C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.4 9/09 Copyright © 2009 by Silicon Laboratories C8051F34x
Full Speed USB Flash MCU Family
Analog Peripherals
-10-Bit ADC (C8051F340/1/2/3/4/5/6/7/A/B only)
•Up to 200 ksps
•Built-in analog multiplexer with single-ended and
differential mode
•VREF from external pin, internal reference, or VDD
•Built-in temperature sensor
•External conversion start input option
-Two comparators
-Internal voltage reference
(C8051F340/1/2/3/4/5/6/7/A/B only)
-Brown-out detector and POR Circuitry
USB Function Controller
-USB specification 2.0 compliant
-Full speed (12 Mbps) or low speed (1.5 Mbps) operation
-Integrated clock recovery; no external crystal required for
full speed or low speed
-Supports eight flexible endpoints
-1 kB USB buffer memory
-Integrated transceiver; no external resistors required
On-Chip Debug
-On-chip debug circuitry facilitates full speed, non-intru-
sive in-system debug (No emulator required)
-Provides breakpoints, single stepping,
inspect/modify memory and registers
-Superior performance to emulation systems using
ICE-chips, target pods, and sockets
Voltage Supply Input: 2.7 to 5.25 V
-Voltages from 3.6 to 5.25 V supported using On-C hip
Voltage Regulator
HIgh Sp eed 8051 µC Core
-Pipelined instruction architecture; executes 70% of
Instructions in 1 or 2 system clocks
-48 MIPS and 25 MIPS versions available.
-Expanded interrupt handler
Memory
-4352 or 2304 Bytes RAM
-64 or 32 kB Flash; In-system programmable in 512-byte
sectors
Digital Peripherals
-40/25 Port I/O; All 5 V tolerant with high sink current
-Hardware enhanced SPI™, SMBus™, and one or two
enhanced UART serial ports
-Four general purpose 16-bit counter/timers
-16-bit programmable counter array (PCA) with five cap-
ture/compare modules
-External Memory Interface (EMIF)
Clock Sources
-Internal Oscillator: ±0.25% accuracy with clock recovery
enabled. Supports all USB and UART modes
-External Oscillator: Crystal, RC, C, or clock (1 or 2 Pin
modes)
-Low Frequency (80 kHz) Internal Oscillator
-Can switch between clock sources on-the-fly
Packages
-48-pin TQFP (C8051F340 /1/4/5/8/C)
-32-pin LQFP (C8051F342/3/6/7/9/A/B/D)
-5x5 mm 32-pin QFN (C8051F342/3/6/7/9/A/B)
Temperature Range: –40 to +85 °C
ANALOG
PERIPHERALS
10-bit
200 ksps
ADC
64/32 kB
ISP FLASH 4/2 kB RAM
POR
DEBUG
CIRCUITRY
FLEXIBLE
INTERRUPTS
8051 CPU
(48/25 MIPS)
DIGITAL I/O
PRECISION INTERNAL
OSCILLATORS
HIGH-SPEED CONTROLLER CORE
A
M
U
X
CROSSBAR
+
-
WDT
+
-
USB Controller /
Transceiver
Port 0
Port 1
Port 2
Port 3
TEMP
SENSOR VREG
VREF Port 4
Ext. Memory I/F
48 Pin Onl y
UART0
SMBus
PCA
4 Timers
SPI
UART1*
C8051F340/1/2/34/5/6/7/A/B Only * C8051F340/1/4/5/8/A/B/C Only
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
2 Rev. 1.4
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 3
Table of Contents
1. System Overview.................................................................................................... 17
2. Absolute Maximum Ratings .................................................................................. 24
3. Global DC Electrical Characteristics.................................................................... 25
4. Pinout and Package Definitions............................................................................ 28
5. 10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)........................................ 41
5.1. Analog Multiplexer ............................................................................................ 42
5.2. Temperature Sensor......................................................................................... 43
5.3. Modes of Operation .......................................................................................... 45
5.3.1. Starting a Conversion............................................................................... 45
5.3.2. Tracking Modes........................................................................................ 46
5.3.3. Settling Time Requirements..................................................................... 47
5.4. Programmable Window Detector...................................................................... 52
5.4.1. Window Detector In Single-Ended Mode ................................................. 54
5.4.2. Window Detector In Differential Mode...................................................... 55
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only). ...................................... 57
7. Comparators........................................................................................................... 59
8. Voltage Regulator (REG0)...................................................................................... 69
8.1. Regulator Mode Selection................................................................................. 69
8.2. VBUS Detection................................................................................................ 69
9. CIP-51 Microcontroller........................................................................................... 73
9.1. Instruction Set................................................................................................... 74
9.1.1. Instruction and CPU Timing ..................................................................... 74
9.1.2. MOVX Instruction and Program Memory ................................................. 75
9.2. Memory Organization........................................................................................ 79
9.2.1. Program Memory...................................................................................... 80
9.2.2. Data Memory............................................................................................ 81
9.2.3. General Purpose Registers...................................................................... 81
9.2.4. Bit Addressable Locations........................................................................ 81
9.2.5. Stack ....................................................................................................... 81
9.2.6. Special Function Registers....................................................................... 82
9.2.7. Register Descriptions............................................................................... 86
9.3. Interrupt Handler............................................................................................... 88
9.3.1. MCU Interrupt Sources and Vectors ........................................................ 88
9.3.2. External Interrupts.................................................................................... 88
9.3.3. Interrupt Priorities..................................................................................... 89
9.3.4. Interrupt Latency ...................................................................................... 89
9.3.5. Interrupt Register Descriptions................................................................. 90
9.4. Power Management Modes.............................................................................. 97
9.4.1. Idle Mode.................................................................................................. 97
9.4.2. Stop Mode................................................................................................ 97
10.Prefet ch Engine........... ........................................................................................... 99
11.Reset Sources....................................................................................................... 100
11.1.Power-On Reset............................................................................................. 101
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11.2.Power-Fail Reset / VDD Monitor .................................................................... 102
11.3.External Reset................................................................................................ 103
11.4.Missing Clock Detector Reset ........................................................................ 103
11.5.Comparator0 Reset........................................................................................ 103
11.6.PCA Watchdog Timer Reset .......................................................................... 103
11.7.Flash Error Reset ........................................................................................... 103
11.8.Software Reset............................................................................................... 104
11.9.USB Reset...................................................................................................... 104
12.Flash Memory ....................................................................................................... 107
12.1.Programming The Flash Memory................................................................... 107
12.1.1.Flash Lock and Key Functions............................................................... 107
12.1.2.Flash Erase Procedure .......................................................................... 107
12.1.3.Flash Write Procedure ........................................................................... 108
12.2.Non-Volatile Data Storage.............................................................................. 109
12.3.Security Options............................................................................................. 109
13.External Data Memory Interface and On-Chip XRAM........................................ 114
13.1.Accessing XRAM............................................................................................ 114
13.1.1.16-Bit MOVX Example........................................................................... 114
13.1.2.8-Bit MOVX Example............................................................................. 114
13.2.Accessing USB FIFO Space .......................................................................... 115
13.3.Configuring the External Memory Interface.................................................... 116
13.4.Port Configuration........................................................................................... 116
13.5.Multiplexed and Non-multiplexed Selection.................................................... 119
13.5.1.Multiplexed Configuration....................................................................... 119
13.5.2.Non-multiplexed Configuration............................................................... 120
13.6.Memory Mode Selection................................................................................. 120
13.6.1.Internal XRAM Only ............................................................................... 121
13.6.2.Split Mode without Bank Select.............................................................. 121
13.6.3.Split Mode with Bank Select................................................................... 122
13.6.4.External Only.......................................................................................... 122
13.7.Timing .......................................................................................................... 122
13.7.1.Non-multiplexed Mode........................................................................... 124
13.7.2.Multiplexed Mode................................................................................... 127
14.Oscillators............................................................................................................. 131
14.1.Programmable Internal High-Frequency (H-F) Oscillator............................... 132
14.1.1.Internal H-F Oscillator Suspend Mode................................................... 132
14.2.Programmable Internal Low-Frequency (L-F) Oscillator ................................ 133
14.2.1.Calibrating the Internal L-F Oscillator..................................................... 133
14.3.External Oscillator Drive Circuit...................................................................... 135
14.3.1.Clocking Timers Directly Through the External Oscillator...................... 135
14.3.2.External Crystal Example....................................................................... 135
14.3.3.External RC Example............................................................................. 136
14.3.4.External Capacitor Example................................................................... 136
14.4.4x Clock Multiplier .......................................................................................... 138
14.5.System and USB Clock Selection .................................................................. 139
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14.5.1.System Clock Selection ......................................................................... 139
14.5.2.USB Clock Selection.............................................................................. 139
15.Port Input/Output.................................................................................................. 142
15.1.Priority Crossbar Decoder.............................................................................. 144
15.2.Port I/O Initialization ....................................................................................... 147
15.3.General Purpose Port I/O............................................................................... 150
16.Universal Serial Bus Controller (USB0).............................................................. 159
16.1.Endpoint Addressing ...................................................................................... 160
16.2.USB Transceiver ............................................................................................ 160
16.3.USB Register Access..................................................................................... 162
16.4.USB Clock Configuration................................................................................ 166
16.5.FIFO Management ......................................................................................... 167
16.5.1.FIFO Split Mode..................................................................................... 167
16.5.2.FIFO Double Buffering........................................................................... 168
16.5.3.FIFO Access .......................................................................................... 168
16.6.Function Addressing....................................................................................... 169
16.7.Function Configuration and Control................................................................ 169
16.8.Interrupts ........................................................................................................ 172
16.9.The Serial Interface Engine............................................................................ 176
16.10.Endpoint0 ..................................................................................................... 176
16.10.1.Endpoint0 SETUP Transactions .......................................................... 177
16.10.2.Endpoint0 IN Transactions................................................................... 177
16.10.3.Endpoint0 OUT Transactions............................................................... 178
16.11.Configuring Endpoints1-3............................................................................. 180
16.12.Controlling Endpoints1-3 IN.......................................................................... 180
16.12.1.Endpoints1-3 IN Interrupt or Bulk Mode............................................... 180
16.12.2.Endpoints1-3 IN Isochronous Mode..................................................... 181
16.13.Controlling Endpoints1-3 OUT...................................................................... 183
16.13.1.Endpoints1-3 OUT Interrupt or Bulk Mode........................................... 183
16.13.2.Endpoints1-3 OUT Isochronous Mode................................................. 184
17.SMBus ................................................................................................................... 188
17.1.Supporting Documents................................................................................... 189
17.2.SMBus Configuration...................................................................................... 189
17.3.SMBus Operation........................................................................................... 189
17.3.1.Arbitration............................................................................................... 190
17.3.2.Clock Low Extension.............................................................................. 191
17.3.3.SCL Low Timeout................................................................................... 191
17.3.4.SCL High (SMBus Free) Timeout .......................................................... 191
17.4.Using the SMBus............................................................................................ 191
17.4.1.SMBus Configuration Register............................................................... 192
17.4.2.SMB0CN Control Register..................................................................... 195
17.4.3.Data Register......................................................................................... 198
17.5.SMBus Transfer Modes.................................................................................. 198
17.5.1.Master Transmitter Mode....................................................................... 198
17.5.2.Master Receiver Mode........................................................................... 200
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17.5.3.Slave Receiver Mode............................................................................. 201
17.5.4.Slave Transmitter Mode......................................................................... 202
17.6.SMBus Status Decoding................................................................................. 202
18.UART0.................................................................................................................... 205
18.1.Enhanced Baud Rate Generation................................................................... 206
18.2.Operational Modes......................................................................................... 206
