices is the external reference clock (ICSERCLK).
The selected clock source must run at a frequency such that the ADC conversion clock (ADCK) runs at a
frequency within its specified range (fADCK) after being divided down from the ALTCLK input as
determined by the ADIV bits.
ALTCLK is active while the MCU is in wait mode provided the conditions described above are met. This
allows ALTCLK to be used as the conversion clock source for the ADC while the MCU is in wait mode.
ALTCLK cannot be used as the ADC conversion clock source while the MCU is in either stop2 or stop3.
9.1.3 Hardware Trigger
The ADC hardware trigger, ADHWT, is the output from the real time counter (RTC). The RTC counter
can be clocked by either ICSERCLK, ICSIRCLK or a nominal 1 kHz clock source.
The period of the RTC is determined by the input clock frequency, the RTCPS bits, and the RTCMOD
register. When the ADC hardware trigger is enabled, a conversion is initiated upon an RTC counter
overflow. The RTIE does not have to be set for RTC to cause a hardware trigger.
The RTC can be configured to cause a hardware trigger in MCU run, wait, and stop3.
9.1.4 Temperature Sensor
To use the on-chip temperature sensor, the user must perform the following:
• Configure ADC for long sample with a maximum of 1 MHz clock
• Convert the bandgap voltage reference channel (AD27)
— By converting the digital value of the bandgap voltage reference channel using the value of
VBG the user can determine VDD. For value of bandgap voltage, see Section A.6, “DC
Characteristics”.
• Convert the temperature sensor channel (AD26)
— By using the calculated value of VDD, convert the digital value of AD26 into a voltage, VTEMP
Equation 9-1 provides an approximate transfer function of the on-chip temperature sensor.
TempC = 25 - ((VTEMP - VTEMP25) mEqn. 9-1
where:
•V
TEMP is the voltage of the temperature sensor channel at the ambient temperature.
•V
TEMP25 is the voltage of the temperature sensor channel at 25C.
• m is the hot or cold voltage versus temperature slope in V/C.
Chapter 9 Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 121
For temperature calculations, use the VTEMP25 and m values from the ADC Electricals table.
In application code, the user reads the temperature sensor channel, calculates VTEMP
, and compares to
VTEMP25. If VTEMP is greater than VTEMP25, the cold slope value is applied in Equation 9-1. If VTEMP is
less than VTEMP25, the hot slope value is applied in Equation 9-1. To improve accuracy , calibrate the
bandgap voltage reference and temperature sensor.
Calibrating at 25C will improve accuracy to 4.5C.
Calibration at 3 points, -40C, 25C, and 125C will improve accuracy to 2.5C. Once calibration has
been completed, the user will need to calculate the slope for both hot and cold. In application code, the
user would then calculate the temperature using Equation 9-1 as detailed above and then determine if the
temperature is above or below 25C. Once determined if the temperature is above or below 25C, the user
can recalculate the temperature using the hot or cold slope value obtained during calibration.
Figure 9-1 shows the MC9S08SG8 block diagram with the ADC module highlighted.
Chapter 9 Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
122 Freescale Semiconductor
Figure 9-1. MC9S08SG8 Block Diagram with ADC Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 123
9.1.5 Features
Features of the ADC module include:
• Linear successive approximation algorithm with 10 bits resolution.
• Up to 28 analog inputs.
• Output formatted in 10- or 8-bit right-justified format.
• Single or continuous conversion (automatic return to idle after single conversion).
• Configurable sample time and conversion speed/power.
• Conversion complete flag and interrupt.
• Input clock selectable from up to four sources.
• Operation in wait or stop3 modes for lower noise operation.
• Asynchronous clock source for lower noise operation.
• Selectable asynchronous hardware conversion trigger.
• Automatic compare with interrupt for less-than, or greater-than or equal-to, programmable value.
9.1.6 Block Diagram
Figure 9-2 provides a block diagram of the ADC module
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
124 Freescale Semiconductor
Figure 9-2. ADC Block Diagram
9.2 External Signal Description
The ADC module supports up to 28 separate analog inputs. It also requires four supply/reference/ground
connections.
Table 9-2. Signal Properties
Name Function
AD27–AD0 Analog Channel inputs
VREFH High reference voltage
VREFL Low reference voltage
VDDAD Analog power supply
VSSAD Analog ground
AD0
• • •
AD27
VREFH
VREFL
ADVIN
ADCH
Control Sequencer
initialize
sample
convert
transfer
abort
Clock
Divide
ADCK
Async
Clock Gen
Bus Clock
ALTCLK
ADICLK
ADIV
ADACK
ADCO
ADLSMP
ADLPC
MODE
complete
Data Registers
SAR Converter
Compare Value Registers
Compare
Value
Sum
AIEN
COCO
Interrupt
AIEN
COCO
ADTRG
1
2
1 2
MCU STOP
ADHWT
Logic
ACFGT
3
Compare true
3Compare true ADCCFG
ADCSC1
ADCSC2
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 125
9.2.1 Analog Power (VDDAD)
The ADC analog portion uses VDDAD as its power connection. In some packages, VDDAD is connected
internally to VDD. If externally available, connect the VDDAD pin to the same voltage potential as VDD.
External filtering may be necessary to ensure clean VDDAD for good results.
9.2.2 Analog Ground (VSSAD)
The ADC analog portion uses VSSAD as its ground connection. In some packages, VSSAD is connected
internally to VSS. If externally available, connect the VSSAD pin to the same voltage potential as VSS.
9.2.3 Voltage Reference High (VREFH)
VREFH is the high reference voltage for the converter. In some packages, VREFH is connected internally to
VDDAD. If externally available, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD).
9.2.4 Voltage Reference Low (VREFL)
VREFL is the low reference voltage for the converter. In some packages, VREFL is connected internally to
VSSAD. If externally available, connect the VREFL pin to the same voltage potential as VSSAD.
9.2.5 Analog Channel Inputs (ADx)
The ADC module supports up to 28 separate analog inputs. An input is selected for conversion through
the ADCH channel select bits.
9.3 Register Definition
These memory mapped registers control and monitor operation of the ADC:
• Status and control register, ADCSC1
• Status and control register, ADCSC2
• Data result registers, ADCRH and ADCRL
• Compare value registers, ADCCVH and ADCCVL
• Configuration register, ADCCFG
• Pin enable registers, APCTL1, APCTL2, APCTL3
9.3.1 Status and Control Register 1 (ADCSC1)
This section describes the function of the ADC status and control register (ADCSC1). Writing ADCSC1
aborts the current conversion and initiates a new conversion (if the ADCH bits are equal to a value other
than all 1s).
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
126 Freescale Semiconductor
7654 3 210
RCOCO
AIEN ADCO ADCH
W
Reset:0001 1 111
= Unimplemented or Reserved
Figure 9-3. Status and Control Register (ADCSC1)
Table 9-3. ADCSC1 Register Field Descriptions
Field Description
7
COCO
Conversion Complete Flag — The COCO flag is a read-only bit which is set each time a conversion is
completed when the compare function is disabled (ACFE = 0). When the compare function is enabled (ACFE =
1) the COCO flag is set upon completion of a conversion only if the compare result is true. This bit is cleared
whenever ADCSC1 is written or whenever ADCRL is read.
0 Conversion not completed
1 Conversion completed
6
AIEN
Interrupt Enable — AIEN is used to enable conversion complete interrupts. When COCO becomes set while
AIEN is high, an interrupt is asserted.
0 Conversion complete interrupt disabled
1 Conversion complete interrupt enabled
5
ADCO
Continuous Conversion Enable — ADCO is used to enable continuous conversions.
0 One conversion following a write to the ADCSC1 when software triggered operation is selected, or one
conversion following assertion of ADHWT when hardware triggered operation is selected.
1 Continuous conversions initiated following a write to ADCSC1 when software triggered operation is selected.
Continuous conversions are initiated by an ADHWT event when hardware triggered operation is selected.
4:0
ADCH
Input Channel Select — The ADCH bits form a 5-bit field which is used to select one of the input channels. The
input channels are detailed in Figure 9-4.
The successive approximation converter subsystem is turned off when the channel select bits are all set to 1.
This feature allows for explicit disabling of the ADC and isolation of the input channel from all sources.
Terminating continuous conversions this way will prevent an additional, single conversion from being performed.
It is not necessary to set the channel select bits to all 1s to place the ADC in a low-power state when continuous
conversions are not enabled because the module automatically enters a low-power state when a conversion
completes.
Figure 9-4. Input Channel Select
ADCH Input Select ADCH Input Select
00000 AD0 10000 AD16
00001 AD1 10001 AD17
00010 AD2 10010 AD18
00011 AD3 10011 AD19
00100 AD4 10100 AD20
00101 AD5 10101 AD21
00110 AD6 10110 AD22
00111 AD7 10111 AD23
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 127
9.3.2 Status and Control Register 2 (ADCSC2)
The ADCSC2 register is used to control the compare function, conversion trigger and conversion active
of the ADC module.
Figure 9-5. Status and Control Register 2 (ADCSC2)
01000 AD8 11000 AD24
01001 AD9 11001 AD25
01010 AD10 11010 AD26
01011 AD11 11011 AD27
01100 AD12 11100 Reserved
01101 AD13 11101 VREFH
01110 AD14 11110 VREFL
01111 AD15 11111 Module disabled
7654 3 210
RADACT
ADTRG ACFE ACFGT
00
R1
1Bits 1 and 0 are reserved bits that must always be written to 0.
R1
W
Reset:0000 0 000
= Unimplemented or Reserved
Table 9-4. ADCSC2 Register Field Descriptions
Field Description
7
ADACT
Conversion Active — ADACT indicates that a conversion is in progress. ADACT is set when a conversion is
initiated and cleared when a conversion is completed or aborted.
0 Conversion not in progress
1 Conversion in progress
6
ADTRG
Conversion Trigger Select — ADTRG is used to select the type of trigger to be used for initiating a conversion.
Two types of trigger are selectable: software trigger and hardware trigger. When software trigger is selected, a
conversion is initiated following a write to ADCSC1. When hardware trigger is selected, a conversion is initiated
following the assertion of the ADHWT input.
0 Software trigger selected
1 Hardware trigger selected
Figure 9-4. Input Channel Select (continued)
ADCH Input Select ADCH Input Select
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
128 Freescale Semiconductor
9.3.3 Data Result High Register (ADCRH)
ADCRH contains the upper two bits of the result of a 10-bit conversion. When configured for 8-bit
conversions both ADR8 and ADR9 are equal to zero. ADCRH is updated each time a conversion
completes except when automatic compare is enabled and the compare condition is not met. In 10-bit
MODE, reading ADCRH prevents the ADC from transferring subsequent conversion results into the result
registers until ADCRL is read. If ADCRL is not read until after the next conversion is completed, then the
intermediate conversion result will be lost. In 8-bit mode there is no interlocking with ADCRL. In the case
that the MODE bits are changed, any data in ADCRH becomes invalid.
9.3.4 Data Result Low Register (ADCRL)
ADCRL contains the lower eight bits of the result of a 10-bit conversion, and all eight bits of an 8-bit
conversion. This register is updated each time a conversion completes except when automatic compare is
enabled and the compare condition is not met. In 10-bit mode, reading ADCRH prevents the ADC from
transferring subsequent conversion results into the result registers until ADCRL is read. If ADCRL is not
read until the after next conversion is completed, then the intermediate conversion results will be lost. In
8-bit mode, there is no interlocking with ADCRH. In the case that the MODE bits are changed, any data
in ADCRL becomes invalid.
5
ACFE
Compare Function Enable — ACFE is used to enable the compare function.
0 Compare function disabled
1 Compare function enabled
4
ACFGT
Compare Function Greater Than Enable — ACFGT is used to configure the compare function to trigger when
the result of the conversion of the input being monitored is greater than or equal to the compare value. The
compare function defaults to triggering when the result of the compare of the input being monitored is less than
the compare value.
0 Compare triggers when input is less than compare level
1 Compare triggers when input is greater than or equal to compare level
7 6543210
R 0 0 0 0 0 0 ADR9 ADR8
W
Reset: 0 0 0 0 0 0 0 0
= Unimplemented or Reserved
Figure 9-6. Data Result High Register (ADCRH)
Table 9-4. ADCSC2 Register Field Descriptions (continued)
Field Description
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 129
9.3.5 Compare Value High Register (ADCCVH)
This register holds the upper two bits of the 10-bit compare value. These bits are compared to the upper
two bits of the result following a conversion in 10-bit mode when the compare function is enabled.In 8-bit
operation, ADCCVH is not used during compare.
9.3.6 Compare Value Low Register (ADCCVL)
This register holds the lower 8 bits of the 10-bit compare value, or all 8 bits of the 8-bit compare value.
Bits ADCV7:ADCV0 are compared to the lower 8 bits of the result following a conversion in either 10-bit
or 8-bit mode.
9.3.7 Configuration Register (ADCCFG)
ADCCFG is used to select the mode of operation, clock source, clock divide, and configure for low power
or long sample time.
7 6543210
R ADR7 ADR6 ADR5 ADR4 ADR3 ADR2 ADR1 ADR0
W
Reset: 0 0 0 0 0 0 0 0
= Unimplemented or Reserved
Figure 9-7. Data Result Low Register (ADCRL)
7654 3 210
R0 0 0 0
ADCV9 ADCV8
W
Reset:0000 0 000
= Unimplemented or Reserved
Figure 9-8. Compare Value High Register (ADCCVH)
7 6543210
R
ADCV7 ADCV6 ADCV5 ADCV4 ADCV3 ADCV2 ADCV1 ADCV0
W
Reset: 0 0 0 0 0 0 0 0
Figure 9-9. Compare Value Low Register(ADCCVL)
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
130 Freescale Semiconductor
7654 3 210
R
ADLPC ADIV ADLSMP MODE ADICLK
W
Reset:0000 0 000
Figure 9-10. Configuration Register (ADCCFG)
Table 9-5. ADCCFG Register Field Descriptions
Field Description
7
ADLPC
Low Power Configuration — ADLPC controls the speed and power configuration of the successive
approximation converter. This is used to optimize power consumption when higher sample rates are not required.
0 High speed configuration
1 Low power configuration: {FC31}The power is reduced at the expense of maximum clock speed.
6:5
ADIV
Clock Divide Select — ADIV select the divide ratio used by the ADC to generate the internal clock ADCK.
Ta ble 9 - 6 shows the available clock configurations.
4
ADLSMP
Long Sample Time Configuration — ADLSMP selects between long and short sample time. This adjusts the
sample period to allow higher impedance inputs to be accurately sampled or to maximize conversion speed for
lower impedance inputs. Longer sample times can also be used to lower overall power consumption when
continuous conversions are enabled if high conversion rates are not required.
0 Short sample time
1 Long sample time
3:2
MODE
Conversion Mode Selection — MODE bits are used to select between 10- or 8-bit operation. See Table 9-7.
1:0
ADICLK
Input Clock Select — ADICLK bits select the input clock source to generate the internal clock ADCK. See
Ta ble 9 - 8 .
Table 9-6. Clock Divide Select
ADIV Divide Ratio Clock Rate
00 1 Input clock
01 2 Input clock 2
10 4 Input clock 4
11 8 Input clock 8
Table 9-7. Conversion Modes
MODE Mode Description
00 8-bit conversion (N=8)
01 Reserved
10 10-bit conversion (N=10)
11 Reserved
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 131
9.3.8 Pin Control 1 Register (APCTL1)
The pin control registers are used to disable the I/O port control of MCU pins used as analog inputs.
APCTL1 is used to control the pins associated with channels 0–7 of the ADC module.
Table 9-8. Input Clock Select
ADICLK Selected Clock Source
00 Bus clock
01 Bus clock divided by 2
10 Alternate clock (ALTCLK)
11 Asynchronous clock (ADACK)
7654 3 210
R
ADPC7 ADPC6 ADPC5 ADPC4 ADPC3 ADPC2 ADPC1 ADPC0
W
Reset:0000 0 000
Figure 9-11. Pin Control 1 Register (APCTL1)
Table 9-9. APCTL1 Register Field Descriptions
Field Description
7
ADPC7
ADC Pin Control 7 — ADPC7 is used to control the pin associated with channel AD7.
0 AD7 pin I/O control enabled
1 AD7 pin I/O control disabled
6
ADPC6
ADC Pin Control 6 — ADPC6 is used to control the pin associated with channel AD6.
0 AD6 pin I/O control enabled
1 AD6 pin I/O control disabled
5
ADPC5
ADC Pin Control 5 — ADPC5 is used to control the pin associated with channel AD5.
0 AD5 pin I/O control enabled
1 AD5 pin I/O control disabled
4
ADPC4
ADC Pin Control 4 — ADPC4 is used to control the pin associated with channel AD4.
0 AD4 pin I/O control enabled
1 AD4 pin I/O control disabled
3
ADPC3
ADC Pin Control 3 — ADPC3 is used to control the pin associated with channel AD3.
0 AD3 pin I/O control enabled
1 AD3 pin I/O control disabled
2
ADPC2
ADC Pin Control 2 — ADPC2 is used to control the pin associated with channel AD2.
0 AD2 pin I/O control enabled
1 AD2 pin I/O control disabled
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
132 Freescale Semiconductor
9.3.9 Pin Control 2 Register (APCTL2)
APCTL2 is used to control channels 8–15 of the ADC module.
1
ADPC1
ADC Pin Control 1 — ADPC1 is used to control the pin associated with channel AD1.
0 AD1 pin I/O control enabled
1 AD1 pin I/O control disabled
0
ADPC0
ADC Pin Control 0 — ADPC0 is used to control the pin associated with channel AD0.
0 AD0 pin I/O control enabled
1 AD0 pin I/O control disabled
7654 3 210
R
ADPC15 ADPC14 ADPC13 ADPC12 ADPC11 ADPC10 ADPC9 ADPC8
W
Reset:0000 0 000
Figure 9-12. Pin Control 2 Register (APCTL2)
Table 9-10. APCTL2 Register Field Descriptions
Field Description
7
ADPC15
ADC Pin Control 15 — ADPC15 is used to control the pin associated with channel AD15.
0 AD15 pin I/O control enabled
1 AD15 pin I/O control disabled
6
ADPC14
ADC Pin Control 14 — ADPC14 is used to control the pin associated with channel AD14.
0 AD14 pin I/O control enabled
1 AD14 pin I/O control disabled
5
ADPC13
ADC Pin Control 13 — ADPC13 is used to control the pin associated with channel AD13.
0 AD13 pin I/O control enabled
1 AD13 pin I/O control disabled
4
ADPC12
ADC Pin Control 12 — ADPC12 is used to control the pin associated with channel AD12.
0 AD12 pin I/O control enabled
1 AD12 pin I/O control disabled
3
ADPC11
ADC Pin Control 11 — ADPC11 is used to control the pin associated with channel AD11.
0 AD11 pin I/O control enabled
1 AD11 pin I/O control disabled
2
ADPC10
ADC Pin Control 10 — ADPC10 is used to control the pin associated with channel AD10.
0 AD10 pin I/O control enabled
1 AD10 pin I/O control disabled
Table 9-9. APCTL1 Register Field Descriptions (continued)
Field Description
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 133
9.3.10 Pin Control 3 Register (APCTL3)
APCTL3 is used to control channels 16–23 of the ADC module.
1
ADPC9
ADC Pin Control 9 — ADPC9 is used to control the pin associated with channel AD9.
0 AD9 pin I/O control enabled
1 AD9 pin I/O control disabled
0
ADPC8
ADC Pin Control 8 — ADPC8 is used to control the pin associated with channel AD8.
0 AD8 pin I/O control enabled
1 AD8 pin I/O control disabled
7654 3 210
R
ADPC23 ADPC22 ADPC21 ADPC20 ADPC19 ADPC18 ADPC17 ADPC16
W
Reset:0000 0 000
Figure 9-13. Pin Control 3 Register (APCTL3)
Table 9-11. APCTL3 Register Field Descriptions
Field Description
7
ADPC23
ADC Pin Control 23 — ADPC23 is used to control the pin associated with channel AD23.
0 AD23 pin I/O control enabled
1 AD23 pin I/O control disabled
6
ADPC22
ADC Pin Control 22 — ADPC22 is used to control the pin associated with channel AD22.
0 AD22 pin I/O control enabled
1 AD22 pin I/O control disabled
5
ADPC21
ADC Pin Control 21 — ADPC21 is used to control the pin associated with channel AD21.
0 AD21 pin I/O control enabled
1 AD21 pin I/O control disabled
4
ADPC20
ADC Pin Control 20 — ADPC20 is used to control the pin associated with channel AD20.
0 AD20 pin I/O control enabled
1 AD20 pin I/O control disabled
3
ADPC19
ADC Pin Control 19 — ADPC19 is used to control the pin associated with channel AD19.
0 AD19 pin I/O control enabled
1 AD19 pin I/O control disabled
2
ADPC18
ADC Pin Control 18 — ADPC18 is used to control the pin associated with channel AD18.
0 AD18 pin I/O control enabled
1 AD18 pin I/O control disabled
Table 9-10. APCTL2 Register Field Descriptions (continued)
Field Description
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
134 Freescale Semiconductor
9.4 Functional Description
The ADC module is disabled during reset or when the ADCH bits are all high. The module is idle when a
conversion has completed and another conversion has not been initiated. When idle, the module is in its
lowest power state.
The ADC can perform an analog-to-digital conversion on any of the software selectable channels. The
selected channel voltage is converted by a successive approximation algorithm into an 11-bit digital result.
In 8-bit mode, the selected channel voltage is converted by a successive approximation algorithm into a
9-bit digital result.
When the conversion is completed, the result is placed in the data registers (ADCRH and ADCRL).In
10-bit mode, the result is rounded to 10 bits and placed in ADCRH and ADCRL. In 8-bit mode, the result
is rounded to 8 bits and placed in ADCRL. The conversion complete flag (COCO) is then set and an
interrupt is generated if the conversion complete interrupt has been enabled (AIEN = 1).
The ADC module has the capability of automatically comparing the result of a conversion with the
contents of its compare registers. The compare function is enabled by setting the ACFE bit and operates
in conjunction with any of the conversion modes and configurations.
9.4.1 Clock Select and Divide Control
One of four clock sources can be selected as the clock source for the ADC module. This clock source is
then divided by a configurable value to generate the input clock to the converter (ADCK). The clock is
selected from one of the following sources by means of the ADICLK bits.
• The bus clock, which is equal to the frequency at which software is executed. This is the default
selection following reset.
• The bus clock divided by 2. For higher bus clock rates, this allows a maximum divide by 16 of the
bus clock.
• ALTCLK, as defined for this MCU (See module section introduction).
• The asynchronous clock (ADACK) – This clock is generated from a clock source within the ADC
module. When selected as the clock source this clock remains active while the MCU is in wait or
stop3 mode and allows conversions in these modes for lower noise operation.
Whichever clock is selected, its frequency must fall within the specified frequency range for ADCK. If the
available clocks are too slow, the ADC will not perform according to specifications. If the available clocks
1
ADPC17
ADC Pin Control 17 — ADPC17 is used to control the pin associated with channel AD17.
0 AD17 pin I/O control enabled
1 AD17 pin I/O control disabled
0
ADPC16
ADC Pin Control 16 — ADPC16 is used to control the pin associated with channel AD16.
0 AD16 pin I/O control enabled
1 AD16 pin I/O control disabled
Table 9-11. APCTL3 Register Field Descriptions (continued)
Field Description
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 135
are too fast, then the clock must be divided to the appropriate frequency. This divider is specified by the
ADIV bits and can be divide-by 1, 2, 4, or 8.
9.4.2 Input Select and Pin Control
The pin control registers (APCTL3, APCTL2, and APCTL1) are used to disable the I/O port control of the
pins used as analog inputs.When a pin control register bit is set, the following conditions are forced for the
associated MCU pin:
• The output buffer is forced to its high impedance state.
• The input buffer is disabled. A read of the I/O port returns a zero for any pin with its input buffer
disabled.
• The pullup is disabled.
9.4.3 Hardware Trigger
The ADC module has a selectable asynchronous hardware conversion trigger, ADHWT, that is enabled
when the ADTRG bit is set. This source is not available on all MCUs. Consult the module introduction for
information on the ADHWT source specific to this MCU.
When ADHWT source is available and hardware trigger is enabled (ADTRG=1), a conversion is initiated
on the rising edge of ADHWT. If a conversion is in progress when a rising edge occurs, the rising edge is
ignored. In continuous convert configuration, only the initial rising edge to launch continuous conversions
is observed. The hardware trigger function operates in conjunction with any of the conversion modes and
configurations.
9.4.4 Conversion Control
Conversions can be performed in either 10-bit mode or 8-bit mode as determined by the MODE bits.
Conversions can be initiated by either a software or hardware trigger. In addition, the ADC module can be
configured for low power operation, long sample time, continuous conversion, and automatic compare of
the conversion result to a software determined compare value.
9.4.4.1 Initiating Conversions
A conversion is initiated:
• Following a write to ADCSC1 (with ADCH bits not all 1s) if software triggered operation is
selected.
• Following a hardware trigger (ADHWT) event if hardware triggered operation is selected.
• Following the transfer of the result to the data registers when continuous conversion is enabled.
If continuous conversions are enabled a new conversion is automatically initiated after the completion of
the current conversion. In software triggered operation, continuous conversions begin after ADCSC1 is
written and continue until aborted. In hardware triggered operation, continuous conversions begin after a
hardware trigger event and continue until aborted.
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
136 Freescale Semiconductor
9.4.4.2 Completing Conversions
A conversion is completed when the result of the conversion is transferred into the data result registers,
ADCRH and ADCRL. This is indicated by the setting of COCO. An interrupt is generated if AIEN is high
at the time that COCO is set.
A blocking mechanism prevents a new result from overwriting previous data in ADCRH and ADCRL if
the previous data is in the process of being read while in 10-bit MODE (the ADCRH register has been read
but the ADCRL register has not). When blocking is active, the data transfer is blocked, COCO is not set,
and the new result is lost. In the case of single conversions with the compare function enabled and the
compare condition false, blocking has no effect and ADC operation is terminated. In all other cases of
operation, when a data transfer is blocked, another conversion is initiated regardless of the state of ADCO
(single or continuous conversions enabled).
If single conversions are enabled, the blocking mechanism could result in several discarded conversions
and excess power consumption. To avoid this issue, the data registers must not be read after initiating a
single conversion until the conversion completes.
9.4.4.3 Aborting Conversions
Any conversion in progress will be aborted when:
• A write to ADCSC1 occurs (the current conversion will be aborted and a new conversion will be
initiated, if ADCH are not all 1s).
• A write to ADCSC2, ADCCFG, ADCCVH, or ADCCVL occurs. This indicates a mode of
operation change has occurred and the current conversion is therefore invalid.
• The MCU is reset.
• The MCU enters stop mode with ADACK not enabled.
When a conversion is aborted, the contents of the data registers, ADCRH and ADCRL, are not altered but
continue to be the values transferred after the completion of the last successful conversion. In the case that
the conversion was aborted by a reset, ADCRH and ADCRL return to their reset states.
9.4.4.4 Power Control
The ADC module remains in its idle state until a conversion is initiated. If ADACK is selected as the
conversion clock source, the ADACK clock generator is also enabled.
Power consumption when active can be reduced by setting ADLPC. This results in a lower maximum
value for fADCK (see the electrical specifications).
9.4.4.5 Total Conversion Time
The total conversion time depends on the sample time (as determined by ADLSMP), the MCU bus
frequency, the conversion mode (8-bit or 10-bit), and the frequency of the conversion clock (fADCK). After
the module becomes active, sampling of the input begins. ADLSMP is used to select between short and
long sample times.When sampling is complete, the converter is isolated from the input channel and a
successive approximation algorithm is performed to determine the digital value of the analog signal. The
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 137
result of the conversion is transferred to ADCRH and ADCRL upon completion of the conversion
algorithm.
If the bus frequency is less than the fADCK frequency, precise sample time for continuous conversions
cannot be guaranteed when short sample is enabled (ADLSMP=0). If the bus frequency is less than 1/11th
of the fADCK frequency, precise sample time for continuous conversions cannot be guaranteed when long
sample is enabled (ADLSMP=1).
The maximum total conversion time for different conditions is summarized in Table 9-12.
The maximum total conversion time is determined by the clock source chosen and the divide ratio selected.
The clock source is selectable by the ADICLK bits, and the divide ratio is specified by the ADIV bits. For
example, in 10-bit mode, with the bus clock selected as the input clock source, the input clock divide-by-1
ratio selected, and a bus frequency of 8 MHz, then the conversion time for a single conversion is:
NOTE
The ADCK frequency must be between fADCK minimum and fADCK
maximum to meet ADC specifications.
Table 9-12. Total Conversion Time vs. Control Conditions
Conversion Type ADICLK ADLSMP Max Total Conversion Time
Single or first continuous 8-bit 0x, 10 0 20 ADCK cycles + 5 bus clock cycles
Single or first continuous 10-bit 0x, 10 0 23 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit 0x, 10 1 40 ADCK cycles + 5 bus clock cycles
Single or first continuous 10-bit 0x, 10 1 43 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit 11 0 5 s + 20 ADCK + 5 bus clock cycles
Single or first continuous 10-bit 11 0 5 s + 23 ADCK + 5 bus clock cycles
Single or first continuous 8-bit 11 1 5 s + 40 ADCK + 5 bus clock cycles
Single or first continuous 10-bit 11 1 5 s + 43 ADCK + 5 bus clock cycles
Subsequent continuous 8-bit;
fBUS fADCK
xx 0 17 ADCK cycles
Subsequent continuous 10-bit;
fBUS fADCK
xx 0 20 ADCK cycles
Subsequent continuous 8-bit;
fBUS fADCK/11
xx 1 37 ADCK cycles
Subsequent continuous 10-bit;
fBUS fADCK/11
xx 1 40 ADCK cycles
23 ADCK
cyc
Conversion time =
8 MHz/1
Number of bus cycles = 3.5 s x 8 MHz = 28 cycles
5 bus cyc
8 MHz
+
= 3.5 s
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
138 Freescale Semiconductor
9.4.5 Automatic Compare Function
The compare function can be configured to check for either an upper limit or lower limit. After the input
is sampled and converted, the result is added to the two’s complement of the compare value (ADCCVH
and ADCCVL). When comparing to an upper limit (ACFGT = 1), if the result is greater-than or equal-to
the compare value, COCO is set. When comparing to a lower limit (ACFGT = 0), if the result is less than
the compare value, COCO is set. The value generated by the addition of the conversion result and the two’s
complement of the compare value is transferred to ADCRH and ADCRL.
Upon completion of a conversion while the compare function is enabled, if the compare condition is not
true, COCO is not set and no data is transferred to the result registers. An ADC interrupt is generated upon
the setting of COCO if the ADC interrupt is enabled (AIEN = 1).
NOTE
The compare function can be used to monitor the voltage on a channel while
the MCU is in either wait or stop3 mode. The ADC interrupt will wake the
MCU when the compare condition is met.
9.4.6 MCU Wait Mode Operation
The WAIT instruction puts the MCU in a lower power-consumption standby mode from which recovery
is very fast because the clock sources remain active. If a conversion is in progress when the MCU enters
wait mode, it continues until completion. Conversions can be initiated while the MCU is in wait mode by
means of the hardware trigger or if continuous conversions are enabled.
The bus clock, bus clock divided by two, and ADACK are available as conversion clock sources while in
wait mode. The use of ALTCLK as the conversion clock source in wait is dependent on the definition of
ALTCLK for this MCU. Consult the module introduction for information on ALTCLK specific to this
MCU.
A conversion complete event sets the COCO and generates an ADC interrupt to wake the MCU from wait
mode if the ADC interrupt is enabled (AIEN = 1).
9.4.7 MCU Stop3 Mode Operation
The STOP instruction is used to put the MCU in a low power-consumption standby mode during which
most or all clock sources on the MCU are disabled.
9.4.7.1 Stop3 Mode With ADACK Disabled
If the asynchronous clock, ADACK, is not selected as the conversion clock, executing a STOP instruction
aborts the current conversion and places the ADC in its idle state. The contents of ADCRH and ADCRL
are unaffected by stop3 mode.After exiting from stop3 mode, a software or hardware trigger is required to
resume conversions.
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 139
9.4.7.2 Stop3 Mode With ADACK Enabled
If ADACK is selected as the conversion clock, the ADC continues operation during stop3 mode. For
guaranteed ADC operation, the MCU’s voltage regulator must remain active during stop3 mode. Consult
the module introduction for configuration information for this MCU.
If a conversion is in progress when the MCU enters stop3 mode, it continues until completion. Conversions
can be initiated while the MCU is in stop3 mode by means of the hardware trigger or if continuous
conversions are enabled.
A conversion complete event sets the COCO and generates an ADC interrupt to wake the MCU from stop3
mode if the ADC interrupt is enabled (AIEN = 1).
NOTE
It is possible for the ADC module to wake the system from low power stop
and cause the MCU to begin consuming run-level currents without
generating a system level interrupt. To prevent this scenario, software
should ensure that the data transfer blocking mechanism (discussed in
Section 9.4.4.2, “Completing Conversions) is cleared when entering stop3
and continuing ADC conversions.
9.4.8 MCU Stop1 and Stop2 Mode Operation
The ADC module is automatically disabled when the MCU enters either stop1 or stop2 mode. All module
registers contain their reset values following exit from stop1 or stop2. Therefore the module must be
re-enabled and re-configured following exit from stop1 or stop2.
9.5 Initialization Information
This section gives an example which provides some basic direction on how a user would initialize and
configure the ADC module. The user has the flexibility of choosing between configuring the module for
8-bit or 10-bit resolution, single or continuous conversion, and a polled or interrupt approach, among many
other options. Refer to Table 9-6, Table 9-7, and Table 9-8 for information used in this example.
NOTE
Hexadecimal values designated by a preceding 0x, binary values designated
by a preceding %, and decimal values have no preceding character.
9.5.1 ADC Module Initialization Example
9.5.1.1 Initialization Sequence
Before the ADC module can be used to complete conversions, an initialization procedure must be
performed. A typical sequence is as follows:
1. Update the configuration register (ADCCFG) to select the input clock source and the divide ratio
used to generate the internal clock, ADCK. This register is also used for selecting sample time and
low-power configuration.
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
140 Freescale Semiconductor
2. Update status and control register 2 (ADCSC2) to select the conversion trigger (hardware or
software) and compare function options, if enabled.
3. Update status and control register 1 (ADCSC1) to select whether conversions will be continuous
or completed only once, and to enable or disable conversion complete interrupts. The input channel
on which conversions will be performed is also selected here.
9.5.1.2 Pseudo — Code Example
In this example, the ADC module will be set up with interrupts enabled to perform a single 10-bit
conversion at low power with a long sample time on input channel 1, where the internal ADCK clock will
be derived from the bus clock divided by 1.
ADCCFG = 0x98 (%10011000)
Bit 7 ADLPC 1 Configures for low power (lowers maximum clock speed)
Bit 6:5 ADIV 00 Sets the ADCK to the input clock 1
Bit 4 ADLSMP 1 Configures for long sample time
Bit 3:2 MODE 10 Sets mode at 10-bit conversions
Bit 1:0 ADICLK 00 Selects bus clock as input clock source
ADCSC2 = 0x00 (%00000000)
Bit 7 ADACT 0 Flag indicates if a conversion is in progress
Bit 6 ADTRG 0 Software trigger selected
Bit 5 ACFE 0 Compare function disabled
Bit 4 ACFGT 0 Not used in this example
Bit 3:2 00 Unimplemented or reserved, always reads zero
Bit 1:0 00 Reserved for Freescale’s internal use; always write zero
ADCSC1 = 0x41 (%01000001)
Bit 7 COCO 0 Read-only flag which is set when a conversion completes
Bit 6 AIEN 1 Conversion complete interrupt enabled
Bit 5 ADCO 0 One conversion only (continuous conversions disabled)
Bit 4:0 ADCH 00001 Input channel 1 selected as ADC input channel
ADCRH/L = 0xxx
Holds results of conversion. Read high byte (ADCRH) before low byte (ADCRL) so that conversion
data cannot be overwritten with data from the next conversion.
ADCCVH/L = 0xxx
Holds compare value when compare function enabled
APCTL1=0x02
AD1 pin I/O control disabled. All other AD pins remain general purpose I/O pins
APCTL2=0x00
All other AD pins remain general purpose I/O pins
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 141
Figure 9-14. Initialization Flowchart for Example
9.6 Application Information
This section contains information for using the ADC module in applications. The ADC has been designed
to be integrated into a microcontroller for use in embedded control applications requiring an A/D
converter.
9.6.1 External Pins and Routing
The following sections discuss the external pins associated with the ADC module and how they should be
used for best results.
9.6.1.1 Analog Supply Pins
The ADC module has analog power and ground supplies (VDDAD and VSSAD) which are available as
separate pins on some devices. On other devices, VSSAD is shared on the same pin as the MCU digital VSS,
and on others, both VSSAD and VDDAD are shared with the MCU digital supply pins. In these cases, there
are separate pads for the analog supplies which are bonded to the same pin as the corresponding digital
supply so that some degree of isolation between the supplies is maintained.
When available on a separate pin, both VDDAD and VSSAD must be connected to the same voltage potential
as their corresponding MCU digital supply (VDD and VSS) and must be routed carefully for maximum
noise immunity and bypass capacitors placed as near as possible to the package.
YES
NO
RESET
INITIALIZE ADC
ADCCFG = $98
ADCSC1 = $41
ADCSC2 = $00
CHECK
COCO=1?
READ ADCRH
THEN ADCRL TO
CLEAR COCO BIT
CONTINUE
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
142 Freescale Semiconductor
In cases where separate power supplies are used for analog and digital power, the ground connection
between these supplies must be at the VSSAD pin. This should be the only ground connection between these
supplies if possible. The VSSAD pin makes a good single point ground location.
9.6.1.2 Analog Reference Pins
In addition to the analog supplies, the ADC module has connections for two reference voltage inputs. The
high reference is VREFH, which may be shared on the same pin as VDDAD on some devices. The low
reference is VREFL, which may be shared on the same pin as VSSAD on some devices.
When available on a separate pin, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD). When available on a separate pin, VREFL must be connected to the same
voltage potential as VSSAD. Both VREFH and VREFL must be routed carefully for maximum noise
immunity and bypass capacitors placed as near as possible to the package.
AC current in the form of current spikes required to supply charge to the capacitor array at each successive
approximation step is drawn through the VREFH and VREFL loop. The best external component to meet this
current demand is a 0.1 F capacitor with good high frequency characteristics. This capacitor is connected
between VREFH and VREFL and must be placed as near as possible to the package pins. Resistance in the
path is not recommended because the current will cause a voltage drop which could result in conversion
errors. Inductance in this path must be minimum (parasitic only).
9.6.1.3 Analog Input Pins
The external analog inputs are typically shared with digital I/O pins on MCU devices. The pin I/O control
is disabled by setting the appropriate control bit in one of the pin control registers. Conversions can be
performed on inputs without the associated pin control register bit set. It is recommended that the pin
control register bit always be set when using a pin as an analog input. This avoids problems with contention
because the output buffer will be in its high impedance state and the pullup is disabled. Also, the input
buffer draws dc current when its input is not at either VDD or VSS. Setting the pin control register bits for
all pins used as analog inputs should be done to achieve lowest operating current.
Empirical data shows that capacitors on the analog inputs improve performance in the presence of noise
or when the source impedance is high. Use of 0.01 F capacitors with good high-frequency characteristics
is sufficient. These capacitors are not necessary in all cases, but when used they must be placed as near as
possible to the package pins and be referenced to VSSA.