18.2.1.8-Bit UART............................................................................................. 207
18.2.2.9-Bit UART............................................................................................. 208
18.3.Multiprocessor Communications .................................................................... 208
19.UART1 (C8051F340/1/4/5/8/A/B/C Only).............................................................. 213
19.1.Baud Rate Generator ..................................................................................... 214
19.2.Data Format.................................................................................................... 215
19.3.Configuration and Operation .......................................................................... 216
19.3.1.Data Transmission................................................................................. 216
19.3.2.Data Reception ...................................................................................... 216
19.3.3.Multiprocessor Communications............................................................ 217
20.Enhanced Serial Peripheral Interface (SPI0)...................................................... 222
20.1.Signal Descriptions......................................................................................... 223
20.1.1.Master Out, Slave In (MOSI).................................................................. 223
20.1.2.Master In, Slave Out (MISO).................................................................. 223
20.1.3.Serial Clock (SCK)................................................................................. 223
20.1.4.Slave Select (NSS) ................................................................................ 223
20.2.SPI0 Master Mode Operation......................................................................... 224
20.3.SPI0 Slave Mode Operation........................................................................... 226
20.4.SPI0 Interrupt Sources................................................................................... 226
20.5.Serial Clock Timing......................................................................................... 227
20.6.SPI Special Function Registers...................................................................... 229
21.Timers.................................................................................................................... 235
21.1.Timer 0 and Timer 1....................................................................................... 235
21.1.1.Mode 0: 13-bit Counter/Timer................................................................ 235
21.1.2.Mode 1: 16-bit Counter/Timer................................................................ 236
21.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 237
21.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 238
21.2.Timer 2 .......................................................................................................... 243
21.2.1.16-bit Timer with Auto-Reload................................................................ 243
21.2.2.8-bit Timers with Auto-Reload................................................................ 244
21.2.3.Timer 2 Capture Modes: USB Start-of-Frame or LFO Falling Edge ...... 245
21.3.Timer 3 .......................................................................................................... 249
21.3.1.16-bit Timer with Auto-Reload................................................................ 249
21.3.2.8-bit Timers with Auto-Reload................................................................ 250
21.3.3.USB Start-of-Frame Capture.................................................................. 251
22.Programmable Counter Array (PCA0)................................................................ 255
22.1.PCA Counter/Timer........................................................................................ 256
22.2.Capture/Compare Modules ............................................................................ 257
22.2.1.Edge-triggered Capture Mode................................................................ 258
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22.2.2.Software Timer (Compare) Mode........................................................... 259
22.2.3.High Speed Output Mode....................................................................... 260
22.2.4.Frequency Output Mode ........................................................................ 261
22.2.5.8-Bit Pulse Width Modulator Mode......................................................... 262
22.2.6.16-Bit Pulse Width Modulator Mode....................................................... 263
22.3.Watchdog Timer Mode................................................................................... 264
22.3.1.Watchdog Timer Operation.................................................................... 264
22.3.2.Watchdog Timer Usage ......................................................................... 265
22.4.Register Descriptions for PCA........................................................................ 266
23.C2 Interface........................................................................................................... 271
23.1.C2 Interface Registers.................................................................................... 271
23.2.C2 Pin Sharing ............................................................................................... 273
Document Change List............................................................................................. 274
Contact Information.................................................................................................. 276
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
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List of Figures
1. System Overview
Figure 1.1. C8051F340/1/4/5 Block Diagram........................................................... 19
Figure 1.2. C8051F342/3/6/7 Block Diagram........................................................... 20
Figure 1.3. C8051F348/C Block Diagram................................................................. 21
Figure 1.4. C8051F349/D Block Diagram................................................................. 22
Figure 1.5. C8051F34A/B Block Diagram ................................................................ 23
4. Pinout and Package Definitions
Figure 4.1. TQFP-48 Pinout Diagram (Top View) .................................................... 31
Figure 4.2. TQFP-48 Package Diagram................................................................... 32
Figure 4.3. TQFP-48 Recommended PCB Land Pattern......................................... 33
Figure 4.4. LQFP-32 Pinout Diagram (Top View)..................................................... 34
Figure 4.5. LQFP-32 Package Diagram................................................................... 35
Figure 4.6. LQFP-32 Recommended PCB Land Pattern ......................................... 36
Figure 4.7. QFN-32 Pinout Diagram (Top View) ...................................................... 37
5. 10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)
Figure 5.1. ADC0 Functional Block Diagram............................................................ 41
Figure 5.2. Temperature Sensor Transfer Function................................................. 43
Figure 5.3. Temperature Sensor Error with 1-Point Calibration (VREF = 2.40 V).... 44
Figure 5.4. 10-Bit ADC Track and Conversion Example Timing .............................. 46
Figure 5.5. ADC0 Equivalent Input Circuits.............................................................. 47
Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data... 54
Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data ...... 54
Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data........ 55
Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data.......... 55
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)
Figure 6.1. Voltage Reference Functional Block Diagram........................................ 57
7. Comparators
Figure 7.1. Comparator Functional Block Diagram .................................................. 60
Figure 7.2. Comparator Hysteresis Plot ................................................................... 61
8. Voltage Regulator (REG0)
Figure 8.1. REG0 Configuration: USB Bus-Powered............................................... 70
Figure 8.2. REG0 Configuration: USB Self-Powered............................................... 70
Figure 8.3. REG0 Configuration: USB Self-Powered, Regulator Disabled............... 71
Figure 8.4. REG0 Configuration: No USB Connection............................................. 71
9. CIP-51 Microcontroller
Figure 9.1. CIP-51 Block Diagram............................................................................ 73
Figure 9.2. On-Chip Memory Map for 64 kB Devices............................................... 79
Figure 9.3. On-Chip Memory Map for 32 kB Devices............................................... 80
11. Reset Sources
Figure 11.1. Reset Sources.................................................................................... 100
Figure 11.2. Power-On and VDD Monitor Reset Timing ........................................ 101
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12. Flash Memory
Figure 12.1. Flash Program Memory Map and Secur ity Byte................................. 110
13. External Data Memory Interface and On-Chip XRAM
Figure 13.1. USB FIFO Space and XRAM Memory Map
with USBFAE set to ‘1’...................................................................................... 115
Figure 13.2. Multiplexed Configuration Example.................................................... 119
Figure 13.3. Non-multiplexed Configuration Example............................................ 120
Figure 13.4. EMIF Operating Modes...................................................................... 120
Figure 13.5. Non-multiplexed 16-bit MOVX Timing................................................ 124
Figure 13.6. Non-multiplexed 8-bit MOVX without Bank Select Timing ................. 125
Figure 13.7. Non-multiplexed 8-bit MOVX with Bank Select Timing ...................... 126
Figure 13.8. Multiplexed 16-bit MOVX Timing........................................................ 127
Figure 13.9. Multiplexed 8-bit MOVX without Bank Select Timing......................... 128
Figure 13.10. Multiplexed 8-bit MOVX with Bank Select Timing............................ 129
14. Oscillators
Figure 14.1. Oscillator Diagram.............................................................................. 131
15. Port Input/Output
Figure 15.1. Port I/O Functional Block Diagram (Port 0 through Port 3)................ 142
Figure 15.2. Port I/O Cell Block Diagram ............................................................... 143
Figure 15.3. Peripheral Availability on Port I/O Pins............................................... 144
Figure 15.4. Crossbar Priority Decoder in Example Configuration
(No Pins Skipped)............................................................................................. 145
Figure 15.5. Crossbar Priority Decoder in
Example Configuration (3 Pins Skipped) .......................................................... 146
16. Universal Serial Bus Controller (USB0)
Figure 16.1. USB0 Block Diagram.......................................................................... 159
Figure 16.2. USB0 Register Access Scheme......................................................... 162
Figure 16.3. USB FIFO Allocation.......................................................................... 167
17. SMBus
Figure 17.1. SMBus Block Diagram ....................................................................... 188
Figure 17.2. Typical SMBus Configuration............................................................. 189
Figure 17.3. SMBus Transaction............................................................................ 190
Figure 17.4. Typical SMBus SCL Generation......................................................... 193
Figure 17.5. Typical Master Transmitter Sequence................................................ 199
Figure 17.6. Typical Master Receiver Sequence.................................................... 200
Figure 17.7. Typical Slave Receiver Sequence...................................................... 201
Figure 17.8. Typical Slave Transmitter Sequence.................................................. 202
18. UART0
Figure 18.1. UART0 Block Diagram....................................................................... 205
Figure 18.2. UART0 Baud Rate Logic.................................................................... 206
Figure 18.3. UART Interconnect Diagram.............................................................. 207
Figure 18.4. 8-Bit UART Timing Diagram............................................................... 207
Figure 18.5. 9-Bit UART Timing Diagram............................................................... 208
Figure 18.6. UART Multi-Processor Mode Interconnect Diagram.......................... 209
19. UART1 (C8051F340/1/4/5/8/A/B/C Only)
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Figure 19.1. UART1 Block Diagram....................................................................... 213
Figure 19.2. UART1 Timing Without Parity or Extra Bit.......................................... 215
Figure 19.3. UART1 Timing With Parity ................................................................. 215
Figure 19.4. UART1 Timing With Extra Bit............................................................. 215
Figure 19.5. Typical UART Interconnect Diagram.................................................. 216
Figure 19.6. UART Multi-Processor Mode Interconnect Diagram.......................... 218
20. Enhanced Serial Peripheral Interface (SPI0)
Figure 20.1. SPI Block Diagram............................................................................. 222
Figure 20.2. Multiple-Master Mode Connection Diagram....................................... 225
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram............. 225
Figure 20.4. 4-Wire Single Master Mode and Slave Mode Connection Diagram... 225
Figure 20.5. Master Mode Data/Clock Timing........................................................ 227
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0).................................... 228
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1).................................... 228
Figure 20.8. SPI Master Timing (CKPHA = 0)........................................................ 232
Figure 20.9. SPI Master Timing (CKPHA = 1)........................................................ 232
Figure 20.10. SPI Slave Timing (CKPHA = 0)........................................................ 233
Figure 20.11. SPI Slave Timing (CKPHA = 1)........................................................ 233
21. Timers
Figure 21.1. T0 Mode 0 Block Diagram.................................................................. 236
Figure 21.2. T0 Mode 2 Block Diagram.................................................................. 237
Figure 21.3. T0 Mode 3 Block Diagram.................................................................. 238
Figure 21.4. Timer 2 16-Bit Mode Block Diagram .................................................. 243
Figure 21.5. Timer 2 8-Bit Mode Block Diagram .................................................... 244
Figure 21.6. Timer 2 Capture Mode (T2SPLIT = ‘0’).............................................. 245
Figure 21.7. Timer 2 Capture Mode (T2SPLIT = ‘1’).............................................. 246
Figure 21.8. Timer 3 16-Bit Mode Block Diagram .................................................. 249
Figure 21.9. Timer 3 8-Bit Mode Block Diagram .................................................... 250
Figure 21.10. Timer 3 Capture Mode (T3SPLIT = ‘0’)............................................ 251
Figure 21.11. Timer 3 Capture Mode (T3SPLIT = ‘1’)............................................ 252
22. Programmable Counter Array (PCA0)
Figure 22.1. PCA Block Diagram............................................................................ 255
Figure 22.2. PCA Counter/Timer Block Diagram.................................................... 256
Figure 22.3. PCA Interrupt Block Diagram............................................................. 257
Figure 22.4. PCA Capture Mode Diagram.............................................................. 258
Figure 22.5. PCA Software Timer Mode Diagram.................................................. 259
Figure 22.6. PCA High Speed Output Mode Diagram............................................ 260
Figure 22.7. PCA Frequency Output Mode............................................................ 261
Figure 22.8. PCA 8-Bit PWM Mode Diagram......................................................... 262
Figure 22.9. PCA 16-Bit PWM Mode...................................................................... 263
Figure 22.10. PCA Module 4 with Watchdog Timer Enabled................................. 264
23. C2 Interface
Figure 23.1. Typical C2 Pin Sharing....................................................................... 273
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List of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 18
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings* .................................................................. 24
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics ....................................................... 25
Table 3.2. Index to Electrical Characteristics Tables ............................................... 27
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D ................. 28
Table 4.2. TQFP-48 Package Dimensions .............................................................. 32
Table 4.3. TQFP-48 PCB Land Pattern Dimensions ............................................... 33
Table 4.4. LQFP-32 Package Dimensions .............................................................. 35
Table 4.5. LQFP-32 PCB Land Pattern Dimensions ............................................... 36