For proper conversion, the input voltage must fall between VREFH and VREFL. If the input is equal to or
exceeds VREFH, the converter circuit converts the signal to $3FF (full scale 10-bit representation) or $FF
(full scale 8-bit representation). If the input is equal to or less than VREFL, the converter circuit converts it
to $000. Input voltages between VREFH and VREFL are straight-line linear conversions. There will be a
brief current associated with VREFL when the sampling capacitor is charging. The input is sampled for
3.5 cycles of the ADCK source when ADLSMP is low, or 23.5 cycles when ADLSMP is high.
For minimal loss of accuracy due to current injection, pins adjacent to the analog input pins should not be
transitioning during conversions.
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 143
9.6.2 Sources of Error
Several sources of error exist for A/D conversions. These are discussed in the following sections.
9.6.2.1 Sampling Error
For proper conversions, the input must be sampled long enough to achieve the proper accuracy. Given the
maximum input resistance of approximately 7k and input capacitance of approximately 5.5 pF, sampling
to within 1/4LSB (at 10-bit resolution) can be achieved within the minimum sample window (3.5 cycles @
8 MHz maximum ADCK frequency) provided the resistance of the external analog source (RAS) is kept
below 5 k.
Higher source resistances or higher-accuracy sampling is possible by setting ADLSMP (to increase the
sample window to 23.5 cycles) or decreasing ADCK frequency to increase sample time.
9.6.2.2 Pin Leakage Error
Leakage on the I/O pins can cause conversion error if the external analog source resistance (RAS) is high.
If this error cannot be tolerated by the application, keep RAS lower than VDDAD / (2N*ILEAK) for less than
1/4LSB leakage error (N = 8 in 8-bit mode or 10 in 10-bit mode).
9.6.2.3 Noise-Induced Errors
System noise which occurs during the sample or conversion process can affect the accuracy of the
conversion. The ADC accuracy numbers are guaranteed as specified only if the following conditions are
met:
• There is a 0.1 F low-ESR capacitor from VREFH to VREFL.
• There is a 0.1 F low-ESR capacitor from VDDAD to VSSAD.
• If inductive isolation is used from the primary supply, an additional 1 F capacitor is placed from
VDDAD to VSSAD.
•V
SSAD (and VREFL, if connected) is connected to VSS at a quiet point in the ground plane.
• Operate the MCU in wait or stop3 mode before initiating (hardware triggered conversions) or
immediately after initiating (hardware or software triggered conversions) the ADC conversion.
— For software triggered conversions, immediately follow the write to the ADCSC1 with a WAIT
instruction or STOP instruction.
— For stop3 mode operation, select ADACK as the clock source. Operation in stop3 reduces VDD
noise but increases effective conversion time due to stop recovery.
• There is no I/O switching, input or output, on the MCU during the conversion.
There are some situations where external system activity causes radiated or conducted noise emissions or
excessive VDD noise is coupled into the ADC. In these situations, or when the MCU cannot be placed in
wait or stop3 or I/O activity cannot be halted, these recommended actions may reduce the effect of noise
on the accuracy:
• Place a 0.01 F capacitor (CAS) on the selected input channel to VREFL or VSSAD (this will
improve noise issues but will affect sample rate based on the external analog source resistance).
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
144 Freescale Semiconductor
• Average the result by converting the analog input many times in succession and dividing the sum
of the results. Four samples are required to eliminate the effect of a 1LSB, one-time error.
• Reduce the effect of synchronous noise by operating off the asynchronous clock (ADACK) and
averaging. Noise that is synchronous to ADCK cannot be averaged out.
9.6.2.4 Code Width and Quantization Error
The ADC quantizes the ideal straight-line transfer function into 1024 steps (in 10-bit mode). Each step
ideally has the same height (1 code) and width. The width is defined as the delta between the transition
points to one code and the next. The ideal code width for an N bit converter (in this case N can be 8 or 10),
defined as 1LSB, is:
1LSB = (VREFH - VREFL) / 2NEqn. 9-2
There is an inherent quantization error due to the digitization of the result. For 8-bit or 10-bit conversions
the code will transition when the voltage is at the midpoint between the points where the straight line
transfer function is exactly represented by the actual transfer function. Therefore, the quantization error
will be 1/2LSB in 8- or 10-bit mode. As a consequence, however, the code width of the first ($000)
conversion is only 1/2LSB and the code width of the last ($FF or $3FF) is 1.5LSB.
9.6.2.5 Linearity Errors
The ADC may also exhibit non-linearity of several forms. Every effort has been made to reduce these
errors but the system should be aware of them because they affect overall accuracy. These errors are:
• Zero-scale error (EZS) (sometimes called offset) — This error is defined as the difference between
the actual code width of the first conversion and the ideal code width (1/2LSB). Note, if the first
conversion is $001, then the difference between the actual $001 code width and its ideal (1LSB) is
used.
• Full-scale error (EFS) — This error is defined as the difference between the actual code width of
the last conversion and the ideal code width (1.5LSB). Note, if the last conversion is $3FE, then the
difference between the actual $3FE code width and its ideal (1LSB) is used.
• Differential non-linearity (DNL) — This error is defined as the worst-case difference between the
actual code width and the ideal code width for all conversions.
• Integral non-linearity (INL) — This error is defined as the highest-value the (absolute value of the)
running sum of DNL achieves. More simply, this is the worst-case difference of the actual
transition voltage to a given code and its corresponding ideal transition voltage, for all codes.
• Total unadjusted error (TUE) — This error is defined as the difference between the actual transfer
function and the ideal straight-line transfer function, and therefore includes all forms of error.
9.6.2.6 Code Jitter, Non-Monotonicity and Missing Codes
Analog-to-digital converters are susceptible to three special forms of error. These are code jitter,
non-monotonicity, and missing codes.
Code jitter is when, at certain points, a given input voltage converts to one of two values when sampled
repeatedly. Ideally, when the input voltage is infinitesimally smaller than the transition voltage, the
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 145
converter yields the lower code (and vice-versa). However, even very small amounts of system noise can
cause the converter to be indeterminate (between two codes) for a range of input voltages around the
transition voltage. This range is normally around ±1/2 LSB and will increase with noise. This error may be
reduced by repeatedly sampling the input and averaging the result. Additionally the techniques discussed
in Section 9.6.2.3 will reduce this error.
Non-monotonicity is defined as when, except for code jitter, the converter converts to a lower code for a
higher input voltage. Missing codes are those values which are never converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and to have no missing codes.
Analog-to-Digital Converter (S08ADCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
146 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 147
Chapter 10
Internal Clock Source (S08ICSV2)
10.1 Introduction
The internal clock source (ICS) module provides clock source choices for the MCU. The module contains
a frequency-locked loop (FLL) as a clock source that is controllable by either an internal or an external
reference clock. The module can provide this FLL clock or either of the internal or external reference
clocks as a source for the MCU system clock. There are also signals provided to control a low power
oscillator (XOSC) module to allow the use of an external crystal/resonator as the external reference clock.
Whichever clock source is chosen, it is passed through a reduced bus divider (BDIV) which allows a lower
final output clock frequency to be derived.
The bus frequency will be one-half of the ICSOUT frequency.
NOTE
For MC9S08SG8, it is 1.5% deviation for -40 °C to 125 °C
standard-temperature rated devices and 3% deviation for AEC Grade 0
high-temperature rated devices (-40 to 150 °C).
10.1.1 Module Configuration
When the internal reference is enabled in stop mode (IREFSTEN = 1), the voltage regulator must also be
enabled in stop mode by setting the LVDE and LVDSE bits in the SPMSC1 register.
Figure 10-1 shows the MC9S08SG8 block diagram with the ICS module highlighted.
Chapter 10 Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
148 Freescale Semiconductor
Figure 10-1. MC9S08SG8 Block Diagram with ICS Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 149
10.1.2 Features
Key features of the ICS module follow. For device specific information, refer to the ICS Characteristics in
the Electricals section of the documentation.
• Frequency-locked loop (FLL) is trimmable for accuracy
— 0.2% resolution using internal 32kHz reference
— 1.5% deviation over voltage and temperature using internal 32kHz reference
• Internal or external reference clocks up to 5MHz can be used to control the FLL
— 3 bit select for reference divider is provided
• Internal reference clock has 9 trim bits available
• Internal or external reference clocks can be selected as the clock source for the MCU
• Whichever clock is selected as the source can be divided down
— 2 bit select for clock divider is provided
– Allowable dividers are: 1, 2, 4, 8
– BDC clock is provided as a constant divide by 2 of the DCO output
• Control signals for a low power oscillator as the external reference clock are provided
— HGO, RANGE, EREFS, ERCLKEN, EREFSTEN
• FLL Engaged Internal mode is automatically selected out of reset
10.1.3 Block Diagram
Figure 10-2 is the ICS block diagram.
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
150 Freescale Semiconductor
Figure 10-2. Internal Clock Source (ICS) Block Diagram
10.1.4 Modes of Operation
There are seven modes of operation for the ICS: FEI, FEE, FBI, FBILP, FBE, FBELP, and stop.
10.1.4.1 FLL Engaged Internal (FEI)
In FLL engaged internal mode, which is the default mode, the ICS supplies a clock derived from the FLL
which is controlled by the internal reference clock. The BDC clock is supplied from the FLL.
10.1.4.2 FLL Engaged External (FEE)
In FLL engaged external mode, the ICS supplies a clock derived from the FLL which is controlled by an
external reference clock. The BDC clock is supplied from the FLL.
10.1.4.3 FLL Bypassed Internal (FBI)
In FLL bypassed internal mode, the FLL is enabled and controlled by the internal reference clock, but is
bypassed. The ICS supplies a clock derived from the internal reference clock. The BDC clock is supplied
from the FLL.
DCO
Filter
RDIV
TRIM
/ 2
9
External Reference
IREFS
Clock Source
Block
CLKS
n=0-7
/ 2n
n=0-3
/ 2n
Internal
Reference
Clock
BDIV
9ICSLCLK
ICSOUT
ICSIRCLK
EREFS
RANGE
EREFSTENHGO
Optional
IREFSTEN
ICSERCLK
Internal Clock Source Block
LP
ICSFFCLK
ERCLKEN
IRCLKEN
DCOOUT
FLL
RDIV_CLK
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 151
10.1.4.4 FLL Bypassed Internal Low Power (FBILP)
In FLL bypassed internal low power mode, the FLL is disabled and bypassed, and the ICS supplies a clock
derived from the internal reference clock. The BDC clock is not available.
10.1.4.5 FLL Bypassed External (FBE)
In FLL bypassed external mode, the FLL is enabled and controlled by an external reference clock, but is
bypassed. The ICS supplies a clock derived from the external reference clock. The external reference clock
can be an external crystal/resonator supplied by an OSC controlled by the ICS, or it can be another external
clock source. The BDC clock is supplied from the FLL.
10.1.4.6 FLL Bypassed External Low Power (FBELP)
In FLL bypassed external low power mode, the FLL is disabled and bypassed, and the ICS supplies a clock
derived from the external reference clock. The external reference clock can be an external crystal/resonator
supplied by an OSC controlled by the ICS, or it can be another external clock source. The BDC clock is
not available.
10.1.4.7 Stop (STOP)
In stop mode the FLL is disabled and the internal or external reference clocks can be selected to be enabled
or disabled. The BDC clock is not available and the ICS does not provide an MCU clock source.
10.2 External Signal Description
There are no ICS signals that connect off chip.
10.3 Register Definition
Figure 10-1 is a summary of ICS registers.
Table 10-1. ICS Register Summary
Name 76543 2 1 0
ICSC1
R
CLKS RDIV IREFS IRCLKEN IREFSTEN
W
ICSC2
R
BDIV RANGE HGO LP EREFS ERCLKEN EREFSTEN
W
ICSTRM
R
TRIM
W
ICSSC
R 0 0 0 IREFST CLKST OSCINIT
FTRIM
W
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
152 Freescale Semiconductor
10.3.1 ICS Control Register 1 (ICSC1)
7 6543210
R
CLKS RDIV IREFS IRCLKEN IREFSTEN
W
Reset: 0 0 0 0 0 1 0 0
Figure 10-3. ICS Control Register 1 (ICSC1)
Table 10-2. ICS Control Register 1 Field Descriptions
Field Description
7:6
CLKS
Clock Source Select — Selects the clock source that controls the bus frequency. The actual bus frequency
depends on the value of the BDIV bits.
00 Output of FLL is selected.
01 Internal reference clock is selected.
10 External reference clock is selected.
11 Reserved, defaults to 00.
5:3
RDIV
Reference Divider — Selects the amount to divide down the FLL reference clock selected by the IREFS bits.
Resulting frequency must be in the range 31.25 kHz to 39.0625 kHz.
000 Encoding 0 — Divides reference clock by 1 (reset default)
001 Encoding 1 — Divides reference clock by 2
010 Encoding 2 — Divides reference clock by 4
011 Encoding 3 — Divides reference clock by 8
100 Encoding 4 — Divides reference clock by 16
101 Encoding 5 — Divides reference clock by 32
110 Encoding 6 — Divides reference clock by 64
111 Encoding 7 — Divides reference clock by 128
2
IREFS
Internal Reference Select — The IREFS bit selects the reference clock source for the FLL.
1 Internal reference clock selected
0 External reference clock selected
1
IRCLKEN
Internal Reference Clock Enable — The IRCLKEN bit enables the internal reference clock for use as
ICSIRCLK.
1 ICSIRCLK active
0 ICSIRCLK inactive
0
IREFSTEN
Internal Reference Stop Enable — The IREFSTEN bit controls whether or not the internal reference clock
remains enabled when the ICS enters stop mode.
1 Internal reference clock stays enabled in stop if IRCLKEN is set or if ICS is in FEI, FBI, or FBILP mode before
entering stop
0 Internal reference clock is disabled in stop
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 153
10.3.2 ICS Control Register 2 (ICSC2)
7 6543210
R
BDIV RANGE HGO LP EREFS ERCLKEN EREFSTEN
W
Reset:0 1000000
Figure 10-4. ICS Control Register 2 (ICSC2)
Table 10-3. ICS Control Register 2 Field Descriptions
Field Description
7:6
BDIV
Bus Frequency Divider — Selects the amount to divide down the clock source selected by the CLKS bits. This
controls the bus frequency.
00 Encoding 0 — Divides selected clock by 1
01 Encoding 1 — Divides selected clock by 2 (reset default)
10 Encoding 2 — Divides selected clock by 4
11 Encoding 3 — Divides selected clock by 8
5
RANGE
Frequency Range Select — Selects the frequency range for the external oscillator.
1 High frequency range selected for the external oscillator
0 Low frequency range selected for the external oscillator
4
HGO
High Gain Oscillator Select — The HGO bit controls the external oscillator mode of operation.
1 Configure external oscillator for high gain operation
0 Configure external oscillator for low power operation
3
LP
Low Power Select — The LP bit controls whether the FLL is disabled in FLL bypassed modes.
1 FLL is disabled in bypass modes unless BDM is active
0 FLL is not disabled in bypass mode
2
EREFS
External Reference Select — The EREFS bit selects the source for the external reference clock.
1 Oscillator requested
0 External Clock Source requested
1
ERCLKEN
External Reference Enable — The ERCLKEN bit enables the external reference clock for use as ICSERCLK.
1ICSERCLK active
0 ICSERCLK inactive
0
EREFSTEN
External Reference Stop Enable — The EREFSTEN bit controls whether or not the external reference clock
remains enabled when the ICS enters stop mode.
1 External reference clock stays enabled in stop if ERCLKEN is set or if ICS is in FEE, FBE, or FBELP mode
before entering stop
0 External reference clock is disabled in stop
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
154 Freescale Semiconductor
10.3.3 ICS Trim Register (ICSTRM)
10.3.4 ICS Status and Control (ICSSC)
7 6543210
R
TRIM
W
POR: 1 0 0 0 0 0 0 0
Reset:U UUUUUUU
Figure 10-5. ICS Trim Register (ICSTRM)
Table 10-4. ICS Trim Register Field Descriptions
Field Description
7:0
TRIM
ICS Trim Setting — The TRIM bits control the internal reference clock frequency by controlling the internal
reference clock period. The bits’ effect are binary weighted (i.e., bit 1 will adjust twice as much as bit 0).
Increasing the binary value in TRIM will increase the period, and decreasing the value will decrease the period.
An additional fine trim bit is available in ICSSC as the FTRIM bit.
7 6543210
R 0 0 0 IREFST CLKST OSCINIT
FTRIM
W
POR:
Reset:
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
U
Figure 10-6. ICS Status and Control Register (ICSSC)
Table 10-5. ICS Status and Control Register Field Descriptions
Field Description
7:5 Reserved, should be cleared.
4
IREFST
Internal Reference Status — The IREFST bit indicates the current source for the reference clock. The IREFST
bit does not update immediately after a write to the IREFS bit due to internal synchronization between clock
domains.
0 Source of reference clock is external clock.
1 Source of reference clock is internal clock.
3-2
CLKST
Clock Mode Status — The CLKST bits indicate the current clock mode. The CLKST bits don’t update
immediately after a write to the CLKS bits due to internal synchronization between clock domains.
00 Output of FLL is selected.
01 FLL Bypassed, Internal reference clock is selected.
10 FLL Bypassed, External reference clock is selected.
11 Reserved.
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 155
10.4 Functional Description
10.4.1 Operational Modes
Figure 10-7. Clock Switching Modes
The seven states of the ICS are shown as a state diagram and are described below. The arrows indicate the
allowed movements between the states.
10.4.1.1 FLL Engaged Internal (FEI)
FLL engaged internal (FEI) is the default mode of operation and is entered when all the following
conditions occur:
1OSC Initialization — If the external reference clock is selected by ERCLKEN or by the ICS being in FEE, FBE,
or FBELP mode, and if EREFS is set, then this bit is set after the initialization cycles of the external oscillator
clock have completed. This bit is only cleared when either ERCLKEN or EREFS are cleared.
0ICS Fine Trim — The FTRIM bit controls the smallest adjustment of the internal reference clock frequency.
Setting FTRIM will increase the period and clearing FTRIM will decrease the period by the smallest amount
possible.
Table 10-5. ICS Status and Control Register Field Descriptions (continued)
Field Description
FLL Bypassed
Internal Low
Power(FBILP)
IREFS=1
CLKS=00
Entered from any state
when MCU enters stop
FLL Engaged
Internal (FEI)
FLL Bypassed
Internal (FBI)
FLL Bypassed
External (FBE)
FLL Engaged
External (FEE)
FLL Bypassed
External Low
Power(FBELP)
IREFS=0
CLKS=00
IREFS=0
CLKS=10
BDM Enabled
or LP =0
Returns to state that was active
before MCU entered stop, unless
RESET occurs while in stop.
IREFS=0
CLKS=10
BDM Disabled
and LP=1
IREFS=1
CLKS=01
BDM Enabled
or LP=0
IREFS=1
CLKS=01
BDM Disabled
and LP=1
Stop
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
156 Freescale Semiconductor
• CLKS bits are written to 00
• IREFS bit is written to 1
• RDIV bits are written to divide trimmed reference clock to be within the range of 31.25 kHz to
39.0625 kHz.
In FLL engaged internal mode, the ICSOUT clock is derived from the FLL clock, which is controlled by
the internal reference clock. The FLL loop will lock the frequency to 1024 times the reference frequency,
as selected by the RDIV bits. The ICSLCLK is available for BDC communications, and the internal
reference clock is enabled.
10.4.1.2 FLL Engaged External (FEE)
The FLL engaged external (FEE) mode is entered when all the following conditions occur:
• CLKS bits are written to 00
• IREFS bit is written to 0
• RDIV bits are written to divide reference clock to be within the range of 31.25 kHz to 39.0625 kHz
In FLL engaged external mode, the ICSOUT clock is derived from the FLL clock which is controlled by
the external reference clock.The FLL loop will lock the frequency to 1024 times the reference frequency,
as selected by the RDIV bits. The ICSLCLK is available for BDC communications, and the external
reference clock is enabled.
10.4.1.3 FLL Bypassed Internal (FBI)
The FLL bypassed internal (FBI) mode is entered when all the following conditions occur:
• CLKS bits are written to 01
• IREFS bit is written to 1.
• BDM mode is active or LP bit is written to 0
In FLL bypassed internal mode, the ICSOUT clock is derived from the internal reference clock. The FLL
clock is controlled by the internal reference clock, and the FLL loop will lock the FLL frequency to 1024
times the reference frequency, as selected by the RDIV bits. The ICSLCLK will be available for BDC
communications, and the internal reference clock is enabled.
10.4.1.4 FLL Bypassed Internal Low Power (FBILP)
The FLL bypassed internal low power (FBILP) mode is entered when all the following conditions occur:
• CLKS bits are written to 01
• IREFS bit is written to 1.
• BDM mode is not active and LP bit is written to 1
In FLL bypassed internal low power mode, the ICSOUT clock is derived from the internal reference clock
and the FLL is disabled. The ICSLCLK will be not be available for BDC communications, and the internal
reference clock is enabled.
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 157
10.4.1.5 FLL Bypassed External (FBE)
The FLL bypassed external (FBE) mode is entered when all the following conditions occur:
• CLKS bits are written to 10.
• IREFS bit is written to 0.
• BDM mode is active or LP bit is written to 0.
In FLL bypassed external mode, the ICSOUT clock is derived from the external reference clock. The FLL
clock is controlled by the external reference clock, and the FLL loop will lock the FLL frequency to 1024
times the reference frequency, as selected by the RDIV bits, so that the ICSLCLK will be available for
BDC communications, and the external reference clock is enabled.
10.4.1.6 FLL Bypassed External Low Power (FBELP)
The FLL bypassed external low power (FBELP) mode is entered when all the following conditions occur:
• CLKS bits are written to 10.
• IREFS bit is written to 0.
• BDM mode is not active and LP bit is written to 1.
In FLL bypassed external low power mode, the ICSOUT clock is derived from the external reference clock
and the FLL is disabled. The ICSLCLK will be not be available for BDC communications. The external
reference clock is enabled.
10.4.1.7 Stop
Stop mode is entered whenever the MCU enters a STOP state. In this mode, all ICS clock signals are static
except in the following cases:
ICSIRCLK will be active in stop mode when all the following conditions occur:
• IRCLKEN bit is written to 1
• IREFSTEN bit is written to 1
ICSERCLK will be active in stop mode when all the following conditions occur:
• ERCLKEN bit is written to 1
• EREFSTEN bit is written to 1
10.4.2 Mode Switching
When switching between FLL engaged internal (FEI) and FLL engaged external (FEE) modes the IREFS
bit can be changed at anytime, but the RDIV bits must be changed simultaneously so that the resulting
frequency stays in the range of 31.25 kHz to 39.0625 kHz. After a change in the IREFS value the FLL will
begin locking again after a few full cycles of the resulting divided reference frequency. The completion of
the switch is shown by the IREFST bit.
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
158 Freescale Semiconductor
The CLKS bits can also be changed at anytime, but the RDIV bits must be changed simultaneously so that
the resulting frequency stays in the range of 31.25 kHz to 39.0625 kHz. The actual switch to the newly
selected clock will not occur until after a few full cycles of the new clock. If the newly selected clock is
not available, the previous clock will remain selected.
10.4.3 Bus Frequency Divider
The BDIV bits can be changed at anytime and the actual switch to the new frequency will occur
immediately.
10.4.4 Low Power Bit Usage
The low power bit (LP) is provided to allow the FLL to be disabled and thus conserve power when it is
not being used. However, in some applications it may be desirable to enable the FLL and allow it to lock
for maximum accuracy before switching to an FLL engaged mode. Do this by writing the LP bit to 0.
10.4.5 Internal Reference Clock
When IRCLKEN is set the internal reference clock signal will be presented as ICSIRCLK, which can be
used as an additional clock source. The ICSIRCLK frequency can be re-targeted by trimming the period
of the internal reference clock. This can be done by writing a new value to the TRIM bits in the ICSTRM
register. Writing a larger value will slow down the ICSIRCLK frequency, and writing a smaller value to
the ICSTRM register will speed up the ICSIRCLK frequency. The TRIM bits will effect the ICSOUT
frequency if the ICS is in FLL engaged internal (FEI), FLL bypassed internal (FBI), or FLL bypassed
internal low power (FBILP) mode. The TRIM and FTRIM value will not be affected by a reset.
Until ICSIRCLK is trimmed, programming low reference divider (RDIV) factors may result in ICSOUT
frequencies that exceed the maximum chip-level frequency and violate the chip-level clock timing
specifications (see the Device Overview chapter).
If IREFSTEN is set and the IRCLKEN bit is written to 1, the internal reference clock will keep running
during stop mode in order to provide a fast recovery upon exiting stop.
All MCU devices are factory programmed with a trim value in a reserved memory location. This value can
be copied to the ICSTRM register during reset initialization. The factory trim value does not include the
FTRIM bit. For finer precision, the user can trim the internal oscillator in the application and set the
FTRIM bit accordingly.
10.4.6 Optional External Reference Clock
The ICS module can support an external reference clock with frequencies between 31.25 kHz to 5 MHz
in all modes. When the ERCLKEN is set, the external reference clock signal will be presented as
ICSERCLK, which can be used as an additional clock source. When IREFS = 1, the external reference
clock will not be used by the FLL and will only be used as ICSERCLK. In these modes, the frequency can
be equal to the maximum frequency the chip-level timing specifications will support (see the Device
Overview chapter).
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 159
If EREFSTEN is set and the ERCLKEN bit is written to 1, the external reference clock will keep running
during stop mode in order to provide a fast recovery upon exiting stop.
10.4.7 Fixed Frequency Clock
The ICS presents the divided FLL reference clock as ICSFFCLK for use as an additional clock source for
peripheral modules. The ICS provides an output signal (ICSFFE) which indicates when the ICS is
providing ICSOUT frequencies four times or greater than the divided FLL reference clock (ICSFFCLK).
In FLL Engaged mode (FEI and FEE) this is always true and ICSFFE is always high. In ICS Bypass
modes, ICSFFE will get asserted for the following combinations of BDIV and RDIV values:
• BDIV=00 (divide by 1), RDIV
• BDIV=01 (divide by 2), RDIV
• BDIV=10 (divide by 4), RDIV
• BDIV=11 (divide by 8), RDIV
Internal Clock Source (S08ICSV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
160 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 161
Chapter 11
Inter-Integrated Circuit (S08IICV2)
11.1 Introduction
The inter-integrated circuit (IIC) provides a method of communication between a number of devices. The
interface is designed to operate up to 100 kbps with maximum bus loading and timing. The device is
capable of operating at higher baud rates, up to a maximum of clock/20, with reduced bus loading. The
maximum communication length and the number of devices that can be connected are limited by a
maximum bus capacitance of 400 pF.
NOTE
The SDA and SCL should not be driven above VDD. These pins are pseudo
open-drain containing a protection diode to VDD.
11.1.1 Module Configuration
The IIC module pins, SDA and SCL can be repositioned under software control using IICPS in SOPT1 as
as shown in Table 11-1. IICPS in SOPT1 selects which general-purpose I/O ports are associated with IIC
operation.
Figure 11-1 shows the MC9S08SG8 block diagram with the IIC module highlighted.
Table 11-1. IIC Position Options
IICPS in SOPT1 Port Pin for SDA Port Pin for SCL
0 (default) PTA2 PTA3
1 PTB6 PTB7
Chapter 11 Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
162 Freescale Semiconductor
Figure 11-1. MC9S08SG8 Block Diagram with IIC Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 163
11.1.2 Features
The IIC includes these distinctive features:
• Compatible with IIC bus standard
• Multi-master operation
• Software programmable for one of 64 different serial clock frequencies
• Software selectable acknowledge bit
• Interrupt driven byte-by-byte data transfer
• Arbitration lost interrupt with automatic mode switching from master to slave
• Calling address identification interrupt
• Start and stop signal generation/detection
• Repeated start signal generation
• Acknowledge bit generation/detection
• Bus busy detection
• General call recognition
• 10-bit address extension
11.1.3 Modes of Operation
A brief description of the IIC in the various MCU modes is given here.
•Run mode — This is the basic mode of operation. To conserve power in this mode, disable the
module.
•Wait mode — The module continues to operate while the MCU is in wait mode and can provide
a wake-up interrupt.
•Stop mode — The IIC is inactive in stop3 mode for reduced power consumption. The stop
instruction does not affect IIC register states. Stop2 resets the register contents.
11.1.4 Block Diagram
Figure 11-2 is a block diagram of the IIC.
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
164 Freescale Semiconductor
Figure 11-2. IIC Functional Block Diagram
11.2 External Signal Description
This section describes each user-accessible pin signal.
11.2.1 SCL — Serial Clock Line
The bidirectional SCL is the serial clock line of the IIC system.
11.2.2 SDA — Serial Data Line
The bidirectional SDA is the serial data line of the IIC system.
11.3 Register Definition
This section consists of the IIC register descriptions in address order.
Refer to the direct-page register summary in the memory chapter of this document for the absolute address
assignments for all IIC registers. This section refers to registers and control bits only by their names. A
Input
Sync
In/Out
Data
Shift
Register
Address
Compare
Interrupt
Clock
Control
Start
Stop
Arbitration
Control
CTRL_REG FREQ_REG ADDR_REG STATUS_REG DATA_REG
ADDR_DECODE DATA_MUX
Data Bus
SCL SDA
Address
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 165
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
11.3.1 IIC Address Register (IICA)
11.3.2 IIC Frequency Divider Register (IICF)
76543210
R
AD7 AD6 AD5 AD4 AD3 AD2 AD1
0
W
Reset00000000
= Unimplemented or Reserved
Figure 11-3. IIC Address Register (IICA)
Table 11-2. IICA Field Descriptions
Field Description
7–1
AD[7:1]
Slave Address. The AD[7:1] field contains the slave address to be used by the IIC module. This field is used on
the 7-bit address scheme and the lower seven bits of the 10-bit address scheme.
76543210
R
MULT ICR
W
Reset00000000
Figure 11-4. IIC Frequency Divider Register (IICF)
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
166 Freescale Semiconductor
For example, if the bus speed is 8 MHz, the table below shows the possible hold time values with different
ICR and MULT selections to achieve an IIC baud rate of 100 kbps.
Table 11-3. IICF Field Descriptions
Field Description
7–6
MULT
IIC Multiplier Factor. The MULT bits define the multiplier factor, mul. This factor, along with the SCL divider,
generates the IIC baud rate. The multiplier factor mul as defined by the MULT bits is provided below.
00 mul = 01
01 mul = 02
10 mul = 04
11 Reserved
5–0
ICR
IIC Clock Rate. The ICR bits are used to prescale the bus clock for bit rate selection. These bits and the MULT
bits determine the IIC baud rate, the SDA hold time, the SCL Start hold time, and the SCL Stop hold time.
Ta ble 1 1 - 5 provides the SCL divider and hold values for corresponding values of the ICR.
The SCL divider multiplied by multiplier factor mul generates IIC baud rate.
Eqn. 11-1
SDA hold time is the delay from the falling edge of SCL (IIC clock) to the changing of SDA (IIC data).
SDA hold time = bus period (s) mul SDA hold value Eqn. 11-2
SCL start hold time is the delay from the falling edge of SDA (IIC data) while SCL is high (Start condition) to the
falling edge of SCL (IIC clock).
SCL Start hold time = bus period (s) mul SCL Start hold value Eqn. 11-3
SCL stop hold time is the delay from the rising edge of SCL (IIC clock) to the rising edge of SDA
SDA (IIC data) while SCL is high (Stop condition).
SCL Stop hold time = bus period (s) mul SCL Stop hold value Eqn. 11-4
Table 11-4. Hold Time Values for 8 MHz Bus Speed
MULT ICR
Hold Times (s)
SDA SCL Start SCL Stop
0x2 0x00 3.500 3.000 5.500
0x1 0x07 2.500 4.000 5.250
0x1 0x0B 2.250 4.000 5.250
0x0 0x14 2.125 4.250 5.125
0x0 0x18 1.125 4.750 5.125
IIC baud rate bus speed (Hz)
mul SCLdivider
---------------------------------------------=
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 167
Table 11-5. IIC Divider and Hold Values
ICR
(hex)
SCL
Divider
SDA Hold
Value
SCL Hold
(Start)
Value
SCL Hold
(Stop)
Value
ICR
(hex)
SCL
Divider
SDA Hold
Value
SCL Hold
(Start)
Value
SCL Hold
(Stop)
Value
00 20 7 6 11 20 160 17 78 81
01 22 7 7 12 21 192 17 94 97
02 24 8 8 13 22 224 33 110 113
03 26 8 9 14 23 256 33 126 129
04 28 9 10 15 24 288 49 142 145
05 30 9 11 16 25 320 49 158 161
06 34 10 13 18 26 384 65 190 193
07 40 10 16 21 27 480 65 238 241
08 28 7 10 15 28 320 33 158 161
09 32 7 12 17 29 384 33 190 193
0A 36 9 14 19 2A 448 65 222 225
0B 40 9 16 21 2B 512 65 254 257
0C 44 11 18 23 2C 576 97 286 289
0D 48 11 20 25 2D 640 97 318 321
0E 56 13 24 29 2E 768 129 382 385
0F 68 13 30 35 2F 960 129 478 481
10 48 9 18 25 30 640 65 318 321
11 56 9 22 29 31 768 65 382 385
12 64 13 26 33 32 896 129 446 449
13 72 13 30 37 33 1024 129 510 513
14 80 17 34 41 34 1152 193 574 577
15 88 17 38 45 35 1280 193 638 641
16 104 21 46 53 36 1536 257 766 769
17 128 21 58 65 37 1920 257 958 961
18 80 9 38 41 38 1280 129 638 641
19 96 9 46 49 39 1536 129 766 769
1A 112 17 54 57 3A 1792 257 894 897
1B 128 17 62 65 3B 2048 257 1022 1025
1C 144 25 70 73 3C 2304 385 1150 1153
1D 160 25 78 81 3D 2560 385 1278 1281
1E 192 33 94 97 3E 3072 513 1534 1537
1F 240 33 118 121 3F 3840 513 1918 1921
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
168 Freescale Semiconductor
11.3.3 IIC Control Register (IICC1)
11.3.4 IIC Status Register (IICS)
76543210
R
IICEN IICIE MST TX TXAK
000
WRSTA
Reset00000000
= Unimplemented or Reserved
Figure 11-5. IIC Control Register (IICC1)
Table 11-6. IICC1 Field Descriptions
Field Description
7
IICEN
IIC Enable. The IICEN bit determines whether the IIC module is enabled.
0 IIC is not enabled
1 IIC is enabled
6
IICIE
IIC Interrupt Enable. The IICIE bit determines whether an IIC interrupt is requested.
0 IIC interrupt request not enabled
1 IIC interrupt request enabled
5
MST
Master Mode Select. The MST bit changes from a 0 to a 1 when a start signal is generated on the bus and
master mode is selected. When this bit changes from a 1 to a 0 a stop signal is generated and the mode of
operation changes from master to slave.
0Slave mode
1 Master mode
4
TX
Transmit Mode Select. The TX bit selects the direction of master and slave transfers. In master mode, this bit
should be set according to the type of transfer required. Therefore, for address cycles, this bit is always high.
When addressed as a slave, this bit should be set by software according to the SRW bit in the status register.
0 Receive
1 Transmit
3
TXAK
Transmit Acknowledge Enable. This bit specifies the value driven onto the SDA during data acknowledge
cycles for master and slave receivers.
0 An acknowledge signal is sent out to the bus after receiving one data byte
1 No acknowledge signal response is sent
2
RSTA
Repeat start. Writing a 1 to this bit generates a repeated start condition provided it is the current master. This
bit is always read as cleared. Attempting a repeat at the wrong time results in loss of arbitration.
76543210
RTCF
IAAS
BUSY
ARBL
0SRW
IICIF
RXAK
W
Reset10000000
= Unimplemented or Reserved
Figure 11-6. IIC Status Register (IICS)
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 169
11.3.5 IIC Data I/O Register (IICD)
Table 11-7. IICS Field Descriptions
Field Description
7
TCF
Transfer Complete Flag. This bit is set on the completion of a byte transfer. This bit is only valid during or
immediately following a transfer to the IIC module or from the IIC module.The TCF bit is cleared by reading the
IICD register in receive mode or writing to the IICD in transmit mode.
0 Transfer in progress
1 Transfer complete
6
IAAS
Addressed as a Slave. The IAAS bit is set when the calling address matches the programmed slave address or
when the GCAEN bit is set and a general call is received. Writing the IICC register clears this bit.
0 Not addressed
1 Addressed as a slave
5
BUSY
Bus Busy. The BUSY bit indicates the status of the bus regardless of slave or master mode. The BUSY bit is set
when a start signal is detected and cleared when a stop signal is detected.
0 Bus is idle
1Bus is busy
4
ARBL
Arbitration Lost. This bit is set by hardware when the arbitration procedure is lost. The ARBL bit must be cleared
by software by writing a 1 to it.
0 Standard bus operation
1 Loss of arbitration
2
SRW
Slave Read/Write. When addressed as a slave, the SRW bit indicates the value of the R/W command bit of the
calling address sent to the master.
0 Slave receive, master writing to slave
1 Slave transmit, master reading from slave
1
IICIF
IIC Interrupt Flag. The IICIF bit is set when an interrupt is pending. This bit must be cleared by software, by
writing a 1 to it in the interrupt routine. One of the following events can set the IICIF bit:
• One byte transfer completes
• Match of slave address to calling address
• Arbitration lost
0 No interrupt pending
1 Interrupt pending
0
RXAK
Receive Acknowledge. When the RXAK bit is low, it indicates an acknowledge signal has been received after
the completion of one byte of data transmission on the bus. If the RXAK bit is high it means that no acknowledge
signal is detected.
0 Acknowledge received
1 No acknowledge received
76543210
R
DATA
W
Reset00000000
Figure 11-7. IIC Data I/O Register (IICD)
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
170 Freescale Semiconductor
NOTE
When transitioning out of master receive mode, the IIC mode should be
switched before reading the IICD register to prevent an inadvertent
initiation of a master receive data transfer.
In slave mode, the same functions are available after an address match has occurred.
The TX bit in IICC must correctly reflect the desired direction of transfer in master and slave modes for
the transmission to begin. For instance, if the IIC is configured for master transmit but a master receive is
desired, reading the IICD does not initiate the receive.
Reading the IICD returns the last byte received while the IIC is configured in master receive or slave
receive modes. The IICD does not reflect every byte transmitted on the IIC bus, nor can software verify
that a byte has been written to the IICD correctly by reading it back.
In master transmit mode, the first byte of data written to IICD following assertion of MST is used for the
address transfer and should comprise of the calling address (in bit 7 to bit 1) concatenated with the required
R/W bit (in position bit 0).
11.3.6 IIC Control Register 2 (IICC2)
Table 11-8. IICD Field Descriptions
Field Description
7–0
DATA
Data — In master transmit mode, when data is written to the IICD, a data transfer is initiated. The most significant
bit is sent first. In master receive mode, reading this register initiates receiving of the next byte of data.
76543210
R
GCAEN ADEXT
000
AD10 AD9 AD8
W
Reset00000000
= Unimplemented or Reserved
Figure 11-8. IIC Control Register (IICC2)
Table 11-9. IICC2 Field Descriptions
Field Description
7
GCAEN
General Call Address Enable. The GCAEN bit enables or disables general call address.
0 General call address is disabled
1 General call address is enabled
6
ADEXT
Address Extension. The ADEXT bit controls the number of bits used for the slave address.
0 7-bit address scheme
1 10-bit address scheme
2–0
AD[10:8]
Slave Address. The AD[10:8] field contains the upper three bits of the slave address in the 10-bit address
scheme. This field is only valid when the ADEXT bit is set.
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 171
11.4 Functional Description
This section provides a complete functional description of the IIC module.
11.4.1 IIC Protocol
The IIC bus system uses a serial data line (SDA) and a serial clock line (SCL) for data transfer. All devices
connected to it must have open drain or open collector outputs. A logic AND function is exercised on both
lines with external pullup resistors. The value of these resistors is system dependent.
Normally, a standard communication is composed of four parts:
• Start signal
• Slave address transmission
• Data transfer
• Stop signal
The stop signal should not be confused with the CPU stop instruction. The IIC bus system communication
is described briefly in the following sections and illustrated in Figure 11-9.
Figure 11-9. IIC Bus Transmission Signals
11.4.1.1 Start Signal
When the bus is free, no master device is engaging the bus (SCL and SDA lines are at logical high), a
master may initiate communication by sending a start signal. As shown in Figure 11-9, a start signal is
defined as a high-to-low transition of SDA while SCL is high. This signal denotes the beginning of a new
data transfer (each data transfer may contain several bytes of data) and brings all slaves out of their idle
states.
SCL
SDA
Start
Signal
Ack
Bit
12345678
msb lsb
12345678
msb lsb
Stop
Signal
No
SCL
SDA
1234567 8
msb lsb
12 5678
msb lsb
Repeated
34
9 9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W XXX D7 D6 D5 D4 D3 D2 D1 D0
Calling Address Read/ Data Byte
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
New Calling Address
99
XX
Ack
Bit
Write
Start
Signal
Start
Signal
Ack
Bit
Calling Address Read/
Write
Stop
Signal
No
Ack
Bit
Read/
Write
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
172 Freescale Semiconductor
11.4.1.2 Slave Address Transmission
The first byte of data transferred immediately after the start signal is the slave address transmitted by the
master. This is a seven-bit calling address followed by a R/W bit. The R/W bit tells the slave the desired
direction of data transfer.
1 = Read transfer, the slave transmits data to the master.
0 = Write transfer, the master transmits data to the slave.
Only the slave with a calling address that matches the one transmitted by the master responds by sending
back an acknowledge bit. This is done by pulling the SDA low at the ninth clock (see Figure 11-9).
No two slaves in the system may have the same address. If the IIC module is the master, it must not
transmit an address equal to its own slave address. The IIC cannot be master and slave at the same time.
However, if arbitration is lost during an address cycle, the IIC reverts to slave mode and operates correctly
even if it is being addressed by another master.
11.4.1.3 Data Transfer
Before successful slave addressing is achieved, the data transfer can proceed byte-by-byte in a direction
specified by the R/W bit sent by the calling master.
All transfers that come after an address cycle are referred to as data transfers, even if they carry sub-address
information for the slave device
Each data byte is 8 bits long. Data may be changed only while SCL is low and must be held stable while
SCL is high as shown in Figure 11-9. There is one clock pulse on SCL for each data bit, the msb being
transferred first. Each data byte is followed by a 9th (acknowledge) bit, which is signalled from the
receiving device. An acknowledge is signalled by pulling the SDA low at the ninth clock. In summary, one
complete data transfer needs nine clock pulses.
If the slave receiver does not acknowledge the master in the ninth bit time, the SDA line must be left high
by the slave. The master interprets the failed acknowledge as an unsuccessful data transfer.
If the master receiver does not acknowledge the slave transmitter after a data byte transmission, the slave
interprets this as an end of data transfer and releases the SDA line.
In either case, the data transfer is aborted and the master does one of two things:
• Relinquishes the bus by generating a stop signal.
• Commences a new calling by generating a repeated start signal.
11.4.1.4 Stop Signal
The master can terminate the communication by generating a stop signal to free the bus. However, the
master may generate a start signal followed by a calling command without generating a stop signal first.
This is called repeated start. A stop signal is defined as a low-to-high transition of SDA while SCL at
logical 1 (see Figure 11-9).
The master can generate a stop even if the slave has generated an acknowledge at which point the slave
must release the bus.
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 173
11.4.1.5 Repeated Start Signal
As shown in Figure 11-9, a repeated start signal is a start signal generated without first generating a stop
signal to terminate the communication. This is used by the master to communicate with another slave or
with the same slave in different mode (transmit/receive mode) without releasing the bus.
11.4.1.6 Arbitration Procedure
The IIC bus is a true multi-master bus that allows more than one master to be connected on it. If two or
more masters try to control the bus at the same time, a clock synchronization procedure determines the bus
clock, for which the low period is equal to the longest clock low period and the high is equal to the shortest
one among the masters. The relative priority of the contending masters is determined by a data arbitration
procedure, a bus master loses arbitration if it transmits logic 1 while another master transmits logic 0. The
losing masters immediately switch over to slave receive mode and stop driving SDA output. In this case,
the transition from master to slave mode does not generate a stop condition. Meanwhile, a status bit is set
by hardware to indicate loss of arbitration.
11.4.1.7 Clock Synchronization
Because wire-AND logic is performed on the SCL line, a high-to-low transition on the SCL line affects all
the devices connected on the bus. The devices start counting their low period and after a device’s clock has
gone low, it holds the SCL line low until the clock high state is reached. However, the change of low to
high in this device clock may not change the state of the SCL line if another device clock is still within its
low period. Therefore, synchronized clock SCL is held low by the device with the longest low period.
Devices with shorter low periods enter a high wait state during this time (see Figure 11-10). When all
devices concerned have counted off their low period, the synchronized clock SCL line is released and
pulled high. There is then no difference between the device clocks and the state of the SCL line and all the
devices start counting their high periods. The first device to complete its high period pulls the SCL line
low again.
Figure 11-10. IIC Clock Synchronization
SCL1
SCL2
SCL
Internal Counter Reset
Delay Start Counting High Period
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
174 Freescale Semiconductor
11.4.1.8 Handshaking
The clock synchronization mechanism can be used as a handshake in data transfer. Slave devices may hold
the SCL low after completion of one byte transfer (9 bits). In such a case, it halts the bus clock and forces
the master clock into wait states until the slave releases the SCL line.
11.4.1.9 Clock Stretching
The clock synchronization mechanism can be used by slaves to slow down the bit rate of a transfer. After
the master has driven SCL low the slave can drive SCL low for the required period and then release it. If
the slave SCL low period is greater than the master SCL low period then the resulting SCL bus signal low
period is stretched.
11.4.2 10-bit Address
For 10-bit addressing, 0x11110 is used for the first 5 bits of the first address byte. Various combinations of
read/write formats are possible within a transfer that includes 10-bit addressing.
11.4.2.1 Master-Transmitter Addresses a Slave-Receiver
The transfer direction is not changed (see Table 11-10). When a 10-bit address follows a start condition,
each slave compares the first seven bits of the first byte of the slave address (11110XX) with its own
address and tests whether the eighth bit (R/W direction bit) is 0. More than one device can find a match
and generate an acknowledge (A1). Then, each slave that finds a match compares the eight bits of the
second byte of the slave address with its own address. Only one slave finds a match and generates an
acknowledge (A2). The matching slave remains addressed by the master until it receives a stop condition
(P) or a repeated start condition (Sr) followed by a different slave address.
After the master-transmitter has sent the first byte of the 10-bit address, the slave-receiver sees an IIC
interrupt. Software must ensure the contents of IICD are ignored and not treated as valid data for this
interrupt.
11.4.2.2 Master-Receiver Addresses a Slave-Transmitter
The transfer direction is changed after the second R/W bit (see Table 11-11). Up to and including
acknowledge bit A2, the procedure is the same as that described for a master-transmitter addressing a
slave-receiver. After the repeated start condition (Sr), a matching slave remembers that it was addressed
before. This slave then checks whether the first seven bits of the first byte of the slave address following
Sr are the same as they were after the start condition (S) and tests whether the eighth (R/W) bit is 1. If there
is a match, the slave considers that it has been addressed as a transmitter and generates acknowledge A3.
The slave-transmitter remains addressed until it receives a stop condition (P) or a repeated start condition
(Sr) followed by a different slave address.
SSlave Address 1st 7 bits R/W A1 Slave Address 2nd byte A2 Data A ... Data A/A P
11110 + AD10 + AD9 0 AD[8:1]
Table 11-10. Master-Transmitter Addresses Slave-Receiver with a 10-bit Address
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 175
After a repeated start condition (Sr), all other slave devices also compare the first seven bits of the first
byte of the slave address with their own addresses and test the eighth (R/W) bit. However, none of them
are addressed because R/W = 1 (for 10-bit devices) or the 11110XX slave address (for 7-bit devices) does
not match.
After the master-receiver has sent the first byte of the 10-bit address, the slave-transmitter sees an IIC
interrupt. Software must ensure the contents of IICD are ignored and not treated as valid data for this
interrupt.
11.4.3 General Call Address
General calls can be requested in 7-bit address or 10-bit address. If the GCAEN bit is set, the IIC matches
the general call address as well as its own slave address. When the IIC responds to a general call, it acts as
a slave-receiver and the IAAS bit is set after the address cycle. Software must read the IICD register after
the first byte transfer to determine whether the address matches is its own slave address or a general call.
If the value is 00, the match is a general call. If the GCAEN bit is clear, the IIC ignores any data supplied
from a general call address by not issuing an acknowledgement.
11.5 Resets
The IIC is disabled after reset. The IIC cannot cause an MCU reset.
11.6 Interrupts
The IIC generates a single interrupt.
An interrupt from the IIC is generated when any of the events in Table 11-12 occur, provided the IICIE bit
is set. The interrupt is driven by bit IICIF (of the IIC status register) and masked with bit IICIE (of the IIC
control register). The IICIF bit must be cleared by software by writing a 1 to it in the interrupt routine. You
can determine the interrupt type by reading the status register.
11.6.1 Byte Transfer Interrupt
The TCF (transfer complete flag) bit is set at the falling edge of the ninth clock to indicate the completion
of byte transfer.
S
Slave Address
1st 7 bits R/W A1
Slave Address
2nd byte A2 Sr
Slave Address
1st 7 bits R/W A3 Data A ... Data A P
11110 + AD10 + AD9 0 AD[8:1] 11110 + AD10 + AD9 1
Table 11-11. Master-Receiver Addresses a Slave-Transmitter with a 10-bit Address
Table 11-12. Interrupt Summary
Interrupt Source Status Flag Local Enable
Complete 1-byte transfer TCF IICIF IICIE
Match of received calling address IAAS IICIF IICIE
Arbitration Lost ARBL IICIF IICIE
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
176 Freescale Semiconductor
11.6.2 Address Detect Interrupt
When the calling address matches the programmed slave address (IIC address register) or when the
GCAEN bit is set and a general call is received, the IAAS bit in the status register is set. The CPU is
interrupted, provided the IICIE is set. The CPU must check the SRW bit and set its Tx mode accordingly.
11.6.3 Arbitration Lost Interrupt
The IIC is a true multi-master bus that allows more than one master to be connected on it. If two or more
masters try to control the bus at the same time, the relative priority of the contending masters is determined
by a data arbitration procedure. The IIC module asserts this interrupt when it loses the data arbitration
process and the ARBL bit in the status register is set.
Arbitration is lost in the following circumstances:
• SDA sampled as a low when the master drives a high during an address or data transmit cycle.
• SDA sampled as a low when the master drives a high during the acknowledge bit of a data receive
cycle.
• A start cycle is attempted when the bus is busy.
• A repeated start cycle is requested in slave mode.
• A stop condition is detected when the master did not request it.
This bit must be cleared by software writing a 1 to it.
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 177
11.7 Initialization/Application Information
Figure 11-11. IIC Module Quick Start
Module Initialization (Slave)
1. Write: IICC2
— to enable or disable general call
— to select 10-bit or 7-bit addressing mode
2. Write: IICA
— to set the slave address
3. Write: IICC1
— to enable IIC and interrupts
4. Initialize RAM variables (IICEN = 1 and IICIE = 1) for transmit data
5. Initialize RAM variables used to achieve the routine shown in Figure 11-12
Module Initialization (Master)
1. Write: IICF
— to set the IIC baud rate (example provided in this chapter)
2. Write: IICC1
— to enable IIC and interrupts
3. Initialize RAM variables (IICEN = 1 and IICIE = 1) for transmit data
4. Initialize RAM variables used to achieve the routine shown in Figure 11-12
5. Write: IICC1
— to enable TX
0
IICF
IICA
Baud rate = BUSCLK / (2 x MULT x (SCL DIVIDER))
TX TXAK RSTA 0 0
IICC1 IICEN IICIE MST
Module configuration
ARBL 0 SRW IICIF RXAK
IICS TCF IAAS BUSY
Module status flags
Register Model
AD[7:1]
When addressed as a slave (in slave mode), the module responds to this address
MULT ICR
IICD DATA
Data register; Write to transmit IIC data read to read IIC data
0 AD10 AD9 AD8
IICC2 GCAEN ADEXT
Address configuration
0
0
Inter-Integrated Circuit (S08IICV2)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
178 Freescale Semiconductor
Figure 11-12. Typical IIC Interrupt Routine
Clear
Master
Mode
?
Tx/Rx
?
Last Byte
Transmitted
?
RXAK=0
?
End of
Addr Cycle
(Master Rx)
?
Write Next
Byte to IICD
Switch to
Rx Mode
Dummy Read
from IICD
Generate
Stop Signal
Read Data
from IICD
and Store
Set TXACK =1
Generate
Stop Signal
2nd Last
Byte to Be Read
?
Last
Byte to Be Read
?
Arbitration
Lost
?
Clear ARBL
IAAS=1
?
IAAS=1
?
SRW=1
?
TX/RX
?
Set TX
Mode
Write Data
to IICD
Set RX
Mode
Dummy Read
from IICD
ACK from
Receiver
?
Tx Next
Byte
Read Data
from IICD
and Store
Switch to
Rx Mode
Dummy Read
from IICD
RTI
YN
Y
YY
Y
Y
Y
Y
Y
Y
N
N
N
N
N
N
N
N
N
Y
TX RX
RX
TX
(Write)
(Read)
N
IICIF
Address Transfer Data Transfer
(MST = 0)
(MST = 0)
See Note 1
NOTES:
1If general call is enabled, a check must be done to determine whether the received address was a general call address (0x00).
If the received address was a general call address, then the general call must be handled by user software.
2When 10-bit addressing is used to address a slave, the slave sees an interrupt following the first byte of the extended address.
User software must ensure that for this interrupt, the contents of IICD are ignored and not treated as a valid data transfer.
See Note 2
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 179
Chapter 12
Modulo Timer (S08MTIMV1)
12.1 Introduction
The MTIM is a simple 8-bit timer with several software selectable clock sources and a programmable
interrupt.
The central component of the MTIM is the 8-bit counter, which can operate as a free-running counter or a
modulo counter. A timer overflow interrupt can be enabled to generate periodic interrupts for time-based
software loops.
Figure 12-1 shows the MC9S08SG8 block diagram with the MTIM module highlighted.
12.1.1 MTIM Configuration Information
The external clock for the MTIM module, TCLK, is selected by setting CLKS = 1:1 or 1:0 in MTIMCLK,
which selects the TCLK pin input. The TCLK input on PTA0 can be enabled as external clock inputs to
both MTIM and TPM modules simultaneously.
Chapter 12 Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
180 Freescale Semiconductor
Figure 12-1. MC9S08SG8 Block Diagram with MTIM Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 181
12.1.2 Features
Timer system features include:
• 8-bit up-counter
— Free-running or 8-bit modulo limit
— Software controllable interrupt on overflow
— Counter reset bit (TRST)
— Counter stop bit (TSTP)
• Four software selectable clock sources for input to prescaler:
— System bus clock — rising edge
— Fixed frequency clock (XCLK) — rising edge
— External clock source on the TCLK pin — rising edge
— External clock source on the TCLK pin — falling edge
• Nine selectable clock prescale values:
— Clock source divide by 1, 2, 4, 8, 16, 32, 64, 128, or 256
12.1.3 Modes of Operation
This section defines the MTIM’s operation in stop, wait and background debug modes.
12.1.3.1 MTIM in Wait Mode
The MTIM continues to run in wait mode if enabled before executing the WAIT instruction. Therefore,
the MTIM can be used to bring the MCU out of wait mode if the timer overflow interrupt is enabled. For
lowest possible current consumption, the MTIM should be stopped by software if not needed as an
interrupt source during wait mode.
12.1.3.2 MTIM in Stop Modes
The MTIM is disabled in all stop modes, regardless of the settings before executing the STOP instruction.
Therefore, the MTIM cannot be used as a wake up source from stop modes.
Waking from stop1 and stop2 modes, the MTIM will be put into its reset state. If stop3 is exited with a
reset, the MTIM will be put into its reset state. If stop3 is exited with an interrupt, the MTIM continues
from the state it was in when stop3 was entered. If the counter was active upon entering stop3, the count
will resume from the current value.
12.1.3.3 MTIM in Active Background Mode
The MTIM suspends all counting until the microcontroller returns to normal user operating mode.
Counting resumes from the suspended value as long as an MTIM reset did not occur (TRST written to a 1
or MTIMMOD written).
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
182 Freescale Semiconductor
12.1.4 Block Diagram
The block diagram for the modulo timer module is shown Figure 12-2.
Figure 12-2. Modulo Timer (MTIM) Block Diagram
12.2 External Signal Description
The MTIM includes one external signal, TCLK, used to input an external clock when selected as the
MTIM clock source. The signal properties of TCLK are shown in Table 12-1.
The TCLK input must be synchronized by the bus clock. Also, variations in duty cycle and clock jitter
must be accommodated. Therefore, the TCLK signal must be limited to one-fourth of the bus frequency.
The TCLK pin can be muxed with a general-purpose port pin. See the Pins and Connections chapter for
the pin location and priority of this function.
Table 12-1. Signal Properties
Signal Function I/O
TCLK External clock source input into MTIM I
BUSCLK
TCLK SYNC
CLOCK
SOURCE
SELECT
PRESCALE
AND SELECT
DIVIDE BY
8-BIT COUNTER
(MTIMCNT)
8-BIT MODULO
(MTIMMOD)
8-BIT COMPARATOR
TRST
TSTP
CLKS PS
XCLK
TOIE
MTIM
INTERRUPT
REQUEST
TOF
REG
set_tof_pulse
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 183
12.3 Register Definition
Figure 12-3 is a summary of MTIM registers.
Each MTIM includes four registers:
• An 8-bit status and control register
• An 8-bit clock configuration register
• An 8-bit counter register
• An 8-bit modulo register
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all MTIM registers.This section refers to registers and control bits only by their names and
relative address offsets.
Some MCUs may have more than one MTIM, so register names include placeholder characters to identify
which MTIM is being referenced.
Name 76543210
MTIMSC RTOF TOIE 0TSTP 0000
WTRST
MTIMCLK R0 0 CLKS PS
W
MTIMCNT RCOUNT
W
MTIMMOD RMOD
W
Figure 12-3. MTIM Register Summary
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
184 Freescale Semiconductor
12.3.1 MTIM Status and Control Register (MTIMSC)
MTIMSC contains the overflow status flag and control bits which are used to configure the interrupt enable,
reset the counter, and stop the counter.
7 6543210
RTOF
TOIE
0
TSTP
0000
WTRST
Reset: 0 0 0 1 0 0 0 0
Figure 12-4. MTIM Status and Control Register
Table 12-2. MTIM Status and Control Register Field Descriptions
Field Description
7
TOF
MTIM Overflow Flag — This read-only bit is set when the MTIM counter register overflows to $00 after reaching
the value in the MTIM modulo register. Clear TOF by reading the MTIMSC register while TOF is set, then writing
a 0 to TOF. TOF is also cleared when TRST is written to a 1 or when any value is written to the MTIMMOD register.
0 MTIM counter has not reached the overflow value in the MTIM modulo register.
1 MTIM counter has reached the overflow value in the MTIM modulo register.
6
TOIE
MTIM Overflow Interrupt Enable — This read/write bit enables MTIM overflow interrupts. If TOIE is set, then an
interrupt is generated when TOF = 1. Reset clears TOIE. Do not set TOIE if TOF = 1. Clear TOF first, then set TOIE.
0 TOF interrupts are disabled. Use software polling.
1 TOF interrupts are enabled.
5
TRST
MTIM Counter Reset — When a 1 is written to this write-only bit, the MTIM counter register resets to $00 and TOF
is cleared. Reading this bit always returns 0.
0 No effect. MTIM counter remains at current state.
1 MTIM counter is reset to $00.
4
TSTP
MTIM Counter Stop — When set, this read/write bit stops the MTIM counter at its current value. Counting resumes
from the current value when TSTP is cleared. Reset sets TSTP to prevent the MTIM from counting.
0 MTIM counter is active.
1 MTIM counter is stopped.
3:0 Unused register bits, always read 0.
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 185
12.3.2 MTIM Clock Configuration Register (MTIMCLK)
MTIMCLK contains the clock select bits (CLKS) and the prescaler select bits (PS).
7 6543210
R 0 0
CLKS PS
W
Reset: 0 0 0 0 0 0 0 0
Figure 12-5. MTIM Clock Configuration Register
Table 12-3. MTIM Clock Configuration Register Field Description
Field Description
7:6 Unused register bits, always read 0.
5:4
CLKS
Clock Source Select — These two read/write bits select one of four different clock sources as the input to the
MTIM prescaler. Changing the clock source while the counter is active does not clear the counter. The count
continues with the new clock source. Reset clears CLKS to 000.
00 Encoding 0. Bus clock (BUSCLK)
01 Encoding 1. Fixed-frequency clock (XCLK)
10 Encoding 3. External source (TCLK pin), falling edge
11 Encoding 4. External source (TCLK pin), rising edge
All other encodings default to the bus clock (BUSCLK).
3:0
PS
Clock Source Prescaler — These four read/write bits select one of nine outputs from the 8-bit prescaler. Changing
the prescaler value while the counter is active does not clear the counter. The count continues with the new
prescaler value. Reset clears PS to 0000.
0000 Encoding 0. MTIM clock source 1
0001 Encoding 1. MTIM clock source 2
0010 Encoding 2. MTIM clock source 4
0011 Encoding 3. MTIM clock source 8
0100 Encoding 4. MTIM clock source 16
0101 Encoding 5. MTIM clock source 32
0110 Encoding 6. MTIM clock source 64
0111 Encoding 7. MTIM clock source 128
1000 Encoding 8. MTIM clock source 256
All other encodings default to MTIM clock source 256.
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
186 Freescale Semiconductor
12.3.3 MTIM Counter Register (MTIMCNT)
MTIMCNT is the read-only value of the current MTIM count of the 8-bit counter.
12.3.4 MTIM Modulo Register (MTIMMOD)
7 6543210
RCOUNT
W
Reset: 0 0 0 0 0 0 0 0
Figure 12-6. MTIM Counter Register
Table 12-4. MTIM Counter Register Field Description
Field Description
7:0
COUNT
MTIM Count — These eight read-only bits contain the current value of the 8-bit counter. Writes have no effect to
this register. Reset clears the count to $00.
7 6543210
R
MOD
W
Reset: 0 0 0 0 0 0 0 0
Figure 12-7. MTIM Modulo Register
Table 12-5. MTIM Modulo Register Field Descriptions
Field Description
7:0
MOD
MTIM Modulo — These eight read/write bits contain the modulo value used to reset the count and set TOF. A value
of $00 puts the MTIM in free-running mode. Writing to MTIMMOD resets the COUNT to $00 and clears TOF. Reset
sets the modulo to $00.
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 187
12.4 Functional Description
The MTIM is composed of a main 8-bit up-counter with an 8-bit modulo register, a clock source selector,
and a prescaler block with nine selectable values. The module also contains software selectable interrupt
logic.
The MTIM counter (MTIMCNT) has three modes of operation: stopped, free-running, and modulo. Out of
reset, the counter is stopped. If the counter is started without writing a new value to the modulo register,
then the counter will be in free-running mode. The counter is in modulo mode when a value other than $00
is in the modulo register while the counter is running.
After any MCU reset, the counter is stopped and reset to $00, and the modulus is set to $00. The bus clock
is selected as the default clock source and the prescale value is divide by 1. To start the MTIM in
free-running mode, simply write to the MTIM status and control register (MTIMSC) and clear the MTIM
stop bit (TSTP).
Four clock sources are software selectable: the internal bus clock, the fixed frequency clock (XCLK), and
an external clock on the TCLK pin, selectable as incrementing on either rising or falling edges. The MTIM
clock select bits (CLKS1:CLKS0) in MTIMSC are used to select the desired clock source. If the counter is
active (TSTP = 0) when a new clock source is selected, the counter will continue counting from the
previous value using the new clock source.
Nine prescale values are software selectable: clock source divided by 1, 2, 4, 8, 16, 32, 64, 128, or 256.
The prescaler select bits (PS[3:0]) in MTIMSC select the desired prescale value. If the counter is active
(TSTP = 0) when a new prescaler value is selected, the counter will continue counting from the previous
value using the new prescaler value.
The MTIM modulo register (MTIMMOD) allows the overflow compare value to be set to any value from
$01 to $FF. Reset clears the modulo value to $00, which results in a free running counter.
When the counter is active (TSTP = 0), the counter increments at the selected rate until the count matches
the modulo value. When these values match, the counter overflows to $00 and continues counting. The
MTIM overflow flag (TOF) is set whenever the counter overflows. The flag sets on the transition from the
modulo value to $00. Writing to MTIMMOD while the counter is active resets the counter to $00 and clears
TOF.
Clearing TOF is a two-step process. The first step is to read the MTIMSC register while TOF is set. The
second step is to write a 0 to TOF. If another overflow occurs between the first and second steps, the
clearing process is reset and TOF will remain set after the second step is performed. This will prevent the
second occurrence from being missed. TOF is also cleared when a 1 is written to TRST or when any value
is written to the MTIMMOD register.
The MTIM allows for an optional interrupt to be generated whenever TOF is set. To enable the MTIM
overflow interrupt, set the MTIM overflow interrupt enable bit (TOIE) in MTIMSC. TOIE should never be
written to a 1 while TOF = 1. Instead, TOF should be cleared first, then the TOIE can be set to 1.
Modulo Timer (S08MTIMV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
188 Freescale Semiconductor
12.4.1 MTIM Operation Example
This section shows an example of the MTIM operation as the counter reaches a matching value from the
modulo register.
Figure 12-8. MTIM counter overflow example
In the example of Figure 12-8, the selected clock source could be any of the five possible choices. The
prescaler is set to PS = %0010 or divide-by-4. The modulo value in the MTIMMOD register is set to $AA.
When the counter, MTIMCNT, reaches the modulo value of $AA, the counter overflows to $00 and
continues counting. The timer overflow flag, TOF, sets when the counter value changes from $AA to $00.
An MTIM overflow interrupt is generated when TOF is set, if TOIE = 1.
selected
clock source
MTIMCNT
MTIM clock
(PS=%0010)
MTIMMOD: $AA
$A7 $A8 $A9 $AA $00 $01
TOF
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 189
Chapter 13
Real-Time Counter (S08RTCV1)
13.1 Introduction
The RTC module consists of one 8-bit counter, one 8-bit comparator, several binary-based and
decimal-based prescaler dividers, two clock sources, and one programmable periodic interrupt. This
module can be used for time-of-day, calendar or any task scheduling functions. It can also serve as a cyclic
wake up from low power modes without the need of external components.
Chapter 13 Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
190 Freescale Semiconductor
Figure 13-1. MC9S08SG8 Block Diagram with RTC Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 191
13.1.1 Features
Features of the RTC module include:
• 8-bit up-counter
— 8-bit modulo match limit
— Software controllable periodic interrupt on match
• Three software selectable clock sources for input to prescaler with selectable binary-based and
decimal-based divider values
— 1-kHz internal low-power oscillator (LPO)
— External clock (ERCLK)
— 32-kHz internal clock (IRCLK)
13.1.2 Modes of Operation
This section defines the operation in stop, wait and background debug modes.
13.1.2.1 Wait Mode
The RTC continues to run in wait mode if enabled before executing the appropriate instruction. Therefore,
the RTC can bring the MCU out of wait mode if the real-time interrupt is enabled. For lowest possible
current consumption, the RTC should be stopped by software if not needed as an interrupt source during
wait mode.
13.1.2.2 Stop Modes
The RTC continues to run in stop2 or stop3 mode if the RTC is enabled before executing the STOP
instruction. Therefore, the RTC can bring the MCU out of stop modes with no external components, if the
real-time interrupt is enabled.
The LPO clock can be used in stop2 and stop3 modes. ERCLK and IRCLK clocks are only available in
stop3 mode.
Power consumption is lower when all clock sources are disabled, but in that case, the real-time interrupt
cannot wake up the MCU from stop modes.
13.1.2.3 Active Background Mode
The RTC suspends all counting during active background mode until the microcontroller returns to normal
user operating mode. Counting resumes from the suspended value as long as the RTCMOD register is not
written and the RTCPS and RTCLKS bits are not altered.
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
192 Freescale Semiconductor
13.1.3 Block Diagram
The block diagram for the RTC module is shown in Figure 13-2.
Figure 13-2. Real-Time Counter (RTC) Block Diagram
13.2 External Signal Description
The RTC does not include any off-chip signals.
13.3 Register Definition
The RTC includes a status and control register, an 8-bit counter register, and an 8-bit modulo register.
Refer to the direct-page register summary in the memory section of this document for the absolute address
assignments for all RTC registers.This section refers to registers and control bits only by their names and
relative address offsets.
Table 13-1 is a summary of RTC registers.
Table 13-1. RTC Register Summary
Name 7 6 5 4 3210
RTCSC
R
RTIF RTCLKS RTIE RTCPS
W
RTCCNT
R RTCCNT
W
RTCMOD
R
RTCMOD
W
Clock
Source
Select
Prescaler
Divide-By
8-Bit Counter
(RTCCNT)
8-Bit Modulo
(RTCMOD)
8-Bit Comparator
RTIF
RTIE
Background
VDD
RTC
Interrupt
Request
DQ
R
E
LPO
RTC
Clock
Mode
ERCLK
IRCLK
RTCLKS
Write 1 to
RTIF
RTCPS
RTCLKS[0]
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 193
13.3.1 RTC Status and Control Register (RTCSC)
RTCSC contains the real-time interrupt status flag (RTIF), the clock select bits (RTCLKS), the real-time
interrupt enable bit (RTIE), and the prescaler select bits (RTCPS).
7 6543210
R
RTIF RTCLKS RTIE RTCPS
W
Reset: 0 0 0 0 0 0 0 0
Figure 13-3. RTC Status and Control Register (RTCSC)
Table 13-2. RTCSC Field Descriptions
Field Description
7
RTIF
Real-Time Interrupt Flag This status bit indicates the RTC counter register reached the value in the RTC modulo
register. Writing a logic 0 has no effect. Writing a logic 1 clears the bit and the real-time interrupt request. Reset
clears RTIF.
0 RTC counter has not reached the value in the RTC modulo register.
1 RTC counter has reached the value in the RTC modulo register.
6–5
RTCLKS
Real-Time Clock Source Select. These two read/write bits select the clock source input to the RTC prescaler.
Changing the clock source clears the prescaler and RTCCNT counters. When selecting a clock source, ensure
that the clock source is properly enabled (if applicable) to ensure correct operation of the RTC. Reset clears
RTCLKS.
00 Real-time clock source is the 1-kHz low power oscillator (LPO)
01 Real-time clock source is the external clock (ERCLK)
1x Real-time clock source is the internal clock (IRCLK)
4
RTIE
Real-Time Interrupt Enable. This read/write bit enables real-time interrupts. If RTIE is set, then an interrupt is
generated when RTIF is set. Reset clears RTIE.
0 Real-time interrupt requests are disabled. Use software polling.
1 Real-time interrupt requests are enabled.
3–0
RTCPS
Real-Time Clock Prescaler Select. These four read/write bits select binary-based or decimal-based divide-by
values for the clock source. See Table 13-3. Changing the prescaler value clears the prescaler and RTCCNT
counters. Reset clears RTCPS.
Table 13-3. RTC Prescaler Divide-by values
RTCLKS[0]
RTCPS
0 1 2 3 4 5 6 7 8 9 101112 13 14 15
0Off 232526272829210 122
210 241025x102103
1Off 210 211 212 213 214 215 216 1032x1035x1031042x1045x1041052x105
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
194 Freescale Semiconductor
13.3.2 RTC Counter Register (RTCCNT)
RTCCNT is the read-only value of the current RTC count of the 8-bit counter.
13.3.3 RTC Modulo Register (RTCMOD)
13.4 Functional Description
The RTC is composed of a main 8-bit up-counter with an 8-bit modulo register, a clock source selector,
and a prescaler block with binary-based and decimal-based selectable values. The module also contains
software selectable interrupt logic.
After any MCU reset, the counter is stopped and reset to 0x00, the modulus register is set to 0x00, and the
prescaler is off. The 1-kHz internal oscillator clock is selected as the default clock source. To start the
prescaler, write any value other than zero to the prescaler select bits (RTCPS).
Three clock sources are software selectable: the low power oscillator clock (LPO), the external clock
(ERCLK), and the internal clock (IRCLK). The RTC clock select bits (RTCLKS) select the desired clock
source. If a different value is written to RTCLKS, the prescaler and RTCCNT counters are reset to 0x00.
7 6543210
RRTCCNT
W
Reset: 0 0 0 0 0 0 0 0
Figure 13-4. RTC Counter Register (RTCCNT)
Table 13-4. RTCCNT Field Descriptions
Field Description
7:0
RTCCNT
RTC Count. These eight read-only bits contain the current value of the 8-bit counter. Writes have no effect to this
register. Reset, writing to RTCMOD, or writing different values to RTCLKS and RTCPS clear the count to 0x00.
7 6543210
R
RTCMOD
W
Reset: 0 0 0 0 0 0 0 0
Figure 13-5. RTC Modulo Register (RTCMOD)
Table 13-5. RTCMOD Field Descriptions
Field Description
7:0
RTCMOD
RTC Modulo. These eight read/write bits contain the modulo value used to reset the count to 0x00 upon a compare
match and set the RTIF status bit. A value of 0x00 sets the RTIF bit on each rising edge of the prescaler output.
Writing to RTCMOD resets the prescaler and the RTCCNT counters to 0x00. Reset sets the modulo to 0x00.
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 195
RTCPS and the RTCLKS[0] bit select the desired divide-by value. If a different value is written to RTCPS,
the prescaler and RTCCNT counters are reset to 0x00. Table 13-6 shows different prescaler period values.
The RTC modulo register (RTCMOD) allows the compare value to be set to any value from 0x00 to 0xFF.
When the counter is active, the counter increments at the selected rate until the count matches the modulo
value. When these values match, the counter resets to 0x00 and continues counting. The real-time interrupt
flag (RTIF) is set when a match occurs. The flag sets on the transition from the modulo value to 0x00.
Writing to RTCMOD resets the prescaler and the RTCCNT counters to 0x00.
The RTC allows for an interrupt to be generated when RTIF is set. To enable the real-time interrupt, set
the real-time interrupt enable bit (RTIE) in RTCSC. RTIF is cleared by writing a 1 to RTIF.
13.4.1 RTC Operation Example
This section shows an example of the RTC operation as the counter reaches a matching value from the
modulo register.
Table 13-6. Prescaler Period
RTCPS 1-kHz Internal Clock
(RTCLKS = 00)
1-MHz External Clock
(RTCLKS = 01)
32-kHz Internal Clock
(RTCLKS = 10)
32-kHz Internal Clock
(RTCLKS = 11)
0000 Off Off Off Off
0001 8 ms 1.024 ms 250 s32 ms
0010 32 ms 2.048 ms 1 ms 64 ms
0011 64 ms 4.096 ms 2 ms 128 ms
0100 128 ms 8.192 ms 4 ms 256 ms
0101 256 ms 16.4 ms 8 ms 512 ms
0110 512 ms 32.8 ms 16 ms 1.024 s
0111 1.024 s 65.5 ms 32 ms 2.048 s
1000 1 ms 1 ms 31.25 s 31.25 ms
1001 2 ms 2 ms 62.5 s62.5 ms
1010 4 ms 5 ms 125 s 156.25 ms
1011 10 ms 10 ms 312.5 s 312.5 ms
1100 16 ms 20 ms 0.5 ms 0.625 s
1101 0.1 s 50 ms 3.125 ms 1.5625 s
1110 0.5 s 0.1 s 15.625 ms 3.125 s
1111 1 s 0.2 s 31.25 ms 6.25 s
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
196 Freescale Semiconductor
Figure 13-6. RTC Counter Overflow Example
In the example of Figure 13-6, the selected clock source is the 1-kHz internal oscillator clock source. The
prescaler (RTCPS) is set to 0xA or divide-by-4. The modulo value in the RTCMOD register is set to 0x55.
When the counter, RTCCNT, reaches the modulo value of 0x55, the counter overflows to 0x00 and
continues counting. The real-time interrupt flag, RTIF, sets when the counter value changes from 0x55 to
0x00. A real-time interrupt is generated when RTIF is set, if RTIE is set.
13.5 Initialization/Application Information
This section provides example code to give some basic direction to a user on how to initialize and
configure the RTC module. The example software is implemented in C language.
The example below shows how to implement time of day with the RTC using the 1-kHz clock source to
achieve the lowest possible power consumption. Because the 1-kHz clock source is not as accurate as a
crystal, software can be added for any adjustments. For accuracy without adjustments at the expense of
additional power consumption, the external clock (ERCLK) or the internal clock (IRCLK) can be selected
with appropriate prescaler and modulo values.
/* Initialize the elapsed time counters */
Seconds = 0;
Minutes = 0;
Hours = 0;
Days=0;
/* Configure RTC to interrupt every 1 second from 1-kHz clock source */
RTCMOD.byte = 0x00;
RTCSC.byte = 0x1F;
/**********************************************************************
Function Name : RTC_ISR
Notes : Interrupt service routine for RTC module.
**********************************************************************/
0x55
0x550x540x530x52 0x00 0x01
RTCMOD
RTIF
RTCCNT
RTC Clock
(RTCPS = 0xA)
Internal 1-kHz
Clock Source
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 197
#pragma TRAP_PROC
void RTC_ISR(void)
{
/* Clear the interrupt flag */
RTCSC.byte = RTCSC.byte | 0x80;
/* RTC interrupts every 1 Second */
Seconds++;
/* 60 seconds in a minute */
if (Seconds > 59){
Minutes++;
Seconds = 0;
}
/* 60 minutes in an hour */
if (Minutes > 59){
Hours++;
Minutes = 0;
}
/* 24 hours in a day */
if (Hours > 23){
Days ++;
Hours = 0;
}
Real-Time Counter (S08RTCV1)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
198 Freescale Semiconductor
Chapter 14 Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev.8
200 Freescale Semiconductor
Figure 14-1. MC9S08SG8 Block Diagram with SCI Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 201
14.1.1 Features
Features of SCI module include:
• Full-duplex, standard non-return-to-zero (NRZ) format
• Double-buffered transmitter and receiver with separate enables
• Programmable baud rates (13-bit modulo divider)
• Interrupt-driven or polled operation:
— Transmit data register empty and transmission complete
— Receive data register full
— Receive overrun, parity error, framing error, and noise error
— Idle receiver detect
— Active edge on receive pin
— Break detect supporting LIN
• Hardware parity generation and checking
• Programmable 8-bit or 9-bit character length
• Receiver wakeup by idle-line or address-mark
• Optional 13-bit break character generation / 11-bit break character detection
• Selectable transmitter output polarity
14.1.2 Modes of Operation
See Section 14.3, “Functional Description,” For details concerning SCI operation in these modes:
• 8- and 9-bit data modes
• Stop mode operation
• Loop mode
• Single-wire mode
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
202 Freescale Semiconductor
14.1.3 Block Diagram
Figure 14-2 shows the transmitter portion of the SCI.