5. 10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)
Table 5.1. ADC0 Electrical Characteristics .............................................................. 56
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)
Table 6.1. Voltage Reference Electrical Characteristics ......................................... 58
7. Comparators
Table 7.1. Comparator Electrical Characteristics .................................................... 68
8. Voltage Regulator (REG0)
Table 8.1. Voltage Regulator Electrical Specifications ............................................ 69
9. CIP-51 Microcontroller
Table 9.1. CIP-51 Instruction Set Summary ............................................................ 75
Table 9.2. Special Function Register (SFR) Memory Map ...................................... 82
Table 9.3. Special Function Registers ..................................................................... 83
Table 9.4. Interrupt Summary .................................................................................. 90
11. Reset Sources
Table 11.1. Reset Electrical Characteristics .......................................................... 106
12. Flash Memory
Table 12.1. Flash Electrical Characteristics .......................................................... 109
13. External Data Memory Interface and On-Chip XRAM
Table 13.1. AC Parameters for External Memory Interface ................................... 130
14. Oscillators
Table 14.1. Oscillator Electrical Characteristics .................................................... 141
15. Port Input/Output
Table 15.1. Port I/O DC Electrical Characteristics ................................................. 158
16. Universal Serial Bus Controller (USB0)
Table 16.1. Endpoint Addressing Scheme ............................................................ 160
Table 16.2. USB0 Controller Registers ................................................................. 165
Table 16.3. FIFO Configurations ........................................................................... 168
Table 16.4. USB Transceiver Electrical Characteristics ........................................ 187
17. SMBus
Table 17.1. SMBus Clock Source Selection .......................................................... 192
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Table 17.2. Minimum SDA Setup and Hold Times ................................................ 193
Table 17.3. Sources for Hardware Changes to SMB0CN ..................................... 197
Table 17.4. SMBus Status Decoding ..................................................................... 203
18. UART0
Table 18.1. Timer Settings for Standard Baud Rates
Using the Internal Oscillator ............................................................... 212
19. UART1 (C8051F340/1/4/5/8/A/B/C Only)
Table 19.1. Baud Rate Generator Settings for Standard Baud Rates ................... 214
20. Enhanced Serial Peripheral Interface (SPI0)
Table 20.1. SPI Slave Timing Parameters ............................................................ 234
22. Programmable Counter Array (PCA0)
Table 22.1. PCA Timebase Input Options ............................................................. 256
Table 22.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 257
Table 22.3. Watchdog Timer Timeout Intervals1 ................................................... 265
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 13
List of Registers
SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select . . . . . . . . . . . . . . . . . . . 48
SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select . . . . . . . . . . . . . . . . . . 49
SFR Definition 5.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.4. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.5. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.6. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 52
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 52
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 53
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . 53
SFR Definition 6.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
SFR Definition 7.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 63
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 64
SFR Definition 7.4. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection . . . . . . . . . . . . . . . . . . . . 66
SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . . . . 67
SFR Definition 8.1. REG0CN: Voltage Regulator Control . . . . . . . . . . . . . . . . . . . . . . 72
SFR Definition 9.1. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.2. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.3. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
SFR Definition 9.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
SFR Definition 9.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
SFR Definition 9.7. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
SFR Definition 9.8. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
SFR Definition 9.9. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . . . 93
SFR Definition 9.10. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . . 94
SFR Definition 9.11. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 9.12. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 9.13. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . 96
SFR Definition 9.14. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 10.1. PFE0CN: Prefetch Engine Control . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 11.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . . 102
SFR Definition 11.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
SFR Definition 12.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 112
SFR Definition 12.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
SFR Definition 12.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
SFR Definition 13.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 117
SFR Definition 13.2. EMI0CF: External Memory Configuration . . . . . . . . . . . . . . . . . 118
SFR Definition 13.3. EMI0TC: External Memory Timing Control . . . . . . . . . . . . . . . . 123
SFR Definition 14.1. OSCICN: Internal H-F Oscillator Control . . . . . . . . . . . . . . . . . . 132
SFR Definition 14.2. OSCICL: Internal H-F Oscillator Calibration . . . . . . . . . . . . . . . 133
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14 Rev. 1.3
SFR Definition 14.3. OSCLCN: Internal L-F Oscillator Control . . . . . . . . . . . . . . . . . . 134
SFR Definition 14.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 137
SFR Definition 14.5. CLKMUL: Clock Multiplier Control . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 14.6. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
SFR Definition 15.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 148
SFR Definition 15.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 149
SFR Definition 15.3. XBR2: Port I/O Crossbar Register 2 . . . . . . . . . . . . . . . . . . . . . 149
SFR Definition 15.4. P0: Port0 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
SFR Definition 15.5. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
SFR Definition 15.6. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 15.7. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 15.8. P1: Port1 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 15.9. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 15.10. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 15.11. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 15.12. P2: Port2 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 15.13. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 15.14. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 15.15. P2SKIP: Port2 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 15.16. P3: Port3 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 15.17. P3MDIN: Port3 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 15.18. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 15.19. P3SKIP: Port3 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 15.20. P4: Port4 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 15.21. P4MDIN: Port4 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 15.22. P4MDOUT: Port4 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 16.1. USB0XCN: USB0 Transceiver Control . . . . . . . . . . . . . . . . . . . 161
SFR Definition 16.2. USB0ADR: USB0 Indirect Address . . . . . . . . . . . . . . . . . . . . . . 163
SFR Definition 16.3. USB0DAT: USB0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
USB Register Definition 16.4. INDEX: USB0 Endpoint Index . . . . . . . . . . . . . . . . . . . 165
USB Register Definition 16.5. CLKREC: Clock Recovery Control . . . . . . . . . . . . . . . 166
USB Register Definition 16.6. FIFOn: USB0 Endpoint FIFO Access . . . . . . . . . . . . . 168
USB Register Definition 16.7. FADDR: USB0 Function Address . . . . . . . . . . . . . . . . 169
USB Register Definition 16.8. POWER: USB0 Power . . . . . . . . . . . . . . . . . . . . . . . . 171
USB Register Definition 16.9. FRAMEL: USB0 Frame Number Low . . . . . . . . . . . . . 172
USB Register Definition 16.10. FRAMEH: USB0 Frame Number High . . . . . . . . . . . 172
USB Register Definition 16.11. IN1INT: USB0 IN Endpoint Interrupt . . . . . . . . . . . . . 173
USB Register Definition 16.12. OUT1INT: USB0 Out Endpoint Interrupt . . . . . . . . . . 173
USB Register Definition 16.13. CMINT: USB0 Common Interrupt . . . . . . . . . . . . . . . 174
USB Register Definition 16.14. IN1IE: USB0 IN Endpoint Interrupt Enable . . . . . . . . 175
USB Register Definition 16.15. OUT1IE: USB0 Out Endpoint Interrupt Enable . . . . . 175
USB Register Definition 16.16. CMIE: USB0 Common Interrupt Enable . . . . . . . . . . 176
USB Register Definition 16.17. E0CSR: USB0 Endpoint0 Control . . . . . . . . . . . . . . . 179
USB Register Definition 16.18. E0CNT: USB0 Endpoint 0 Data Count . . . . . . . . . . . 180
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Rev. 1.3 15
USB Register Definition 16.19. EINCSRL: USB0 IN Endpoint Control Low Byte . . . . 182
USB Register Definition 16.20. EINCSRH: USB0 IN Endpoint Control High Byte . . . 183
USB Register Definition 16.21. EOUTCSRL: USB0 OUT
Endpoint Control Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
USB Register Definition 16.22. EOUTCSRH: USB0 OUT
Endpoint Control High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
USB Register Definition 16.23. EOUTCNTL: USB0 OUT Endpoint Count Low . . . . . 186
USB Register Definition 16.24. EOUTCNTH: USB0 OUT Endpoint Count High . . . . 186
SFR Definition 17.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 194
SFR Definition 17.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
SFR Definition 17.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
SFR Definition 18.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 210
SFR Definition 18.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 211
SFR Definition 19.1. SCON1: UART1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
SFR Definition 19.2. SMOD1: UART1 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
SFR Definition 19.3. SBUF1: UART1 Data Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
SFR Definition 19.4. SBCON1: UART1 Baud Rate Generator Control . . . . . . . . . . . 220
SFR Definition 19.5. SBRLH1: UART1 Baud Rate Generator High Byte . . . . . . . . . . 221
SFR Definition 19.6. SBRLL1: UART1 Baud Rate Generator Low Byte . . . . . . . . . . . 221
SFR Definition 20.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 229
SFR Definition 20.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
SFR Definition 20.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
SFR Definition 21.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
SFR Definition 21.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
SFR Definition 21.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
SFR Definition 21.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
SFR Definition 21.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 248
SFR Definition 21.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 248
SFR Definition 21.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 21.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 21.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
SFR Definition 21.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 254
SFR Definition 21.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 254
SFR Definition 21.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 21.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 22.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
SFR Definition 22.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
SFR Definition 22.3. PCA0CPMn: PCA Capture/Compare Mode . . . . . . . . . . . . . . . 268
SFR Definition 22.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 269
SFR Definition 22.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 269
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16 Rev. 1.3
SFR Definition 22.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 269
SFR Definition 22.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 270
C2 Register Definition 23.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
C2 Register Definition 23.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 271
C2 Register Definition 23.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 272
C2 Register Definition 23.4. FPCTL: C2 Flash Programming Control . . . . . . . . . . . . 272
C2 Register Definition 23.5. FPDAT: C2 Flash Programming Data . . . . . . . . . . . . . . 272
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 17
1. System Overview
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D devices are fully integrated mixed-signal System-on-a-Chip MCUs.
Highlighted featu re s ar e liste d be low. Refer to Table 1.1 for specific product feature selection.
• High-speed pipelined 8051-compatible microcontroller core (up to 48 MIPS)
• In-system, full-speed, non-intrusive debug interface (on-chip)
• Universal Serial Bus (USB) Function Control ler with eight flexible endpoint pipes, integrated trans-
ceiver, an d 1 kB FIFO RAM
• Supply Voltage Regulator
• True 10-bit 200 ksps differential / single-ended ADC with analog multiplexer
• On-chip Voltage Reference and Temperature Sensor
• On-chip Voltage Comparators (2)
• Precision internal calibrated 12 MHz internal oscillator and 4x clock multiplier
• Internal low-frequency oscillator for additional power savings
• Up to 64 kB of on-chip Flash mem o ry
• Up to 4352 Bytes of on-chip RAM (256 + 4 kB)
• External Memory Interface (EMIF) available on 48-pin versions.
• SMBus/I2C, up to 2 UARTs, and Enhanced SPI serial interfaces implemented in hardware
• Four general-purpose 16 - bit tim er s
• Programmable Co unter/Timer Array (PCA) with five capture/compare modules and Watchdog Ti mer
function
•On-chip Power-On Reset, VDD Monitor, and Missing Clock Detector
• Up to 40 Port I/O (5 V tolerant)
With on-chip Power-On Reset, VDD monitor, Voltage Regulator, Watchdog Timer, and clock oscillator,
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D devices are truly stand-alone System-on-a-Chip solutions. The
Flash memory can be reprogrammed in-circuit, providing non-volatile data storage, and also allowing field
upgrades of the 8051 firmware. User software has complete con trol o f all pe rip herals, and ma y in dividually
shut down any or all peripherals for power savings.
The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in th e final app lication. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging with-
out occupying package pins.
Each device is specified for 2.7–5.25 V operation over the industrial temperature range (–40 to +85 °C).
For voltages above 3.6 V, the on-chip Voltage Regulator must be used. A minimu m of 3.0 V is required for
USB communication. The Port I/O and RST pins are tolerant of input signals up to 5 V. C8051F340/1/2/3/
4/5/6/7/8/9/A/B/C/D devices are available in 48-pin TQFP, 32-pin LQFP, or 32-pin QFN packages. See
Table 1.1, “Product Selection Guide,” on page 18 for feature and package choices.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
18 Rev. 1.3
Table 1.1. Product Selection Guide
Ordering Part Number
MIPS (Peak)
Flash Memory (Bytes)
RAM
Calibrated Internal Oscillator
Low Frequency Oscillator
USB with 1k Endpoint RAM
Supply Voltage Regulator
SMBus/I2C
Enhanced SPI
UARTs
Timers (16-bit)
Programmable Counter Array
Digital Port I/Os
External Memory Interface (EMIF)
10-bit 200 ksps ADC
Temperature Sensor
Voltage Reference
Analog Comparators
Package
C8051F340-GQ 48 64k 4352  2440  2TQFP48
C8051F341-GQ 48 32k 2304  2440  2TQFP48
C8051F342-GQ 48 64k 4352  1425 —  2LQFP32
C8051F342-GM 48 64k 4352  1425 —  2QFN32
C8051F343-GQ 48 32k 2304  1425 —  2LQFP32
C8051F343-GM 48 32k 2304  1425 —  2QFN32
C8051F344-GQ 25 64k 4352  2440  2TQFP48
C8051F345-GQ 25 32k 2304  2440  2TQFP48
C8051F346-GQ 25 64k 4352 — 1425 —  2LQFP32
C8051F346-GM 25 64k 4352 — 1425 —  2QFN32
C8051F347-GQ 25 32k 2304 — 1425 —  2LQFP32
C8051F347-GM 25 32k 2304 — 1425 —  2QFN32
C8051F348-GQ 25 32k 2304  2440 — — — 2 TQFP48
C8051F349-GQ 25 32k 2304  1425 —— — — 2 LQFP32
C8051F349-GM 25 32k 2304  1425 ————2 QFN32
C8051F34A-GQ 48 64k 4352  2425 — 2LQFP32
C8051F34A-GM 48 64k 4352  2425 — 2QFN32
C8051F34B-GQ 48 32k 2304  2425 — 2LQFP32
C8051F34B-GM 48 32k 2304  2425 — 2QFN32
C8051F34C-GQ 48 64k 4352  2440 — — — 2 TQFP48
C8051F34D-GQ 48 64k 4352  1425 — — — — 2 LQFP32
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 19
Figure 1.1. C8051F340/1/4/5 Block Diagram
Analog Peripherals
10-bit
200ksps
ADC
A
M
U
XTemp
Sensor
2 Comparators
+
-
VREFVDD
CP0
VDD
+
-
CP1
VREF
Debug / Programming
Hardware
Port 0
Drivers
P0.0
AIN0 - AIN19
Port I/O Configuration
Digital Peripherals
Priority
Crossbar
Decoder
Crossbar Control
Power-On
Reset
Power
Net
UART0
Timers 0, 1,
2, 3
PCA/WDT
SMBus
UART1
SPI
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6/XTAL1
P0.7/XTAL2
Port 1
Drivers
Port 2
Drivers
Port 3
Drivers
Port 4
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4/CNVSTR
P1.5/VREF
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
Supply
Monitor
System Clock Setup
External
Oscillator
Internal
Oscillator
XTAL1
XTAL2
Low Freq.
Oscillator
Clock
Multiplier
Clock
Recovery
USB Peripheral
Controller
1k Byte
RAM
Full / Low
Speed
Transceiver
External Memory
Interface
Control
Address
Data
P1
P2 / P3
P4
SFR
Bus
Voltage
Regulator
D+
D-
VBUS
VDD
VREG
GND
C2CK/RST
Reset
C2D
CIP-51 8051
Controller Core
64/32k Byte ISP FLASH
Program Memory
256 Byte RAM
4/2k By te XRAM
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
20 Rev. 1.3
Figure 1.2. C8051F342/3/6/7 Block Diagram
Analog Peripherals
10-bit
200 ksps
ADC
A
M
U
XTemp
Sensor
2 Comparators
+
-
VREFVDD
CP0
VDD
+
-
CP1
VREF
Debug / Programming
Hardware
Port 0
Drivers
P0.0
AIN0 - AIN20
Port I/O Configuration
Digital Peripherals
Priority
Crossbar
Decoder
Crossbar Control
Power-On
Reset
Power
Net
UART0
Timers 0, 1,
2, 3
PCA/WDT
SMBus
SPI
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4
P0.5
P0.6/CNVSTR
P0.7/VREF
Port 1
Drivers
Port 2
Drivers
Port 3
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
Supply
Monitor
System Clock Setup
External
Oscillator
Internal
Oscillator
XTAL1
XTAL2
Low Freq.
Oscillator*
Clock
Multiplier
Clock
Recovery
USB Peripheral
Controller
1 kB RAM
Full / Low
Speed
Transceiver
SFR
Bus
Voltage
Regulator
D+
D-
VBUS
VDD
VREG
GND
C2CK/RST
Reset CIP-51 8051
Controller Core
64/32 kB ISP FLASH
Program Memory
256 Byte RAM
4/2 kB XRAM
C2D
*Low Frequency Oscillator option not available on C8051F346/7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 21
Figure 1.3. C8051F348/C Block Diagram
Debug / Programming
Hardware
Port 0
Drivers
P0.0
Port I/O Configuration
Digital Peripherals
Priority
Crossbar
Decoder
Crossbar Control
Power-O n
Reset
Power
Net
UART0
Timers 0, 1,
2, 3
PCA/WDT
SMBus
UART1
SPI
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6/XTAL1
P0.7/XTAL2
Port 1
Drivers
Port 2
Drivers
Port 3
Drivers
Port 4
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4/CNVSTR
P1.5/VREF
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
Supply
Monitor
System Clock Setup
External
Oscillator
Internal
Oscillator
XTAL1
XTAL2
Low Freq.
Oscillator
Clock
Multiplier
Clock
Recovery
USB Peripheral
Controller
1k Byte
RAM
Full / Low
Speed
Transceiver
Exter nal Memory
Interface
Control
Address
Data
P1
P2 / P3
P4
Voltage
Regulator
D+
D-
VBUS
VDD
VREG
GND
C2CK/RST
Reset
C2D
CIP-51 8051
Controller Core
64/32 kB ISP FLASH
Program Memory
256 Byte RAM
4/2 kB XRAM
Analog Peripherals
2 Comparators
+
-
CP0
+
-
CP1
SFR
Bus
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22 Rev. 1.3
Figure 1.4. C8051F349/D Block Diagram
Debug / Programming
Hardware
Port 0
Drivers
P0.0
Port I/O Configuration
Digital Peripherals
Priority
Crossbar
Decoder
Crossbar Control
Power-On
Reset
Power
Net
UART0
Timers 0, 1,
2, 3
PCA/WDT
SMBus
SPI
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4
P0.5
P0.6/CNVSTR
P0.7/VREF
Port 1
Drivers
Port 2
Drivers
Port 3
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
Supply
Monitor
System Clock Setup
External
Oscillator
Internal
Oscillator
XTAL1
XTAL2
Low Freq.
Oscillator
Clock
Multiplier
Clock
Recovery
USB Peripheral
Controller
1 kB RAM
Full / Low
Speed
Transceiver
SFR
Bus
Voltage
Regulator
D+
D-
VBUS
VDD
VREG
GND
C2CK/RST
Reset CIP-51 8051
Controller Core
64/32 kB ISP FLASH
Program Memory
256 Byte RAM
4/2 kB XRAM
C2D
Analog Peripherals
2 Comparators
+
-
CP0
+
-
CP1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 23
Figure 1.5. C8051F34A/B Block Diagram
Analog Peripherals
10-bit
200 ksps
ADC
A
M
U
XTemp
Sensor
2 Comparators
+
-
VREFVDD
CP0
VDD
+
-
CP1
VREF
Debug / Programming
Hardware
Port 0
Drivers
P0.0
AIN0 - AIN20
Port I/O Configuration
Digital Peripherals
Priority
Crossbar
Decoder
Crossbar Control
Power-On
Reset
Power
Net
UART0
Timers 0, 1,
2, 3
PCA/WDT
SMBus
SPI
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4
P0.5
P0.6/CNVSTR
P0.7/VREF
Port 1
Drivers
Port 2
Drivers
Port 3
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0/C2D
Supply
Monitor
System Clock Setup
External
Oscillator
Inte rn a l
Oscillator
XTAL1
XTAL2
Low Freq.
Oscillator*
Clock
Multiplier
Clock
Recovery
USB P eripheral
Controller
1 kB RA M
Full / L o w
Speed
Transceiver
SFR
Bus
Voltage
Regulator
D+
D-
VBUS
VDD
VREG
GND
C2CK/RST
Reset CIP-51 8051
Controller Core
64 /3 2 kB IS P FLA SH
Program Mem ory
256 Byte RAM
4/2 kB XRAM
C2D
UART1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
24 Rev. 1.3
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings*
Parameter Conditions Min Typ Max Units
Ambient temperature under bias –55 125 °C
Storage Temperature –65 150 °C
Voltage on any Port I/O Pin or RST with
respect to GND –0.3 5.8 V
Voltage on VDD with respect to GND –0.3 4.2 V
Maximum Total current through VDD and
GND 500 mA
Maximum output current sunk by RST or any
Port pin 100 mA
*Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the devices at those or any other conditions
above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 25
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40 to +85 °C, 25 MHz System Clock unless otherwise specified.
Parameter Conditions Min Typ Max Units
Digital Supply Voltage1VRST 3.3 3.6 V
Digital Supply RAM Data
Retention Voltage 1.5 V
SYSCLK (System Clock)2C8051F340/1/2/3/A/B/C/D
C8051F344/5/6/7/8/9 0
048
25 MHz
Specified Operating
Temperature Range –40 +85 °C
Digital Supply Current - CPU Active (Normal Mode, accessing Flash)
IDD3VDD = 3.3 V, SYSCLK = 48 MHz
VDD = 3.3 V, SYSCLK = 24 MHz
VDD = 3.3 V, SYSCLK = 1 MHz
VDD = 3.3 V, SYSCLK = 80 kHz
VDD = 3.6 V, SYSCLK = 48 MHz
VDD = 3.6 V, SYSCLK = 24 MHz
25.9
13.9
0.69
55
29.7
15.9
28.5
15.7
32.3
18
mA
mA
mA
µA
mA
mA
IDD Supply Sensitivity3,4 SYSCLK = 1 MHz,
relative to VDD = 3.3 V
SYSCLK = 24 MHz,
relative to VDD = 3.3 V
47
46
%/V
%/V
IDD Frequency Sensitivity3,5 VDD = 3.3 V, SYSCLK < 30 MHz,
T = 25 ºC
VDD = 3.3 V, SYSCLK > 30 MHz,
T = 25 ºC
VDD = 3.6 V, SYSCLK < 30 MHz,
T = 25 ºC
VDD = 3.6 V, SYSCLK > 30 MHz,
T = 25 ºC
0.69
0.44
0.80
0.50
mA/MHz
mA/MHz
mA/MHz
mA/MHz
Digital Supply Current - CPU Inactive (Idle Mode, not accessing Flash)
IDD3VDD = 3.3 V, SYSCLK = 48 MHz
VDD = 3.3 V, SYSCLK = 24 MHz
VDD = 3.3 V, SYSCLK = 1 MHz
VDD = 3.3 V, SYSCLK = 80 kHz
VDD = 3.6 V, SYSCLK = 48 MHz
VDD = 3.6 V, SYSCLK = 24 MHz
16.6
8.25
0.44
35
18.6
9.26
18.75
9.34
20.9
10.5
mA
mA
mA
µA
mA
mA
IDD Supply Sensitivity3,4 SYSCLK = 1 MHz,
relative to VDD = 3.3 V
SYSCLK = 24 MHz,
relative to VDD = 3.3 V
41
39
%/V
%/V
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
26 Rev. 1.3
Other electric al characteristics tables ar e found in the data sheet section corresponding to the associated
peripherals. For more information on electrical characteristics for a specific peripheral, refer to the page
indicated in Table 3.2.
IDD Frequency Sensitivity3,6 VDD = 3.3 V, SYSCLK < 1 MHz,
T = 25 ºC
VDD = 3.3 V, SYSCLK > 1 MHz,
T = 25 ºC
VDD = 3.6 V, SYSCLK < 1 MHz,
T = 25 ºC
VDD = 3.6 V, SYSCLK > 1 MHz,
T = 25 ºC
0.44
0.32
0.49
0.36
mA/MHz
mA/MHz
mA/MHz
mA/MHz
Digital Supply Current (Stop
Mode, shutdown) Oscillator not running,
VDD monitor disabled < 0.1 µA
Digital Supply Current for USB
Module (USB Active Mode) VDD = 3.3 V, USB Clock = 48 MHz
VDD = 3.6 V, USB Clock = 48 MHz
8.69
9.59
mA
mA
Digital Supply Current for USB
Module (USB Suspend Mode) Oscillator not running
VDD monitor disabled < 0.1 µA
Notes:
1. USB Requires 3.0 V Minimum Supply Voltage.
2. SYSCLK must be at least 32 kHz to enable debugging.
3. Based on device characterization of data; Not production tested.
4. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated using the IDD
Supply Sensitivity. For example, if the VDD is 3.0 V instead of 3.3 V at 24 MHz: IDD = 13.9 mA typical at 3. 3 V
and SYSCLK = 24 MHz. From this, IDD = 13.9 mA + 0.46 x (3.0 V – 3.3 V) = 13.76 mA at 3.0 V and SYSCLK
= 24 MHz.
5. IDD can be estimat e d fo r fr eq u enc i e s < 30 MHz by multiplying the frequency of interest by the frequency
sensitivity number for that range. When using these numbers to estimate IDD for > 30 MHz, the estimate should
be the current at 24 MHz (or 48 MHz) minus the difference in current indicated by the frequency sensitivity
number . For example: VDD = 3.3 V ; SYSCLK = 35 MHz, IDD = 13.9 mA – (24 MHz – 35 MHz) x 0.44 mA/MHz =
18.74 mA.
6. Idle IDD can be estimated for frequencies < 1 MHz by multiplying the frequency of interest by the frequency
sensitivity number for that range. When using these numbers to estimate Idle IDD for > 1 MHz, the estimate
should be the current at 24 MHz (or 48 MHz) minus the difference in current indicated by the frequency
sensitivity number. For example: VDD = 3.3 V; SYSCLK = 5 MHz, Idle IDD = 8.25 mA – (24 MHz – 5 MHz) x
0.32 mA/MHz = 2.17 mA.
Table 3.1. Global DC Electrical Characteristics (Continued)
–40 to +85 °C, 25 MHz System Clock unless otherwise specified.
Parameter Conditions Min Typ Max Units
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 27
Table 3.2. Index to Electrical Characteristics Tables
Table Title Page No.
ADC0 Electrical Characteristics 56
Voltage Refe rence Electrical Characteristics 58
Comparator Electrical Characteristics 68
Voltage Regulator Electrical Specifications 69
Reset Electrical Characteristics 106
Flash Electrical Characteristics 109
AC Parameters for External Memory Interface 130
Oscillator Electrical Characteristics 141
Port I/O DC Electrical Characteristics 158
USB Transceiver Electrical Char ac te rist ics 187
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
28 Rev. 1.3
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Name Pin Numbers Type Description
48-pin 32-pin
VDD 10 6Power In
Power
Out
2.7–3.6 V Power Supply Voltage Input.