Figure 14-2. SCI Transmitter Block Diagram
H876543210L
SCID – Tx BUFFER
(WRITE-ONLY)
INTERNAL BUS
STOP
11-BIT TRANSMIT SHIFT REGISTER
START
SHIFT DIRECTION
LSB
1 BAUD
RATE CLOCK
PARITY
GENERATION
TRANSMIT CONTROL
SHIFT ENABLE
PREAMBLE (ALL 1s)
BREAK (ALL 0s)
SCI CONTROLS TxD
TxD DIRECTION
TO TxD
PIN LOGIC
LOOP
CONTROL TO RECEIVE
DATA IN
TO TxD PIN
Tx INTERRUPT
REQUEST
LOOPS
RSRC
TIE
TC
TDRE
M
PT
PE
TCIE
TE
SBK
T8
TXDIR
LOAD FROM SCID
TXINV
BRK13
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 203
Figure 14-3 shows the receiver portion of the SCI.
Figure 14-3. SCI Receiver Block Diagram
H876543210L
SCID – Rx BUFFER
(READ-ONLY)
INTERNAL BUS
STOP
11-BIT RECEIVE SHIFT REGISTER
START
SHIFT DIRECTION
LSB
FROM RxD PIN
RATE CLOCK
Rx INTERRUPT
REQUEST
DATA RECOVERY
DIVIDE
16 BAUD
SINGLE-WIRE
LOOP CONTROL
WAKEUP
LOGIC
ALL 1s
MSB
FROM
TRANSMITTER
ERROR INTERRUPT
REQUEST
PARITY
CHECKING
BY 16
RDRF
RIE
IDLE
ILIE
OR
ORIE
FE
FEIE
NF
NEIE
PF
LOOPS
PEIE
PT
PE
RSRC
WAKE
ILT
RWU
M
LBKDIF
LBKDIE
RXEDGIF
RXEDGIE
ACTIVE EDGE
DETECT
RXINV
LBKDE
RWUID
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
204 Freescale Semiconductor
14.2 Register Definition
The SCI has eight 8-bit registers to control baud rate, select SCI options, report SCI status, and for
transmit/receive data.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all SCI registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
14.2.1 SCI Baud Rate Registers (SCIBDH, SCIBDL)
This pair of registers controls the prescale divisor for SCI baud rate generation. To update the 13-bit baud
rate setting [SBR12:SBR0], first write to SCIBDH to buffer the high half of the new value and then write
to SCIBDL. The working value in SCIBDH does not change until SCIBDL is written.
SCIBDL is reset to a non-zero value, so after reset the baud rate generator remains disabled until the first
time the receiver or transmitter is enabled (RE or TE bits in SCIC2 are written to 1).
76543210
R
LBKDIE RXEDGIE
0
SBR12 SBR11 SBR10 SBR9 SBR8
W
Reset00000000
= Unimplemented or Reserved
Figure 14-4. SCI Baud Rate Register (SCIBDH)
Table 14-1. SCIBDH Field Descriptions
Field Description
7
LBKDIE
LIN Break Detect Interrupt Enable (for LBKDIF)
0 Hardware interrupts from LBKDIF disabled (use polling).
1 Hardware interrupt requested when LBKDIF flag is 1.
6
RXEDGIE
RxD Input Active Edge Interrupt Enable (for RXEDGIF)
0 Hardware interrupts from RXEDGIF disabled (use polling).
1 Hardware interrupt requested when RXEDGIF flag is 1.
4:0
SBR[12:8]
Baud Rate Modulo Divisor — The 13 bits in SBR[12:0] are referred to collectively as BR, and they set the
modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to
reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16BR). See also BR bits in
Ta ble 1 4 - 2 .
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 205
14.2.2 SCI Control Register 1 (SCIC1)
This read/write register is used to control various optional features of the SCI system.
76543210
R
SBR7 SBR6 SBR5 SBR4 SBR3 SBR2 SBR1 SBR0
W
Reset00000100
Figure 14-5. SCI Baud Rate Register (SCIBDL)
Table 14-2. SCIBDL Field Descriptions
Field Description
7:0
SBR[7:0]
Baud Rate Modulo Divisor — These 13 bits in SBR[12:0] are referred to collectively as BR, and they set the
modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to
reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16BR). See also BR bits in
Ta ble 1 4 - 1 .
76543210
R
LOOPS SCISWAI RSRC M WAKE ILT PE PT
W
Reset00000000
Figure 14-6. SCI Control Register 1 (SCIC1)
Table 14-3. SCIC1 Field Descriptions
Field Description
7
LOOPS
Loop Mode Select — Selects between loop back modes and normal 2-pin full-duplex modes. When LOOPS = 1,
the transmitter output is internally connected to the receiver input.
0 Normal operation — RxD and TxD use separate pins.
1 Loop mode or single-wire mode where transmitter outputs are internally connected to receiver input. (See
RSRC bit.) RxD pin is not used by SCI.
6
SCISWAI
SCI Stops in Wait Mode
0 SCI clocks continue to run in wait mode so the SCI can be the source of an interrupt that wakes up the CPU.
1 SCI clocks freeze while CPU is in wait mode.
5
RSRC
Receiver Source Select — This bit has no meaning or effect unless the LOOPS bit is set to 1. When
LOOPS = 1, the receiver input is internally connected to the TxD pin and RSRC determines whether this
connection is also connected to the transmitter output.
0 Provided LOOPS = 1, RSRC = 0 selects internal loop back mode and the SCI does not use the RxD pins.
1 Single-wire SCI mode where the TxD pin is connected to the transmitter output and receiver input.
4
M
9-Bit or 8-Bit Mode Select
0 Normal — start + 8 data bits (LSB first) + stop.
1 Receiver and transmitter use 9-bit data characters
start + 8 data bits (LSB first) + 9th data bit + stop.
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
206 Freescale Semiconductor
14.2.3 SCI Control Register 2 (SCIC2)
This register can be read or written at any time.
3
WAKE
Receiver Wakeup Method Select — Refer to Section 14.3.3.2, “Receiver Wakeup Operation” for more
information.
0 Idle-line wakeup.
1 Address-mark wakeup.
2
ILT
Idle Line Type Select — Setting this bit to 1 ensures that the stop bit and logic 1 bits at the end of a character
do not count toward the 10 or 11 bit times of logic high level needed by the idle line detection logic. Refer to
Section 14.3.3.2.1, “Idle-Line Wakeup” for more information.
0 Idle character bit count starts after start bit.
1 Idle character bit count starts after stop bit.
1
PE
Parity Enable — Enables hardware parity generation and checking. When parity is enabled, the most significant
bit (MSB) of the data character (eighth or ninth data bit) is treated as the parity bit.
0 No hardware parity generation or checking.
1 Parity enabled.
0
PT
Parity Type — Provided parity is enabled (PE = 1), this bit selects even or odd parity. Odd parity means the total
number of 1s in the data character, including the parity bit, is odd. Even parity means the total number of 1s in
the data character, including the parity bit, is even.
0 Even parity.
1 Odd parity.
76543210
R
TIE TCIE RIE ILIE TE RE RWU SBK
W
Reset00000000
Figure 14-7. SCI Control Register 2 (SCIC2)
Table 14-4. SCIC2 Field Descriptions
Field Description
7
TIE
Transmit Interrupt Enable (for TDRE)
0 Hardware interrupts from TDRE disabled (use polling).
1 Hardware interrupt requested when TDRE flag is 1.
6
TCIE
Transmission Complete Interrupt Enable (for TC)
0 Hardware interrupts from TC disabled (use polling).
1 Hardware interrupt requested when TC flag is 1.
5
RIE
Receiver Interrupt Enable (for RDRF)
0 Hardware interrupts from RDRF disabled (use polling).
1 Hardware interrupt requested when RDRF flag is 1.
4
ILIE
Idle Line Interrupt Enable (for IDLE)
0 Hardware interrupts from IDLE disabled (use polling).
1 Hardware interrupt requested when IDLE flag is 1.
Table 14-3. SCIC1 Field Descriptions (continued)
Field Description
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 207
14.2.4 SCI Status Register 1 (SCIS1)
This register has eight read-only status flags. Writes have no effect. Special software sequences (which do
not involve writing to this register) are used to clear these status flags.
3
TE
Transmitter Enable
0 Transmitter off.
1 Transmitter on.
TE must be 1 in order to use the SCI transmitter. When TE = 1, the SCI forces the TxD pin to act as an output
for the SCI system.
When the SCI is configured for single-wire operation (LOOPS = RSRC = 1), TXDIR controls the direction of
traffic on the single SCI communication line (TxD pin).
TE also can be used to queue an idle character by writing TE = 0 then TE = 1 while a transmission is in progress.
Refer to Section 14.3.2.1, “Send Break and Queued Idle” for more details.
When TE is written to 0, the transmitter keeps control of the port TxD pin until any data, queued idle, or queued
break character finishes transmitting before allowing the pin to revert to a general-purpose I/O pin.
2
RE
Receiver Enable — When the SCI receiver is off, the RxD pin reverts to being a general-purpose port I/O pin. If
LOOPS = 1 the RxD pin reverts to being a general-purpose I/O pin even if RE = 1.
0 Receiver off.
1 Receiver on.
1
RWU
Receiver Wakeup Control — This bit can be written to 1 to place the SCI receiver in a standby state where it
waits for automatic hardware detection of a selected wakeup condition. The wakeup condition is either an idle
line between messages (WAKE = 0, idle-line wakeup), or a logic 1 in the most significant data bit in a character
(WAKE = 1, address-mark wakeup). Application software sets RWU and (normally) a selected hardware
condition automatically clears RWU. Refer to Section 14.3.3.2, “Receiver Wakeup Operation” for more details.
0 Normal SCI receiver operation.
1 SCI receiver in standby waiting for wakeup condition.
0
SBK
Send Break — Writing a 1 and then a 0 to SBK queues a break character in the transmit data stream. Additional
break characters of 10 or 11 (13 or 14 if BRK13 = 1) bit times of logic 0 are queued as long as SBK = 1.
Depending on the timing of the set and clear of SBK relative to the information currently being transmitted, a
second break character may be queued before software clears SBK. Refer to Section 14.3.2.1, “Send Break and
Queued Idle” for more details.
0 Normal transmitter operation.
1 Queue break character(s) to be sent.
76543210
R TDRE TC RDRF IDLE OR NF FE PF
W
Reset11000000
= Unimplemented or Reserved
Figure 14-8. SCI Status Register 1 (SCIS1)
Table 14-4. SCIC2 Field Descriptions (continued)
Field Description
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
208 Freescale Semiconductor
Table 14-5. SCIS1 Field Descriptions
Field Description
7
TDRE
Transmit Data Register Empty Flag — TDRE is set out of reset and when a transmit data value transfers from
the transmit data buffer to the transmit shifter, leaving room for a new character in the buffer. To clear TDRE, read
SCIS1 with TDRE = 1 and then write to the SCI data register (SCID).
0 Transmit data register (buffer) full.
1 Transmit data register (buffer) empty.
6
TC
Transmission Complete Flag — TC is set out of reset and when TDRE = 1 and no data, preamble, or break
character is being transmitted.
0 Transmitter active (sending data, a preamble, or a break).
1 Transmitter idle (transmission activity complete).
TC is cleared automatically by reading SCIS1 with TC = 1 and then doing one of the following three things:
• Write to the SCI data register (SCID) to transmit new data
• Queue a preamble by changing TE from 0 to 1
• Queue a break character by writing 1 to SBK in SCIC2
5
RDRF
Receive Data Register Full Flag — RDRF becomes set when a character transfers from the receive shifter into
the receive data register (SCID). To clear RDRF, read SCIS1 with RDRF = 1 and then read the SCI data register
(SCID).
0 Receive data register empty.
1 Receive data register full.
4
IDLE
Idle Line Flag — IDLE is set when the SCI receive line becomes idle for a full character time after a period of
activity. When ILT = 0, the receiver starts counting idle bit times after the start bit. So if the receive character is
all 1s, these bit times and the stop bit time count toward the full character time of logic high (10 or 11 bit times
depending on the M control bit) needed for the receiver to detect an idle line. When ILT = 1, the receiver doesn’t
start counting idle bit times until after the stop bit. So the stop bit and any logic high bit times at the end of the
previous character do not count toward the full character time of logic high needed for the receiver to detect an
idle line.
To clear IDLE, read SCIS1 with IDLE = 1 and then read the SCI data register (SCID). After IDLE has been
cleared, it cannot become set again until after a new character has been received and RDRF has been set. IDLE
will get set only once even if the receive line remains idle for an extended period.
0 No idle line detected.
1 Idle line was detected.
3
OR
Receiver Overrun Flag — OR is set when a new serial character is ready to be transferred to the receive data
register (buffer), but the previously received character has not been read from SCID yet. In this case, the new
character (and all associated error information) is lost because there is no room to move it into SCID. To clear
OR, read SCIS1 with OR = 1 and then read the SCI data register (SCID).
0 No overrun.
1 Receive overrun (new SCI data lost).
2
NF
Noise Flag — The advanced sampling technique used in the receiver takes seven samples during the start bit
and three samples in each data bit and the stop bit. If any of these samples disagrees with the rest of the samples
within any bit time in the frame, the flag NF will be set at the same time as the flag RDRF gets set for the character.
To clear NF, read SCIS1 and then read the SCI data register (SCID).
0 No noise detected.
1 Noise detected in the received character in SCID.
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 209
14.2.5 SCI Status Register 2 (SCIS2)
This register has one read-only status flag.
1
FE
Framing Error Flag — FE is set at the same time as RDRF when the receiver detects a logic 0 where the stop
bit was expected. This suggests the receiver was not properly aligned to a character frame. To clear FE, read
SCIS1 with FE = 1 and then read the SCI data register (SCID).
0 No framing error detected. This does not guarantee the framing is correct.
1 Framing error.
0
PF
Parity Error Flag — PF is set at the same time as RDRF when parity is enabled (PE = 1) and the parity bit in
the received character does not agree with the expected parity value. To clear PF, read SCIS1 and then read the
SCI data register (SCID).
0 No parity error.
1 Parity error.
76543210
R
LBKDIF RXEDGIF
0
RXINV RWUID BRK13 LBKDE
RAF
W
Reset00000000
= Unimplemented or Reserved
Figure 14-9. SCI Status Register 2 (SCIS2)
Table 14-6. SCIS2 Field Descriptions
Field Description
7
LBKDIF
LIN Break Detect Interrupt Flag — LBKDIF is set when the LIN break detect circuitry is enabled and a LIN break
character is detected. LBKDIF is cleared by writing a “1” to it.
0 No LIN break character has been detected.
1 LIN break character has been detected.
6
RXEDGIF
RxD Pin Active Edge Interrupt Flag — RXEDGIF is set when an active edge (falling if RXINV = 0, rising if
RXINV=1) on the RxD pin occurs. RXEDGIF is cleared by writing a “1” to it.
0 No active edge on the receive pin has occurred.
1 An active edge on the receive pin has occurred.
4
RXINV1Receive Data Inversion — Setting this bit reverses the polarity of the received data input.
0 Receive data not inverted
1 Receive data inverted
3
RWUID
Receive Wake Up Idle Detect— RWUID controls whether the idle character that wakes up the receiver sets the
IDLE bit.
0 During receive standby state (RWU = 1), the IDLE bit does not get set upon detection of an idle character.
1 During receive standby state (RWU = 1), the IDLE bit gets set upon detection of an idle character.
2
BRK13
Break Character Generation Length — BRK13 is used to select a longer transmitted break character length.
Detection of a framing error is not affected by the state of this bit.
0 Break character is transmitted with length of 10 bit times (11 if M = 1)
1 Break character is transmitted with length of 13 bit times (14 if M = 1)
Table 14-5. SCIS1 Field Descriptions (continued)
Field Description
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
210 Freescale Semiconductor
When using an internal oscillator in a LIN system, it is necessary to raise the break detection threshold by
one bit time. Under the worst case timing conditions allowed in LIN, it is possible that a 0x00 data
character can appear to be 10.26 bit times long at a slave which is running 14% faster than the master. This
would trigger normal break detection circuitry which is designed to detect a 10 bit break symbol. When
the LBKDE bit is set, framing errors are inhibited and the break detection threshold changes from 10 bits
to 11 bits, preventing false detection of a 0x00 data character as a LIN break symbol.
14.2.6 SCI Control Register 3 (SCIC3)
1
LBKDE
LIN Break Detection Enable— LBKDE is used to select a longer break character detection length. While LBKDE
is set, framing error (FE) and receive data register full (RDRF) flags are prevented from setting.
0 Break character is detected at length of 10 bit times (11 if M = 1).
1 Break character is detected at length of 11 bit times (12 if M = 1).
0
RAF
Receiver Active Flag — RAF is set when the SCI receiver detects the beginning of a valid start bit, and RAF is
cleared automatically when the receiver detects an idle line. This status flag can be used to check whether an
SCI character is being received before instructing the MCU to go to stop mode.
0 SCI receiver idle waiting for a start bit.
1 SCI receiver active (RxD input not idle).
1Setting RXINV inverts the RxD input for all cases: data bits, start and stop bits, break, and idle.
76543210
RR8
T8 TXDIR TXINV ORIE NEIE FEIE PEIE
W
Reset00000000
= Unimplemented or Reserved
Figure 14-10. SCI Control Register 3 (SCIC3)
Table 14-7. SCIC3 Field Descriptions
Field Description
7
R8
Ninth Data Bit for Receiver — When the SCI is configured for 9-bit data (M = 1), R8 can be thought of as a ninth
receive data bit to the left of the MSB of the buffered data in the SCID register. When reading 9-bit data, read R8
before reading SCID because reading SCID completes automatic flag clearing sequences which could allow R8
and SCID to be overwritten with new data.
6
T8
Ninth Data Bit for Transmitter — When the SCI is configured for 9-bit data (M = 1), T8 may be thought of as a
ninth transmit data bit to the left of the MSB of the data in the SCID register. When writing 9-bit data, the entire
9-bit value is transferred to the SCI shift register after SCID is written so T8 should be written (if it needs to change
from its previous value) before SCID is written. If T8 does not need to change in the new value (such as when it
is used to generate mark or space parity), it need not be written each time SCID is written.
5
TXDIR
TxD Pin Direction in Single-Wire Mode — When the SCI is configured for single-wire half-duplex operation
(LOOPS = RSRC = 1), this bit determines the direction of data at the TxD pin.
0 TxD pin is an input in single-wire mode.
1 TxD pin is an output in single-wire mode.
Table 14-6. SCIS2 Field Descriptions (continued)
Field Description
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 211
14.2.7 SCI Data Register (SCID)
This register is actually two separate registers. Reads return the contents of the read-only receive data
buffer and writes go to the write-only transmit data buffer. Reads and writes of this register are also
involved in the automatic flag clearing mechanisms for the SCI status flags.
14.3 Functional Description
The SCI allows full-duplex, asynchronous, NRZ serial communication among the MCU and remote
devices, including other MCUs. The SCI comprises a baud rate generator, transmitter, and receiver block.
The transmitter and receiver operate independently, although they use the same baud rate generator.
During normal operation, the MCU monitors the status of the SCI, writes the data to be transmitted, and
processes received data. The following describes each of the blocks of the SCI.
14.3.1 Baud Rate Generation
As shown in Figure 14-12, the clock source for the SCI baud rate generator is the bus-rate clock.
4
TXINV1Transmit Data Inversion — Setting this bit reverses the polarity of the transmitted data output.
0 Transmit data not inverted
1 Transmit data inverted
3
ORIE
Overrun Interrupt Enable — This bit enables the overrun flag (OR) to generate hardware interrupt requests.
0 OR interrupts disabled (use polling).
1 Hardware interrupt requested when OR = 1.
2
NEIE
Noise Error Interrupt Enable — This bit enables the noise flag (NF) to generate hardware interrupt requests.
0 NF interrupts disabled (use polling).
1 Hardware interrupt requested when NF = 1.
1
FEIE
Framing Error Interrupt Enable — This bit enables the framing error flag (FE) to generate hardware interrupt
requests.
0 FE interrupts disabled (use polling).
1 Hardware interrupt requested when FE = 1.
0
PEIE
Parity Error Interrupt Enable — This bit enables the parity error flag (PF) to generate hardware interrupt
requests.
0 PF interrupts disabled (use polling).
1 Hardware interrupt requested when PF = 1.
1Setting TXINV inverts the TxD output for all cases: data bits, start and stop bits, break, and idle.
76543210
RR7R6R5R4R3R2R1R0
WT7T6T5T4T3T2T1T0
Reset00000000
Figure 14-11. SCI Data Register (SCID)
Table 14-7. SCIC3 Field Descriptions (continued)
Field Description
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
212 Freescale Semiconductor
Figure 14-12. SCI Baud Rate Generation
SCI communications require the transmitter and receiver (which typically derive baud rates from
independent clock sources) to use the same baud rate. Allowed tolerance on this baud frequency depends
on the details of how the receiver synchronizes to the leading edge of the start bit and how bit sampling is
performed.
The MCU resynchronizes to bit boundaries on every high-to-low transition, but in the worst case, there are
no such transitions in the full 10- or 11-bit time character frame so any mismatch in baud rate is
accumulated for the whole character time. For a Freescale Semiconductor SCI system whose bus
frequency is driven by a crystal, the allowed baud rate mismatch is about ±4.5 percent for 8-bit data format
and about ±4 percent for 9-bit data format. Although baud rate modulo divider settings do not always
produce baud rates that exactly match standard rates, it is normally possible to get within a few percent,
which is acceptable for reliable communications.
14.3.2 Transmitter Functional Description
This section describes the overall block diagram for the SCI transmitter, as well as specialized functions
for sending break and idle characters. The transmitter block diagram is shown in Figure 14-2.
The transmitter output (TxD) idle state defaults to logic high (TXINV = 0 following reset). The transmitter
output is inverted by setting TXINV = 1. The transmitter is enabled by setting the TE bit in SCIC2. This
queues a preamble character that is one full character frame of the idle state. The transmitter then remains
idle until data is available in the transmit data buffer. Programs store data into the transmit data buffer by
writing to the SCI data register (SCID).
The central element of the SCI transmitter is the transmit shift register that is either 10 or 11 bits long
depending on the setting in the M control bit. For the remainder of this section, we will assume M = 0,
selecting the normal 8-bit data mode. In 8-bit data mode, the shift register holds a start bit, eight data bits,
and a stop bit. When the transmit shift register is available for a new SCI character, the value waiting in
the transmit data register is transferred to the shift register (synchronized with the baud rate clock) and the
transmit data register empty (TDRE) status flag is set to indicate another character may be written to the
transmit data buffer at SCID.
If no new character is waiting in the transmit data buffer after a stop bit is shifted out the TxD pin, the
transmitter sets the transmit complete flag and enters an idle mode, with TxD high, waiting for more
characters to transmit.
SBR12:SBR0
DIVIDE BY Tx BAUD RATE
Rx SAMPLING CLOCK
(16 BAUD RATE)
BAUD RATE GENERATOR
OFF IF [SBR12:SBR0] = 0
BUSCLK
BAUD RATE = BUSCLK
[SBR12:SBR0] 16
16
MODULO DIVIDE BY
(1 THROUGH 8191)
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 213
Writing 0 to TE does not immediately release the pin to be a general-purpose I/O pin. Any transmit activity
that is in progress must first be completed. This includes data characters in progress, queued idle
characters, and queued break characters.
14.3.2.1 Send Break and Queued Idle
The SBK control bit in SCIC2 is used to send break characters which were originally used to gain the
attention of old teletype receivers. Break characters are a full character time of logic 0 (10 bit times
including the start and stop bits). A longer break of 13 bit times can be enabled by setting BRK13 = 1.
Normally, a program would wait for TDRE to become set to indicate the last character of a message has
moved to the transmit shifter, then write 1 and then write 0 to the SBK bit. This action queues a break
character to be sent as soon as the shifter is available. If SBK is still 1 when the queued break moves into
the shifter (synchronized to the baud rate clock), an additional break character is queued. If the receiving
device is another Freescale Semiconductor SCI, the break characters will be received as 0s in all eight data
bits and a framing error (FE = 1) occurs.
When idle-line wakeup is used, a full character time of idle (logic 1) is needed between messages to wake
up any sleeping receivers. Normally, a program would wait for TDRE to become set to indicate the last
character of a message has moved to the transmit shifter, then write 0 and then write 1 to the TE bit. This
action queues an idle character to be sent as soon as the shifter is available. As long as the character in the
shifter does not finish while TE = 0, the SCI transmitter never actually releases control of the TxD pin. If
there is a possibility of the shifter finishing while TE = 0, set the general-purpose I/O controls so the pin
that is shared with TxD is an output driving a logic 1. This ensures that the TxD line will look like a normal
idle line even if the SCI loses control of the port pin between writing 0 and then 1 to TE.
The length of the break character is affected by the BRK13 and M bits as shown below.
14.3.3 Receiver Functional Description
In this section, the receiver block diagram (Figure 14-3) is used as a guide for the overall receiver
functional description. Next, the data sampling technique used to reconstruct receiver data is described in
more detail. Finally, two variations of the receiver wakeup function are explained.
The receiver input is inverted by setting RXINV = 1. The receiver is enabled by setting the RE bit in
SCIC2. Character frames consist of a start bit of logic 0, eight (or nine) data bits (LSB first), and a stop bit
of logic 1. For information about 9-bit data mode, refer to Section 14.3.5.1, “8- and 9-Bit Data Modes.”
For the remainder of this discussion, we assume the SCI is configured for normal 8-bit data mode.
After receiving the stop bit into the receive shifter, and provided the receive data register is not already
full, the data character is transferred to the receive data register and the receive data register full (RDRF)
Table 14-8. Break Character Length
BRK13 M Break Character Length
0 0 10 bit times
0 1 11 bit times
1 0 13 bit times
1 1 14 bit times
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
214 Freescale Semiconductor
status flag is set. If RDRF was already set indicating the receive data register (buffer) was already full, the
overrun (OR) status flag is set and the new data is lost. Because the SCI receiver is double-buffered, the
program has one full character time after RDRF is set before the data in the receive data buffer must be
read to avoid a receiver overrun.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCID. The RDRF flag is cleared automatically by a 2-step sequence which is
normally satisfied in the course of the user’s program that handles receive data. Refer to Section 14.3.4,
“Interrupts and Status Flags” for more details about flag clearing.
14.3.3.1 Data Sampling Technique
The SCI receiver uses a 16 baud rate clock for sampling. The receiver starts by taking logic level samples
at 16 times the baud rate to search for a falling edge on the RxD serial data input pin. A falling edge is
defined as a logic 0 sample after three consecutive logic 1 samples. The 16 baud rate clock is used to
divide the bit time into 16 segments labeled RT1 through RT16. When a falling edge is located, three more
samples are taken at RT3, RT5, and RT7 to make sure this was a real start bit and not merely noise. If at
least two of these three samples are 0, the receiver assumes it is synchronized to a receive character.
The receiver then samples each bit time, including the start and stop bits, at RT8, RT9, and RT10 to
determine the logic level for that bit. The logic level is interpreted to be that of the majority of the samples
taken during the bit time. In the case of the start bit, the bit is assumed to be 0 if at least two of the samples
at RT3, RT5, and RT7 are 0 even if one or all of the samples taken at RT8, RT9, and RT10 are 1s. If any
sample in any bit time (including the start and stop bits) in a character frame fails to agree with the logic
level for that bit, the noise flag (NF) will be set when the received character is transferred to the receive
data buffer.
The falling edge detection logic continuously looks for falling edges, and if an edge is detected, the sample
clock is resynchronized to bit times. This improves the reliability of the receiver in the presence of noise
or mismatched baud rates. It does not improve worst case analysis because some characters do not have
any extra falling edges anywhere in the character frame.
In the case of a framing error, provided the received character was not a break character, the sampling logic
that searches for a falling edge is filled with three logic 1 samples so that a new start bit can be detected
almost immediately.
In the case of a framing error, the receiver is inhibited from receiving any new characters until the framing
error flag is cleared. The receive shift register continues to function, but a complete character cannot
transfer to the receive data buffer if FE is still set.
14.3.3.2 Receiver Wakeup Operation
Receiver wakeup is a hardware mechanism that allows an SCI receiver to ignore the characters in a
message that is intended for a different SCI receiver. In such a system, all receivers evaluate the first
character(s) of each message, and as soon as they determine the message is intended for a different
receiver, they write logic 1 to the receiver wake up (RWU) control bit in SCIC2. When RWU bit is set, the
status flags associated with the receiver (with the exception of the idle bit, IDLE, when RWUID bit is set)
are inhibited from setting, thus eliminating the software overhead for handling the unimportant message
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 215
characters. At the end of a message, or at the beginning of the next message, all receivers automatically
force RWU to 0 so all receivers wake up in time to look at the first character(s) of the next message.
14.3.3.2.1 Idle-Line Wakeup
When WAKE = 0, the receiver is configured for idle-line wakeup. In this mode, RWU is cleared
automatically when the receiver detects a full character time of the idle-line level. The M control bit selects
8-bit or 9-bit data mode that determines how many bit times of idle are needed to constitute a full character
time (10 or 11 bit times because of the start and stop bits).
When RWU is one and RWUID is zero, the idle condition that wakes up the receiver does not set the IDLE
flag. The receiver wakes up and waits for the first data character of the next message which will set the
RDRF flag and generate an interrupt if enabled. When RWUID is one, any idle condition sets the IDLE
flag and generates an interrupt if enabled, regardless of whether RWU is zero or one.
The idle-line type (ILT) control bit selects one of two ways to detect an idle line. When ILT = 0, the idle
bit counter starts after the start bit so the stop bit and any logic 1s at the end of a character count toward
the full character time of idle. When ILT = 1, the idle bit counter does not start until after a stop bit time,
so the idle detection is not affected by the data in the last character of the previous message.
14.3.3.2.2 Address-Mark Wakeup
When WAKE = 1, the receiver is configured for address-mark wakeup. In this mode, RWU is cleared
automatically when the receiver detects a logic 1 in the most significant bit of a received character (eighth
bit in M = 0 mode and ninth bit in M = 1 mode).
Address-mark wakeup allows messages to contain idle characters but requires that the MSB be reserved
for use in address frames. The logic 1 MSB of an address frame clears the RWU bit before the stop bit is
received and sets the RDRF flag. In this case the character with the MSB set is received even though the
receiver was sleeping during most of this character time.
14.3.4 Interrupts and Status Flags
The SCI system has three separate interrupt vectors to reduce the amount of software needed to isolate the
cause of the interrupt. One interrupt vector is associated with the transmitter for TDRE and TC events.
Another interrupt vector is associated with the receiver for RDRF, IDLE, RXEDGIF and LBKDIF events,
and a third vector is used for OR, NF, FE, and PF error conditions. Each of these ten interrupt sources can
be separately masked by local interrupt enable masks. The flags can still be polled by software when the
local masks are cleared to disable generation of hardware interrupt requests.
The SCI transmitter has two status flags that optionally can generate hardware interrupt requests. Transmit
data register empty (TDRE) indicates when there is room in the transmit data buffer to write another
transmit character to SCID. If the transmit interrupt enable (TIE) bit is set, a hardware interrupt will be
requested whenever TDRE = 1. Transmit complete (TC) indicates that the transmitter is finished
transmitting all data, preamble, and break characters and is idle with TxD at the inactive level. This flag is
often used in systems with modems to determine when it is safe to turn off the modem. If the transmit
complete interrupt enable (TCIE) bit is set, a hardware interrupt will be requested whenever TC = 1.
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
216 Freescale Semiconductor
Instead of hardware interrupts, software polling may be used to monitor the TDRE and TC status flags if
the corresponding TIE or TCIE local interrupt masks are 0s.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCID. The RDRF flag is cleared by reading SCIS1 while RDRF = 1 and then
reading SCID.
When polling is used, this sequence is naturally satisfied in the normal course of the user program. If
hardware interrupts are used, SCIS1 must be read in the interrupt service routine (ISR). Normally, this is
done in the ISR anyway to check for receive errors, so the sequence is automatically satisfied.
The IDLE status flag includes logic that prevents it from getting set repeatedly when the RxD line remains
idle for an extended period of time. IDLE is cleared by reading SCIS1 while IDLE = 1 and then reading
SCID. After IDLE has been cleared, it cannot become set again until the receiver has received at least one
new character and has set RDRF.
If the associated error was detected in the received character that caused RDRF to be set, the error flags
— noise flag (NF), framing error (FE), and parity error flag (PF) — get set at the same time as RDRF.
These flags are not set in overrun cases.
If RDRF was already set when a new character is ready to be transferred from the receive shifter to the
receive data buffer, the overrun (OR) flag gets set instead the data along with any associated NF, FE, or PF
condition is lost.
At any time, an active edge on the RxD serial data input pin causes the RXEDGIF flag to set. The
RXEDGIF flag is cleared by writing a “1” to it. This function does depend on the receiver being enabled
(RE = 1).
14.3.5 Additional SCI Functions
The following sections describe additional SCI functions.
14.3.5.1 8- and 9-Bit Data Modes
The SCI system (transmitter and receiver) can be configured to operate in 9-bit data mode by setting the
M control bit in SCIC1. In 9-bit mode, there is a ninth data bit to the left of the MSB of the SCI data
register. For the transmit data buffer, this bit is stored in T8 in SCIC3. For the receiver, the ninth bit is held
in R8 in SCIC3.
For coherent writes to the transmit data buffer, write to the T8 bit before writing to SCID.
If the bit value to be transmitted as the ninth bit of a new character is the same as for the previous character,
it is not necessary to write to T8 again. When data is transferred from the transmit data buffer to the
transmit shifter, the value in T8 is copied at the same time data is transferred from SCID to the shifter.
9-bit data mode typically is used in conjunction with parity to allow eight bits of data plus the parity in the
ninth bit. Or it is used with address-mark wakeup so the ninth data bit can serve as the wakeup bit. In
custom protocols, the ninth bit can also serve as a software-controlled marker.
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 217
14.3.5.2 Stop Mode Operation
During all stop modes, clocks to the SCI module are halted.
In stop1 and stop2 modes, all SCI register data is lost and must be re-initialized upon recovery from these
two stop modes. No SCI module registers are affected in stop3 mode.
The receive input active edge detect circuit is still active in stop3 mode, but not in stop2. . An active edge
on the receive input brings the CPU out of stop3 mode if the interrupt is not masked (RXEDGIE = 1).
Note, because the clocks are halted, the SCI module will resume operation upon exit from stop (only in
stop3 mode). Software should ensure stop mode is not entered while there is a character being transmitted
out of or received into the SCI module.
14.3.5.3 Loop Mode
When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or
single-wire mode (RSRC = 1). Loop mode is sometimes used to check software, independent of
connections in the external system, to help isolate system problems. In this mode, the transmitter output is
internally connected to the receiver input and the RxD pin is not used by the SCI, so it reverts to a
general-purpose port I/O pin.
14.3.5.4 Single-Wire Operation
When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or
single-wire mode (RSRC = 1). Single-wire mode is used to implement a half-duplex serial connection.
The receiver is internally connected to the transmitter output and to the TxD pin. The RxD pin is not used
and reverts to a general-purpose port I/O pin.
In single-wire mode, the TXDIR bit in SCIC3 controls the direction of serial data on the TxD pin. When
TXDIR = 0, the TxD pin is an input to the SCI receiver and the transmitter is temporarily disconnected
from the TxD pin so an external device can send serial data to the receiver. When TXDIR = 1, the TxD pin
is an output driven by the transmitter. In single-wire mode, the internal loop back connection from the
transmitter to the receiver causes the receiver to receive characters that are sent out by the transmitter.
Serial Communications Interface (S08SCIV4)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
218 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 219
Chapter 15
Serial Peripheral Interface (S08SPIV3)
15.1 Introduction
The serial peripheral interface (SPI) module provides for full-duplex, synchronous, serial communication
between the MCU and peripheral devices. These peripheral devices can include other microcontrollers,
analog-to-digital converters, shift registers, sensors, memories, etc.
The SPI runs at a baud rate up to the bus clock divided by two. Software can poll the status flags, or SPI
operation can be interrupt driven.
Figure 15-1 shows the MC9S08SG8 block diagram with the SPI module highlighted.
Chapter 15 Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
220 Freescale Semiconductor
Figure 15-1. MC9S08SG8 Block Diagram with SPI Module Highlighted
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 221
15.1.1 Features
Features of the SPI module include:
• Master or slave mode operation
• Full-duplex or single-wire bidirectional option
• Programmable transmit bit rate
• Double-buffered transmit and receive
• Serial clock phase and polarity options
• Slave select output
• Selectable MSB-first or LSB-first shifting
15.1.2 Block Diagrams
This section includes block diagrams showing SPI system connections, the internal organization of the SPI
module, and the SPI clock dividers that control the master mode bit rate.
15.1.2.1 SPI System Block Diagram
Figure 15-2 shows the SPI modules of two MCUs connected in a master-slave arrangement. The master
device initiates all SPI data transfers. During a transfer, the master shifts data out (on the MOSI pin) to the
slave while simultaneously shifting data in (on the MISO pin) from the slave. The transfer effectively
exchanges the data that was in the SPI shift registers of the two SPI systems. The SPSCK signal is a clock
output from the master and an input to the slave. The slave device must be selected by a low level on the
slave select input (SS pin). In this system, the master device has configured its SS pin as an optional slave
select output.
Figure 15-2. SPI System Connections
7 6 5 4 3 2 1 0
SPI SHIFTER
CLOCK
GENERATOR
76543210
SPI SHIFTER
SS
SPSCK
MISO
MOSI
SS
SPSCK
MISO
MOSI
MASTER SLAVE
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
222 Freescale Semiconductor
The most common uses of the SPI system include connecting simple shift registers for adding input or
output ports or connecting small peripheral devices such as serial A/D or D/A converters. Although
Figure 15-2 shows a system where data is exchanged between two MCUs, many practical systems involve
simpler connections where data is unidirectionally transferred from the master MCU to a slave or from a
slave to the master MCU.
15.1.2.2 SPI Module Block Diagram
Figure 15-3 is a block diagram of the SPI module. The central element of the SPI is the SPI shift register.
Data is written to the double-buffered transmitter (write to SPID) and gets transferred to the SPI shift
register at the start of a data transfer. After shifting in a byte of data, the data is transferred into the
double-buffered receiver where it can be read (read from SPID). Pin multiplexing logic controls
connections between MCU pins and the SPI module.
When the SPI is configured as a master, the clock output is routed to the SPSCK pin, the shifter output is
routed to MOSI, and the shifter input is routed from the MISO pin.
When the SPI is configured as a slave, the SPSCK pin is routed to the clock input of the SPI, the shifter
output is routed to MISO, and the shifter input is routed from the MOSI pin.
In the external SPI system, simply connect all SPSCK pins to each other, all MISO pins together, and all
MOSI pins together. Peripheral devices often use slightly different names for these pins.
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 223
Figure 15-3. SPI Module Block Diagram
15.1.3 SPI Baud Rate Generation
As shown in Figure 15-4, the clock source for the SPI baud rate generator is the bus clock. The three
prescale bits (SPPR2:SPPR1:SPPR0) choose a prescale divisor of 1, 2, 3, 4, 5, 6, 7, or 8. The three rate
select bits (SPR2:SPR1:SPR0) divide the output of the prescaler stage by 2, 4, 8, 16, 32, 64, 128, or 256
to get the internal SPI master mode bit-rate clock.