3.3 V Voltage Regulator Output. See Section 8.
GND 7 3 Ground.
RST/
C2CK
13 9D I/O
D I/O
Device Reset. Open-drain output of internal POR or VDD
monitor. An external source can initiate a system reset by
driving this pin low for at least 15 µs. See Section 11.
Clock signal for the C2 Debug Interface.
C2D 14 —D I/O Bi-directional data signal for the C2 Debug Interface.
P3.0 /
C2D
—10 D I/O
D I/O
Port 3.0. See Section 15 for a complete description of Port
3.
Bi-directional data signal for the C2 Debug Interface.
REGIN 11 7Power In 5 V Regulator Input. This pin is the input to the on-chip volt-
age regulator.
VBUS 12 8D In VBUS Sense Input. This pin should be connected to the
VBUS signal of a USB network. A 5 V signal on this pin indi-
cates a USB network connection.
D+ 8 4 D I/O USB D+.
D- 9 5 D I/O USB D–.
P0.0 6 2 D I/O or
A In Port 0.0. See Section 15 for a complete description of Port
0.
P0.1 5 1 D I/O or
A In Port 0.1.
P0.2 432 D I/O or
A In Port 0.2.
P0.3 331 D I/O or
A In Port 0.3.
P0.4 230 D I/O or
A In Port 0.4.
P0.5 129 D I/O or
A In Port 0.5.
P0.6 48 28 D I/O or
A In Port 0.6.
P0.7 47 27 D I/O or
A In Port 0.7.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 29
P1.0 46 26 D I/O or
A In Port 1.0. See Section 15 for a complete description of Port
1.
P1.1 45 25 D I/O or
A In Port 1.1.
P1.2 44 24 D I/O or
A In Port 1.2.
P1.3 43 23 D I/O or
A In Port 1.3.
P1.4 42 22 D I/O or
A In Port 1.4.
P1.5 41 21 D I/O or
A In Port 1.5.
P1.6 40 20 D I/O or
A In Port 1.6.
P1.7 39 19 D I/O or
A In Port 1.7.
P2.0 38 18 D I/O or
A In Port 2.0. See Section 15 for a complete description of Port
2.
P2.1 37 17 D I/O or
A In Port 2.1.
P2.2 36 16 D I/O or
A In Port 2.2.
P2.3 35 15 D I/O or
A In Port 2.3.
P2.4 34 14 D I/O or
A In Port 2.4.
P2.5 33 13 D I/O or
A In Port 2.5.
P2.6 32 12 D I/O or
A In Port 2.6.
P2.7 31 11 D I/O or
A In Port 2.7.
P3.0 30 —D I/O or
A In Port 3.0. See Section 15 for a complete description of Port
3.
P3.1 29 —D I/O or
A In Port 3.1.
P3.2 28 —D I/O or
A In Port 3.2.
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D (Continued)
Name Pin Numbers Type Description
48-pin 32-pin
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
30 Rev. 1.3
P3.3 27 —D I/O or
A In Port 3.3.
P3.4 26 —D I/O or
A In Port 3.4.
P3.5 25 —D I/O or
A In Port 3.5.
P3.6 24 —D I/O or
A In Port 3.6.
P3.7 23 —D I/O or
A In Port 3.7.
P4.0 22 —D I/O or
A In Port 4.0. See Section 15 for a complete description of Port
4.
P4.1 21 —D I/O or
A In Port 4.1.
P4.2 20 —D I/O or
A In Port 4.2.
P4.3 19 —D I/O or
A In Port 4.3.
P4.4 18 —D I/O or
A In Port 4.4.
P4.5 17 —D I/O or
A In Port 4.5.
P4.6 16 —D I/O or
A In Port 4.6.
P4.7 15 —D I/O or
A In Port 4.7.
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D (Continued)
Name Pin Numbers Type Description
48-pin 32-pin
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 31
Figure 4.1. TQFP-48 Pinout Diagram (Top View)
1
2
3
4
5
6
7
8
9
10
11
12
36
35
34
33
32
31
30
29
28
27
26
25
48
47
46
45
44
43
42
41
40
39
38
37
VBUS
P2.2
P2.0
P1.7
P1.6
P1.2
P2.4
P2.3
P3.5
P3.4
P3.2
P3.1
P2.1
P0.6
P3.3
P0.7
P0.2
D-
REGIN
P0.3
P3.0
P1.4
P1.5
P0.5
P1.1
P1.0
P0.4
P1.3
13
14
15
16
17
18
19
20
21
22
23
24
P2.6
P2.5
C8051F340/1/4/5/8/C-GQ
Top View
GND
D+
P0.1
P0.0
VDD
P2.7
P3.6
P4.1
P4.0
P3.7
P4.2
P4.5
P4.4
P4.3
P4.6
RST / C2CK
C2D
P4.7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
32 Rev. 1.3
Figure 4.2. TQFP-48 Package Diagram
Table 4.2. TQFP-48 Package Dimensions
Dimension Min Nom Max
A——1.20
A1 0.05 — 0.15
A2 0.95 1.00 1.05
b 0.170.220.27
c 0.09 — 0.20
D9.00 BSC
D1 7.00 BSC
e0.50 BSC
E9.00 BSC
E1 7.00 BSC
L 0.450.600.75
aaa 0.20
bbb 0.20
ccc 0.08
ddd 0.08
θ0° 3.5° 7°
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MS-026, variation ABC.
4. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 33
Figure 4.3. TQFP-48 Recommended PCB Land Pattern
Table 4.3. TQFP-48 PCB Land Pattern Dimensions
Dimension Min Max
C1 8.30 8.40
C2 8.30 8.40
E 0.50 BSC
X1 0.20 0.30
Y1 1.40 1.50
Notes:
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-73 51 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between
the solder mask and the metal pad is to be 60 µm minimum, all the way around
the pad.
Stencil Design:
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls
should be used to assure good solder paste release.
5. The stencil thickness should be 0.12 5 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all pads.
Card Assembly:
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
34 Rev. 1.3
Figure 4.4. LQFP-32 Pinout Diagram (Top View)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 35
Figure 4.5. LQFP-32 Package Diagram
Table 4.4. LQFP-32 Package Dimensions
Dimension Min Nom Max
A——1.60
A1 0.05 — 0.15
A2 1.35 1.40 1.45
b 0.300.370.45
c 0.09 — 0.20
D9.00 BSC
D1 7.00 BSC
e0.80 BSC
E9.00 BSC
E1 7.00 BSC
L 0.450.600.75
aaa 0.20
bbb 0.20
ccc 0.10
ddd 0.20
θ0° 3.5° 7°
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MS-026, variation BBA.
4. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
36 Rev. 1.3
Figure 4.6. LQFP-32 Recommended PCB Land Pattern
Table 4.5. LQFP-32 PCB Land Pattern Dimensions
Dimension Min Max
C1 8.40 8.50
C2 8.40 8.50
E 0.80 BSC
X1 0.40 0.50
Y1 1.25 1.35
Notes:
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-73 51 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between
the solder mask and the metal pad is to be 60 µm minimum, all the way around
the pad.
Stencil Design:
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls
should be used to assure good solder paste release.
5. The stencil thickness should be 0.12 5 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all pads.
Card Assembly:
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 37
Figure 4.7. QFN-32 Pinout Diagram (Top View)
25 P1.1
17 P2.1
16P2.2
8VBUS
32
31
30
29
28
27
26
1
2
3
4
5
6
7
9
10
11
12
13
14
15
24
23
22
21
20
19
18
GND (op tion al)
C8051F342/3/6/7/9/A/B-GM
Top View
P1.0
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
GND
D+
D-
VDD
REGIN
RST / C2CK
P3.0 / C2D
P2.7
P2.6
P2.5
P2.4
P2.3
P2.0
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
38 Rev. 1.3
Figure 4.8. QFN-32 Package Drawing
Table 4.6. QFN-32 Package Dimensions
Dimension Min Nom Max
A0.80 0.9 1.00
A1 0.00 0.02 0.05
b0.18 0.25 0.30
D5.00 BSC
D2 3.20 3.30 3.40
e0.50 BSC
E5.00 BSC
E2 3.20 3.30 3.40
L0.30 0.40 0.50
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid S tate Outline MO-220,
variation VHHD except for custom features D2, E2, and L which are
toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-02 0
specification for Small Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 39
L1 0.00 —0.15
aaa — — 0.15
bbb — — 0.10
ddd — — 0.05
eee — — 0.08
Table 4.6. QFN-32 Package Dimensions (Continued)
Dimension Min Nom Max
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid S tate Outline MO-220,
variation VHHD except for custom features D2, E2, and L which are
toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-02 0
specification for Small Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
40 Rev. 1.3
Figure 4.9. QFN-32 Recommended PCB Land Pattern
Table 4.7. QFN-32 PCB Land Pattern Dimesions
Dimension Min Max Dimension Min Max
C1 4.80 4.90 X2 3.20 3.40
C2 4.80 4.90 Y1 0.75 0.85
E0.50 BSC Y2 3.20 3.40
X1 0.20 0.30
Notes:
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder
mask and the metal pad is to be 60μm minimum, all the way around the pad.
Stencil Design:
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used
to assure good solder paste release.
5. The sten ci l th ickness should be 0.125 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
7. A 3x3 array of 1.0 mm openings on a 1.2mm pitch should be used for the center pad to assure
the proper paste volume.
Card Assembly:
8. A No-Clean, Type-3 solder paste is recommended.
9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small
Body Components.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 41
5. 10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)
The ADC0 subsystem for the C8051F34x devices consists of two analog multiplexers (referred to collec-
tively as AMUX0), and a 200 ksps, 10-bit successive-approximation-register ADC with integrated
track-and-hold and programmable window detector. The AMUX0, data conversion modes, and window
detector ar e all configured un der software control via the Spe cial Function Reg isters shown in Figure 5.1.
ADC0 operates in both Single-ended and Differential modes, and may be configured to measure voltages
at port pins, the Temperature Sensor output, or V DD with respect to a po rt pin, VREF, or GND. The connec-
tion options for AMUX0 are detailed in SFR Definition 5.1 and SFR Definition 5.2. The ADC0 subsystem is
enabled only when the AD0EN b it in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 sub-
system is in low power shutdown when this bit is logic 0.
Figure 5.1. ADC0 Functional Block Diagram
ADC0CF
AD0LJST
AD0SC0
AD0SC1
AD0SC2
AD0SC3
AD0SC4
10-Bit
SAR
ADC
REF
SYSCLK
ADC0H
32
ADC0CN
AD0CM0
AD0CM1
AD0CM2
AD0WINT
AD0BUSY
AD0INT
AD0TM
AD0EN
Timer 0 Ov er f lo w
Timer 2 Ov er f lo w
Timer 1 Ov er f lo w
Start
Conversion
000 AD0BUSY (W)
VDD
ADC0LTH
AD0WINT
001
010
011
100 CNVSTR Input
Window
Compare
Logic
GND
101 Timer 3 Over f lo w
ADC0LTL
ADC0GTH ADC0GTL
ADC0L
AMX0P
AMX0P4
AMX0P3
AMX0P2
AMX0P1
AMX0P0
AMX0N
AMX0N4
AMX0N3
AMX0N2
AMX0N1
AMX0N0
AIN+
AIN-
VREF
Positive
Input
(AIN+)
AMUX
VDD
Negative
Input
(AIN-)
AMUX
Temp
Sensor
Port I/O
Pins*
Port I/O
Pins*
* 21 Selections on 32-pin package
20 Selections on 48-pin package
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
42 Rev. 1.3
5.1. Analog Multiplexer
AMUX0 selects the po sitive and negative input s to the ADC. The positive input (AIN+) can be conn ected to
individual Port pins, the on-chip temperature sensor, or the positive power supply (VDD). The negative
input (AIN-) can be connected to individual Port pins, VREF, or GND. When GND is selected as the neg-
ative input, ADC0 operates in Single-ended Mode; at all other times, ADC0 operates in Differential
Mode. The ADC0 input channels are selected in the AMX0P and AMX0N registers as described in SFR
Definition 5.1 and SFR Definition 5.2.
The conversion code format differs between Single-ended and Differential modes. The registers ADC0H
and ADC0L contain the high and low bytes of the output conversion code fro m the ADC at the comple tion
of each conversion. Data can be righ t-justifie d or left-justified, depending o n the setting of the AD0 LJST bit
(ADC0CN.0). When in Single-ende d Mode, conversion codes ar e repre sented as 10- bit unsigned integers.