SPI SHIFT REGISTER
SHIFT
CLOCK
SHIFT
DIRECTION
Rx BUFFER
FULL
Tx BUFFER
EMPTY
SHIFT
OUT
SHIFT
IN
ENABLE
SPI SYSTEM
CLOCK
LOGIC
CLOCK GENERATOR
BUS RATE
CLOCK
MASTER/SLAVE
MODE SELECT
MODE FAULT
DETECTION
MASTER CLOCK
SLAVE CLOCK
SPI
INTERRUPT
REQUEST
PIN CONTROL
M
S
MASTER/
SLAVE
MOSI
(MOMI)
MISO
(SISO)
SPSCK
SS
M
S
S
M
MODF
SPE
LSBFE
MSTR
SPRF SPTEF
SPTIE
SPIE
MODFEN
SSOE
SPC0
BIDIROE
SPIBR
Tx BUFFER (WRITE SPID)
Rx BUFFER (READ SPID)
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
224 Freescale Semiconductor
Figure 15-4. SPI Baud Rate Generation
15.2 External Signal Description
The SPI optionally shares four port pins. The function of these pins depends on the settings of SPI control
bits. When the SPI is disabled (SPE = 0), these four pins revert to being general-purpose port I/O pins that
are not controlled by the SPI.
15.2.1 SPSCK — SPI Serial Clock
When the SPI is enabled as a slave, this pin is the serial clock input. When the SPI is enabled as a master,
this pin is the serial clock output.
15.2.2 MOSI — Master Data Out, Slave Data In
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this
pin is the serial data output. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data
input. If SPC0 = 1 to select single-wire bidirectional mode, and master mode is selected, this pin becomes
the bidirectional data I/O pin (MOMI). Also, the bidirectional mode output enable bit determines whether
the pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and slave mode is
selected, this pin is not used by the SPI and reverts to being a general-purpose port I/O pin.
15.2.3 MISO — Master Data In, Slave Data Out
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this
pin is the serial data input. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data
output. If SPC0 = 1 to select single-wire bidirectional mode, and slave mode is selected, this pin becomes
the bidirectional data I/O pin (SISO) and the bidirectional mode output enable bit determines whether the
pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and master mode is selected,
this pin is not used by the SPI and reverts to being a general-purpose port I/O pin.
15.2.4 SS — Slave Select
When the SPI is enabled as a slave, this pin is the low-true slave select input. When the SPI is enabled as
a master and mode fault enable is off (MODFEN = 0), this pin is not used by the SPI and reverts to being
a general-purpose port I/O pin. When the SPI is enabled as a master and MODFEN = 1, the slave select
output enable bit determines whether this pin acts as the mode fault input (SSOE = 0) or as the slave select
output (SSOE = 1).
DIVIDE BY
2, 4, 8, 16, 32, 64, 128, or 256
DIVIDE BY
1, 2, 3, 4, 5, 6, 7, or 8
PRESCALER CLOCK RATE DIVIDER
SPPR2:SPPR1:SPPR0 SPR2:SPR1:SPR0
BUS CLOCK
MASTER
SPI
BIT RATE
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 225
15.3 Modes of Operation
15.3.1 SPI in Stop Modes
The SPI is disabled in all stop modes, regardless of the settings before executing the STOP instruction.
During either stop1 or stop2 mode, the SPI module will be fully powered down. Upon wake-up from stop1
or stop2 mode, the SPI module will be in the reset state. During stop3 mode, clocks to the SPI module are
halted. No registers are affected. If stop3 is exited with a reset, the SPI will be put into its reset state. If
stop3 is exited with an interrupt, the SPI continues from the state it was in when stop3 was entered.
15.4 Register Definition
The SPI has five 8-bit registers to select SPI options, control baud rate, report SPI status, and for
transmit/receive data.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all SPI registers. This section refers to registers and control bits only by their names, and
a Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
15.4.1 SPI Control Register 1 (SPIC1)
This read/write register includes the SPI enable control, interrupt enables, and configuration options.
76543210
R
SPIE SPE SPTIE MSTR CPOL CPHA SSOE LSBFE
W
Reset00000100
Figure 15-5. SPI Control Register 1 (SPIC1)
Table 15-1. SPIC1 Field Descriptions
Field Description
7
SPIE
SPI Interrupt Enable (for SPRF and MODF) — This is the interrupt enable for SPI receive buffer full (SPRF)
and mode fault (MODF) events.
0 Interrupts from SPRF and MODF inhibited (use polling)
1 When SPRF or MODF is 1, request a hardware interrupt
6
SPE
SPI System Enable — Disabling the SPI halts any transfer that is in progress, clears data buffers, and initializes
internal state machines. SPRF is cleared and SPTEF is set to indicate the SPI transmit data buffer is empty.
0 SPI system inactive
1 SPI system enabled
5
SPTIE
SPI Transmit Interrupt Enable — This is the interrupt enable bit for SPI transmit buffer empty (SPTEF).
0 Interrupts from SPTEF inhibited (use polling)
1 When SPTEF is 1, hardware interrupt requested
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
226 Freescale Semiconductor
NOTE
Ensure that the SPI should not be disabled (SPE=0) at the same time as a bit change to the CPHA bit. These
changes should be performed as separate operations or unexpected behavior may occur.
15.4.2 SPI Control Register 2 (SPIC2)
This read/write register is used to control optional features of the SPI system. Bits 7, 6, 5, and 2 are not
implemented and always read 0.
4
MSTR
Master/Slave Mode Select
0 SPI module configured as a slave SPI device
1 SPI module configured as a master SPI device
3
CPOL
Clock Polarity — This bit effectively places an inverter in series with the clock signal from a master SPI or to a
slave SPI device. Refer to Section 15.5.1, “SPI Clock Formats” for more details.
0 Active-high SPI clock (idles low)
1 Active-low SPI clock (idles high)
2
CPHA
Clock Phase — This bit selects one of two clock formats for different kinds of synchronous serial peripheral
devices. Refer to Section 15.5.1, “SPI Clock Formats” for more details.
0 First edge on SPSCK occurs at the middle of the first cycle of an 8-cycle data transfer
1 First edge on SPSCK occurs at the start of the first cycle of an 8-cycle data transfer
1
SSOE
Slave Select Output Enable — This bit is used in combination with the mode fault enable (MODFEN) bit in
SPCR2 and the master/slave (MSTR) control bit to determine the function of the SS pin as shown in Table 15-2.
0
LSBFE
LSB First (Shifter Direction)
0 SPI serial data transfers start with most significant bit
1 SPI serial data transfers start with least significant bit
Table 15-2. SS Pin Function
MODFEN SSOE Master Mode Slave Mode
0 0 General-purpose I/O (not SPI) Slave select input
0 1 General-purpose I/O (not SPI) Slave select input
10SS
input for mode fault Slave select input
1 1 Automatic SS output Slave select input
76543210
R000
MODFEN BIDIROE
0
SPISWAI SPC0
W
Reset00000000
= Unimplemented or Reserved
Figure 15-6. SPI Control Register 2 (SPIC2)
Table 15-1. SPIC1 Field Descriptions (continued)
Field Description
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 227
15.4.3 SPI Baud Rate Register (SPIBR)
This register is used to set the prescaler and bit rate divisor for an SPI master. This register may be read or
written at any time.
Table 15-3. SPIC2 Register Field Descriptions
Field Description
4
MODFEN
Master Mode-Fault Function Enable — When the SPI is configured for slave mode, this bit has no meaning or
effect. (The SS pin is the slave select input.) In master mode, this bit determines how the SS pin is used (refer to
Ta ble 1 5 - 2 for more details).
0 Mode fault function disabled, master SS pin reverts to general-purpose I/O not controlled by SPI
1 Mode fault function enabled, master SS pin acts as the mode fault input or the slave select output
3
BIDIROE
Bidirectional Mode Output Enable — When bidirectional mode is enabled by SPI pin control 0 (SPC0) = 1,
BIDIROE determines whether the SPI data output driver is enabled to the single bidirectional SPI I/O pin.
Depending on whether the SPI is configured as a master or a slave, it uses either the MOSI (MOMI) or MISO
(SISO) pin, respectively, as the single SPI data I/O pin. When SPC0 = 0, BIDIROE has no meaning or effect.
0 Output driver disabled so SPI data I/O pin acts as an input
1 SPI I/O pin enabled as an output
1
SPISWAI
SPI Stop in Wait Mode
0 SPI clocks continue to operate in wait mode
1 SPI clocks stop when the MCU enters wait mode
0
SPC0
SPI Pin Control 0 — The SPC0 bit chooses single-wire bidirectional mode. If MSTR = 0 (slave mode), the SPI
uses the MISO (SISO) pin for bidirectional SPI data transfers. If MSTR = 1 (master mode), the SPI uses the MOSI
(MOMI) pin for bidirectional SPI data transfers. When SPC0 = 1, BIDIROE is used to enable or disable the output
driver for the single bidirectional SPI I/O pin.
0 SPI uses separate pins for data input and data output
1 SPI configured for single-wire bidirectional operation
76543210
R0
SPPR2 SPPR1 SPPR0
0
SPR2 SPR1 SPR0
W
Reset00000000
= Unimplemented or Reserved
Figure 15-7. SPI Baud Rate Register (SPIBR)
Table 15-4. SPIBR Register Field Descriptions
Field Description
6:4
SPPR[2:0]
SPI Baud Rate Prescale Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate prescaler
as shown in Ta ble 1 5 - 5 . The input to this prescaler is the bus rate clock (BUSCLK). The output of this prescaler
drives the input of the SPI baud rate divider (see Figure 15-4).
2:0
SPR[2:0]
SPI Baud Rate Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate divider as shown in
Ta ble 1 5 - 6 . The input to this divider comes from the SPI baud rate prescaler (see Figure 15-4). The output of this
divider is the SPI bit rate clock for master mode.
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
228 Freescale Semiconductor
15.4.4 SPI Status Register (SPIS)
This register has three read-only status bits. Bits 6, 3, 2, 1, and 0 are not implemented and always read 0.
Writes have no meaning or effect.
Table 15-5. SPI Baud Rate Prescaler Divisor
SPPR2:SPPR1:SPPR0 Prescaler Divisor
0:0:0 1
0:0:1 2
0:1:0 3
0:1:1 4
1:0:0 5
1:0:1 6
1:1:0 7
1:1:1 8
Table 15-6. SPI Baud Rate Divisor
SPR2:SPR1:SPR0 Rate Divisor
0:0:0 2
0:0:1 4
0:1:0 8
0:1:1 16
1:0:0 32
1:0:1 64
1:1:0 128
1:1:1 256
76543210
R SPRF 0 SPTEF MODF 0 0 0 0
W
Reset00100000
= Unimplemented or Reserved
Figure 15-8. SPI Status Register (SPIS)
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 229
15.4.5 SPI Data Register (SPID)
Reads of this register return the data read from the receive data buffer. Writes to this register write data to
the transmit data buffer. When the SPI is configured as a master, writing data to the transmit data buffer
initiates an SPI transfer.
Data should not be written to the transmit data buffer unless the SPI transmit buffer empty flag (SPTEF)
is set, indicating there is room in the transmit buffer to queue a new transmit byte.
Data may be read from SPID any time after SPRF is set and before another transfer is finished. Failure to
read the data out of the receive data buffer before a new transfer ends causes a receive overrun condition
and the data from the new transfer is lost.
Table 15-7. SPIS Register Field Descriptions
Field Description
7
SPRF
SPI Read Buffer Full Flag — SPRF is set at the completion of an SPI transfer to indicate that received data may
be read from the SPI data register (SPID). SPRF is cleared by reading SPRF while it is set, then reading the SPI
data register.
0 No data available in the receive data buffer
1 Data available in the receive data buffer
5
SPTEF
SPI Transmit Buffer Empty Flag — This bit is set when there is room in the transmit data buffer. It is cleared by
reading SPIS with SPTEF set, followed by writing a data value to the transmit buffer at SPID. SPIS must be read
with SPTEF = 1 before writing data to SPID or the SPID write will be ignored. SPTEF generates an SPTEF CPU
interrupt request if the SPTIE bit in the SPIC1 is also set. SPTEF is automatically set when a data byte transfers
from the transmit buffer into the transmit shift register. For an idle SPI (no data in the transmit buffer or the shift
register and no transfer in progress), data written to SPID is transferred to the shifter almost immediately so
SPTEF is set within two bus cycles allowing a second 8-bit data value to be queued into the transmit buffer. After
completion of the transfer of the value in the shift register, the queued value from the transmit buffer will
automatically move to the shifter and SPTEF will be set to indicate there is room for new data in the transmit
buffer. If no new data is waiting in the transmit buffer, SPTEF simply remains set and no data moves from the
buffer to the shifter.
0 SPI transmit buffer not empty
1 SPI transmit buffer empty
4
MODF
Master Mode Fault Flag — MODF is set if the SPI is configured as a master and the slave select input goes low,
indicating some other SPI device is also configured as a master. The SS pin acts as a mode fault error input only
when MSTR = 1, MODFEN = 1, and SSOE = 0; otherwise, MODF will never be set. MODF is cleared by reading
MODF while it is 1, then writing to SPI control register 1 (SPIC1).
0 No mode fault error
1 Mode fault error detected
76543210
R
Bit 7654321Bit 0
W
Reset00000000
Figure 15-9. SPI Data Register (SPID)
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
230 Freescale Semiconductor
15.5 Functional Description
An SPI transfer is initiated by checking for the SPI transmit buffer empty flag (SPTEF = 1) and then
writing a byte of data to the SPI data register (SPID) in the master SPI device. When the SPI shift register
is available, this byte of data is moved from the transmit data buffer to the shifter, SPTEF is set to indicate
there is room in the buffer to queue another transmit character if desired, and the SPI serial transfer starts.
During the SPI transfer, data is sampled (read) on the MISO pin at one SPSCK edge and shifted, changing
the bit value on the MOSI pin, one-half SPSCK cycle later. After eight SPSCK cycles, the data that was
in the shift register of the master has been shifted out the MOSI pin to the slave while eight bits of data
were shifted in the MISO pin into the master’s shift register. At the end of this transfer, the received data
byte is moved from the shifter into the receive data buffer and SPRF is set to indicate the data can be read
by reading SPID. If another byte of data is waiting in the transmit buffer at the end of a transfer, it is moved
into the shifter, SPTEF is set, and a new transfer is started.
Normally, SPI data is transferred most significant bit (MSB) first. If the least significant bit first enable
(LSBFE) bit is set, SPI data is shifted LSB first.
When the SPI is configured as a slave, its SS pin must be driven low before a transfer starts and SS must
stay low throughout the transfer. If a clock format where CPHA = 0 is selected, SS must be driven to a
logic 1 between successive transfers. If CPHA = 1, SS may remain low between successive transfers. See
Section 15.5.1, “SPI Clock Formats” for more details.
Because the transmitter and receiver are double buffered, a second byte, in addition to the byte currently
being shifted out, can be queued into the transmit data buffer, and a previously received character can be
in the receive data buffer while a new character is being shifted in. The SPTEF flag indicates when the
transmit buffer has room for a new character. The SPRF flag indicates when a received character is
available in the receive data buffer. The received character must be read out of the receive buffer (read
SPID) before the next transfer is finished or a receive overrun error results.
In the case of a receive overrun, the new data is lost because the receive buffer still held the previous
character and was not ready to accept the new data. There is no indication for such an overrun condition
so the application system designer must ensure that previous data has been read from the receive buffer
before a new transfer is initiated.
15.5.1 SPI Clock Formats
To accommodate a wide variety of synchronous serial peripherals from different manufacturers, the SPI
system has a clock polarity (CPOL) bit and a clock phase (CPHA) control bit to select one of four clock
formats for data transfers. CPOL selectively inserts an inverter in series with the clock. CPHA chooses
between two different clock phase relationships between the clock and data.
Figure 15-10 shows the clock formats when CPHA = 1. At the top of the figure, the eight bit times are
shown for reference with bit 1 starting at the first SPSCK edge and bit 8 ending one-half SPSCK cycle
after the sixteenth SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits
depending on the setting in LSBFE. Both variations of SPSCK polarity are shown, but only one of these
waveforms applies for a specific transfer, depending on the value in CPOL. The SAMPLE IN waveform
applies to the MOSI input of a slave or the MISO input of a master. The MOSI waveform applies to the
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 231
MOSI output pin from a master and the MISO waveform applies to the MISO output from a slave. The SS
OUT waveform applies to the slave select output from a master (provided MODFEN and SSOE = 1). The
master SS output goes to active low one-half SPSCK cycle before the start of the transfer and goes back
high at the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input
of a slave.
Figure 15-10. SPI Clock Formats (CPHA = 1)
When CPHA = 1, the slave begins to drive its MISO output when SS goes to active low, but the data is not
defined until the first SPSCK edge. The first SPSCK edge shifts the first bit of data from the shifter onto
the MOSI output of the master and the MISO output of the slave. The next SPSCK edge causes both the
master and the slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the
third SPSCK edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled,
and shifts the second data bit value out the other end of the shifter to the MOSI and MISO outputs of the
master and slave, respectively. When CHPA = 1, the slave’s SS input is not required to go to its inactive
high level between transfers.
Figure 15-11 shows the clock formats when CPHA = 0. At the top of the figure, the eight bit times are
shown for reference with bit 1 starting as the slave is selected (SS IN goes low), and bit 8 ends at the last
SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending on the setting
BIT TIME #
(REFERENCE)
MSB FIRST
LSB FIRST
SPSCK
(CPOL = 0)
SPSCK
(CPOL = 1)
SAMPLE IN
(MISO OR MOSI)
MOSI
(MASTER OUT)
MISO
(SLAVE OUT)
SS OUT
(MASTER)
SS IN
(SLAVE)
BIT 7
BIT 0
BIT 6
BIT 1
BIT 2
BIT 5
BIT 1
BIT 6
BIT 0
BIT 7
12 67 8
...
...
...
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
232 Freescale Semiconductor
in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms applies for a
specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the MOSI input
of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output pin from a
master and the MISO waveform applies to the MISO output from a slave. The SS OUT waveform applies
to the slave select output from a master (provided MODFEN and SSOE = 1). The master SS output goes
to active low at the start of the first bit time of the transfer and goes back high one-half SPSCK cycle after
the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a
slave.
Figure 15-11. SPI Clock Formats (CPHA = 0)
When CPHA = 0, the slave begins to drive its MISO output with the first data bit value (MSB or LSB
depending on LSBFE) when SS goes to active low. The first SPSCK edge causes both the master and the
slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the second SPSCK
edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled and shifts the
second data bit value out the other end of the shifter to the MOSI and MISO outputs of the master and
slave, respectively. When CPHA = 0, the slave’s SS input must go to its inactive high level between
transfers.
BIT TIME #
(REFERENCE)
MSB FIRST
LSB FIRST
SPSCK
(CPOL = 0)
SPSCK
(CPOL = 1)
SAMPLE IN
(MISO OR MOSI)
MOSI
(MASTER OUT)
MISO
(SLAVE OUT)
SS OUT
(MASTER)
SS IN
(SLAVE)
BIT 7
BIT 0
BIT 6
BIT 1
BIT 2
BIT 5
BIT 1
BIT 6
BIT 0
BIT 7
12 67 8...
...
...
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
Freescale Semiconductor 233
15.5.2 SPI Interrupts
There are three flag bits, two interrupt mask bits, and one interrupt vector associated with the SPI system.
The SPI interrupt enable mask (SPIE) enables interrupts from the SPI receiver full flag (SPRF) and mode
fault flag (MODF). The SPI transmit interrupt enable mask (SPTIE) enables interrupts from the SPI
transmit buffer empty flag (SPTEF). When one of the flag bits is set, and the associated interrupt mask bit
is set, a hardware interrupt request is sent to the CPU. If the interrupt mask bits are cleared, software can
poll the associated flag bits instead of using interrupts. The SPI interrupt service routine (ISR) should
check the flag bits to determine what event caused the interrupt. The service routine should also clear the
flag bit(s) before returning from the ISR (usually near the beginning of the ISR).
15.5.3 Mode Fault Detection
A mode fault occurs and the mode fault flag (MODF) becomes set when a master SPI device detects an
error on the SS pin (provided the SS pin is configured as the mode fault input signal). The SS pin is
configured to be the mode fault input signal when MSTR = 1, mode fault enable is set (MODFEN = 1),
and slave select output enable is clear (SSOE = 0).
The mode fault detection feature can be used in a system where more than one SPI device might become
a master at the same time. The error is detected when a master’s SS pin is low, indicating that some other
SPI device is trying to address this master as if it were a slave. This could indicate a harmful output driver
conflict, so the mode fault logic is designed to disable all SPI output drivers when such an error is detected.
When a mode fault is detected, MODF is set and MSTR is cleared to change the SPI configuration back
to slave mode. The output drivers on the SPSCK, MOSI, and MISO (if not bidirectional mode) are
disabled.
MODF is cleared by reading it while it is set, then writing to the SPI control register 1 (SPIC1). User
software should verify the error condition has been corrected before changing the SPI back to master
mode.
Serial Peripheral Interface (S08SPIV3)
MC9S08SG8 MCU Series Data Sheet, Rev.8
234 Freescale Semiconductor
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 235
Chapter 16
Timer Pulse-Width Modulator (S08TPMV3)
16.1 Introduction
The TPM uses one input/output (I/O) pin per channel, TPMxCHn where x is the TPM number (for
example, 1 or 2) and n is the channel number (for example, 0–1). The TPM shares its I/O pins with
general-purpose I/O port pins (refer to the Pins and Connections chapter for more information).
All MC9S08SG8 MCUs have two TPM modules. The number of channels available depends on the pin
quantity of the package, as shown in Table 16-1:
Figure 16-1 shows the MC9S08SG8 block diagram with the TPM modules highlighted.
16.1.1 ACMP/TPM Configuration Information
The ACMP module can be configured to connect the output of the analog comparator to TPM1 input
capture channel 0 by setting ACIC in SOPT2. With ACIC set, the TPM1CH0 pin is not available externally
regardless of the configuration of the TPM1 module for channel 0.
16.1.2 TPM Configuration Information
The external clock for the TPM modules, TPMCLK, is selected by setting CLKS[B:A] = 1:1 in TPMxSC,
which selects the TCLK pin input. The TCLK input on PTA5 can be enabled as external clock inputs to
both TPM modules and MTIM simultaneously.
Table 16-1. MC9S08SG8 Features by MCU and Package
Feature MC9S08SG8/4
Pin quantity 20 16 8
TPM1 channels 2 2 11
1The 8-pin device does not have TPM1CH1 or TPM2CH1
bonded out, but those timer channels are available to the
user to use as software compares.
TPM2 channels 2 2 11
Chapter 16 Timer Pulse-Width Modulator (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
236 Freescale Semiconductor
Figure 16-1. MC9S08SG8 Block Diagram with TPM Modules Highlighted
16.1.3 TPMV3 Differences from Previous Versions
The TPMV3 is the latest version of the Timer/PWM module that addresses errata found in previous
versions. The following section outlines the differences between TPMV3 and TPMV2 modules, and any
considerations that should be taken when porting code.
PTB7/SCL/EXTAL
PORT B
PTB6/SDA/XTAL
PTB5/TPM1CH1/SS
PTB4/TPM2CH1/MISO
PTB3/PIB3/MOSI/ADP7
PTB2/PIB2/SPSCK/ADP6
PORT A
PTA1/PIA1/TPM2CH0/ADP1/ACMP–
PTB1/PIB1/TxD/ADP5
PTB0/PIB0/RxD/ADP4
PORT C
PTC3/ADP11
PTC2/ADP10
PTC1/TPM1CH1/ADP9
PTC0/TPM1CH0/ADP8
PTA3/PAI3/SCL/ADP3
PTA2/PAI2/SDA/ADP2/ACMPO
PTA0/PIA0/TPM1CH0/TCLK/ADP0/ACMP+
SEE NOTE 1, 2
SEE NOTE 1, 2
= Pin can be enabled as part of the ganged output drive feature.
NOTE 1:
Port B not available on 8-pin packages
NOTE 2: Port C not available on 8-pin or 16-pin packages.
IIC MODULE (IIC)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
USER FLASH
USER RAM
HCS08 CORE
CPU
BDC
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
COP
LVD
INTERFACE MODULE (SCI)
SERIAL COMMUNICATIONS
8-BIT MODULO TIMER
MODULE (MTIM)
VOLTAGE
DEBUG MODULE (DBG)
MISO
SCL
SDA
MOSI
SPSCK
RxD
TxD
LOW-POWER OSCILLATOR
40-MHz INTERNAL CLOCK
SOURCE (ICS)
31.25 kHz to 38.4 kHz
1 MHz to 16 MHz
(XOSC)
EXTAL
XTAL
VSS
VDD
VSSA
VDDA
VREFL
VREFH
ANALOG-TO-DIGITAL
CONVERTER (ADC)
10-BIT
SS
TCLK
BKGD/MS
16-BIT TIMER/PWM
MODULE (TPM2)
TCLK
REAL-TIME COUNTER (RTC)
(MC9S08SG8 = 8,192 BYTES)
(MC9S08SG4 = 4096 BYTES)
(MC9S08SG8 = 512 BYTES)
ANALOG COMPARATOR
(ACMP)
ACMPO
ACMP–
ACMP+
TPM2CH0
TPM2CH1
ADP11-ADP0
16-BIT TIMER/PWM
MODULE (TPM1)
TCLK
TPM1CH0
TPM1CH1
(MC9S08SG4 = 256 BYTES)
NOTE 3: VDDA/VREFH and VSSA/VREFL, are double bonded to VDD and VSS respectively.
RESET
SEE NOTE 3
NOTES
REGULATOR
Chapter 16 Timer Pulse-Width Modulator (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 237
Table 16-2. TPMV2 and TPMV3 Porting Considerations
Action TPMV3 TPMV2
Write to TPMxCnTH:L registers1
Any write to TPMxCNTH or TPMxCNTL registers Clears the TPM counter
(TPMxCNTH:L) and the
prescaler counter.
Clears the TPM counter
(TPMxCNTH:L) only.
Read of TPMxCNTH:L registers1
In BDM mode, any read of TPMxCNTH:L registers Returns the value of the TPM
counter that is frozen.
If only one byte of the
TPMxCNTH:L registers was
read before the BDM mode
became active, returns the
latched value of TPMxCNTH:L
from the read buffer (instead of
the frozen TPM counter value).
In BDM mode, a write to TPMxSC, TPMxCNTH or TPMxCNTL Clears this read coherency
mechanism.
Does not clear this read
coherency mechanism.
Read of TPMxCnVH:L registers2
In BDM mode, any read of TPMxCnVH:L registers Returns the value of the
TPMxCnVH:L register.
If only one byte of the
TPMxCnVH:L registers was
read before the BDM mode
became active, returns the
latched value of TPMxCNTH:L
from the read buffer (instead of
the value in the TPMxCnVH:L
registers).
In BDM mode, a write to TPMxCnSC Clears this read coherency
mechanism.
Does not clear this read
coherency mechanism.
Write to TPMxCnVH:L registers
In Input Capture mode, writes to TPMxCnVH:L registers3Not allowed. Allowed.
In Output Compare mode, when (CLKSB:CLKSA not = 0:0),
writes to TPMxCnVH:L registers3Update the TPMxCnVH:L
registers with the value of
their write buffer at the next
change of the TPM counter
(end of the prescaler
counting) after the second
byte is written.
Always update these registers
when their second byte is
written.
In Edge-Aligned PWM mode when (CLKSB:CLKSA not = 00),
writes to TPMxCnVH:L registers
Update the TPMxCnVH:L
registers with the value of
their write buffer after both
bytes were written and when
the TPM counter changes
from (TPMxMODH:L - 1) to
(TPMxMODH:L).
Note: If the TPM counter is a
free-running counter, then
this update is made when the
TPM counter changes from
0xFFFE to 0xFFFF.
Update after both bytes are
written and when the TPM
counter changes from
TPMxMODH:L to 0x0000.
Chapter 16 Timer Pulse-Width Modulator (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
238 Freescale Semiconductor
16.1.4 Migrating from TPMV1
In addition to Section 16.1.3, “TPMV3 Differences from Previous Versions,” keep in mind the following
considerations when migrating from a device that uses TPMV1.
• You can write to the Channel Value register (TPMxCnV) when the timer is not in input capture
mode for TPMV2, not TPMV3.
In Center-Aligned PWM mode when (CLKSB:CLKSA not =
00), writes to TPMxCnVH:L registers4Update the TPMxCnVH:L
registers with the value of
their write buffer after both
bytes are written and when
the TPM counter changes
from (TPMxMODH:L - 1) to
(TPMxMODH:L).
Note: If the TPM counter is a
free-running counter, then
this update is made when the
TPM counter changes from
0xFFFE to 0xFFFF.
Update after both bytes are
written and when the TPM
counter changes from
TPMxMODH:L to
(TPMxMODH:L - 1).
Center-Aligned PWM
When TPMxCnVH:L = TPMxMODH:L5 Produces 100% duty cycle. Produces 0% duty cycle.
When TPMxCnVH:L = (TPMxMODH:L - 1)6 Produces a near 100% duty
cycle.
Produces 0% duty cycle.
TPMxCnVH:L is changed from 0x0000 to a non-zero value7 Waits for the start of a new
PWM period to begin using
the new duty cycle setting.
Changes the channel output at
the middle of the current PWM
period (when the count
reaches 0x0000).
TPMxCnVH:L is changed from a non-zero value to 0x00008 Finishes the current PWM
period using the old duty
cycle setting.
Finishes the current PWM
period using the new duty
cycle setting.
Write to TPMxMODH:L registers in BDM mode
In BDM mode, a write to TPMxSC register Clears the write coherency
mechanism of
TPMxMODH:L registers.
Does not clear the write
coherency mechanism.
1For more information, refer to Section 16.3.2, “TPM-Counter Registers (TPMxCNTH:TPMxCNTL) .” [SE110-TPM case 7]
2For more information, refer to Section 16.3.5, “TPM Channel Value Registers (TPMxCnVH:TPMxCnVL).”
3For more information, refer to Section 16.4.2.1, “Input Capture Mode .”
4For more information, refer to Section 16.4.2.4, “Center-Aligned PWM Mode.”
5For more information, refer to Section 16.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 1]
6For more information, refer to Section 16.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 2]
7For more information, refer to Section 16.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 3 and 5]
8For more information, refer to Section 16.4.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 4]
Table 16-2. TPMV2 and TPMV3 Porting Considerations (continued)
Action TPMV3 TPMV2
Chapter 16 Timer Pulse-Width Modulator (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 239
• In edge- or center- aligned modes, the Channel Value register (TPMxCnV) registers only update
when the timer changes from TPMMOD-1 to TPMMOD, or in the case of a free running timer
from 0xFFFE to 0xFFFF.
• Also, when configuring the TPM modules, it is best to write to TPMxSC before TPMxCnV as a
write to TPMxSC resets the coherency mechanism on the TPMxCnV registers.
Table 16-3. Migrating to TPMV3 Considerations
When... Action / Best Practice
Writing to the Channel Value Register (TPMxCnV)
register...
Timer must be in Input Capture mode.
Updating the Channel Value Register (TPMxCnV)
register in edge-aligned or center-aligned modes...
Only occurs when the timer changes from
TPMMOD-1 to TPMMOD (or in the case of a free
running timer, from 0xFFFE to 0xFFFF).
Reseting the coherency mechanism for the
Channel Value Register (TPMxCnV) register...
Write to TPMxSC.
Configuring the TPM modules... Write first to TPMxSC and then to TPMxCnV
register.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
240 Freescale Semiconductor
16.1.5 Features
The TPM includes these distinctive features:
• One to eight channels:
— Each channel may be input capture, output compare, or edge-aligned PWM
— Rising-Edge, falling-edge, or any-edge input capture trigger
— Set, clear, or toggle output compare action
— Selectable polarity on PWM outputs
• Module may be configured for buffered, center-aligned pulse-width-modulation (CPWM) on all
channels
• Timer clock source selectable as prescaled bus clock, fixed system clock, or an external clock pin
— Prescale taps for divide-by 1, 2, 4, 8, 16, 32, 64, or 128
— Fixed system clock source are synchronized to the bus clock by an on-chip synchronization
circuit
— External clock pin may be shared with any timer channel pin or a separated input pin
• 16-bit free-running or modulo up/down count operation
• Timer system enable
• One interrupt per channel plus terminal count interrupt
16.1.6 Modes of Operation
In general, TPM channels may be independently configured to operate in input capture, output compare,
or edge-aligned PWM modes. A control bit allows the whole TPM (all channels) to switch to
center-aligned PWM mode. When center-aligned PWM mode is selected, input capture, output compare,
and edge-aligned PWM functions are not available on any channels of this TPM module.
When the microcontroller is in active BDM background or BDM foreground mode, the TPM temporarily
suspends all counting until the microcontroller returns to normal user operating mode. During stop mode,
all system clocks, including the main oscillator, are stopped; therefore, the TPM is effectively disabled
until clocks resume. During wait mode, the TPM continues to operate normally. Provided the TPM does
not need to produce a real time reference or provide the interrupt source(s) needed to wake the MCU from
wait mode, the user can save power by disabling TPM functions before entering wait mode.
• Input capture mode
When a selected edge event occurs on the associated MCU pin, the current value of the 16-bit timer
counter is captured into the channel value register and an interrupt flag bit is set. Rising edges,
falling edges, any edge, or no edge (disable channel) may be selected as the active edge which
triggers the input capture.
• Output compare mode
When the value in the timer counter register matches the channel value register, an interrupt flag
bit is set, and a selected output action is forced on the associated MCU pin. The output compare
action may be selected to force the pin to zero, force the pin to one, toggle the pin, or ignore the
pin (used for software timing functions).
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 241
• Edge-aligned PWM mode
The value of a 16-bit modulo register plus 1 sets the period of the PWM output signal. The channel
value register sets the duty cycle of the PWM output signal. The user may also choose the polarity
of the PWM output signal. Interrupts are available at the end of the period and at the duty-cycle
transition point. This type of PWM signal is called edge-aligned because the leading edges of all
PWM signals are aligned with the beginning of the period, which is the same for all channels within
a TPM.
• Center-aligned PWM mode
Twice the value of a 16-bit modulo register sets the period of the PWM output, and the
channel-value register sets the half-duty-cycle duration. The timer counter counts up until it
reaches the modulo value and then counts down until it reaches zero. As the count matches the
channel value register while counting down, the PWM output becomes active. When the count
matches the channel value register while counting up, the PWM output becomes inactive. This type
of PWM signal is called center-aligned because the centers of the active duty cycle periods for all
channels are aligned with a count value of zero. This type of PWM is required for types of motors
used in small appliances.
This is a high-level description only. Detailed descriptions of operating modes are in later sections.
16.1.7 Block Diagram
The TPM uses one input/output (I/O) pin per channel, TPMxCHn (timer channel n) where n is the channel
number (1-8). The TPM shares its I/O pins with general purpose I/O port pins (refer to I/O pin descriptions
in full-chip specification for the specific chip implementation).
Figure 16-2 shows the TPM structure. The central component of the TPM is the 16-bit counter that can
operate as a free-running counter or a modulo up/down counter. The TPM counter (when operating in
normal up-counting mode) provides the timing reference for the input capture, output compare, and
edge-aligned PWM functions. The timer counter modulo registers, TPMxMODH:TPMxMODL, control
the modulo value of the counter (the values 0x0000 or 0xFFFF effectively make the counter free running).
Software can read the counter value at any time without affecting the counting sequence. Any write to
either half of the TPMxCNT counter resets the counter, regardless of the data value written.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
242 Freescale Semiconductor
Figure 16-2. TPM Block Diagram
PRESCALE AND SELECT
16-BIT COMPARATOR
PS2:PS1:PS0
TOF
TOIE
INTER-
16-BIT COUNTER
RUPT
LOGIC
16-BIT COMPARATOR
16-BIT LATCH
ELS0B ELS0A PORT
CHANNEL 0
CH0IE
CH0F
LOGIC
INTER-
RUPT
LOGIC
CPWMS
MS0B MS0A
COUNTER RESET
CLKSB:CLKSA
³1, 2, 4, 8, 16, 32, 64,
BUS CLOCK
FIXED SYSTEM CLOCK
EXTERNAL CLOCK SYNC
16-BIT COMPARATOR
16-BIT LATCH
CHANNEL 1 ELS1B ELS1A
CH1IE
CH1F
INTERNAL BUS
PORT
LOGIC
INTER-
RUPT
LOGIC
MS1B MS1A
16-BIT COMPARATOR
16-BIT LATCH
CHANNEL 7 ELS7B ELS7A
CH7IE
CH7F
PORT
LOGIC
INTER-
RUPT
LOGIC
MS7B MS7A
Up to 8 channels
CLOCK SOURCE
SELECT
OFF, BUS, FIXED
SYSTEM CLOCK, EXT or ³128
TPMxMODH:TPMxMODL
TPMxC0VH:TPMxC0VL
TPMxC1VH:TPMxC1VL
TPMxCH0
TPMxCH1
TPMxC7VH:TPMxC7VL
TPMxCH7
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 243
The TPM channels are programmable independently as input capture, output compare, or edge-aligned
PWM channels. Alternately, the TPM can be configured to produce CPWM outputs on all channels. When
the TPM is configured for CPWMs, the counter operates as an up/down counter; input capture, output
compare, and EPWM functions are not practical.
If a channel is configured as input capture, an internal pullup device may be enabled for that channel. The
details of how a module interacts with pin controls depends upon the chip implementation because the I/O
pins and associated general purpose I/O controls are not part of the module. Refer to the discussion of the
I/O port logic in a full-chip specification.
Because center-aligned PWMs are usually used to drive 3-phase AC-induction motors and brushless DC
motors, they are typically used in sets of three or six channels.
16.2 Signal Description
Table 16-4 shows the user-accessible signals for the TPM. The number of channels may be varied from
one to eight. When an external clock is included, it can be shared with the same pin as any TPM channel;
however, it could be connected to a separate input pin. Refer to the I/O pin descriptions in full-chip
specification for the specific chip implementation.
Refer to documentation for the full-chip for details about reset states, port connections, and whether there
is any pullup device on these pins.
TPM channel pins can be associated with general purpose I/O pins and have passive pullup devices which
can be enabled with a control bit when the TPM or general purpose I/O controls have configured the
associated pin as an input. When no TPM function is enabled to use a corresponding pin, the pin reverts
to being controlled by general purpose I/O controls, including the port-data and data-direction registers.
Immediately after reset, no TPM functions are enabled, so all associated pins revert to general purpose I/O
control.
16.2.1 Detailed Signal Descriptions
This section describes each user-accessible pin signal in detail. Although Table 16-4 grouped all channel
pins together, any TPM pin can be shared with the external clock source signal. Since I/O pin logic is not
part of the TPM, refer to full-chip documentation for a specific derivative for more details about the
interaction of TPM pin functions and general purpose I/O controls including port data, data direction, and
pullup controls.
Table 16-4. Signal Properties
Name Function
EXTCLK1
1When preset, this signal can share any channel pin; however depending upon full-chip
implementation, this signal could be connected to a separate external pin.
External clock source which may be selected to drive the TPM counter.
TPMxCHn2
2n=channel number (1 to 8)
I/O pin associated with TPM channel n
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
244 Freescale Semiconductor
16.2.1.1 EXTCLK — External Clock Source
Control bits in the timer status and control register allow the user to select nothing (timer disable), the
bus-rate clock (the normal default source), a crystal-related clock, or an external clock as the clock which
drives the TPM prescaler and subsequently the 16-bit TPM counter. The external clock source is
synchronized in the TPM. The bus clock clocks the synchronizer; the frequency of the external source must
be no more than one-fourth the frequency of the bus-rate clock, to meet Nyquist criteria and allowing for
jitter.
The external clock signal shares the same pin as a channel I/O pin, so the channel pin will not be usable
for channel I/O function when selected as the external clock source. It is the user’s responsibility to avoid
such settings. If this pin is used as an external clock source (CLKSB:CLKSA = 1:1), the channel can still
be used in output compare mode as a software timer (ELSnB:ELSnA = 0:0).
16.2.1.2 TPMxCHn — TPM Channel n I/O Pin(s)
Each TPM channel is associated with an I/O pin on the MCU. The function of this pin depends on the
channel configuration. The TPM pins share with general purpose I/O pins, where each pin has a port data
register bit, and a data direction control bit, and the port has optional passive pullups which may be enabled
whenever a port pin is acting as an input.
The TPM channel does not control the I/O pin when (ELSnB:ELSnA = 0:0) or when (CLKSB:CLKSA =
0:0) so it normally reverts to general purpose I/O control. When CPWMS = 1 (and ELSnB:ELSnA not =
0:0), all channels within the TPM are configured for center-aligned PWM and the TPMxCHn pins are all
controlled by the TPM system. When CPWMS=0, the MSnB:MSnA control bits determine whether the
channel is configured for input capture, output compare, or edge-aligned PWM.
When a channel is configured for input capture (CPWMS=0, MSnB:MSnA = 0:0 and ELSnB:ELSnA not
= 0:0), the TPMxCHn pin is forced to act as an edge-sensitive input to the TPM. ELSnB:ELSnA control
bits determine what polarity edge or edges will trigger input-capture events. A synchronizer based on the
bus clock is used to synchronize input edges to the bus clock. This implies the minimum pulse width—that
can be reliably detected—on an input capture pin is four bus clock periods (with ideal clock pulses as near
as two bus clocks can be detected). TPM uses this pin as an input capture input to override the port data
and data direction controls for the same pin.
When a channel is configured for output compare (CPWMS=0, MSnB:MSnA = 0:1 and ELSnB:ELSnA
not = 0:0), the associated data direction control is overridden, the TPMxCHn pin is considered an output
controlled by the TPM, and the ELSnB:ELSnA control bits determine how the pin is controlled. The
remaining three combinations of ELSnB:ELSnA determine whether the TPMxCHn pin is toggled, cleared,
or set each time the 16-bit channel value register matches the timer counter.
When the output compare toggle mode is initially selected, the previous value on the pin is driven out until
the next output compare event—then the pin is toggled.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 245
When a channel is configured for edge-aligned PWM (CPWMS=0, MSnB=1 and ELSnB:ELSnA not =
0:0), the data direction is overridden, the TPMxCHn pin is forced to be an output controlled by the TPM,
and ELSnA controls the polarity of the PWM output signal on the pin. When ELSnB:ELSnA=1:0, the
TPMxCHn pin is forced high at the start of each new period (TPMxCNT=0x0000), and the pin is forced
low when the channel value register matches the timer counter. When ELSnA=1, the TPMxCHn pin is
forced low at the start of each new period (TPMxCNT=0x0000), and the pin is forced high when the
channel value register matches the timer counter.
Figure 16-3. High-True Pulse of an Edge-Aligned PWM
Figure 16-4. Low-True Pulse of an Edge-Aligned PWM
CHnF BIT
TOF BIT
0... 123456780 12...
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
TPMxCHn
CHnF BIT
TOF BIT
0... 123456780 12...
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
TPMxCHn
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
246 Freescale Semiconductor
When the TPM is configured for center-aligned PWM (and ELSnB:ELSnA not = 0:0), the data direction
for all channels in this TPM are overridden, the TPMxCHn pins are forced to be outputs controlled by the
TPM, and the ELSnA bits control the polarity of each TPMxCHn output. If ELSnB:ELSnA=1:0, the
corresponding TPMxCHn pin is cleared when the timer counter is counting up, and the channel value
register matches the timer counter; the TPMxCHn pin is set when the timer counter is counting down, and
the channel value register matches the timer counter. If ELSnA=1, the corresponding TPMxCHn pin is set
when the timer counter is counting up and the channel value register matches the timer counter; the
TPMxCHn pin is cleared when the timer counter is counting down and the channel value register matches
the timer counter.
Figure 16-5. High-True Pulse of a Center-Aligned PWM
Figure 16-6. Low-True Pulse of a Center-Aligned PWM
CHnF BIT
TOF BIT
... 787654321 0123456 78 76 5 ...
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
TPMxCHn
CHnF BIT
TOF BIT
... 787654321 0123456 78 76 5...
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
TPMxCHn
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 247
16.3 Register Definition
This section consists of register descriptions in address order.
16.3.1 TPM Status and Control Register (TPMxSC)
TPMxSC contains the overflow status flag and control bits used to configure the interrupt enable, TPM
configuration, clock source, and prescale factor. These controls relate to all channels within this timer
module.
76543210
RTOF
TOIE CPWMS CLKSB CLKSA PS2 PS1 PS0
W0
Reset00000000
Figure 16-7. TPM Status and Control Register (TPMxSC)
Table 16-5. TPMxSC Field Descriptions
Field Description
7
TOF
Timer overflow flag. This read/write flag is set when the TPM counter resets to 0x0000 after reaching the modulo
value programmed in the TPM counter modulo registers. Clear TOF by reading the TPM status and control
register when TOF is set and then writing a logic 0 to TOF. If another TPM overflow occurs before the clearing
sequence is complete, the sequence is reset so TOF would remain set after the clear sequence was completed
for the earlier TOF. This is done so a TOF interrupt request cannot be lost during the clearing sequence for a
previous TOF. Reset clears TOF. Writing a logic 1 to TOF has no effect.
0 TPM counter has not reached modulo value or overflow
1 TPM counter has overflowed
6
TOIE
Timer overflow interrupt enable. This read/write bit enables TPM overflow interrupts. If TOIE is set, an interrupt is
generated when TOF equals one. Reset clears TOIE.
0 TOF interrupts inhibited (use for software polling)
1 TOF interrupts enabled
5
CPWMS
Center-aligned PWM select. When present, this read/write bit selects CPWM operating mode. By default, the TPM
operates in up-counting mode for input capture, output compare, and edge-aligned PWM functions. Setting
CPWMS reconfigures the TPM to operate in up/down counting mode for CPWM functions. Reset clears CPWMS.
0 All channels operate as input capture, output compare, or edge-aligned PWM mode as selected by the
MSnB:MSnA control bits in each channel’s status and control register.
1 All channels operate in center-aligned PWM mode.
4–3
CLKS[B:A]
Clock source selects. As shown in Table 16-6, this 2-bit field is used to disable the TPM system or select one of
three clock sources to drive the counter prescaler. The fixed system clock source is only meaningful in systems
with a PLL-based system clock. When there is no PLL, the fixed-system clock source is the same as the bus rate
clock. The external source is synchronized to the bus clock by TPM module, and the fixed system clock source
(when a PLL is present) is synchronized to the bus clock by an on-chip synchronization circuit. When a PLL is
present but not enabled, the fixed-system clock source is the same as the bus-rate clock.
2–0
PS[2:0]
Prescale factor select. This 3-bit field selects one of 8 division factors for the TPM clock input as shown in
Ta ble 1 6 - 7 . This prescaler is located after any clock source synchronization or clock source selection so it affects
the clock source selected to drive the TPM system. The new prescale factor will affect the clock source on the
next system clock cycle after the new value is updated into the register bits.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
248 Freescale Semiconductor
16.3.2 TPM-Counter Registers (TPMxCNTH:TPMxCNTL)
The two read-only TPM counter registers contain the high and low bytes of the value in the TPM counter.
Reading either byte (TPMxCNTH or TPMxCNTL) latches the contents of both bytes into a buffer where
they remain latched until the other half is read. This allows coherent 16-bit reads in either big-endian or
little-endian order which makes this more friendly to various compiler implementations. The coherency
mechanism is automatically restarted by an MCU reset or any write to the timer status/control register
(TPMxSC).
Reset clears the TPM counter registers. Writing any value to TPMxCNTH or TPMxCNTL also clears the
TPM counter (TPMxCNTH:TPMxCNTL) and resets the coherency mechanism, regardless of the data
involved in the write.
Table 16-6. TPM-Clock-Source Selection
CLKSB:CLKSA TPM Clock Source to Prescaler Input
00 No clock selected (TPM counter disable)
01 Bus rate clock
10 Fixed system clock
11 External source
Table 16-7. Prescale Factor Selection
PS2:PS1:PS0 TPM Clock Source Divided-by
000 1
001 2
010 4
011 8
100 16
101 32
110 64
111 128
76543210
R Bit 15 14 13 12 11 10 9 Bit 8
W Any write to TPMxCNTH clears the 16-bit counter
Reset00000000
Figure 16-8. TPM Counter Register High (TPMxCNTH)
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 249
When BDM is active, the timer counter is frozen (this is the value that will be read by user); the coherency
mechanism is frozen such that the buffer latches remain in the state they were in when the BDM became
active, even if one or both counter halves are read while BDM is active. This assures that if the user was
in the middle of reading a 16-bit register when BDM became active, it will read the appropriate value from
the other half of the 16-bit value after returning to normal execution.
In BDM mode, writing any value to TPMxSC, TPMxCNTH or TPMxCNTL registers resets the read
coherency mechanism of the TPMxCNTH:L registers, regardless of the data involved in the write.
16.3.3 TPM Counter Modulo Registers (TPMxMODH:TPMxMODL)
The read/write TPM modulo registers contain the modulo value for the TPM counter. After the TPM
counter reaches the modulo value, the TPM counter resumes counting from 0x0000 at the next clock, and
the overflow flag (TOF) becomes set. Writing to TPMxMODH or TPMxMODL inhibits the TOF bit and
overflow interrupts until the other byte is written. Reset sets the TPM counter modulo registers to 0x0000
which results in a free running timer counter (modulo disabled).
Writing to either byte (TPMxMODH or TPMxMODL) latches the value into a buffer and the registers are
updated with the value of their write buffer according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), then the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), then the registers are updated after both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
the TPM counter is a free-running counter, the update is made when the TPM counter changes from
0xFFFE to 0xFFFF
The latching mechanism may be manually reset by writing to the TPMxSC address (whether BDM is
active or not).
When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxSC register)
such that the buffer latches remain in the state they were in when the BDM became active, even if one or
both halves of the modulo register are written while BDM is active. Any write to the modulo registers
bypasses the buffer latches and directly writes to the modulo register while BDM is active.
76543210
RBit 7654321Bit 0
W Any write to TPMxCNTL clears the 16-bit counter
Reset00000000
Figure 16-9. TPM Counter Register Low (TPMxCNTL)
76543210
R
Bit 15 14 13 12 11 10 9 Bit 8
W
Reset00000000
Figure 16-10. TPM Counter Modulo Register High (TPMxMODH)
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
250 Freescale Semiconductor
Reset the TPM counter before writing to the TPM modulo registers to avoid confusion about when the first
counter overflow will occur.
16.3.4 TPM Channel n Status and Control Register (TPMxCnSC)
TPMxCnSC contains the channel-interrupt-status flag and control bits used to configure the interrupt
enable, channel configuration, and pin function.
76543210
R
Bit 7654321Bit 0
W
Reset00000000
76543210
RCHnF
CHnIE MSnB MSnA ELSnB ELSnA
00
W0
Reset00000000
= Unimplemented or Reserved
Figure 16-12. TPM Channel n Status and Control Register (TPMxCnSC)
Table 16-8. TPMxCnSC Field Descriptions
Field Description
7
CHnF
Channel n flag. When channel n is an input-capture channel, this read/write bit is set when an active edge occurs
on the channel n pin. When channel n is an output compare or edge-aligned/center-aligned PWM channel, CHnF
is set when the value in the TPM counter registers matches the value in the TPM channel n value registers. When
channel n is an edge-aligned/center-aligned PWM channel and the duty cycle is set to 0% or 100%, CHnF will not
be set even when the value in the TPM counter registers matches the value in the TPM channel n value registers.
A corresponding interrupt is requested when CHnF is set and interrupts are enabled (CHnIE = 1). Clear CHnF by
reading TPMxCnSC while CHnF is set and then writing a logic 0 to CHnF. If another interrupt request occurs
before the clearing sequence is complete, the sequence is reset so CHnF remains set after the clear sequence
completed for the earlier CHnF. This is done so a CHnF interrupt request cannot be lost due to clearing a previous
CHnF.
Reset clears the CHnF bit. Writing a logic 1 to CHnF has no effect.
0 No input capture or output compare event occurred on channel n
1 Input capture or output compare event on channel n
6
CHnIE
Channel n interrupt enable. This read/write bit enables interrupts from channel n. Reset clears CHnIE.
0 Channel n interrupt requests disabled (use for software polling)
1 Channel n interrupt requests enabled
5
MSnB
Mode select B for TPM channel n. When CPWMS=0, MSnB=1 configures TPM channel n for edge-aligned PWM
mode. Refer to the summary of channel mode and setup controls in Table 16-9.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 251
16.3.5 TPM Channel Value Registers (TPMxCnVH:TPMxCnVL)
These read/write registers contain the captured TPM counter value of the input capture function or the
output compare value for the output compare or PWM functions. The channel registers are cleared by
reset.
4
MSnA
Mode select A for TPM channel n. When CPWMS=0 and MSnB=0, MSnA configures TPM channel n for
input-capture mode or output compare mode. Refer to Table 16-9 for a summary of channel mode and setup
controls.
Note: If the associated port pin is not stable for at least two bus clock cycles before changing to input capture
mode, it is possible to get an unexpected indication of an edge trigger.
3–2
ELSnB
ELSnA
Edge/level select bits. Depending upon the operating mode for the timer channel as set by CPWMS:MSnB:MSnA
and shown in Table 16-9, these bits select the polarity of the input edge that triggers an input capture event, select
the level that will be driven in response to an output compare match, or select the polarity of the PWM output.
Setting ELSnB:ELSnA to 0:0 configures the related timer pin as a general purpose I/O pin not related to any timer
functions. This function is typically used to temporarily disable an input capture channel or to make the timer pin
available as a general purpose I/O pin when the associated timer channel is set up as a software timer that does
not require the use of a pin.
Table 16-9. Mode, Edge, and Level Selection
CPWMS MSnB:MSnA ELSnB:ELSnA Mode Configuration
X XX 00 Pin not used for TPM - revert to general
purpose I/O or other peripheral control
0 00 01 Input capture Capture on rising edge
only
10 Capture on falling edge
only
11 Capture on rising or
falling edge
01 01 Output compare Toggle output on
compare
10 Clear output on
compare
11 Set output on compare
1X 10 Edge-aligned
PWM
High-true pulses (clear
output on compare)
X1 Low-true pulses (set
output on compare)
1 XX 10 Center-aligned
PWM
High-true pulses (clear
output on compare-up)
X1 Low-true pulses (set
output on compare-up)
Table 16-8. TPMxCnSC Field Descriptions (continued)
Field Description
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
252 Freescale Semiconductor
In input capture mode, reading either byte (TPMxCnVH or TPMxCnVL) latches the contents of both bytes
into a buffer where they remain latched until the other half is read. This latching mechanism also resets
(becomes unlatched) when the TPMxCnSC register is written (whether BDM mode is active or not). Any
write to the channel registers will be ignored during the input capture mode.
When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxCnSC register)
such that the buffer latches remain in the state they were in when the BDM became active, even if one or
both halves of the channel register are read while BDM is active. This assures that if the user was in the
middle of reading a 16-bit register when BDM became active, it will read the appropriate value from the
other half of the 16-bit value after returning to normal execution. The value read from the TPMxCnVH
and TPMxCnVL registers in BDM mode is the value of these registers and not the value of their read
buffer.
In output compare or PWM modes, writing to either byte (TPMxCnVH or TPMxCnVL) latches the value
into a buffer. After both bytes are written, they are transferred as a coherent 16-bit value into the
timer-channel registers according to the value of CLKSB:CLKSA bits and the selected mode, so:
• If (CLKSB:CLKSA = 0:0), then the registers are updated when the second byte is written.
• If (CLKSB:CLKSA not = 0:0 and in output compare mode) then the registers are updated after the
second byte is written and on the next change of the TPM counter (end of the prescaler counting).
• If (CLKSB:CLKSA not = 0:0 and in EPWM or CPWM modes), then the registers are updated after
the both bytes were written, and the TPM counter changes from (TPMxMODH:TPMxMODL - 1)
to (TPMxMODH:TPMxMODL). If the TPM counter is a free-running counter then the update is
made when the TPM counter changes from 0xFFFE to 0xFFFF.
The latching mechanism may be manually reset by writing to the TPMxCnSC register (whether BDM
mode is active or not). This latching mechanism allows coherent 16-bit writes in either big-endian or
little-endian order which is friendly to various compiler implementations.
When BDM is active, the coherency mechanism is frozen such that the buffer latches remain in the state
they were in when the BDM became active even if one or both halves of the channel register are written
while BDM is active. Any write to the channel registers bypasses the buffer latches and directly write to
the channel register while BDM is active. The values written to the channel register while BDM is active
76543210
R
Bit 15 14 13 12 11 10 9 Bit 8
W
Reset00000000
Figure 16-13. TPM Channel Value Register High (TPMxCnVH)
76543210
R
Bit 7654321Bit 0
W
Reset00000000
Figure 16-14. TPM Channel Value Register Low (TPMxCnVL)
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 253
are used for PWM & output compare operation once normal execution resumes. Writes to the channel
registers while BDM is active do not interfere with partial completion of a coherency sequence. After the
coherency mechanism has been fully exercised, the channel registers are updated using the buffered values
written (while BDM was not active) by the user.
16.4 Functional Description
All TPM functions are associated with a central 16-bit counter which allows flexible selection of the clock
source and prescale factor. There is also a 16-bit modulo register associated with the main counter.
The CPWMS control bit chooses between center-aligned PWM operation for all channels in the TPM
(CPWMS=1) or general purpose timing functions (CPWMS=0) where each channel can independently be
configured to operate in input capture, output compare, or edge-aligned PWM mode. The CPWMS control
bit is located in the main TPM status and control register because it affects all channels within the TPM
and influences the way the main counter operates. (In CPWM mode, the counter changes to an up/down
mode rather than the up-counting mode used for general purpose timer functions.)
The following sections describe the main counter and each of the timer operating modes (input capture,
output compare, edge-aligned PWM, and center-aligned PWM). Because details of pin operation and
interrupt activity depend upon the operating mode, these topics will be covered in the associated mode
explanation sections.
16.4.1 Counter
All timer functions are based on the main 16-bit counter (TPMxCNTH:TPMxCNTL). This section
discusses selection of the clock source, end-of-count overflow, up-counting vs. up/down counting, and
manual counter reset.
16.4.1.1 Counter Clock Source
The 2-bit field, CLKSB:CLKSA, in the timer status and control register (TPMxSC) selects one of three
possible clock sources or OFF (which effectively disables the TPM). See Table 16-6. After any MCU reset,
CLKSB:CLKSA=0:0 so no clock source is selected, and the TPM is in a very low power state. These
control bits may be read or written at any time and disabling the timer (writing 00 to the CLKSB:CLKSA
field) does not affect the values in the counter or other timer registers.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
254 Freescale Semiconductor
The bus rate clock is the main system bus clock for the MCU. This clock source requires no
synchronization because it is the clock that is used for all internal MCU activities including operation of
the CPU and buses.
In MCUs that have no PLL or the PLL is not engaged, the fixed system clock source is the same as the
bus-rate-clock source, and it does not go through a synchronizer. When a PLL is present and engaged, a
synchronizer is required between the crystal divided-by two clock source and the timer counter so counter
transitions will be properly aligned to bus-clock transitions. A synchronizer will be used at chip level to
synchronize the crystal-related source clock to the bus clock.
The external clock source may be connected to any TPM channel pin. This clock source always has to pass
through a synchronizer to assure that counter transitions are properly aligned to bus clock transitions. The
bus-rate clock drives the synchronizer; therefore, to meet Nyquist criteria even with jitter, the frequency
of the external clock source must not be faster than the bus rate divided-by four. With ideal clocks the
external clock can be as fast as bus clock divided by four.
When the external clock source shares the TPM channel pin, this pin should not be used for other channel
timing functions. For example, it would be ambiguous to configure channel 0 for input capture when the
TPM channel 0 pin was also being used as the timer external clock source. (It is the user’s responsibility
to avoid such settings.) The TPM channel could still be used in output compare mode for software timing
functions (pin controls set not to affect the TPM channel pin).
16.4.1.2 Counter Overflow and Modulo Reset
An interrupt flag and enable are associated with the 16-bit main counter. The flag (TOF) is a
software-accessible indication that the timer counter has overflowed. The enable signal selects between
software polling (TOIE=0) where no hardware interrupt is generated, or interrupt-driven operation
(TOIE=1) where a static hardware interrupt is generated whenever the TOF flag is equal to one.
The conditions causing TOF to become set depend on whether the TPM is configured for center-aligned
PWM (CPWMS=1). In the simplest mode, there is no modulus limit and the TPM is not in CPWMS=1
mode. In this case, the 16-bit timer counter counts from 0x0000 through 0xFFFF and overflows to 0x0000
on the next counting clock. TOF becomes set at the transition from 0xFFFF to 0x0000. When a modulus
limit is set, TOF becomes set at the transition from the value set in the modulus register to 0x0000. When
the TPM is in center-aligned PWM mode (CPWMS=1), the TOF flag gets set as the counter changes
direction at the end of the count value set in the modulus register (that is, at the transition from the value
set in the modulus register to the next lower count value). This corresponds to the end of a PWM period
(the 0x0000 count value corresponds to the center of a period).
Table 16-10. TPM Clock Source Selection
CLKSB:CLKSA TPM Clock Source to Prescaler Input
00 No clock selected (TPM counter disabled)
01 Bus rate clock
10 Fixed system clock
11 External source
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 255
16.4.1.3 Counting Modes
The main timer counter has two counting modes. When center-aligned PWM is selected (CPWMS=1), the
counter operates in up/down counting mode. Otherwise, the counter operates as a simple up counter. As
an up counter, the timer counter counts from 0x0000 through its terminal count and then continues with
0x0000. The terminal count is 0xFFFF or a modulus value in TPMxMODH:TPMxMODL.
When center-aligned PWM operation is specified, the counter counts up from 0x0000 through its terminal
count and then down to 0x0000 where it changes back to up counting. Both 0x0000 and the terminal count
value are normal length counts (one timer clock period long). In this mode, the timer overflow flag (TOF)
becomes set at the end of the terminal-count period (as the count changes to the next lower count value).
16.4.1.4 Manual Counter Reset
The main timer counter can be manually reset at any time by writing any value to either half of
TPMxCNTH or TPMxCNTL. Resetting the counter in this manner also resets the coherency mechanism
in case only half of the counter was read before resetting the count.
16.4.2 Channel Mode Selection
Provided CPWMS=0, the MSnB and MSnA control bits in the channel n status and control registers
determine the basic mode of operation for the corresponding channel. Choices include input capture,
output compare, and edge-aligned PWM.
16.4.2.1 Input Capture Mode
With the input-capture function, the TPM can capture the time at which an external event occurs. When
an active edge occurs on the pin of an input-capture channel, the TPM latches the contents of the TPM
counter into the channel-value registers (TPMxCnVH:TPMxCnVL). Rising edges, falling edges, or any
edge may be chosen as the active edge that triggers an input capture.
In input capture mode, the TPMxCnVH and TPMxCnVL registers are read only.
When either half of the 16-bit capture register is read, the other half is latched into a buffer to support
coherent 16-bit accesses in big-endian or little-endian order. The coherency sequence can be manually
reset by writing to the channel status/control register (TPMxCnSC).
An input capture event sets a flag bit (CHnF) which may optionally generate a CPU interrupt request.
While in BDM, the input capture function works as configured by the user. When an external event occurs,
the TPM latches the contents of the TPM counter (which is frozen because of the BDM mode) into the
channel value registers and sets the flag bit.
16.4.2.2 Output Compare Mode
With the output-compare function, the TPM can generate timed pulses with programmable position,
polarity, duration, and frequency. When the counter reaches the value in the channel-value registers of an
output-compare channel, the TPM can set, clear, or toggle the channel pin.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
256 Freescale Semiconductor
In output compare mode, values are transferred to the corresponding timer channel registers only after both
8-bit halves of a 16-bit register have been written and according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated at the next change of the TPM counter
(end of the prescaler counting) after the second byte is written.
The coherency sequence can be manually reset by writing to the channel status/control register
(TPMxCnSC).
An output compare event sets a flag bit (CHnF) which may optionally generate a CPU-interrupt request.
16.4.2.3 Edge-Aligned PWM Mode
This type of PWM output uses the normal up-counting mode of the timer counter (CPWMS=0) and can
be used when other channels in the same TPM are configured for input capture or output compare
functions. The period of this PWM signal is determined by the value of the modulus register
(TPMxMODH:TPMxMODL) plus 1. The duty cycle is determined by the setting in the timer channel
register (TPMxCnVH:TPMxCnVL). The polarity of this PWM signal is determined by the setting in the
ELSnA control bit. 0% and 100% duty cycle cases are possible.
The output compare value in the TPM channel registers determines the pulse width (duty cycle) of the
PWM signal (Figure 16-15). The time between the modulus overflow and the output compare is the pulse
width. If ELSnA=0, the counter overflow forces the PWM signal high, and the output compare forces the
PWM signal low. If ELSnA=1, the counter overflow forces the PWM signal low, and the output compare
forces the PWM signal high.
Figure 16-15. PWM Period and Pulse Width (ELSnA=0)
When the channel value register is set to 0x0000, the duty cycle is 0%. 100% duty cycle can be achieved
by setting the timer-channel register (TPMxCnVH:TPMxCnVL) to a value greater than the modulus
setting. This implies that the modulus setting must be less than 0xFFFF in order to get 100% duty cycle.
Because the TPM may be used in an 8-bit MCU, the settings in the timer channel registers are buffered to
ensure coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers
TPMxCnVH and TPMxCnVL, actually write to buffer registers. In edge-aligned PWM mode, values are
transferred to the corresponding timer-channel registers according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated after the both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
PERIOD
PULSE
WIDTH
OVERFLOW OVERFLOW OVERFLOW
OUTPUT
COMPARE OUTPUT
COMPARE
OUTPUT
COMPARE
TPMxCHn
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 257
the TPM counter is a free-running counter then the update is made when the TPM counter changes
from 0xFFFE to 0xFFFF.
16.4.2.4 Center-Aligned PWM Mode
This type of PWM output uses the up/down counting mode of the timer counter (CPWMS=1). The output
compare value in TPMxCnVH:TPMxCnVL determines the pulse width (duty cycle) of the PWM signal
while the period is determined by the value in TPMxMODH:TPMxMODL. TPMxMODH:TPMxMODL
should be kept in the range of 0x0001 to 0x7FFF because values outside this range can produce ambiguous
results. ELSnA will determine the polarity of the CPWM output.
pulse width = 2 x (TPMxCnVH:TPMxCnVL)
period = 2 x (TPMxMODH:TPMxMODL); TPMxMODH:TPMxMODL=0x0001-0x7FFF
If the channel-value register TPMxCnVH:TPMxCnVL is zero or negative (bit 15 set), the duty cycle will
be 0%. If TPMxCnVH:TPMxCnVL is a positive value (bit 15 clear) and is greater than the (non-zero)
modulus setting, the duty cycle will be 100% because the duty cycle compare will never occur. This
implies the usable range of periods set by the modulus register is 0x0001 through 0x7FFE (0x7FFF if you
do not need to generate 100% duty cycle). This is not a significant limitation. The resulting period would
be much longer than required for normal applications.
TPMxMODH:TPMxMODL=0x0000 is a special case that should not be used with center-aligned PWM
mode. When CPWMS=0, this case corresponds to the counter running free from 0x0000 through 0xFFFF,
but when CPWMS=1 the counter needs a valid match to the modulus register somewhere other than at
0x0000 in order to change directions from up-counting to down-counting.
The output compare value in the TPM channel registers (times 2) determines the pulse width (duty cycle)
of the CPWM signal (Figure 16-16). If ELSnA=0, a compare occurred while counting up forces the
CPWM output signal low and a compare occurred while counting down forces the output high. The
counter counts up until it reaches the modulo setting in TPMxMODH:TPMxMODL, then counts down
until it reaches zero. This sets the period equal to two times TPMxMODH:TPMxMODL.
Figure 16-16. CPWM Period and Pulse Width (ELSnA=0)
Center-aligned PWM outputs typically produce less noise than edge-aligned PWMs because fewer I/O pin
transitions are lined up at the same system clock edge. This type of PWM is also required for some types
of motor drives.
PERIOD
PULSE WIDTH
COUNT=
COUNT= 0
COUNT=
OUTPUT
COMPARE
(COUNT DOWN)
OUTPUT
COMPARE
(COUNT UP)
TPMxCHn
2 x TPMxMODH:TPMxMODL
2 x TPMxCnVH:TPMxCnVL
TPMxMODH:TPMxMODLTPMxMODH:TPMxMODL
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
258 Freescale Semiconductor
Input capture, output compare, and edge-aligned PWM functions do not make sense when the counter is
operating in up/down counting mode so this implies that all active channels within a TPM must be used in
CPWM mode when CPWMS=1.
The TPM may be used in an 8-bit MCU. The settings in the timer channel registers are buffered to ensure
coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers
TPMxMODH, TPMxMODL, TPMxCnVH, and TPMxCnVL, actually write to buffer registers.
In center-aligned PWM mode, the TPMxCnVH:L registers are updated with the value of their write buffer
according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated after the both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
the TPM counter is a free-running counter, the update is made when the TPM counter changes from
0xFFFE to 0xFFFF.
When TPMxCNTH:TPMxCNTL=TPMxMODH:TPMxMODL, the TPM can optionally generate a TOF
interrupt (at the end of this count).
Writing to TPMxSC cancels any values written to TPMxMODH and/or TPMxMODL and resets the
coherency mechanism for the modulo registers. Writing to TPMxCnSC cancels any values written to the
channel value registers and resets the coherency mechanism for TPMxCnVH:TPMxCnVL.
16.5 Reset Overview
16.5.1 General
The TPM is reset whenever any MCU reset occurs.
16.5.2 Description of Reset Operation
Reset clears the TPMxSC register which disables clocks to the TPM and disables timer overflow interrupts
(TOIE=0). CPWMS, MSnB, MSnA, ELSnB, and ELSnA are all cleared which configures all TPM
channels for input-capture operation with the associated pins disconnected from I/O pin logic (so all MCU
pins related to the TPM revert to general purpose I/O pins).
16.6 Interrupts
16.6.1 General
The TPM generates an optional interrupt for the main counter overflow and an interrupt for each channel.
The meaning of channel interrupts depends on each channel’s mode of operation. If the channel is
configured for input capture, the interrupt flag is set each time the selected input capture edge is
recognized. If the channel is configured for output compare or PWM modes, the interrupt flag is set each
time the main timer counter matches the value in the 16-bit channel value register.
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 259
All TPM interrupts are listed in Table 16-11 which shows the interrupt name, the name of any local enable
that can block the interrupt request from leaving the TPM and getting recognized by the separate interrupt
processing logic.
The TPM module will provide a high-true interrupt signal. Vectors and priorities are determined at chip
integration time in the interrupt module so refer to the user’s guide for the interrupt module or to the chip’s
complete documentation for details.
16.6.2 Description of Interrupt Operation
For each interrupt source in the TPM, a flag bit is set upon recognition of the interrupt condition such as
timer overflow, channel-input capture, or output-compare events. This flag may be read (polled) by
software to determine that the action has occurred, or an associated enable bit (TOIE or CHnIE) can be set
to enable hardware interrupt generation. While the interrupt enable bit is set, a static interrupt will generate
whenever the associated interrupt flag equals one. The user’s software must perform a sequence of steps
to clear the interrupt flag before returning from the interrupt-service routine.
TPM interrupt flags are cleared by a two-step process including a read of the flag bit while it is set (1)
followed by a write of zero (0) to the bit. If a new event is detected between these two steps, the sequence
is reset and the interrupt flag remains set after the second step to avoid the possibility of missing the new
event.
16.6.2.1 Timer Overflow Interrupt (TOF) Description
The meaning and details of operation for TOF interrupts varies slightly depending upon the mode of
operation of the TPM system (general purpose timing functions versus center-aligned PWM operation).
The flag is cleared by the two step sequence described above.
16.6.2.1.1 Normal Case
Normally TOF is set when the timer counter changes from 0xFFFF to 0x0000. When the TPM is not
configured for center-aligned PWM (CPWMS=0), TOF gets set when the timer counter changes from the
terminal count (the value in the modulo register) to 0x0000. This case corresponds to the normal meaning
of counter overflow.
Table 16-11. Interrupt Summary
Interrupt Local
Enable Source Description
TOF TOIE Counter overflow Set each time the timer counter reaches its terminal
count (at transition to next count value which is
usually 0x0000)
CHnF CHnIE Channel event An input capture or output compare event took
place on channel n
Timer/PWM Module (S08TPMV3)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
260 Freescale Semiconductor
16.6.2.1.2 Center-Aligned PWM Case
When CPWMS=1, TOF gets set when the timer counter changes direction from up-counting to
down-counting at the end of the terminal count (the value in the modulo register). In this case the TOF
corresponds to the end of a PWM period.
16.6.2.2 Channel Event Interrupt Description
The meaning of channel interrupts depends on the channel’s current mode (input-capture, output-compare,
edge-aligned PWM, or center-aligned PWM).
16.6.2.2.1 Input Capture Events
When a channel is configured as an input capture channel, the ELSnB:ELSnA control bits select no edge
(off), rising edges, falling edges or any edge as the edge which triggers an input capture event. When the
selected edge is detected, the interrupt flag is set. The flag is cleared by the two-step sequence described
in Section 16.6.2, “Description of Interrupt Operation.”
16.6.2.2.2 Output Compare Events
When a channel is configured as an output compare channel, the interrupt flag is set each time the main
timer counter matches the 16-bit value in the channel value register. The flag is cleared by the two-step
sequence described Section 16.6.2, “Description of Interrupt Operation.”
16.6.2.2.3 PWM End-of-Duty-Cycle Events
For channels configured for PWM operation there are two possibilities. When the channel is configured
for edge-aligned PWM, the channel flag gets set when the timer counter matches the channel value register
which marks the end of the active duty cycle period. When the channel is configured for center-aligned
PWM, the timer count matches the channel value register twice during each PWM cycle. In this CPWM
case, the channel flag is set at the start and at the end of the active duty cycle period which are the times
when the timer counter matches the channel value register. The flag is cleared by the two-step sequence
described Section 16.6.2, “Description of Interrupt Operation.”
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 261
Chapter 17
Development Support
17.1 Introduction
Development support systems in the HCS08 include the background debug controller (BDC) and the
on-chip debug module (DBG). The BDC provides a single-wire debug interface to the target MCU that
provides a convenient interface for programming the on-chip FLASH and other nonvolatile memories. The
BDC is also the primary debug interface for development and allows non-intrusive access to memory data
and traditional debug features such as CPU register modify, breakpoints, and single instruction trace
commands.
In the HCS08 Family, address and data bus signals are not available on external pins (not even in test
modes). Debug is done through commands fed into the target MCU via the single-wire background debug
interface. The debug module provides a means to selectively trigger and capture bus information so an
external development system can reconstruct what happened inside the MCU on a cycle-by-cycle basis
without having external access to the address and data signals.
17.1.1 Forcing Active Background
The method for forcing active background mode depends on the specific HCS08 derivative. For the
MC9S08SG8, you can force active background after a power-on reset by holding the BKGD pin low as
the device exits the reset condition. You can also force active background by driving BKGD low
immediately after a serial background command that writes a one to the BDFR bit in the SBDFR register.
Other causes of reset including an external pin reset or an internally generated error reset ignore the state
of the BKGD pin and reset into normal user mode. If no debug pod is connected to the BKGD pin, the
MCU will always reset into normal operating mode.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
262 Freescale Semiconductor
17.1.2 Features
Features of the BDC module include:
• Single pin for mode selection and background communications
• BDC registers are not located in the memory map
• SYNC command to determine target communications rate
• Non-intrusive commands for memory access
• Active background mode commands for CPU register access
• GO and TRACE1 commands
• BACKGROUND command can wake CPU from stop or wait modes
• One hardware address breakpoint built into BDC
• Oscillator runs in stop mode, if BDC enabled
• COP watchdog disabled while in active background mode
Features of the ICE system include:
• Two trigger comparators: Two address + read/write (R/W) or one full address + data + R/W
• Flexible 8-word by 16-bit FIFO (first-in, first-out) buffer for capture information:
— Change-of-flow addresses or
— Event-only data
• Two types of breakpoints:
— Tag breakpoints for instruction opcodes
— Force breakpoints for any address access
• Nine trigger modes:
— Basic: A-only, A OR B
— Sequence: A then B
— Full: A AND B data, A AND NOT B data
— Event (store data): Event-only B, A then event-only B
— Range: Inside range (A address B), outside range (address < A or address > B)
17.2 Background Debug Controller (BDC)
All MCUs in the HCS08 Family contain a single-wire background debug interface that supports in-circuit
programming of on-chip nonvolatile memory and sophisticated non-intrusive debug capabilities. Unlike
debug interfaces on earlier 8-bit MCUs, this system does not interfere with normal application resources.
It does not use any user memory or locations in the memory map and does not share any on-chip
peripherals.
BDC commands are divided into two groups:
• Active background mode commands require that the target MCU is in active background mode (the
user program is not running). Active background mode commands allow the CPU registers to be
read or written, and allow the user to trace one user instruction at a time, or GO to the user program
from active background mode.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 263
• Non-intrusive commands can be executed at any time even while the user’s program is running.
Non-intrusive commands allow a user to read or write MCU memory locations or access status and
control registers within the background debug controller.
Typically, a relatively simple interface pod is used to translate commands from a host computer into
commands for the custom serial interface to the single-wire background debug system. Depending on the
development tool vendor, this interface pod may use a standard RS-232 serial port, a parallel printer port,
or some other type of communications such as a universal serial bus (USB) to communicate between the
host PC and the pod. The pod typically connects to the target system with ground, the BKGD pin, RESET,
and sometimes VDD. An open-drain connection to reset allows the host to force a target system reset,
which is useful to regain control of a lost target system or to control startup of a target system before the
on-chip nonvolatile memory has been programmed. Sometimes VDD can be used to allow the pod to use
power from the target system to avoid the need for a separate power supply. However, if the pod is powered
separately, it can be connected to a running target system without forcing a target system reset or otherwise
disturbing the running application program.
Figure 17-1. BDM Tool Connector
17.2.1 BKGD Pin Description
BKGD is the single-wire background debug interface pin. The primary function of this pin is for
bidirectional serial communication of active background mode commands and data. During reset, this pin
is used to select between starting in active background mode or starting the user’s application program.
This pin is also used to request a timed sync response pulse to allow a host development tool to determine
the correct clock frequency for background debug serial communications.
BDC serial communications use a custom serial protocol first introduced on the M68HC12 Family of
microcontrollers. This protocol assumes the host knows the communication clock rate that is determined
by the target BDC clock rate. All communication is initiated and controlled by the host that drives a
high-to-low edge to signal the beginning of each bit time. Commands and data are sent most significant
bit first (MSB first). For a detailed description of the communications protocol, refer to Section 17.2.2,
“Communication Details.”