Inputs are measured from ‘0’ to VREF x 1023/1024. Example codes are shown below for both right-justi-
fied and left-justified data. Unused bits in the ADC0H and ADC0L registers are set to ‘0’.
When in Differential Mode, conversion codes are represented as 10-bit signed 2’s complement numbers.
Inputs are measured from –VREF to VREF x 511/512. Example codes are shown below for both right-jus-
tified and left-justified dat a. For right-justified data, the u nused MSBs of ADC0H are a sig n-exte nsion of the
data word. For left-justified data, the unused LSBs in the ADC0L register are se t to ‘0’.
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be config-
ured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog
input, set to ‘0’ the corresponding bit in register PnMDIN (for n = 0,1,2,3). To force the Crossbar to skip a
Port pin, set to ‘1’ the corresponding bit in register PnSKIP (for n = 0,1,2). See Section “15. Port Input/
Output” on page 142 for more Port I/O configuration de tails.
Input Voltage
(Single-Ended) Right-Justified ADC0H:ADC0L
(AD0LJST = 0) Left-Justified ADC0H:AD C 0L
(AD0LJST = 1)
VREF x 1023/1024 0x03FF 0xFFC0
VREF x 512/1024 0x0200 0x8000
VREF x 256/1024 0x0100 0x4000
0 0x0000 0x0000
Input Voltage
(Differential) Right-Justified ADC0H:ADC0L
(AD0LJST = 0) Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
VREF x 511/512 0x01FF 0x7FC0
VREF x 256/512 0x0100 0x4000
0 0x0000 0x0000
–VREF x 256/512 0xFF00 0xC000
–VREF 0xFE00 0x8000
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 43
5.2. Temperature Sensor
The temperature sensor transfe r function is shown in Figure 5.2. The output vo lt age (VTEMP) is the positive
ADC input when the temperature sensor is selected by bits AMX0P4-0 in register AMX0P. Values for the
Offset and Slope parameters can be found in Table 5.1.
Figure 5.2. Temperature Sensor Transfer Function
The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature mea-
surements (see Table 5.1 for linearity specifications). For absolute temperature measurements, offset and/
or gain calibration is recom m e nd ed . Typically a 1-point (offset) calibration includes the following steps:
Step 1. Control/measure the ambient temperature (this temperature must be known).
Step 2. Power the device, and delay for a few seconds to allow for self-heating.
Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input
and GND selected as the negative input.
Step 4. Calculate the offset characteristics, and store this value in non-volatile memory for use
with subsequent temperature sensor measurements.
Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 °C. Note that
parameters which affect ADC measurement, in particular the voltage reference value, will also
affect temperature measurement.
Temperature
Voltage
VTEMP = (Gain x TempC) + Offset
Offset (V at 0 Celsius)
Gain (V / deg C)
TempC = (VTEMP - Offset) / Gain
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
44 Rev. 1.3
Figure 5.3. Temperature Sensor Error with 1-Point Calibration (VREF = 2.40 V)
-40.00 -20.00 0.0
020.0
0
40.0
060.0
080.0
0
Temperature (degrees C)
Error (degrees C)
-5.00
-4.00
-3.00
-2.00
-1.00
0.0
0
1.0
0
2.0
0
3.0
0
4.0
0
5.0
0
-5.00
-4.00
-3.00
-2.00
-1.00
0.0
0
1.0
0
2.0
0
3.0
0
4.0
0
5.0
0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 45
5.3. Modes of Operation
ADC0 has a maximum conversion speed of 200 ksps. The ADC0 conversion clock is a divided version of
the system clock, determined by the AD0SC bits in the ADC0CF register (system clock divided by
(AD0SC + 1) for 0 ≤ AD0SC ≤ 31).
5.3.1. Starting a Conversion
A conversion ca n be in itiated in one of five way s, dep ending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM2–0) in registe r ADC0CN. Conversions may be initiate d by one of the fol-
lowing:
1. Writing a ‘1’ to the AD0BUSY bit of register ADC0CN
2. A Timer 0 overflow (i.e., timed continuous conversions)
3. A Timer 2 overflow
4. A Timer 1 overflow
5. A rising edge on the CNVSTR input signal
6. A Timer 3 overflow
Writing a ‘1’ to AD0BUSY provides software control of ADC0 whereby conversions are performed
"on-demand". During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conver-
sion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0
interrupt flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag
(AD0INT) should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when
bit AD0INT is logic 1. Note that when Timer 2 or T imer 3 overflows a re used as th e conversion sour ce, Low
Byte overflows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit
mode. See Section “21. Tim ers” on page 235 for timer configuration.
Important Note About Using CNVSTR: The CNVSTR input pin also functions as a Port pin. When the
CNVSTR input is used as the ADC0 conversion source, the associated Port pin should be skipped by the
Digital Crossbar. To conf igure the Crossbar to skip a pin, set the corres ponding bit in the PnSKIP re gister
to ‘1’. See Section “15. Port Input/Output” on page 142 for details on Port I/O configuration.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
46 Rev. 1.3
5.3.2. Tracking Modes
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0
input is continuously tracked, except when a conversion is in progress. When the AD0TM bit is logic 1,
ADC0 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a track-
ing period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR signal is used to initi-
ate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR is low; conversion begins
on the rising edge of CNVSTR (see Figure 5.4). T racking can also be disabled (shut down) when the device
is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX set-
tings are frequently changed, due to the settling time requirements described in Section “5.3.3. Settling
Time Requ irements” on page 47.
Figure 5.4. 10-Bit ADC Track and Conversion Example Timing
Write '1' to AD0BUSY,
Timer 0, Timer 2,
Timer 1, Timer 3 Overflow
(AD0CM[2:0]=000, 001,010
011, 101)
AD0TM=1 Track Convert Low Power Mode
AD0TM=0 Track or
Convert Convert Track
Low Powe r
or Convert
SAR Clocks
123456789101112
123456789
SAR Clocks
B. ADC0 Timing for Internal Trigger Source
123456789
CNVSTR
(AD0CM[2:0]=100)
AD0TM=1
A. ADC0 Timing for External Trigger Source
SAR Clocks
Track or Convert Convert TrackAD0TM=0
Track Convert Low Power
Mode
Low Power
or Convert
10 11
13 14
10 11
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 47
5.3.3. Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different AMUX0 selection is made), a minimum
tracking time is required before an accurate conversion can be performed. This tracking time is determined
by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance, and the accu-
racy required for the conversion. Note that in low-power tracking mode, three SAR clocks are used for
tracking at the start of every conversion. For most applications, these three SAR clocks will meet the mini-
mum tracking time requirements.
Figure 5.5 shows the equiv alent ADC0 input circu its for both Differential and Single-ended modes. Notice
that the equivalent time constant for both input circuits is the same. The required ADC0 settling time for a
given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature
Sensor output or VDD with respect to GND, RTOTAL reduces to RMUX. See Table 5.1 for ADC0 minimum
settling time requirements.
Equation 5.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the AMUX0 resistance and any external source resistance.
n is the ADC resolution in bits (10).
Figure 5.5. ADC0 Equivalent Input Circuits
t2n
SA
-------

RTOTALCSAMPLE
×ln=
R
MUX
= 5k
RC
Input
= R
MUX
* C
SAMPLE
R
MUX
= 5k
C
SAMPLE
= 5pF
C
SAMPLE
= 5pF
MUX
Select
MUX Select
Differential Mode
Px.x
Px.x
R
MUX
= 5k
C
SAMPLE
= 5pF
RC
Input
= R
MUX
* C
SAMPLE
MUX Selec t
Single-Ended Mode
Px.x
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
48 Rev. 1.3
SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AMX0P4–0: AMUX0 Positive Input Selection
R R R R/W R/W R/W R/W R/W Reset Value
- - - AMX0P4 AMX0P3 AMX0P2 AMX0P1 AMX0P0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBB
AMX0P4-0 ADC0 Positive Input
(32-pin Package) ADC0 Positive Input
(48-pin Pa ck ag e )
00000 P1.0 P2.0
00001 P1.1 P2.1
00010 P1.2 P2.2
00011 P1.3 P2.3
00100 P1.4 P2.5
00101 P1.5 P2.6
00110 P1.6 P3.0
00111 P1.7 P3.1
01000 P2.0 P3.4
01001 P2.1 P3.5
01010 P2.2 P3.7
01011 P2.3 P4.0
01100 P2.4 P4.3
01101 P2.5 P4.4
01110 P2.6 P4.5
01111 P2.7 P4.6
10000 P3.0 RESERVED
10001 P0.0 P0.3
10010 P0.1 P0.4
10011 P0.4 P1.1
10100 P0.5 P1.2
10101 - 11101 RESERVED RESERVED
11110 Temp Sensor Temp Sensor
11111 VDD VDD
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 49
SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AMX0N4–0: AMUX0 Negative Input Selection.
Note that when GND is selected as the Negative Input, ADC0 operates in Single-ended
mode. For all other Negative Input selections, ADC0 operates in Differential mode.
R R R R/W R/W R/W R/W R/W Reset Value
- - - AMX0N4 AMX0N3 AMX0N2 AMX0N1 AMX0N0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBA
AMX0N4-0 ADC0 Negative Input
(32-pin Package) ADC0 Negative Input
(48-pin Package)
00000 P1.0 P2.0
00001 P1.1 P2.1
00010 P1.2 P2.2
00011 P1.3 P2.3
00100 P1.4 P2.5
00101 P1.5 P2.6
00110 P1.6 P3.0
00111 P1.7 P3.1
01000 P2.0 P3.4
01001 P2.1 P3.5
01010 P2.2 P3.7
01011 P2.3 P4.0
01100 P2.4 P4.3
01101 P2.5 P4.4
01110 P2.6 P4.5
01111 P2.7 P4.6
10000 P3.0 RESERVED
10001 P0.0 P0.3
10010 P0.1 P0.4
10011 P0.4 P1.1
10100 P0.5 P1.2
10101 - 11101 RESERVED RESERVED
11110 VREF VREF
11111 GND (Single-Ended Mode) GND (Single-Ended Mode)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
50 Rev. 1.3
SFR Definition 5.3. ADC0CF: ADC0 Configuration
SFR Definition 5.4. ADC0H: ADC0 Data Word MSB
SFR Definition 5.5. ADC0L: ADC0 Data Word LSB
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in bit s AD0SC4-0. SAR Conversion clock requirement s
are given in Table 5.1.
Bit2: AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified .
1: Data in ADC0H:ADC0L registers are left-justified.
Bits1–0: UNUSED. Read = 00b; Write = don’t care.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AD0LJST - - 11111000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBC
AD0SC SYSCLK
CLKSAR
----------------------1–=
Bits7–0: ADC0 Data Word High-Order Bits.
For AD0LJST = 0: Bits 7–2 are the sign extension of Bit1. Bits 1-0 are th e upper 2 bits of the
10-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 10-bit ADC0 Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBE
Bits7–0: ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 10-bit Data Word.
For AD0LJST = 1: Bits 7–6 are the lower 2 bits of the 10-bit Data Word. Bit s 5–0 will always
read ‘0’.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xBD
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 51
SFR Definition 5.6. ADC0CN: ADC0 Control
Bit7: AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
Bit6: AD0TM: ADC0 Track Mode Bit.
0: Normal Track Mode: When ADC0 is enabled, tracking is continuous unless a conversion
is in progress.
1: Low-power Track Mode: Tracking Defined by AD0CM2-0 bits (see below).
Bit5: AD0INT: ADC0 Conversion Complete Interrupt Flag.
0: ADC0 has not completed a data conversion since the last time AD0INT was cleared.
1: ADC0 has completed a data conversion.
Bit4: AD0BUSY: ADC0 Busy Bit.
Read:
0: ADC0 conversion is complete or a conversion is not currently in progress. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM2-0 = 000b
Bit3: AD0WINT: ADC0 Window Compare Interrupt Flag.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
Bits2–0: AD0CM2–0: ADC0 Start of Conversion Mo de Select.
When AD0TM = 0:
000: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
001: ADC0 conversion initiated on overflow of Timer 0.
010: ADC0 conversion initiated on overflow of T imer 2.
011: ADC0 conversion initiated on overflow of Timer 1.
100: ADC0 conversion initiated on rising edge of external CNVSTR.
101: ADC0 conversion initiated on overflow of Timer 3.
11x: Reserved.
When AD0TM = 1:
000: Tracking initiated on write of ‘1’ to AD0BUSY and lasts 3 SAR clocks, followed by conversion.
001: Tracking initiated on overflow of Timer 0 and lasts 3 SAR clocks, followed by conversion.
010: Tracking initiated on overflow of Timer 2 and lasts 3 SAR clocks, followed by conversion.
011: Tracking initiated on overflow of Timer 1 and lasts 3 SAR clocks, followed by conversion.
100: ADC0 tracks only when CNVSTR input is logic low; conversion starts on rising CNVSTR edge.
101: Tracking initiated on overflow of Timer 3 and lasts 3 SAR clocks, followed by conversion.
11x: Reserved.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0EN AD0TM AD0INT AD0BUSY AD0WINT AD0CM2 AD0CM1 AD0CM0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xE8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
52 Rev. 1.3
5.4. Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 conversion results to
user-programmed limits, and notifies the system when a desired condition is detected. This is especially
effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster sys-
tem response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used
in polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL)
registers hold the comp arison values. The window detector flag can be programmed to in dicate when mea-
sured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0
Less-Than and ADC0 Greater-Than registers.
The Window Detector registers must be written with the same format (left/right justified, signed/unsigned)
as that of the current ADC configuration (left/right justified, single-ended/differential).
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
Bits7–0: High byte of ADC0 Greater-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC4
Bits7–0: Low byte of ADC0 Greater-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 53
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Dat a High Byte
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte
Bits7–0: High byte of ADC0 Less-Than Data W ord.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC6
Bits7–0: Low byte of ADC0 Le ss-Than Data Word.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC5
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
54 Rev. 1.3
5.4.1. Window Detector In Single-Ended Mode
Figure 5.6 shows two example window comparisons for right-justified, single-ended data, with
ADC0LTH:ADC0LTL = 0x0080 (128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). In single-ended mode,
the input voltage can range from ‘0’ to VREF x (1023/1024) with respect to GND, and is represented by a
10-bit unsigned integer value. In the left example, an AD0WINT interrupt will be generated if the ADC0
conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and
ADC0LTH:ADC0LTL (if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and AD0WINT interrupt
will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and
ADC0LT registers (if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 5.7 shows an exam-
ple using left-justified data with equivalent ADC0GT and ADC0LT register settings.
Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data
Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data
0x03FF
0x0081
0x0080
0x007F
0x0041
0x0040
0x003F
0x0000
0
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
VREF x (128/ 1 024)
VREF x (64/1024)
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
0x03FF
0x0081
0x0080
0x007F
0x0041
0x0040
0x003F
0x0000
0
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
VREF x (128/1024)
VREF x (64/1024)
AD0WINT
not affe c ted
AD0WINT=1
AD0WINT=1
ADC0H:ADC0L ADC0H:ADC0L
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0xFFC0
0x2040
0x2000
0x1FC0
0x1040
0x1000
0x0FC0
0x0000
0
Input Voltage
(Px.x - G N D)
VREF x (1023/1024)
VREF x (128/1024)
VREF x (64/1024)
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
0xFFC0
0x2040
0x2000
0x1FC0
0x1040
0x1000
0x0FC0
0x0000
0
Input Voltage
(Px.x - GN D)
VREF x (1023/1024)
VREF x (128/1024)
VREF x (64/10 24)
AD0WINT
not affected
AD0WINT=1
AD0WINT=1
ADC0H:ADC0L ADC0H:ADC0L
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 55
5.4.2. Window Detector In Differential Mode
Figure 5.8 shows two example window comparisons for right-justified, differential data, with
ADC0LTH:ADC0LTL = 0x0040 (+64d) and ADC0GTH:ADC0GTH = 0xFFFF (-1d). In differential mode, the
measurable volt age between the inp ut pins is between -VREF a nd VREF*(511/512). Output codes are rep-
resented as 10-bit 2’s complement signed integers. In the left example, an AD0WINT interrupt will be gen-
erated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL
and ADC0LTH:ADC0LTL (if 0xFFFF (-1d) < ADC0H:ADC0L < 0x0040 (64d)). In the right example, an
AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the
ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0xFFFF (-1d) or ADC0H:ADC0L > 0x0040 (+64d)).
Figure 5.9 shows an example using left-justified data with equivalent ADC0GT and ADC0LT register set-
tings.
Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data
Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data
0x01FF
0x0041
0x0040
0x003F
0x0000
0xFFFF
0xFFFE
0x0200
-VREF
Input Voltage
(Px.x - Px.x)
VREF x (511/512)
VREF x (64/512)
VREF x (-1/512)
0x01FF
0x0041
0x0040
0x003F
0x0000
0xFFFF
0xFFFE
0x0200
-VREF
Input Voltage
(Px.x - Px.x)
VREF x (511/512 )
VREF x (64/512)
VREF x (-1/512)
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
AD0WINT
not affected
AD0WINT=1
AD0WINT=1
ADC0H:ADC0LADC0H:ADC0L
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0x7FC0
0x1040
0x1000
0x0FC0
0x0000
0xFFC0
0xFF80
0x8000
-VREF
Input Voltage
(Px.x - Px.y)
VREF x (511/512)
VREF x (64/512)
VREF x (-1/512)
0x7FC0
0x1040
0x1000
0x0FC0
0x0000
0xFFC0
0xFF80
0x8000
-VREF
Input Voltage
(Px.x - Px.x)
VREF x (511/512 )
VREF x (64/512)
VREF x (-1/512)
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
AD0WINT
not affected
ADC0GTH:ADC0GTL
AD0WINT=1
AD0WINT=1
ADC0H:ADC0LADC0H:ADC0L
ADC0LTH:ADC0LTL
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
56 Rev. 1.3
Table 5.1. ADC0 Electrical Characteristics
VDD = 3.0 V, VREF = 2.40 V, –40 to +85 °C unless otherwise specified
Parameter Conditions Min Typ Max Units
DC Accuracy
Resolution 10 bits
Integral Nonlinearity ±0.5 ±1 LSB
Differential Nonlinearity Guaranteed Monotonic ±0.5 ±1 LSB
Offset Error –15 0+15 LSB
Full Scale Error –15 –1 +15 LSB
Offset Temperature Coefficient 10 ppm/°C
Dynamic Performance (10 kHz sine-wave Single-ended input, 1 dB below Full Scale, 200 ksps)
Signal-to-Noise Plus Distortion 51 52.5 dB
Total Harmonic Distortion Up to the 5th harmonic –67 dB
Spurious-Free Dynamic Range 78 dB
Conversion Rate
SAR Conversion Clock 3MHz
Conversion Time in SAR Clocks 10 clocks
Track/Hold Acquisition Time 300 ns
Throughput Rate 200 ksps
Analog Inputs
ADC Input Voltage Range Single Ended (AIN+ – GND)
Dif ferential (AIN+ – AIN–) 0
–VREF VREF
VREF V
V
Absolute Pin Voltage with respe ct
to GND Single Ended or Differential 0VDD V
Input Capacitance 5pF
Temperature Sensor
Linearity1±0.1 °C
Gain 2.86 mV/°C
Gain Error2±33.5 µV/ºC
Offset1(Temp = 0 °C) 776 mV
Offset Error2±8.51 mV
Power Specifications
Power Supply Curre nt (VDD sup-
plied to ADC0) Operating Mode, 20 0 ksps 400 900 µA
Power Supply Rejection ±0.3 mV/V
Notes:
1. Includes ADC offset, gain, and linearity variations.
2. Represents one standard deviation from the mean.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 57
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)
The Voltage referenc e MUX on C805 1F3 4x devi ces is configu ra ble to use an externa lly connecte d vo ltage
reference, the on-chip reference voltage generator, or the power supply voltage VDD (see Figure 6.1). The
REFSL bit in the Reference Control register (REF0CN) select s the reference sou rce. For the internal refe r-
ence or an external source, REFSL should be set to ‘0’; For VDD as the referenc e source, REFSL should
be set to ‘1’.
The BIASE bit enables the internal ADC bias generator, which is used by the ADC and Internal Oscillator.
This enable is forced to logic 1 when either of the aforementioned peripherals is enabled. The ADC bias
generator may be enabled manually by writing a ‘1’ to the BIASE bit in register REF0CN; see SFR Defini-
tion 6.1 for REF0CN register details. The Reference bias generator (see Figure 6.1) is used by the Internal
Voltage Reference, Temperature Sensor, and Clock Multiplier. The Reference bias is automatically
enabled when any of the aforementioned peripherals are enabled. The electrical specifications for the volt-
age reference and bias circuits are given in Table 6.1.
Important Note About the VREF Pin: The VREF pin, when not using the on-chip voltage reference or an
external pr ec isio n r e fer e nce , ca n be co n fig ur ed a s a G PIO Po rt pin. When u sin g an e xte r na l vo ltage ref er-
ence or the on-ch ip refe rence, th e VREF pin should be con figured as analog p in and ski ppe d by the Digit al
Crossbar. To configure the VREF pin for analog mode, set the corresponding bit in the PnMDIN register to
‘0’. To configure the Crossbar to skip the VREF pin, set the corresponding bit in register PnSKIP to ‘1’.
Refer to Section “15. Port Input/Output” on page 142 for complete Port I/O configuration details.
The temperature sensor con nect s to the ADC0 positive inp ut multiplexer (see Section “5.1. Analog Multi-
plexer” on page 42 for details). The TEMPE bit in register REF0CN enables/disables the temperature
sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0 mea-
surements performed on the sensor resu lt in meaningless data.
Figure 6.1. Voltage Reference Functional Block Diagram
VREF
(to ADC)
To An al og Mux
VDD
VREF
R1
VDD External
Voltage
Reference
Circuit
GND
Temp Sensor
EN
0
1
REF0CN
REFSL
TEMPE
BIASE
REFBE
REFBE
Internal
Reference
EN
Reference
Bias
EN
CLKMUL
Enable
TEMPE To Cloc k Multiplier,
Temp Sensor
ADC Bias To ADC,
Intern al Oscilla tor
EN
IOSCEN
AD0EN
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
58 Rev. 1.3
SFR Definition 6.1. REF0CN: Reference Control
Table 6.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V; –40 to +85 °C Unless Otherwise Specified
Parameter Conditions Min Typ Max Units
Internal Reference (REFBE = 1)
Output Voltage 25 °C ambient 2.38 2.44 2.50 V
VREF Short-Circuit Current 10 mA
VREF Temperature Coeffi-
cient 15 ppm/°C
Load Regulation Load = 0 to 200 µA to GND 1.5 ppm/µA
VREF Turn-on Time 1 4.7 µF tantalum, 0.1 µF ceramic
bypass 2ms
VREF Turn-on Time 2 0.1 µF ceramic bypass 20 µs
VREF Turn-on Time 3 no bypass cap 10 µs
Power Supply Rejection 140 ppm/V
External Refere nc e (REF BE = 0)
Input Voltage Range 0 VDD V
Input Current Sample Rate = 200 ksps; VREF =
3.0 V 12 µA
Bias Generators
ADC Bias Generator BIASE = ‘1’ 100 µA
Reference Bias Generator 40 µA
Bits7–3: UNUSED. Read = 00000b; Write = don’t care.
Bit3: REFSL: Voltage Reference Select.
This bit selects the source for the internal voltage reference.
0: VREF pin used as voltage reference.
1: VDD used as voltage referenc e.
Bit2: TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor off.
1: Internal Temperature Sensor on.
Bit1: BIASE: Internal Analog Bias Generator Enable Bit.
0: Internal Bias Generator off.
1: Internal Bias Generator on.
Bit0: REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer disabled.
1: Internal Reference Buffer enabled. Internal voltage reference driven on the VREF pin.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - REFSL TEMPE BIASE REFBE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 59
7. Comparators
C8051F34x devices include two on -chip progr amm able voltage Comp ara tors. A block diagr am of the com -
parators is shown in Figure 7.1, where “n” is the comparator number (0 or 1). The two Comparators oper-
ate identically with the following exceptions: (1) Their input selections differ, and (2) Comparator0 can be
used as a reset source. For input selection details, refer to SFR Definition 7.2 an d SFR Definition 7.5.
Each Comp arator of fers p rogrammable re sponse time a nd hysteresis, an an alog input multip lexer, and two
outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an
asynchronous “raw” output (CP0A, CP1A). The asynchronous signal is available even when the system
clock is not active. This allows the Comparators to operate and generate an output with the device in
STOP mode. When assigned to a Port pin, the Comparator outputs may be configured as open drain or
push-pull (see Secti on “15. 2. Port I/O Initialization” on page 147). Comparator0 may also be used as a
reset source (s ee Section “11.5. Comparator0 Reset” on page 103).
The Compara tor0 input s are se lected in the CPT0 MX register (SFR Definition 7.2). The CMX0P1-CMX0P0
bits select the Comparator0 positive input; the CMX0N1-CMX0N0 bits select the Comparator0 negative
input. The Comparator1 inputs are selected in the CPT1MX register (SFR Definition 7.5). The CMX-
1P1-CMX1P0 bits select the Comparator1 positive input; the CMX1N1-CMX1N0 bits select the Compara-
tor1 negative input.
Important Note About Comparator Inputs: The Port pins selected as Comparator inputs should be con-
figured as analog inputs in their associated Port configuration register, and configured to be skipped by the
Crossbar (for details on Port configuration, see Section “15.3. General Purpose Port I/O” on page 150).