If a host is attempting to communicate with a target MCU that has an unknown BDC clock rate, a SYNC
command may be sent to the target MCU to request a timed sync response signal from which the host can
determine the correct communication speed.
BKGD is a pseudo-open-drain pin and there is an on-chip pullup so no external pullup resistor is required.
Unlike typical open-drain pins, the external RC time constant on this pin, which is influenced by external
capacitance, plays almost no role in signal rise time. The custom protocol provides for brief, actively
driven speedup pulses to force rapid rise times on this pin without risking harmful drive level conflicts.
Refer to Section 17.2.2, “Communication Details,” for more detail.
2
4
6NO CONNECT 5
NO CONNECT 3
1
RESET
BKGD GND
VDD
MC9S08SG8 MCU Series Data Sheet, Rev. 8
264 Freescale Semiconductor
When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD
chooses normal operating mode. When a debug pod is connected to BKGD it is possible to force the MCU
into active background mode after reset. The specific conditions for forcing active background depend
upon the HCS08 derivative (refer to the introduction to this Development Support section). It is not
necessary to reset the target MCU to communicate with it through the background debug interface.
17.2.2 Communication Details
The BDC serial interface requires the external controller to generate a falling edge on the BKGD pin to
indicate the start of each bit time. The external controller provides this falling edge whether data is
transmitted or received.
BKGD is a pseudo-open-drain pin that can be driven either by an external controller or by the MCU. Data
is transferred MSB first at 16 BDC clock cycles per bit (nominal speed). The interface times out if
512 BDC clock cycles occur between falling edges from the host. Any BDC command that was in progress
when this timeout occurs is aborted without affecting the memory or operating mode of the target MCU
system.
The custom serial protocol requires the debug pod to know the target BDC communication clock speed.
The clock switch (CLKSW) control bit in the BDC status and control register allows the user to select the
BDC clock source. The BDC clock source can either be the bus or the alternate BDC clock source.
The BKGD pin can receive a high or low level or transmit a high or low level. The following diagrams
show timing for each of these cases. Interface timing is synchronous to clocks in the target BDC, but
asynchronous to the external host. The internal BDC clock signal is shown for reference in counting
cycles.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 265
Figure 17-2 shows an external host transmitting a logic 1 or 0 to the BKGD pin of a target HCS08 MCU.
The host is asynchronous to the target so there is a 0-to-1 cycle delay from the host-generated falling edge
to where the target perceives the beginning of the bit time. Ten target BDC clock cycles later, the target
senses the bit level on the BKGD pin. Typically, the host actively drives the pseudo-open-drain BKGD pin
during host-to-target transmissions to speed up rising edges. Because the target does not drive the BKGD
pin during the host-to-target transmission period, there is no need to treat the line as an open-drain signal
during this period.
Figure 17-2. BDC Host-to-Target Serial Bit Timing
EARLIEST START
TARGET SENSES BIT LEVEL
10 CYCLES
SYNCHRONIZATION
UNCERTAINTY
BDC CLOCK
(TARGET MCU)
HOST
TRANSMIT 1
HOST
TRANSMIT 0
PERCEIVED START
OF BIT TIME
OF NEXT BIT
MC9S08SG8 MCU Series Data Sheet, Rev. 8
266 Freescale Semiconductor
Figure 17-3 shows the host receiving a logic 1 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the perceived start of the bit time in the target MCU. The host holds the BKGD pin low long
enough for the target to recognize it (at least two target BDC cycles). The host must release the low drive
before the target MCU drives a brief active-high speedup pulse seven cycles after the perceived start of the
bit time. The host should sample the bit level about 10 cycles after it started the bit time.
Figure 17-3. BDC Target-to-Host Serial Bit Timing (Logic 1)
HOST SAMPLES BKGD PIN
10 CYCLES
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
TARGET MCU
SPEEDUP PULSE
PERCEIVED START
OF BIT TIME
HIGH-IMPEDANCE
HIGH-IMPEDANCE HIGH-IMPEDANCE
BKGD PIN
R-C RISE
10 CYCLES
EARLIEST START
OF NEXT BIT
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 267
Figure 17-4 shows the host receiving a logic 0 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the start of the bit time as perceived by the target MCU. The host initiates the bit time but the
target HCS08 finishes it. Because the target wants the host to receive a logic 0, it drives the BKGD pin low
for 13 BDC clock cycles, then briefly drives it high to speed up the rising edge. The host samples the bit
level about 10 cycles after starting the bit time.
Figure 17-4. BDM Target-to-Host Serial Bit Timing (Logic 0)
10 CYCLES
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
TARGET MCU
DRIVE AND
PERCEIVED START
OF BIT TIME
HIGH-IMPEDANCE
BKGD PIN
10 CYCLES
SPEED-UP PULSE
SPEEDUP
PULSE
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
MC9S08SG8 MCU Series Data Sheet, Rev. 8
268 Freescale Semiconductor
17.2.3 BDC Commands
BDC commands are sent serially from a host computer to the BKGD pin of the target HCS08 MCU. All
commands and data are sent MSB-first using a custom BDC communications protocol. Active background
mode commands require that the target MCU is currently in the active background mode while
non-intrusive commands may be issued at any time whether the target MCU is in active background mode
or running a user application program.
Table 17-1 shows all HCS08 BDC commands, a shorthand description of their coding structure, and the
meaning of each command.
Coding Structure Nomenclature
This nomenclature is used in Table 17-1 to describe the coding structure of the BDC commands.
Commands begin with an 8-bit hexadecimal command code in the host-to-target
direction (most significant bit first)
/ = separates parts of the command
d = delay 16 target BDC clock cycles
AAAA = a 16-bit address in the host-to-target direction
RD = 8 bits of read data in the target-to-host direction
WD = 8 bits of write data in the host-to-target direction
RD16 = 16 bits of read data in the target-to-host direction
WD16 = 16 bits of write data in the host-to-target direction
SS = the contents of BDCSCR in the target-to-host direction (STATUS)
CC = 8 bits of write data for BDCSCR in the host-to-target direction (CONTROL)
RBKP = 16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint
register)
WBKP = 16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 269
Table 17-1. BDC Command Summary
Command
Mnemonic
Active BDM/
Non-intrusive
Coding
Structure Description
SYNC Non-intrusive n/a1
1The SYNC command is a special operation that does not have a command code.
Request a timed reference pulse to determine
target BDC communication speed
ACK_ENABLE Non-intrusive D5/d Enable acknowledge protocol. Refer to
Freescale document order no. HCS08RMv1/D.
ACK_DISABLE Non-intrusive D6/d Disable acknowledge protocol. Refer to
Freescale document order no. HCS08RMv1/D.
BACKGROUND Non-intrusive 90/d Enter active background mode if enabled
(ignore if ENBDM bit equals 0)
READ_STATUS Non-intrusive E4/SS Read BDC status from BDCSCR
WRITE_CONTROL Non-intrusive C4/CC Write BDC controls in BDCSCR
READ_BYTE Non-intrusive E0/AAAA/d/RD Read a byte from target memory
READ_BYTE_WS Non-intrusive E1/AAAA/d/SS/RD Read a byte and report status
READ_LAST Non-intrusive E8/SS/RD Re-read byte from address just read and report
status
WRITE_BYTE Non-intrusive C0/AAAA/WD/d Write a byte to target memory
WRITE_BYTE_WS Non-intrusive C1/AAAA/WD/d/SS Write a byte and report status
READ_BKPT Non-intrusive E2/RBKP Read BDCBKPT breakpoint register
WRITE_BKPT Non-intrusive C2/WBKP Write BDCBKPT breakpoint register
GO Active BDM 08/d Go to execute the user application program
starting at the address currently in the PC
TRACE1 Active BDM 10/d Trace 1 user instruction at the address in the
PC, then return to active background mode
TAGGO Active BDM 18/d Same as GO but enable external tagging
(HCS08 devices have no external tagging pin)
READ_A Active BDM 68/d/RD Read accumulator (A)
READ_CCR Active BDM 69/d/RD Read condition code register (CCR)
READ_PC Active BDM 6B/d/RD16 Read program counter (PC)
READ_HX Active BDM 6C/d/RD16 Read H and X register pair (H:X)
READ_SP Active BDM 6F/d/RD16 Read stack pointer (SP)
READ_NEXT Active BDM 70/d/RD Increment H:X by one then read memory byte
located at H:X
READ_NEXT_WS Active BDM 71/d/SS/RD Increment H:X by one then read memory byte
located at H:X. Report status and data.
WRITE_A Active BDM 48/WD/d Write accumulator (A)
WRITE_CCR Active BDM 49/WD/d Write condition code register (CCR)
WRITE_PC Active BDM 4B/WD16/d Write program counter (PC)
WRITE_HX Active BDM 4C/WD16/d Write H and X register pair (H:X)
WRITE_SP Active BDM 4F/WD16/d Write stack pointer (SP)
WRITE_NEXT Active BDM 50/WD/d Increment H:X by one, then write memory byte
located at H:X
WRITE_NEXT_WS Active BDM 51/WD/d/SS Increment H:X by one, then write memory byte
located at H:X. Also report status.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
270 Freescale Semiconductor
The SYNC command is unlike other BDC commands because the host does not necessarily know the
correct communications speed to use for BDC communications until after it has analyzed the response to
the SYNC command.
To issue a SYNC command, the host:
• Drives the BKGD pin low for at least 128 cycles of the slowest possible BDC clock (The slowest
clock is normally the reference oscillator/64 or the self-clocked rate/64.)
• Drives BKGD high for a brief speedup pulse to get a fast rise time (This speedup pulse is typically
one cycle of the fastest clock in the system.)
• Removes all drive to the BKGD pin so it reverts to high impedance
• Monitors the BKGD pin for the sync response pulse
The target, upon detecting the SYNC request from the host (which is a much longer low time than would
ever occur during normal BDC communications):
• Waits for BKGD to return to a logic high
• Delays 16 cycles to allow the host to stop driving the high speedup pulse
• Drives BKGD low for 128 BDC clock cycles
• Drives a 1-cycle high speedup pulse to force a fast rise time on BKGD
• Removes all drive to the BKGD pin so it reverts to high impedance
The host measures the low time of this 128-cycle sync response pulse and determines the correct speed for
subsequent BDC communications. Typically, the host can determine the correct communication speed
within a few percent of the actual target speed and the communication protocol can easily tolerate speed
errors of several percent.
17.2.4 BDC Hardware Breakpoint
The BDC includes one relatively simple hardware breakpoint that compares the CPU address bus to a
16-bit match value in the BDCBKPT register. This breakpoint can generate a forced breakpoint or a tagged
breakpoint. A forced breakpoint causes the CPU to enter active background mode at the first instruction
boundary following any access to the breakpoint address. The tagged breakpoint causes the instruction
opcode at the breakpoint address to be tagged so that the CPU will enter active background mode rather
than executing that instruction if and when it reaches the end of the instruction queue. This implies that
tagged breakpoints can only be placed at the address of an instruction opcode while forced breakpoints can
be set at any address.
The breakpoint enable (BKPTEN) control bit in the BDC status and control register (BDCSCR) is used to
enable the breakpoint logic (BKPTEN = 1). When BKPTEN = 0, its default value after reset, the
breakpoint logic is disabled and no BDC breakpoints are requested regardless of the values in other BDC
breakpoint registers and control bits. The force/tag select (FTS) control bit in BDCSCR is used to select
forced (FTS = 1) or tagged (FTS = 0) type breakpoints.
The on-chip debug module (DBG) includes circuitry for two additional hardware breakpoints that are more
flexible than the simple breakpoint in the BDC module.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 271
17.3 On-Chip Debug System (DBG)
Because HCS08 devices do not have external address and data buses, the most important functions of an
in-circuit emulator have been built onto the chip with the MCU. The debug system consists of an 8-stage
FIFO that can store address or data bus information, and a flexible trigger system to decide when to capture
bus information and what information to capture. The system relies on the single-wire background debug
system to access debug control registers and to read results out of the eight stage FIFO.
The debug module includes control and status registers that are accessible in the user’s memory map.
These registers are located in the high register space to avoid using valuable direct page memory space.
Most of the debug module’s functions are used during development, and user programs rarely access any
of the control and status registers for the debug module. The one exception is that the debug system can
provide the means to implement a form of ROM patching. This topic is discussed in greater detail in
Section 17.3.6, “Hardware Breakpoints.”
17.3.1 Comparators A and B
Two 16-bit comparators (A and B) can optionally be qualified with the R/W signal and an opcode tracking
circuit. Separate control bits allow you to ignore R/W for each comparator. The opcode tracking circuitry
optionally allows you to specify that a trigger will occur only if the opcode at the specified address is
actually executed as opposed to only being read from memory into the instruction queue. The comparators
are also capable of magnitude comparisons to support the inside range and outside range trigger modes.
Comparators are disabled temporarily during all BDC accesses.
The A comparator is always associated with the 16-bit CPU address. The B comparator compares to the
CPU address or the 8-bit CPU data bus, depending on the trigger mode selected. Because the CPU data
bus is separated into a read data bus and a write data bus, the RWAEN and RWA control bits have an
additional purpose, in full address plus data comparisons they are used to decide which of these buses to
use in the comparator B data bus comparisons. If RWAEN = 1 (enabled) and RWA = 0 (write), the CPU’s
write data bus is used. Otherwise, the CPU’s read data bus is used.
The currently selected trigger mode determines what the debugger logic does when a comparator detects
a qualified match condition. A match can cause:
• Generation of a breakpoint to the CPU
• Storage of data bus values into the FIFO
• Starting to store change-of-flow addresses into the FIFO (begin type trace)
• Stopping the storage of change-of-flow addresses into the FIFO (end type trace)
17.3.2 Bus Capture Information and FIFO Operation
The usual way to use the FIFO is to setup the trigger mode and other control options, then arm the
debugger. When the FIFO has filled or the debugger has stopped storing data into the FIFO, you would
read the information out of it in the order it was stored into the FIFO. Status bits indicate the number of
words of valid information that are in the FIFO as data is stored into it. If a trace run is manually halted by
writing 0 to ARM before the FIFO is full (CNT = 1:0:0:0), the information is shifted by one position and
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the host must perform ((8 – CNT) – 1) dummy reads of the FIFO to advance it to the first significant entry
in the FIFO.
In most trigger modes, the information stored in the FIFO consists of 16-bit change-of-flow addresses. In
these cases, read DBGFH then DBGFL to get one coherent word of information out of the FIFO. Reading
DBGFL (the low-order byte of the FIFO data port) causes the FIFO to shift so the next word of information
is available at the FIFO data port. In the event-only trigger modes (see Section 17.3.5, “Trigger Modes”),
8-bit data information is stored into the FIFO. In these cases, the high-order half of the FIFO (DBGFH) is
not used and data is read out of the FIFO by simply reading DBGFL. Each time DBGFL is read, the FIFO
is shifted so the next data value is available through the FIFO data port at DBGFL.
In trigger modes where the FIFO is storing change-of-flow addresses, there is a delay between CPU
addresses and the input side of the FIFO. Because of this delay, if the trigger event itself is a
change-of-flow address or a change-of-flow address appears during the next two bus cycles after a trigger
event starts the FIFO, it will not be saved into the FIFO. In the case of an end-trace, if the trigger event is
a change-of-flow, it will be saved as the last change-of-flow entry for that debug run.
The FIFO can also be used to generate a profile of executed instruction addresses when the debugger is
not armed. When ARM = 0, reading DBGFL causes the address of the most-recently fetched opcode to be
saved in the FIFO. To use the profiling feature, a host debugger would read addresses out of the FIFO by
reading DBGFH then DBGFL at regular periodic intervals. The first eight values would be discarded
because they correspond to the eight DBGFL reads needed to initially fill the FIFO. Additional periodic
reads of DBGFH and DBGFL return delayed information about executed instructions so the host debugger
can develop a profile of executed instruction addresses.
17.3.3 Change-of-Flow Information
To minimize the amount of information stored in the FIFO, only information related to instructions that
cause a change to the normal sequential execution of instructions is stored. With knowledge of the source
and object code program stored in the target system, an external debugger system can reconstruct the path
of execution through many instructions from the change-of-flow information stored in the FIFO.
For conditional branch instructions where the branch is taken (branch condition was true), the source
address is stored (the address of the conditional branch opcode). Because BRA and BRN instructions are
not conditional, these events do not cause change-of-flow information to be stored in the FIFO.
Indirect JMP and JSR instructions use the current contents of the H:X index register pair to determine the
destination address, so the debug system stores the run-time destination address for any indirect JMP or
JSR. For interrupts, RTI, or RTS, the destination address is stored in the FIFO as change-of-flow
information.
17.3.4 Tag vs. Force Breakpoints and Triggers
Tagging is a term that refers to identifying an instruction opcode as it is fetched into the instruction queue,
but not taking any other action until and unless that instruction is actually executed by the CPU. This
distinction is important because any change-of-flow from a jump, branch, subroutine call, or interrupt
causes some instructions that have been fetched into the instruction queue to be thrown away without being
executed.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 273
A force-type breakpoint waits for the current instruction to finish and then acts upon the breakpoint
request. The usual action in response to a breakpoint is to go to active background mode rather than
continuing to the next instruction in the user application program.
The tag vs. force terminology is used in two contexts within the debug module. The first context refers to
breakpoint requests from the debug module to the CPU. The second refers to match signals from the
comparators to the debugger control logic. When a tag-type break request is sent to the CPU, a signal is
entered into the instruction queue along with the opcode so that if/when this opcode ever executes, the
CPU will effectively replace the tagged opcode with a BGND opcode so the CPU goes to active
background mode rather than executing the tagged instruction. When the TRGSEL control bit in the DBGT
register is set to select tag-type operation, the output from comparator A or B is qualified by a block of
logic in the debug module that tracks opcodes and only produces a trigger to the debugger if the opcode at
the compare address is actually executed. There is separate opcode tracking logic for each comparator so
more than one compare event can be tracked through the instruction queue at a time.
17.3.5 Trigger Modes
The trigger mode controls the overall behavior of a debug run. The 4-bit TRG field in the DBGT register
selects one of nine trigger modes. When TRGSEL = 1 in the DBGT register, the output of the comparator
must propagate through an opcode tracking circuit before triggering FIFO actions. The BEGIN bit in
DBGT chooses whether the FIFO begins storing data when the qualified trigger is detected (begin trace),
or the FIFO stores data in a circular fashion from the time it is armed until the qualified trigger is detected
(end trigger).
A debug run is started by writing a 1 to the ARM bit in the DBGC register, which sets the ARMF flag and
clears the AF and BF flags and the CNT bits in DBGS. A begin-trace debug run ends when the FIFO gets
full. An end-trace run ends when the selected trigger event occurs. Any debug run can be stopped manually
by writing a 0 to ARM or DBGEN in DBGC.
In all trigger modes except event-only modes, the FIFO stores change-of-flow addresses. In event-only
trigger modes, the FIFO stores data in the low-order eight bits of the FIFO.
The BEGIN control bit is ignored in event-only trigger modes and all such debug runs are begin type
traces. When TRGSEL = 1 to select opcode fetch triggers, it is not necessary to use R/W in comparisons
because opcode tags would only apply to opcode fetches that are always read cycles. It would also be
unusual to specify TRGSEL = 1 while using a full mode trigger because the opcode value is normally
known at a particular address.
The following trigger mode descriptions only state the primary comparator conditions that lead to a trigger.
Either comparator can usually be further qualified with R/W by setting RWAEN (RWBEN) and the
corresponding RWA (RWB) value to be matched against R/W. The signal from the comparator with
optional R/W qualification is used to request a CPU breakpoint if BRKEN = 1 and TAG determines
whether the CPU request will be a tag request or a force request.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
274 Freescale Semiconductor
A-Only — Trigger when the address matches the value in comparator A
A OR B — Trigger when the address matches either the value in comparator A or the value in
comparator B
A Then B — Trigger when the address matches the value in comparator B but only after the address for
another cycle matched the value in comparator A. There can be any number of cycles after the A match
and before the B match.
A AND B Data (Full Mode) — This is called a full mode because address, data, and R/W (optionally)
must match within the same bus cycle to cause a trigger event. Comparator A checks address, the low byte
of comparator B checks data, and R/W is checked against RWA if RWAEN = 1. The high-order half of
comparator B is not used.
In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you
do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the
CPU breakpoint is issued when the comparator A address matches.
A AND NOT B Data (Full Mode) — Address must match comparator A, data must not match the low
half of comparator B, and R/W must match RWA if RWAEN = 1. All three conditions must be met within
the same bus cycle to cause a trigger.
In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you
do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the
CPU breakpoint is issued when the comparator A address matches.
Event-Only B (Store Data) — Trigger events occur each time the address matches the value in
comparator B. Trigger events cause the data to be captured into the FIFO. The debug run ends when the
FIFO becomes full.
A Then Event-Only B (Store Data) — After the address has matched the value in comparator A, a trigger
event occurs each time the address matches the value in comparator B. Trigger events cause the data to be
captured into the FIFO. The debug run ends when the FIFO becomes full.
Inside Range (A Address B) — A trigger occurs when the address is greater than or equal to the value
in comparator A and less than or equal to the value in comparator B at the same time.
Outside Range (Address < A or Address > B) — A trigger occurs when the address is either less than
the value in comparator A or greater than the value in comparator B.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 275
17.3.6 Hardware Breakpoints
The BRKEN control bit in the DBGC register may be set to 1 to allow any of the trigger conditions
described in Section 17.3.5, “Trigger Modes,” to be used to generate a hardware breakpoint request to the
CPU. TAG in DBGC controls whether the breakpoint request will be treated as a tag-type breakpoint or a
force-type breakpoint. A tag breakpoint causes the current opcode to be marked as it enters the instruction
queue. If a tagged opcode reaches the end of the pipe, the CPU executes a BGND instruction to go to active
background mode rather than executing the tagged opcode. A force-type breakpoint causes the CPU to
finish the current instruction and then go to active background mode.
If the background mode has not been enabled (ENBDM = 1) by a serial WRITE_CONTROL command
through the BKGD pin, the CPU will execute an SWI instruction instead of going to active background
mode.
17.4 Register Definition
This section contains the descriptions of the BDC and DBG registers and control bits.
Refer to the high-page register summary in the device overview chapter of this data sheet for the absolute
address assignments for all DBG registers. This section refers to registers and control bits only by their
names. A Freescale-provided equate or header file is used to translate these names into the appropriate
absolute addresses.
17.4.1 BDC Registers and Control Bits
The BDC has two registers:
• The BDC status and control register (BDCSCR) is an 8-bit register containing control and status
bits for the background debug controller.
• The BDC breakpoint match register (BDCBKPT) holds a 16-bit breakpoint match address.
These registers are accessed with dedicated serial BDC commands and are not located in the memory
space of the target MCU (so they do not have addresses and cannot be accessed by user programs).
Some of the bits in the BDCSCR have write limitations; otherwise, these registers may be read or written
at any time. For example, the ENBDM control bit may not be written while the MCU is in active
background mode. (This prevents the ambiguous condition of the control bit forbidding active background
mode while the MCU is already in active background mode.) Also, the four status bits (BDMACT, WS,
WSF, and DVF) are read-only status indicators and can never be written by the WRITE_CONTROL serial
BDC command. The clock switch (CLKSW) control bit may be read or written at any time.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
276 Freescale Semiconductor
17.4.1.1 BDC Status and Control Register (BDCSCR)
This register can be read or written by serial BDC commands (READ_STATUS and WRITE_CONTROL)
but is not accessible to user programs because it is not located in the normal memory map of the MCU.
76543210
R
ENBDM
BDMACT
BKPTEN FTS CLKSW
WS WSF DVF
W
Normal
Reset
00000000
Reset in
Active BDM:
11001000
= Unimplemented or Reserved
Figure 17-5. BDC Status and Control Register (BDCSCR)
Table 17-2. BDCSCR Register Field Descriptions
Field Description
7
ENBDM
Enable BDM (Permit Active Background Mode) — Typically, this bit is written to 1 by the debug host shortly
after the beginning of a debug session or whenever the debug host resets the target and remains 1 until a normal
reset clears it.
0 BDM cannot be made active (non-intrusive commands still allowed)
1 BDM can be made active to allow active background mode commands
6
BDMACT
Background Mode Active Status — This is a read-only status bit.
0 BDM not active (user application program running)
1 BDM active and waiting for serial commands
5
BKPTEN
BDC Breakpoint Enable — If this bit is clear, the BDC breakpoint is disabled and the FTS (force tag select)
control bit and BDCBKPT match register are ignored.
0 BDC breakpoint disabled
1 BDC breakpoint enabled
4
FTS
Force/Tag Select — When FTS = 1, a breakpoint is requested whenever the CPU address bus matches the
BDCBKPT match register. When FTS = 0, a match between the CPU address bus and the BDCBKPT register
causes the fetched opcode to be tagged. If this tagged opcode ever reaches the end of the instruction queue,
the CPU enters active background mode rather than executing the tagged opcode.
0 Tag opcode at breakpoint address and enter active background mode if CPU attempts to execute that
instruction
1 Breakpoint match forces active background mode at next instruction boundary (address need not be an
opcode)
3
CLKSW
Select Source for BDC Communications Clock — CLKSW defaults to 0, which selects the alternate BDC clock
source.
0 Alternate BDC clock source
1 MCU bus clock
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 277
17.4.1.2 BDC Breakpoint Match Register (BDCBKPT)
This 16-bit register holds the address for the hardware breakpoint in the BDC. The BKPTEN and FTS
control bits in BDCSCR are used to enable and configure the breakpoint logic. Dedicated serial BDC
commands (READ_BKPT and WRITE_BKPT) are used to read and write the BDCBKPT register but is
not accessible to user programs because it is not located in the normal memory map of the MCU.
Breakpoints are normally set while the target MCU is in active background mode before running the user
application program. For additional information about setup and use of the hardware breakpoint logic in
the BDC, refer to Section 17.2.4, “BDC Hardware Breakpoint.”
17.4.2 System Background Debug Force Reset Register (SBDFR)
This register contains a single write-only control bit. A serial background mode command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
2
WS
Wait or Stop Status — When the target CPU is in wait or stop mode, most BDC commands cannot function.
However, the BACKGROUND command can be used to force the target CPU out of wait or stop and into active
background mode where all BDC commands work. Whenever the host forces the target MCU into active
background mode, the host should issue a READ_STATUS command to check that BDMACT = 1 before
attempting other BDC commands.
0 Target CPU is running user application code or in active background mode (was not in wait or stop mode when
background became active)
1 Target CPU is in wait or stop mode, or a BACKGROUND command was used to change from wait or stop to
active background mode
1
WSF
Wait or Stop Failure Status — This status bit is set if a memory access command failed due to the target CPU
executing a wait or stop instruction at or about the same time. The usual recovery strategy is to issue a
BACKGROUND command to get out of wait or stop mode into active background mode, repeat the command
that failed, then return to the user program. (Typically, the host would restore CPU registers and stack values and
re-execute the wait or stop instruction.)
0 Memory access did not conflict with a wait or stop instruction
1 Memory access command failed because the CPU entered wait or stop mode
0
DVF
Data Valid Failure Status — This status bit is not used in the MC9S08SG8 because it does not have any slow
access memory.
0 Memory access did not conflict with a slow memory access
1 Memory access command failed because CPU was not finished with a slow memory access
Table 17-2. BDCSCR Register Field Descriptions (continued)
Field Description
MC9S08SG8 MCU Series Data Sheet, Rev. 8
278 Freescale Semiconductor
Figure 17-6. System Background Debug Force Reset Register (SBDFR)
17.4.3 DBG Registers and Control Bits
The debug module includes nine bytes of register space for three 16-bit registers and three 8-bit control
and status registers. These registers are located in the high register space of the normal memory map so
they are accessible to normal application programs. These registers are rarely if ever accessed by normal
user application programs with the possible exception of a ROM patching mechanism that uses the
breakpoint logic.
17.4.3.1 Debug Comparator A High Register (DBGCAH)
This register contains compare value bits for the high-order eight bits of comparator A. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
17.4.3.2 Debug Comparator A Low Register (DBGCAL)
This register contains compare value bits for the low-order eight bits of comparator A. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
17.4.3.3 Debug Comparator B High Register (DBGCBH)
This register contains compare value bits for the high-order eight bits of comparator B. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
17.4.3.4 Debug Comparator B Low Register (DBGCBL)
This register contains compare value bits for the low-order eight bits of comparator B. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
76543210
R00000000
WBDFR1
1BDFR is writable only through serial background mode debug commands, not from user programs.
Reset00000000
= Unimplemented or Reserved
Table 17-3. SBDFR Register Field Description
Field Description
0
BDFR
Background Debug Force Reset — A serial active background mode command such as WRITE_BYTE allows
an external debug host to force a target system reset. Writing 1 to this bit forces an MCU reset. This bit cannot
be written from a user program.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 279
17.4.3.5 Debug FIFO High Register (DBGFH)
This register provides read-only access to the high-order eight bits of the FIFO. Writes to this register have
no meaning or effect. In the event-only trigger modes, the FIFO only stores data into the low-order byte
of each FIFO word, so this register is not used and will read 0x00.
Reading DBGFH does not cause the FIFO to shift to the next word. When reading 16-bit words out of the
FIFO, read DBGFH before reading DBGFL because reading DBGFL causes the FIFO to advance to the
next word of information.
17.4.3.6 Debug FIFO Low Register (DBGFL)
This register provides read-only access to the low-order eight bits of the FIFO. Writes to this register have
no meaning or effect.
Reading DBGFL causes the FIFO to shift to the next available word of information. When the debug
module is operating in event-only modes, only 8-bit data is stored into the FIFO (high-order half of each
FIFO word is unused). When reading 8-bit words out of the FIFO, simply read DBGFL repeatedly to get
successive bytes of data from the FIFO. It isn’t necessary to read DBGFH in this case.
Do not attempt to read data from the FIFO while it is still armed (after arming but before the FIFO is filled
or ARMF is cleared) because the FIFO is prevented from advancing during reads of DBGFL. This can
interfere with normal sequencing of reads from the FIFO.
Reading DBGFL while the debugger is not armed causes the address of the most-recently fetched opcode
to be stored to the last location in the FIFO. By reading DBGFH then DBGFL periodically, external host
software can develop a profile of program execution. After eight reads from the FIFO, the ninth read will
return the information that was stored as a result of the first read. To use the profiling feature, read the FIFO
eight times without using the data to prime the sequence and then begin using the data to get a delayed
picture of what addresses were being executed. The information stored into the FIFO on reads of DBGFL
(while the FIFO is not armed) is the address of the most-recently fetched opcode.
MC9S08SG8 MCU Series Data Sheet, Rev. 8
280 Freescale Semiconductor
17.4.3.7 Debug Control Register (DBGC)
This register can be read or written at any time.
76543210
R
DBGEN ARM TAG BRKEN RWA RWAEN RWB RWBEN
W
Reset00000000
Figure 17-7. Debug Control Register (DBGC)
Table 17-4. DBGC Register Field Descriptions
Field Description
7
DBGEN
Debug Module Enable — Used to enable the debug module. DBGEN cannot be set to 1 if the MCU is secure.
0DBG disabled
1 DBG enabled
6
ARM
Arm Control — Controls whether the debugger is comparing and storing information in the FIFO. A write is used
to set this bit (and ARMF) and completion of a debug run automatically clears it. Any debug run can be manually
stopped by writing 0 to ARM or to DBGEN.
0 Debugger not armed
1 Debugger armed
5
TAG
Tag/Force Select — Controls whether break requests to the CPU will be tag or force type requests. If
BRKEN = 0, this bit has no meaning or effect.
0 CPU breaks requested as force type requests
1 CPU breaks requested as tag type requests
4
BRKEN
Break Enable — Controls whether a trigger event will generate a break request to the CPU. Trigger events can
cause information to be stored in the FIFO without generating a break request to the CPU. For an end trace, CPU
break requests are issued to the CPU when the comparator(s) and R/W meet the trigger requirements. For a
begin trace, CPU break requests are issued when the FIFO becomes full. TRGSEL does not affect the timing of
CPU break requests.
0 CPU break requests not enabled
1 Triggers cause a break request to the CPU
3
RWA
R/W Comparison Value for Comparator A — When RWAEN = 1, this bit determines whether a read or a write
access qualifies comparator A. When RWAEN = 0, RWA and the R/W signal do not affect comparator A.
0 Comparator A can only match on a write cycle
1 Comparator A can only match on a read cycle
2
RWAEN
Enable R/W for Comparator A — Controls whether the level of R/W is considered for a comparator A match.
0 R/W is not used in comparison A
1 R/W is used in comparison A
1
RWB
R/W Comparison Value for Comparator B — When RWBEN = 1, this bit determines whether a read or a write
access qualifies comparator B. When RWBEN = 0, RWB and the R/W signal do not affect comparator B.
0 Comparator B can match only on a write cycle
1 Comparator B can match only on a read cycle
0
RWBEN
Enable R/W for Comparator B — Controls whether the level of R/W is considered for a comparator B match.
0 R/W is not used in comparison B
1 R/W is used in comparison B
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 281
17.4.3.8 Debug Trigger Register (DBGT)
This register can be read any time, but may be written only if ARM = 0, except bits 4 and 5 are hard-wired
to 0s.
76543210
R
TRGSEL BEGIN
00
TRG3 TRG2 TRG1 TRG0
W
Reset00000000
= Unimplemented or Reserved
Figure 17-8. Debug Trigger Register (DBGT)
Table 17-5. DBGT Register Field Descriptions
Field Description
7
TRGSEL
Trigger Type — Controls whether the match outputs from comparators A and B are qualified with the opcode
tracking logic in the debug module. If TRGSEL is set, a match signal from comparator A or B must propagate
through the opcode tracking logic and a trigger event is only signalled to the FIFO logic if the opcode at the match
address is actually executed.
0 Trigger on access to compare address (force)
1 Trigger if opcode at compare address is executed (tag)
6
BEGIN
Begin/End Trigger Select — Controls whether the FIFO starts filling at a trigger or fills in a circular manner until
a trigger ends the capture of information. In event-only trigger modes, this bit is ignored and all debug runs are
assumed to be begin traces.
0 Data stored in FIFO until trigger (end trace)
1 Trigger initiates data storage (begin trace)
3:0
TRG[3:0]
Select Trigger Mode — Selects one of nine triggering modes, as described below.
0000 A-only
0001 A OR B
0010 A Then B
0011 Event-only B (store data)
0100 A then event-only B (store data)
0101 A AND B data (full mode)
0110 A AND NOT B data (full mode)
0111 Inside range: A address B
1000 Outside range: address < A or address > B
1001 – 1111 (No trigger)
MC9S08SG8 MCU Series Data Sheet, Rev. 8
282 Freescale Semiconductor
17.4.3.9 Debug Status Register (DBGS)
This is a read-only status register.
76543210
R AF BF ARMF 0 CNT3 CNT2 CNT1 CNT0
W
Reset00000000
= Unimplemented or Reserved
Figure 17-9. Debug Status Register (DBGS)
Table 17-6. DBGS Register Field Descriptions
Field Description
7
AF
Trigger Match A Flag — AF is cleared at the start of a debug run and indicates whether a trigger match A
condition was met since arming.
0 Comparator A has not matched
1 Comparator A match
6
BF
Trigger Match B Flag — BF is cleared at the start of a debug run and indicates whether a trigger match B
condition was met since arming.
0 Comparator B has not matched
1 Comparator B match
5
ARMF
Arm Flag — While DBGEN = 1, this status bit is a read-only image of ARM in DBGC. This bit is set by writing 1
to the ARM control bit in DBGC (while DBGEN = 1) and is automatically cleared at the end of a debug run. A
debug run is completed when the FIFO is full (begin trace) or when a trigger event is detected (end trace). A
debug run can also be ended manually by writing 0 to ARM or DBGEN in DBGC.
0 Debugger not armed
1 Debugger armed
3:0
CNT[3:0]
FIFO Valid Count — These bits are cleared at the start of a debug run and indicate the number of words of valid
data in the FIFO at the end of a debug run. The value in CNT does not decrement as data is read out of the FIFO.
The external debug host is responsible for keeping track of the count as information is read out of the FIFO.
0000 Number of valid words in FIFO = No valid data
0001 Number of valid words in FIFO = 1
0010 Number of valid words in FIFO = 2
0011 Number of valid words in FIFO = 3
0100 Number of valid words in FIFO = 4
0101 Number of valid words in FIFO = 5
0110 Number of valid words in FIFO = 6
0111 Number of valid words in FIFO = 7
1000 Number of valid words in FIFO = 8
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 283
Appendix A
Electrical Characteristics
A.1 Introduction
This section contains electrical and timing specifications for the MC9S08SG8 Series of microcontrollers
available at the time of publication.
The MC9S08SG8 Series includes both:
• Standard (STD) – devices that are standard-temperature rated.
• AEC Grade 0 – devices that are high-temperature rated.
A.2 Parameter Classification
The electrical parameters shown in this supplement are guaranteed by various methods. To give the
customer a better understanding the following classification is used and the parameters are tagged
accordingly in the tables where appropriate:
NOTE
The classification is shown in the column labeled “C” in the parameter
tables where appropriate.
A.3 Absolute Maximum Ratings
Absolute maximum ratings are stress ratings only, and functional operation at the maxima is not
guaranteed. Stress beyond the limits specified in Table A-2 may affect device reliability or cause
permanent damage to the device. For functional operating conditions, refer to the remaining tables in this
section.
Table A-1. Parameter Classifications
PThose parameters are guaranteed during production testing on each individual device.
CThose parameters are achieved by the design characterization by measuring a statistically relevant
sample size across process variations.
T
Those parameters are achieved by design characterization on a small sample size from typical devices
under typical conditions unless otherwise noted. All values shown in the typical column are within this
category.
DThose parameters are derived mainly from simulations.
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
284 Freescale Semiconductor
This device contains circuitry protecting against damage due to high static voltage or electrical fields;
however, it is advised that normal precautions be taken to avoid application of any voltages higher than
maximum-rated voltages to this high-impedance circuit. Reliability of operation is enhanced if unused
inputs are tied to an appropriate logic voltage level (for instance, either VSS or VDD) or the programmable
pull-up resistor associated with the pin is enabled.
Table A-2. Absolute Maximum Ratings
Rating Symbol Value Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Standard AEC
Grade 0
Supply voltage VDD –0.3 to +5.8 V x x
Maximum current into VDD IDD 120 mA x x
Digital input voltage VIn –0.3 to VDD + 0.3 V x x
Instantaneous maximum current
Single pin limit (applies to all port pins)2, 3, 4
2 Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate
resistance values for positive (VDD) and negative (VSS) clamp voltages, then use the larger of the two resistance values.
3All functional non-supply pins are internally clamped to VSS and VDD.
4Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current
conditions. If positive injection current (VIn > VDD) is greater than IDD, the injection current may flow out of VDD and could result
in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum injection
current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or
if the clock rate is very low (which would reduce overall power consumption).
ID 25 mA x x
Storage temperature range Tstg –55 to 150 Cx x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 285
A.4 Thermal Characteristics
This section provides information about operating temperature range, power dissipation, and package
thermal resistance. Power dissipation on I/O pins is usually small compared to the power dissipation in
on-chip logic and voltage regulator circuits, and it is user-determined rather than being controlled by the
MCU design. To take PI/O into account in power calculations, determine the difference between actual pin
voltage and VSS or VDD and multiply by the pin current for each I/O pin. Except in cases of unusually high
pin current (heavy loads), the difference between pin voltage and VSS or VDD will be very small.
Table A-3. Thermal Characteristics
Num C Rating Symbol Value Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Standar
d
AEC
Grade 0
1 — Operating temperature range
(packaged)
TL to TH
C
C
TA
–40 to 85 x
V–40 to 105x
M–40 to 125x
W–40 to 150 x
2 D Maximum junction temperature C
CT
J95 x
V115x
M135x
W155 x
D Thermal resistance 2,3
Single-layer board
2Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board) temperature,
ambient temperature, air flow, power dissipation of other components on the board, and board thermal resistance.
3Junction to Ambient Natural Convection
JA
Airflow at
200 ft/min
Natural
Convection
3 8-pin NB SOIC 131 153
C/W
x
16-pin TSSOP 115 135 x x
20-pin TSSOP 95 115 x
4 D Thermal resistance2,3
Four-layer board
JA
Airflow at
200 ft/min
Natural
Convection
8-pin NB SOIC 95 102
C/W
x
16-pin TSSOP 86 94 x x
20-pin TSSOP 69 76 x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
286 Freescale Semiconductor
The average chip-junction temperature (TJ) in C can be obtained from:
TJ = TA + (PD JA)Eqn. A-1
where:
TA = Ambient temperature, C
JA = Package thermal resistance, junction-to-ambient, C/W
PD = Pint PI/O
Pint = IDD VDD, Watts — chip internal power
PI/O = Power dissipation on input and output pins — user determined
For most applications, PI/O Pint and can be neglected. An approximate relationship between PD and TJ
(if PI/O is neglected) is:
PD = K (TJ + 273C) Eqn. A-2
Solving Equation A-1 and Equation A-2 for K gives:
K = PD (TA + 273C) + JA (PD)2Eqn. A-3
where K is a constant pertaining to the particular part. K can be determined from equation 3 by measuring
PD (at equilibrium) for a known TA. Using this value of K, the values of PD and TJ can be obtained by
solving Equation A-1 and Equation A-2 iteratively for any value of TA.
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 287
A.5 ESD Protection and Latch-Up Immunity
Although damage from electrostatic discharge (ESD) is much less common on these devices than on early
CMOS circuits, normal handling precautions should be used to avoid exposure to static discharge.
Qualification tests are performed to ensure that these devices can withstand exposure to reasonable levels
of static without suffering any permanent damage.
All ESD testing is in conformity with AEC-Q100 Stress Test Qualification for Automotive Grade
Integrated Circuits. During the device qualification ESD stresses were performed for the human body
model (HBM) and the charge device model (CDM).
A device is defined as a failure if after exposure to ESD pulses the device no longer meets the device
specification. Complete DC parametric and functional testing is performed per the applicable device
specification at room temperature followed by hot temperature, unless specified otherwise in the device
specification.
Table A-4. ESD and Latch-up Test Conditions
Model Description Symbol Value Unit
Human
Body
Series resistance R1 1500
Storage capacitance C 100 pF
Number of pulses per pin — 3
Latch-up Minimum input voltage limit – 2.5 V
Maximum input voltage limit 7.5 V
Table A-5. ESD and Latch-Up Protection Characteristics
No. Rating1
1Parameter is achieved by design characterization on a small sample size from typical devices
under typical conditions unless otherwise noted.
Symbol Min Max Unit
1 Human body model (HBM) VHBM 2000 — V
2 Charge device model (CDM) VCDM 500 — V
3Latch-up current at TA = 125CI
LAT 100 — mA
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
288 Freescale Semiconductor
A.6 DC Characteristics
This section includes information about power supply requirements and I/O pin characteristics.
Table A-6. DC Characteristics
Num C Characteristic Symbol Condition Min Typ1Max Unit
Temp Rated2
Stand
ard
AEC
Grade
0
1 — Operating voltage VDD —2.7—5.5Vxx
2
C All I/O pins, 5 V, ILoad = –4 mA VDD – 1.5 — — x x
P low-drive strength 5 V, ILoad = –2 mA VDD – 0.8 — — x x
C Output high VOH 3 V, ILoad = –1 mA VDD – 0.8 — — V x x
C voltage 5 V, ILoad = –20 mA VDD – 1.5 — — x x
P All I/O pins, 5 V, ILoad = –10 mA VDD – 0.8 — — x x
C high-drive strength 3 V, ILoad = –5 mA VDD – 0.8 — — x x
3C
Output high
current
Max total IOH for
all ports IOHT VOUT < VDD 0—
–100 mA x
–50 x
4
C All I/O pins 5 V, ILoad = 4 mA — — 1.5 x x
P low-drive strength 5 V, ILoad = 2 mA — — 0.8 x x
COutput low V
OL 3 V, ILoad = 1 mA — — 0.8 V x x
C voltage 5 V, ILoad = 20 mA — — 1.5 x x
P All I/O pins 5 V, ILoad = 10 mA — — 0.8 x x
C high-drive strength 3 V, ILoad = 5 mA — — 0.8 x x
5C
Output low
current
Max total IOL for
all ports IOLT VOUT > VSS 0— mA100 x
50 x
6P Input high voltage; all digital inputs VIH 5V 0.65 x VDD ——Vxx
C 3V 0.7 x VDD —— xx
7P Input low voltage; all digital inputs VIL 5V — — 0.35 x VDD Vx x
C 3V — — 0.35 x VDD xx
8 C Input hysteresis Vhys 0.06 x VDD Vxx
xx
9 P Input leakage current (per pin) IInVIn = VDD or VSS —0.1 1 Ax
temperature > 125 C—2 x
10
PHi-Z (off-state) leakage current (per
pin)
input/output port pins IOZVIn = VDD or VSS,— 0.1 1Ax
PTB6/SDA/XTAL, RESET VIn = VDD or VSS —0.2 2Ax
input/output port pins VIn = VDD or VSS
temperature > 125 C—0.2 2Ax
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 289
11
Pullup or Pulldown3 resistors; when
enabled
P I/O pins RPU,RPD 17 37 52 kxx
C RESET4RPU 17 37 52 kxx
12
DDC injection current 5, 6, 7, 8
Single pin limit VIN > VDD 0—2mAxx
IIC VIN < VSS 0 — –0.2 mA x x
Total MCU limit,
includes VIN > VDD 0—25mAxx
sum of all stressed
pins VIN < VSS 0—–5mAxx
13 D Input Capacitance, all pins CIn —— 8pFxx
14 D RAM retention voltage VRAM —0.61.0Vxx
15 D POR re-arm voltage9VPOR 0.9 1.4 2.0 V x x
16 D POR re-arm time10 tPOR 10 — — sx x
17 P
Low-voltage
detection
threshold —
high range
VDD falling
VLVD1
3.9
3.88
4.0
4.0
4.1
4.12 V
x
x
VDD rising 4.0
3.98
4.1
4.1
4.2
4.22
x
x
18 P
Low-voltage detection threshold —
low range11,12
VDD falling
VDD rising
VLVD0 2.48
2.54
2.56
2.62
2.64
2.70 Vx
x
x
x
19 P
Low-voltage
warning
threshold —
high range 1
VDD falling
VLVW 3
.
4.5
4.48
4.6
4.6
4.7
4.72
V
x
x
VDD rising 4.6
4.58
4.7
4.7
4.8
4.82
x
x
20 P
Low-voltage
warning
threshold —
high range 0
VDD falling
VLVW 2
4.2
4.18
4.3
4.3
4.4
4.42
V
x
x
VDD rising 4.3
4.28
4.4
4.4
4.5
4.52
x
x
21 P
Low-voltage warning threshold
low range 1
VDD falling
VDD rising
VLVW 1 2.84
2.90
2.92
2.98
3.00
3.06 Vx
x
x
x
22 P
Low-voltage warning threshold —
low range 0
VDD falling
VDD rising
VLVW 0 2.66
2.72
2.74
2.80
2.82
2.88 Vx
x
x
x
Table A-6. DC Characteristics (continued)
Num C Characteristic Symbol Condition Min Typ1Max Unit
Temp Rated2
Stand
ard
AEC
Grade
0
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
290 Freescale Semiconductor
23 T Low-voltage inhibit reset/recover
hysteresis Vhys
5 V — 100 — mV xx
3 V — 60 — x x
24 P Bandgap Voltage Reference13 VBG
1.18 1.20 1.21 V x
1.17 1.20 1.22 V x
1Typical values are measured at 25C. Characterized, not tested.
2Electrical characteristics only apply to the temperature rated devices marked with x.
3When a pin interrupt is configured to detect rising edges, pulldown resistors are used in place of pullup resistors.
4The specified resistor value is the actual value internal to the device. The pullup value may measure higher when measured externally on
the pin.
5Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current conditions. If
positive injection current (VIn > VDD) is greater than IDD, the injection current may flow out of VDD and could result in external power supply
going out of regulation. Ensure external VDD load will shunt current greater than maximum injection current. This will be the greatest risk
when the MCU is not consuming power. Examples are: if no system clock is present, or if clock rate is very low (which would reduce overall
power consumption).
6All functional non-supply pins are internally clamped to VSS and VDD.
7Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate resistance
values for positive and negative clamp voltages, then use the larger of the two values.
8The RESET pin does not have a clamp diode to VDD. Do not drive this pin above VDD.
9Maximum is highest voltage that POR will occur.
10 Simulated, not tested
11 Device functionality is guaranteed between the LVD threshold VLVD0 and VDD Min.When VDD is below the minimum operating voltage
(VDD Min), the analog parameters for the IO pins, ACMP and ADC, are not guaranteed to meet data sheet performance parameters.
12 In addition to LVD, it is recommended to also use the LVW feature. LVW can trigger an interrupt and be used as an indicator to warn that the
VDD is dropping,so that the software can take actions accordingly before the VDD drops below VDD Min
13 Factory trimmed at VDD = 5.0 V
Table A-6. DC Characteristics (continued)
Num C Characteristic Symbol Condition Min Typ1Max Unit
Temp Rated2
Stand
ard
AEC
Grade
0
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 291
Figure A-1. Typical VOL vs IOL, High Drive Strength
Figure A-2. Typical VOL vs IOL, Low Drive Strength
VOL (V)
I
OL
(mA)
2015105025
0
0.5
1
1.5
2
a) VDD = 5V, High Drive
VOL (V)
I
OL
(mA)
8642010
0
0.2
0.4
0.8
1.0
b) VDD = 3V, High Drive
0.6
150°C
25°C
–40°C
Max 0.8V@5mA
Max 1.5V@20mA
150°C
25°C
–40°C
VOL (V)
I
OL
(mA)
432105
0
0.5
1
1.5
2
150°C
25°C
–40°C
a) VDD = 5V, Low Drive
VOL (V)
I
OL
(mA)
1.61.20.80.402.0
0
0.2
0.4
0.8
1.0
b) VDD = 3V, Low Drive
0.6
150°C
25°C
–40°C
Max 0.8V@1mA
Max 1.5V@4mA
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
292 Freescale Semiconductor
Figure A-3. Typical VDD – VOH vs IOH, High Drive Strength
Figure A-4. Typical VDD – VOH vs IOH, Low Drive Strength
I
OH
(mA)
–20–15–10–50–25
0
0.5
1
1.5
2
150°C
25°C
–40°C
a) VDD = 5V, High Drive
I
OH
(mA)
–8–6–4–20–10
0
0.2
0.4
0.8
1.0
b) VDD = 3V, High Drive
0.6
150°C
25°C
–40°C
Max 0.8V@ –5mA
Max 1.5V@ –20mA
VDD – VOH (V)
VDD – VOH (V)
VDD – VOH (V)
I
OH
(mA)
–4–3–2–10–5
0
0.5
1
1.5
2
150°C
25°C
–40°C
a) VDD = 5V, Low Drive
I
OH
(mA)
–1.6–1.2–0.8–0.40 –2.0
0
0.2
0.4
0.8
1.0
b) VDD = 3V, Low Drive
0.6
150°C
25°C
–40°C
Max 0.8V@ –1mA
Max 1.5V@ –4mA
VDD – VOH (V)
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 293
A.7 Supply Current Characteristics
This section includes information about power supply current in various operating modes.
Table A-7. Supply Current Characteristics
Num C Parameter Symbol VDD
(V) Typ1Max2Unit
Temp Rated3
Standard AEC
Grade 0
1
CRun supply current4 measured at
(CPU clock = 4 MHz, fBus = 2
MHz)
RIDD
51.11.5
mA
xx
C311.5xx
2
PRun supply current3 measured at
(CPU clock = 16 MHz, fBus = 8
MHz)
RIDD
53.9 5
mA
xx
C33.95xx
3
CRun supply current5 measured at
(CPU clock = 32 MHz, fBus = 16
MHz)
RIDD
5 7.25 7.7
mA
xx
C 3 7.15 7.6 x x
4
Stop3 mode supply current
S3IDD
C –40 C (C & M suffix )
5
1.1 —
A
x
P 25 C (All parts) 1.5 — x
P685 C (C suffix only ) 9.0 26 x
P6105 C (V suffix only) 20.6 60 x
P6125 C (M suffix only) 45.2 130 x
C –40 C (C & M suffix )
3
1.0 —
A
x
C 25 C (All parts) 1.4 — x
C85 C (C suffix only ) 7.8 19 x
C 105 C (V suffix only) 18.2 45 x
C 125 C (M suffix only) 40.1 95 x
5
Stop2 mode supply current
S2IDD
C –40 C (C & M suffix )
5
1.1 —
A
x
P 25 C (All parts) 1.4 — x
P685 C (C suffix only ) 6.8 22 x
P6105 C (V suffix only) 15.2 50 x
P6125 C (M suffix only) 32.7 99 x
C –40 C (C & M suffix )
3
1.0 —
A
x
C 25 C (All parts) 1.3 — x
C85 C (C suffix only ) 5.8 16 x
C 105 C (V suffix only) 13.1 36 x
C 125 C (M suffix only) 28.3 76 x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
294 Freescale Semiconductor
Figure A-5. Typical Run IDD vs. Bus Frequency (VDD = 5V)
6C
RTC adder to stop2 or stop37 S23IDDR
TI
5 300 500 nA x
3 300 500 nA x
7C
LVD adder to stop3 (LVDE = LVDSE
= 1) S3IDDLVD
5 110 180 Ax
390160Ax
8C
Adder to stop3 for oscillator
enabled8
(EREFSTEN =1)
S3IDDOS
C
5,
358A
x
x
1Typical values are based on characterization data at 25C. See Figure A-5 through Figure A-7 for typical curves across
voltage/temperature.
2Max values in this column apply for the full operating temperature range of the device unless otherwise noted.
3Electrical characteristics only apply to the temperature rated devices marked with x.
4All modules except ADC active, ICS configured for FBE, and does not include any dc loads on port pins.
5All modules except ADC active, ICS configured for FEI, and does not include any dc loads on port pins.
6Stop currents are tested in production for 25C on all parts. Tests at other temperatures depend upon the part number suffix
and maturity of the product. Freescale may eliminate a test insertion at a particular temperature from the production test flow
once sufficient data has been collected and is approved.
7Most customers are expected to find that auto-wakeup from stop2 or stop3 can be used instead of the higher current wait mode.
8Values given under the following conditions: low range operation (RANGE = 0) with a 32.768kHz crystal and low power mode
(HGO = 0).
Table A-7. Supply Current Characteristics (continued)
Num C Parameter Symbol VDD
(V) Typ1Max2Unit
Temp Rated3
Standard AEC
Grade 0
Run IDD (mA)
f
bus
(MHz)
8421016
0
2
4
10
20
6
8
FEI
FBELP
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 295
Figure A-6. Typical Run IDD vs. Temperature (VDD = 5V; fbus = 8MHz)
Run I
DD
(mA)
Temperature (
°C
)
85250–40 105
0
1
2
5
125
3
4
150
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
296 Freescale Semiconductor
Figure A-7. Typical Stop IDD vs. Temperature (VDD = 5V)
STOP IDD (µA)
Temperature (
°C
)
85250–40 105
0
10
20
50
125
30
40
150
STOP2
STOP3
60
70
80
90
100
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 297
A.8 External Oscillator (XOSC) Characteristics
Table A-8. Oscillator Electrical Specifications (Temperature Range = –40 to 125C Ambient)
Nu
m C Rating Symbol Min Typ1
1Typical data was characterized at 5.0 V, 25C or is recommended value.
Max Uni
t
Temp Rated2
Standard AEC
Grade 0
1C
Oscillator crystal or resonator (EREFS = 1,
ERCLKEN = 1)
Low range (RANGE = 0) flo 32 — 38.4 kHz x x
High range (RANGE = 1) FEE or FBE mode 3fhi 1—5MHzx x
High range (RANGE = 1, HGO = 1) FBELP
mode fhi-hgo 1—16MHzx x
High range (RANGE = 1, HGO = 0) FBELP
mode fhi-lp 1—8MHzx x
2—
Load capacitors C1, C2See crystal or resonator manufacturer’s
recommendation.
3—
Feedback resistor
RFM
xx
Low range (32 kHz to 100 kHz) — 10 —
High range (1 MHz to 16 MHz) — 1 — x x
4—
Series resistor
RSk
Low range, low gain (RANGE = 0, HGO =
0) —0— xx
Low range, high gain (RANGE = 0, HGO =
1) — 100 — xx
High range, low gain (RANGE = 1, HGO =
0) —0— xx
High range, high gain (RANGE = 1, HGO
= 1)
8 MHz — 0 0 x x
MHz — 0 10 x x
MHz — 0 20 x x
5T
Crystal start-up time 4
ms
Low range, low gain (RANGE = 0, HGO =
0)
tCSTL-LP — 200 — xx
Low range, high gain (RANGE = 0, HGO =
1)
tCSTL-HGO — 400 — xx
High range, low gain (RANGE = 1, HGO =
0)5tCSTH-LP —5— xx
High range, high gain (RANGE = 1, HGO
= 1)4tCSTH-HGO —20— xx
6T
Square wave input clock frequency (EREFS = 0,
ERCLKEN = 1)
fextal
FEE or FBE mode 20.03125 — 5 MHz x
FBELP mode 0
0
—
—
40
36
MHz x
x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
298 Freescale Semiconductor
2Electrical characteristics only apply to the temperature rated devices marked with x.
3The input clock source must be divided using RDIV to within the range of 31.25 kHz to 39.0625 kHz.
4This parameter is characterized and not tested on each device. Proper PC board layout procedures must be followed to achieve
specifications.
54 MHz crystal
MCU
EXTAL XTAL
Crystal or Resonator
R
S
C2
RF
C1
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 299
A.9 Internal Clock Source (ICS) Characteristics
Table A-9. ICS Frequency Specifications (Temperature Range = –40 to 125C Ambient)
Nu
m C Rating Symbol Min Typ Max Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Standard AEC
Grade 0
1P
Internal reference frequency - factory
trimmed
at VDD = 5 V
fint_ft — 31.25 — kHz x x
2P
Internal reference frequency -
untrimmed2
2TRIM register at default value (0x80) and FTRIM control bit at default value (0x0).
fint_ut 25 36 41.66 kHz x x
3P
Internal reference frequency - user
trimmed fint_t 31.25 — 39.0625 kHz x x
4 D Internal reference startup time tirefst — 55 100 sx x
5—
DCO output frequency range -
untrimmed1
value provided for reference: fdco_ut =
1024 fint_ut
fdco_ut 25.6 36.86 42.66 MHz x x
6D
DCO output frequency range -
trimmed fdco_t
32 — 40 MHz x
32 — 36 MHz x
7D
Resolution of trimmed DCO output
frequency at fixed voltage and
temperature (using FTRIM)
fdco_res_t —0.1 0.2 %fdco xx
8D
Resolution of trimmed DCO output
frequency at fixed voltage and
temperature (not using FTRIM)
fdco_res_t —0.2 0.4 %fdco xx
9P
Total deviation from actual trimmed
DCO output frequency over voltage
and temperature
fdco_t
—+ 0.5
– 1.0 1.5 %fdco x
—+ 0.5
– 1.0 3%fdco x
10 D
Total deviation of trimmed DCO output
frequency over fixed voltage and
temperature range of 0C to 70 C
fdco_t —0.5 1%fdco xx
11 D FLL acquisition time 3
3This specification applies to any time the FLL reference source or reference divider is changed, trim value changed or
changing from FLL disabled (FBELP, FBILP) to FLL enabled (FEI, FEE, FBE, FBI). If a crystal/resonator is being used
as the reference, this specification assumes it is already running.
tacquire 1ms x x
12 D DCO output clock long term jitter (over
2mS interval) 4
4Jitter is the average deviation from the programmed frequency measured over the specified interval at maximum fBUS.
Measurements are made with the device powered by filtered supplies and clocked by a stable external clock signal.
Noise injected into the FLL circuitry via VDD and VSS and variation in crystal oscillator frequency increase the CJitter
percentage for a given interval.
CJitter —0.020.2
%fdco xx
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
300 Freescale Semiconductor
Figure A-8. Typical Frequency Deviation vs Temperature (ICS Trimmed to 16MHz bus@25°C, 5V, FEI)1
1. Based on the average of several hundred units from a typical characterization lot.
Deviation from Trimmed Frequency
Temperature (
°C
)
85250–40 105
–2%
–1%
+2%
125
+1%
0
150
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 301
A.10 Analog Comparator (ACMP) Electricals
Table A-10. Analog Comparator Electrical Specifications
Num C Rating Symbol Min Typ Max Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Standard AEC Grade
0
1 — Supply voltage VDD 2.7 — 5.5 V x x
2DSupply current (active) IDDAC —2035Ax x
3 D Analog input voltage VAIN VSS – 0.3 — VDD Vx x
4 D Analog input offset voltage VAIO 20 40 mV x x
5D
Analog Comparator hysteresis VH3.0 6.0 20.0 mV x x
6 D Analog input leakage current IALKG ——
1.0 Ax x
7D
Analog Comparator
initialization delay
tAINIT ——1.0sx x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
302 Freescale Semiconductor
A.11 ADC Characteristics
Table A-11. ADC Operating Conditions
Characteristic Conditions Symb Min Typ1
1Typical values assume VDDAD = VDD = 5.0V, Temp = 25C, fADCK=1.0MHz unless otherwise stated. Typical values are for
reference only and are not tested in production.
Max Unit
Temp Rated2
2Electrical characteristics only apply to the temperature rated devices marked with x.
Comment
Standard AEC
Grade 0
Supply voltage Absolute VDDAD 2.7 — 5.5 V x x
Input Voltage VADIN VREFL —V
REFH Vx x
Input
Capacitance CADIN —4.55.5pF x x
Input
Resistance RADIN —3 5kxx
Analog Source
Resistance
10 bit mode
fADCK > 4MHz
fADCK < 4MHz RAS
—
—
—
—
5
10 k
xx
External to
MCU
8 bit mode (all valid
fADCK)——10 x x
ADC
Conversion
Clock Freq.
High Speed
(ADLPC=0)
fADCK
0.4 — 8.0
MHz
xx
Low Power
(ADLPC=1) 0.4 — 4.0 xx
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 303
Figure A-9. ADC Input Impedance Equivalency Diagram
Table A-12. ADC Characteristics
Characteristic Conditions C Symb Min Typ1 Max Unit
Temp Rated2
Comment
Stand
ard
AEC
Grade
0
Supply current
ADLPC=1
ADLSMP=1
ADCO=1
TIDD +
IDDAD
— 133 — Ax x
ADC
current
only
Supply current
ADLPC=1
ADLSMP=0
ADCO=1
T
IDD +
IDDAD — 218 — Ax x
ADC
current
only
Supply current
ADLPC=0
ADLSMP=1
ADCO=1
T
IDD +
IDDAD — 327 — Ax x
ADC
current
only
Supply current
ADLPC=0
ADLSMP=0
ADCO=1
P
IDD +
IDDAD —0.582 1 mA x x
ADC
current
only
ADC
asynchronous
clock source
High speed
(ADLPC=0)
Pf
ADACK
23.3 5
MHz
xx
tADACK =
1/fADACK
Low power
(ADLPC=1) 1.25 2 3.3 xx
+
–
+
–
V
AS
R
AS
C
AS
V
ADIN
Z
AS
Pad
leakage
due to
input
protection
Z
ADIN
SIMPLIFIED
INPUT PIN EQUIVALENT
CIRCUIT
R
ADIN
ADC SAR
ENGINE
SIMPLIFIED
CHANNEL SELECT
CIRCUIT
INPUT PIN
R
ADIN
C
ADIN
INPUT PIN
R
ADIN
INPUT PIN
R
ADIN
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
304 Freescale Semiconductor
Conversion
time (including
sample time)
Short sample
(ADLSMP=0)
Dt
ADC
—20 —
ADCK
cycles
xx
See ADC
Chapter
for
conversion
time
variances
Long sample
(ADLSMP=1) —40 — xx
Sample time
Short sample
(ADLSMP=0)
Dt
ADS
—3.5 —
ADCK
cycles
xx
Long sample
(ADLSMP=1) —23.5 — xx
Total
unadjusted
error (Includes
quantization)
10 bit mode
PE
TUE
—1.5 3.5 LSB2xx
8 bit mode — 0.7 1.5 LSB3xx
Differential
Non-Linearity
10 bit mode
PDNL
—0.5 1.0
LSB3xx
8 bit mode — 0.3 0.5 xx
Monotonicity and No-Missing-Codes guaranteed
Integral
non-linearity
10 bit mode
TINL
—0.5 1.0
LSB3xx
8 bit mode — 0.3 0.5 xx
Zero-scale
error
10 bit mode
PE
ZS
—1.5 2.5
LSB3xx
8 bit mode — 0.5 0.7 x x
Full-scale error
(VADIN = VDD)
10 bit mode
TE
FS
01.0 1.5
LSB3xx
8 bit mode 0 0.5 0.5 xx
Quantization
error
10 bit mode
DE
Q
——0.5
LSB3xx
8 bit mode — — 0.5 xx
Input leakage
error
10 bit mode
DE
IL
00.2 2.5
LSB3xx Pad
leakage3 *
RAS
8 bit mode 0 0.1 1xx
Temp sensor
slope
–40C to 25C
Dm
—3.266 —
mV/C
xx
25C to 125C — 3.638 — x x
Temp sensor
voltage 25CD
VTEMP
25
—1.396 — V x x
1Typical values assume VDD = 5.0 V, Temp = 25C, fADCK = 1.0 MHz unless otherwise stated. Typical values are for reference
only and are not tested in production.
2Electrical characteristics only apply to the temperature rated devices marked with x.
3Based on input pad leakage current. Refer to pad electricals.
Table A-12. ADC Characteristics (continued)
Characteristic Conditions C Symb Min Typ1 Max Unit
Temp Rated2
Comment
Stand
ard
AEC
Grade
0
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 305
A.12 AC Characteristics
This section describes ac timing characteristics for each peripheral system.
A.12.1 Control Timing
Table A-13. Control Timing
Num C Rating Symbol Min Typ1
1Typical values are based on characterization data at VDD = 5.0V, 25C unless otherwise stated.
Max Unit
Temp
Rated2
2Electrical characteristics only apply to the temperature rated devices marked with x.
Sta
ndar
d
AE
C
Gra
de 0
1D
Bus frequency (tcyc = 1/fBus)
–40 C to 125 CfBus dc — 20 MHz x
>125 C18x
2D
Internal low power oscillator period
–40 C to 125 CtLPO
700 1500 sx
>125 C 600 1500 x
3D
External reset pulse width3
3This is the shortest pulse that is guaranteed to be recognized as a reset pin request. Shorter pulses are not guaranteed to
override reset requests from internal sources.
textrst 100 — ns x x
4D
Reset low drive4
4When any reset is initiated, internal circuitry drives the reset pin low for about 66 cycles of tcyc. After POR reset the bus clock
frequency changes to the untrimmed DCO frequency (freset = (fdco_ut)/4) because TRIM is reset to 0x80 and FTRIM is reset to
0, and there is an extra divide-by-two because BDIV is reset to 0:1. After other resets trim stays at the pre-reset value.
trstdrv 66 x tcyc —ns x x
8D
Pin interrupt pulse width
Asynchronous path2
Synchronous path5tILIH, tIHIL
100
1.5 x tcyc
——ns
xx
9C
Port rise and fall time —
Low output drive (PTxDS = 0) (load = 50 pF)5
Slew rate control disabled (PTxSE = 0)
Slew rate control enabled (PTxSE = 1)
5Timing is shown with respect to 20% VDD and 80% VDD levels. Temperature range –40C to 125C.
tRise, tFall —
—
40
75
—
—
ns x x
Port rise and fall time —
High output drive (PTxDS = 1) (load = 50 pF)6
Slew rate control disabled (PTxSE = 0)
Slew rate control enabled (PTxSE = 1)
tRise, tFall —
—
11
35
—
—
ns x x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
306 Freescale Semiconductor
Figure A-10. Reset Timing
Figure A-11. IRQ/Pin Interrupt Timing
textrst
RESET PIN
tIHIL
IRQ/Pin Interrupts
tILIH
IRQ/Pin Interrupts
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 307
A.12.2 TPM/MTIM Module Timing
Synchronizer circuits determine the shortest input pulses that can be recognized or the fastest clock that
can be used as the optional external source to the timer counter. These synchronizers operate from the
current bus rate clock.
Figure A-12. Timer External Clock
Figure A-13. Timer Input Capture Pulse
Table A-14. TPM Input Timing
Num C Rating Symbol Min Max Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Standard AEC
Grade 0
1—
External clock frequency (1/tTCLK)f
TCLK dc fBus/4 MHz x x
2 — External clock period tTCLK 4—
tcyc xx
3 — External clock high time tclkh 1.5 — tcyc xx
4 — External clock low time tclkl 1.5 — tcyc xx
5 — Input capture pulse width tICPW 1.5 — tcyc xx
tTCLK
tclkh
tclkl
TCLK
tICPW
TPMCHn
tICPW
TPMCHn
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
308 Freescale Semiconductor
A.12.3 SPI
Table A-15 and Figure A-14 through Figure A-17 describe the timing requirements for the SPI system.
Table A-15. SPI Electrical Characteristic
Num1
1Refer to Figure A-14 through Figure A-17.
C Rating
2
2All timing is shown with respect to 20% VDD and 70% VDD, unless noted; 100 pF load on all SPI pins. All timing assumes slew
rate control disabled and high drive strength enabled for SPI output pins.
Symbol Min Max Unit
Temp Rated3
3Electrical characteristics only apply to the temperature rated devices marked with x.
Standard AEC Grade
0
1D
Cycle time
Master
Slave
tSCK
tSCK
2
4
2048
—
tcyc
tcyc
xx
2D
Enable lead time
Master
Slave
tLead
tLead
—
1/2
1/2
—
tSCK
tSCK
xx
3D
Enable lag time
Master
Slave
tLag
tLag
—
1/2
1/2
—
tSCK
tSCK
xx
4D
Clock (SPSCK) high time
Master and Slave tSCKH 1/2 tSCK – 25 — ns xx
5D
Clock (SPSCK) low time
Master and Slave tSCKL 1/2 tSCK – 25 — ns xx
6D
Data setup time (inputs)
Master
Slave
tSI(M)
tSI(S)
30
30
—
—
ns
ns
xx
7D
Data hold time (inputs)
Master
Slave
tHI(M)
tHI(S)
30
30
—
—
ns
ns
xx
8 D Access time, slave4
4Time to data active from high-impedance state.
tA040ns
xx
9 D Disable time, slave5
5Hold time to high-impedance state.
tdis —40ns
xx
10 D
Data setup time (outputs)
Master
Slave
tSO
tSO
25
25
—
—
ns
ns
xx
11 D
Data hold time (outputs)
Master
Slave
tHO
tHO
–10
–10
—
—
ns
ns
xx
12 D
Operating frequency
Master
Slave
fop
fop
fBus/2048
dc
56
fBus/4
6Maximum baud rate must be limited to 5 MHz due to input filter characteristics.
MHz xx
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 309
Figure A-14. SPI Master Timing (CPHA = 0)
Figure A-15. SPI Master Timing (CPHA = 1)
SCK
(OUTPUT)
SCK
(OUTPUT)
MISO
(INPUT)
MOSI
(OUTPUT)
SS1
(OUTPUT)
MSB IN2
BIT 6 . . . 1
LSB IN
MSB OUT2LSB OUT
BIT 6 . . . 1
(CPOL = 0)
(CPOL = 1)
NOTES:
2. LSBF = 0. For LSBF = 1, bit order is LSB, bit 1, ..., bit 6, MSB.
1. SS output mode (MODFEN = 1, SSOE = 1).
1
23
5
67
10 11
5
10
4
4
SCK
(OUTPUT)
SCK
(OUTPUT)
MISO
(INPUT)
MOSI
(OUTPUT)
MSB IN(2)
BIT 6 . . . 1
LSB IN
MSB OUT(2) LSB OUT
BIT 6 . . . 1
(CPOL = 0)
(CPOL = 1)
SS(1)
(OUTPUT)
1. SS output mode (MODFEN = 1, SSOE = 1).
2. LSBF = 0. For LSBF = 1, bit order is LSB, bit 1, ..., bit 6, MSB.
NOTES:
2
1
3
4
5
67
10 11
5
4
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
310 Freescale Semiconductor
Figure A-16. SPI Slave Timing (CPHA = 0)
Figure A-17. SPI Slave Timing (CPHA = 1)
SCK
(INPUT)
SCK
(INPUT)
MOSI
(INPUT)
MISO
(OUTPUT)
SS
(INPUT)
MSB IN
BIT 6 . . . 1
LSB IN
MSB OUT SLAVE LSB OUT
BIT 6 . . . 1
(CPOL = 0)
(CPOL = 1)
NOTE:
SLAVE SEE
NOTE
1. Not defined but normally MSB of character just received
1
2
3
4
67
8
9
10 11
5
5
4
SCK
(INPUT)
SCK
(INPUT)
MOSI
(INPUT)
MISO
(OUTPUT)
MSB IN
BIT 6 . . . 1
LSB IN
MSB OUT SLAVE LSB OUT
BIT 6 . . . 1
SEE
(CPOL = 0)
(CPOL = 1)
SS
(INPUT)
NOTE:
SLAVE
NOTE
1. Not defined but normally LSB of character just received
1
2
3
4
67
8
9
10 11
4
5
5
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 311
A.13 FLASH Specifications
This section provides details about program/erase times and program-erase endurance for the FLASH
memory.
Program and erase operations do not require any special power sources other than the normal VDD supply.
For more detailed information about program/erase operations, see the Memory section.
Table A-16. FLASH Characteristics
Nu
m C Characteristic Symbol Min Typical Max Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Stand
ard
AEC
Grade
0
1—
Supply voltage for
program/erase
Vprog/erase 2.7 5.5 Vxx
2—
Supply voltage for read
operation
VRead 2.7 5.5 Vxx
3 — Internal FCLK frequency2
2 The frequency of this clock is controlled by a software setting.
fFCLK 150 200 kHz x x
— Internal FCLK period (1/fFCLK)t
Fcyc 56.67sx x
5—
Byte program time (random
location)3
3These values are hardware state machine controlled. User code does not need to count cycles. This information supplied for
calculating approximate time to program and erase.
tprog 9t
Fcyc xx
6—
Byte program time (burst
mode)2tBurst 4t
Fcyc xx
7 — Page erase time2tPage 4000 tFcyc xx
8 — Mass erase time2tMass 20,000 tFcyc xx
9C
Program/erase endurance4
T
L to TH = –40C to +125C
T
L to TH = –40C to +150C
T = 25C
4Typical endurance for FLASH is based on the intrinsic bit cell performance. For additional information on how Freescale defines
typical endurance, please refer to Engineering Bulletin EB619/D, Typical Endurance for Nonvolatile Memory.
nFLPE 10,000
10,000
10,000
—
—
100,000
—
—
—
cycles x
—
x
—
x
x
10 C Data retention5
5Typical data retention values are based on intrinsic capability of the technology measured at high temperature and de-rated to
25C using the Arrhenius equation. For additional information on how Freescale defines typical data retention, please refer to
Engineering Bulletin EB618/D, Typical Data Retention for Nonvolatile Memory.
tD_ret 15 100 — years x x
Appendix A Electrical Characteristics
MC9S08SG8 MCU Series Data Sheet, Rev. 8
312 Freescale Semiconductor
A.14 EMC Performance
Electromagnetic compatibility (EMC) performance is highly dependant on the environment in which the
MCU resides. Board design and layout, circuit topology choices, location and characteristics of external
components as well as MCU software operation all play a significant role in EMC performance. The
system designer should consult Freescale applications notes such as AN2321, AN1050, AN1263,
AN2764, and AN1259 for advice and guidance specifically targeted at optimizing EMC performance.
A.14.1 Radiated Emissions
Microcontroller radiated RF emissions are measured from 150 kHz to 1 GHz using the TEM/GTEM Cell
method in accordance with the IEC 61967-2 and SAE J1752/3 standards. The measurement is performed
with the microcontroller installed on a custom EMC evaluation board while running specialized EMC test
software. The radiated emissions from the microcontroller are measured in a TEM cell in two package
orientations (North and East).
The maximum radiated RF emissions of the tested configuration in all orientations are less than or equal
to the reported emissions levels.
Table A-17. Radiated Emissions, Electric Field
Parameter Symbol Conditions Frequency fOSC/fBUS
Level
(Max) Unit
Temp Rated1
1Electrical characteristics only apply to the temperature rated devices marked with x.
Standa
rd
AEC
Grade 0
Radiated
emissions,
electric field
VRE_TEM
VDD = 5 V
TA = +25oC
package type
16-TSSOP
0.15 – 50 MHz
4 MHz
crystal
16 MHzbus
0
dBV
xx
50 – 150 MHz 0 x x
150 – 500 MHz –6 x x
500 – 1000 MHz –9 x x
IEC Level N — x x
SAE Level 1 — x x
MC9S08SG8 MCU Series Data Sheet, Rev. 8
Freescale Semiconductor 313
Appendix B
Ordering Information and Mechanical Drawings
B.1 Ordering Information
This section contains ordering information for MC9S08SG8 and MC9S08SG4 devices.
B.1.1 Device Numbering Scheme
Table B-1. Device Numbering System
Device
Number1
1See Table 1-1 for a complete description of modules included on each device.
Memory Temp Rated2
2Apply to the temperature rated devices marked with x only.
Available Packages3
3See Tabl e B - 2 for package information.
FLASH RAM Standard AEC Grade 0 20-Pin 16-Pin 8-Pin
S9S08SG8 8 K 512 x 20 TSSOP 16 TSSOP 8 NB SOIC
S9S08SG4 4 K 256 x
S9S08SG8 8 K 512 x — 16 TSSOP —
S9S08SG4 4 K 256 x
S 9 S08 SG 8 E2 C TJ R
Status
- S = Auto Qualified
Main Memory Type
- 9 = Flash-based
Core
SG Family
Memory Size
- 8 Kbytes
- 4 Kbytes
Mask Set Identifier
- Alpha character references
wafer fab.
- Numeric character identifies
mask.
Temperature Option
- C = -40 to 85 C
- V = -40 to 105 C
- M = -40 to 125 C
- W = -40 to 150 C
Package Designator
Two letter descriptor
(refer to Tabl e B-2 ).
Tape and Reel Suffix (optional)
Appendix B Ordering Information and Mechanical Drawings
MC9S08SG8 MCU Series Data Sheet, Rev. 8
314 Freescale Semiconductor
B.2 Mechanical Drawings
The following pages are mechanical specifications for MC9S08SG8 package options. See Table B-2 for
the document number for each package type.
Table B-2. Package Information
Pin
Count Type Designator Document No.
20 TSSOP TJ 98ASH70169A
16 TSSOP TG 98ASH70247A
8 NB SOIC SC 98ASB42564B
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MC9S08SG8
Rev. 8
1/2014
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