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
60 Rev. 1.3
Figure 7.1. Comparator Functional Block Diagram
Comparator outputs can be polled in software, used as an interrupt source, and/or routed to a Port pin.
When routed to a Port pin, Comparator outputs are available asynchronous or synchronous to the system
clock; the asynchronous output is available even in STOP mode (with no system clock active). When dis-
abled, the Compar ator output ( if assigne d to a Port I/O pin via the Cr ossbar ) defaults to the logic low state,
and supply current falls to less than 100 nA. See Section “15.1. Priority Crossbar Decoder” on
page 144 for details on configuring Comp arator outputs via the digital Crossbar. Comparator inputs can be
externally driven from –0.25 V to (VDD) + 0.25 V without damage or up set. The comple te Comparator ele c-
trical specifications are given in Table 7.1.
Comparator response time may be configured in software via the CPTnMD registers (see SFR Definition
7.3 and SFR Definition 7.6). Selecting a longer response time reduces the Compar ator supply curre nt. See
Table 7.1 for complete timing and supply current specifications.
VDD
CPTnCN
Reset Decision Tree
(Comprator 0 Only)
+
- Crossbar
Interrupt
Logic
Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
(SYNCHRONIZER)
GND
CPn +
CPn -
CPnEN
CPnOUT
CPnRIF
CPnFIF
CPnHYP1
CPnHYP0
CPnHYN1
CPnHYN0
CPTnMD
CPnRIE
CPnFIE
CPnMD1
CPnMD0
CPn
CPnA
CPn
Rising-edge CPn
Falling-edge
CPn
Interrupt
CPnRIE
CPnFIE
CPTnMX
CMXnN1
CMXnN0
CMXnP1
CMXnP0
CMXnN2
CMXnP2
Port I/O connection options vary with
package (32-pin or 48-pin)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 61
Figure 7.2. Comparator Hysteresis Plot
Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN (shown
in SFR Definition 7.1 and SFR Definition 7.4). The amount of negative hysteresis voltage is determined b y
the settings of the CPnHYN bits. As shown in Figure 7.2, various levels of negative hysteresis can be
programmed, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is
determined by the setting the CPnHYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Inter-
rupt enable and prior ity control, see Section “9.3. Int errupt Handler” on p a ge 88.) The CPnFIF flag is set
to ‘1’ upon a Comparator falling-edge, and the CPnRIF flag is set to ‘1’ upon the Comparator rising-edge.
Once set, these bits remain set until cleared by software. The output state of the Comparator can be
obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to
‘1’, and is disabled by clearing this bit to ‘0’.
Positiv e Hy ste r esi s V olt ag e
(Programmed with CP0HYP Bits)
Negative Hyster esi s Voltage
(Programmed by CP0HYN Bits)
VIN-
VIN+
INPUTS
CIRCUIT CONFI GURATION
+
_
CP0+
CP0- CP0
VIN+
VIN- OUT
V
OH
Positiv e Hy ste r esi s
Disabled Maximum
Positive Hy steres is
Negative Hysteresis
Disabled Maximum
Negative Hysteresis
OUTPUT
V
OL
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
62 Rev. 1.3
SFR Definition 7.1. CPT0CN: Comparator0 Control
Bit7: CP0EN: Comparator0 En ab le Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6: CP0OUT: Comparator 0 Ou tp ut State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Bit5: CP0RIF: Comparator 0 Risin g-Ed ge Fla g.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
Bit4: CP0FIF: Comparator0 Falling-Edge Flag.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge Interrupt has occurred.
Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP0HYN1–0: Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hyster esis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
R/W R R/W R/W R/W R/W R/W R/W Reset Value
CP0EN CP0OUT CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9B
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 63
SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection
Bit7: UNUSED. Read = 0b, Write = don’t care.
Bits6–4: CMX0N2–CMX0N0: Comparator0 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator0 negative input.
Bit3: UNUSED. Read = 0b, Write = don’t care.
Bits2–0: CMX0P2–CMX0P0: Comparator0 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator0 positive input.
Note that the port pins used by the comparator depend on the package type (32-pin or 48-pin).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- CMX0N2 CMX0N1 CMX0N0 - CMX0P2 CMX0P1 CMX0P0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9F
CMX0N1 CMX0N1 CMX0N0 Negative Input
(32-pin Package) Negative Input
(48-pin Package)
0 0 0 P1.1 P2.1
0 0 1 P1.5 P2.6
0 1 0 P2.1 P3.5
0 1 1 P2.5 P4.4
1 0 0 P0.1 P0.4
CMX0P1 CMX0P1 CMX0P0 Positive Input
(32-pin Package) Positive Input
(48-pin Package)
000 P1.0 P2.0
001 P1.4 P2.5
010 P2.0 P3.4
011 P2.4 P4.3
100 P0.0 P0.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
64 Rev. 1.3
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection
Bits7–6: UNUSED. Read = 00b. Write = don’t care.
Bit5: CP0RIE: Comparator0 Rising-Edge Interrupt Enable.
0: Comparator0 rising-edge interrupt disabled.
1: Comparator0 rising-edge interrupt enabled.
Bit4: CP0FIE: Comparator0 Falling-Edge Interrupt Enable.
0: Comparator0 falling-edge interrupt disabled.
1: Comparator0 falling-edge interrupt enabled.
Bits3–2: UNUSED. Read = 00b. Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits select the response time for Comparator0.
* See Table 7.1 for response time parameters.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - CP0RIE CP0FIE - - CP0MD1 CP0MD0 00000010
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9D
Mode CP0MD1 CP0MD0 CP0 Response Time*
0 0 0 Fastest Response
101
210
311 Lowest Power
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 65
SFR Definition 7.4. CPT1CN: Comparator1 Control
Bit7: CP1EN: Comparator1 En ab le Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
Bit6: CP1OUT: Comparator 1 Ou tp ut State Flag.
0: Voltage on CP1+ < CP1–.
1: Voltage on CP1+ > CP1–.
Bit5: CP1RIF: Comparator 1 Risin g-Ed ge Fla g.
0: No Comparator1 Rising Edge has occurred since this flag was last cleared.
1: Comparator1 Rising Edge has occurred.
Bit4: CP1FIF: Comparator1 Falling-Edge Flag.
0: No Comparator1 Falling-Edge has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge has occurred.
Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP1HYN1–0: Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hyster esis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
R/W R R/W R/W R/W R/W R/W R/W Reset Value
CP1EN CP1OUT CP1RIF CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9A
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
66 Rev. 1.3
SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection
Bit7: UNUSED. Read = 0b, Write = don’t care.
Bits6–4: CMX1N2–CMX1N0: Comparator1 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator1 negative input.
Bit3: UNUSED. Read = 0b, Write = don’t care.
Bits2–0: CMX1P1–CMX1P0: Comparator1 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator1 positive input.
Note that the port pins used by the comparator depend on the package type (32-pin or 48-pin).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- CMX1N2 CMX1N1 CMX1N0 - CMX1P2 CMX1P1 CMX1P0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9E
CMX1N2 CMX1N1 CMX1N0 Negative Input
(32-pin Package) Negative Input
(48-pin Package)
000 P1.3 P2.3
001 P1.7 P3.1
010 P2.3 P4.0
011 P2.7 P4.6
100 P0.5 P1.2
CMX1P2 CMX1P1 CMX1P0 Positive Input
(32-pin Package) Positive Input
(48-pin Package)
0 0 0 P1.2 P2.2
0 0 1 P1.6 P3.0
0 1 0 P2.2 P3.7
0 1 1 P2.6 P4.5
1 0 0 P0.4 P1.1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 67
SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit5: CP1RIE: Comparator1 Rising-Edge Interrupt Enable.
0: Comparator1 rising-edge interrupt disabled.
1: Comparator1 rising-edge interrupt enabled.
Bit4: CP1FIE: Comparator1 Falling-Edge Interrupt Enable.
0: Comparator1 falling-edge interrupt disabled.
1: Comparator1 falling-edge interrupt enabled.
Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select.
These bits select the response time for Comparator1.
* See Table 7.1 for response time parameters.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - CP1RIE CP1FIE - - CP1MD1 CP1MD0 00000010
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x9C
Mode CP1MD1 CP1MD0 CP1 Response Time*
0 0 0 Fastest Response
101
210
311 Lowest Power
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
68 Rev. 1.3
Table 7.1. Comparator Electrical Characteristics
VDD = 3.0 V, –40 to +85 °C unless otherw is e no t ed .
All specifications apply to both Comparator0 and Comparator1 unless otherwise noted.
Parameter Conditions Min Typ Max Units
Response Time:
Mode 0, Vcm* = 1.5 V CP0+ – CP0– = 100 mV 100 ns
CP0+ – CP0– = –100 mV 250 ns
Response Time:
Mode 1, Vcm* = 1.5 V CP0+ – CP0– = 100 mV 175 ns
CP0+ – CP0– = –100 mV 500 ns
Response Time:
Mode 2, Vcm* = 1.5 V CP0+ – CP0– = 100 mV 320 ns
CP0+ – CP0– = –100 mV 1100 ns
Response Time:
Mode 3, Vcm* = 1.5 V CP0+ – CP0– = 100 mV 1050 ns
CP0+ – CP0– = –100 mV 5200 ns
Common-Mode Rejection
Ratio 1.5 4mV/V
Positive Hysteresis 1 CP0HYP1–0 = 00 0 1 mV
Positive Hysteresis 2 CP0HYP1–0 = 01 2 5 10 mV
Positive Hysteresis 3 CP0HYP1–0 = 10 710 20 mV
Positive Hysteresis 4 CP0HYP1–0 = 11 15 20 30 mV
Negative Hysteresis 1 CP0HYN1–0 = 00 0 1 mV
Negative Hysteresis 2 CP0HYN1–0 = 01 2 5 10 mV
Negative Hysteresis 3 CP0HYN1–0 = 10 710 20 mV
Negative Hysteresis 4 CP0HYN1–0 = 11 15 20 30 mV
Inverting or Non-Inverting
Input Voltage Range –0.25 VDD + 0.25 V
Input Capacitance 3pF
Input Bias Current 0.001 nA
Input Offset Voltage –5 +5 mV
Power Supply
Power Supply Rejection 0.1 mV/V
Power-up Time 10 µs
Supply Current at DC
Mode 0 7.6 µA
Mode 1 3.2 µA
Mode 2 1.3 µA
Mode 3 0.4 µA
*Note: Vcm is the common-mode voltage on CP0+ and CP0–.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 69
8. Voltage Regulator (REG0)
C8051F34x devices include a voltage regulator (REG0). When enabled, the REG0 output appears on the
VDD pin and can be us ed to power extern al devices . REG0 can be enab led/disab led by software using bit
REGEN in register REG0CN. See Table 8.1 for REG0 electrical characteristics.
Note that the VBUS signal must be connected to the VBUS pin when using the device in a USB network.
The VBUS signal should only be conn ected to the REGIN pin when ope rating the device as a bu s-powered
function. REG0 configuration options are shown in Figure 8.1–Figure 8.4.
8.1. Regulator Mode Selection
REG0 offers a low power mode intended for use when the device is in suspend mode. In this low power
mode, the REG0 output remain s as specified; ho wever the REG0 dynami c perfor mance (respo nse time) is
degraded. See Table 8.1 for normal and low power mode supply current specifications. The REG0 mode
selection is controlled via the REGMOD bit in register REG0CN.
8.2. VBUS Detection
When the USB Function Controller is used (see section Section “16. Universal Serial Bus Controller
(USB0)” on page 159), the VBUS signal should be connected to the VBUS pin. The VBSTAT bit (register
REG0CN) indicates the current logic level of the VBUS signal. If enabled, a VBUS interrupt will be gener-
ated when the VBUS signal matches the polarity selected by the VBPOL bit in register REG0CN. The
VBUS interrupt is level-sensitive, and has no associated interrupt pending flag. The VBUS interrupt will be
active as long a s th e VBUS s ign al ma tches the polarity selected by VBPOL. See Table 8.1 for VBUS input
parameters.
Important Note: When USB is selected as a reset source, a system reset will be generated when the
VBUS signal matches the polarity selected by the VBPOL bit. See Section “11. Reset Sources” on
page 100 for details on selecting USB as a reset source
Table 8.1. Voltage Regulator Electrical Specifications
–40 to +85 °C unless ot herwise specified.
Parameter Conditions Min Typ Max Units
Input Voltage Range12.7 5.25 V
Output Voltage (VDD)2Output Current = 1 to 100 mA 3.0 3.3 3.6 V
Output Current2100 mA
VBUS Detection Input Low Voltage 1.0 V
VBUS Detection Input High Voltage 3.0 V
Bias Current Normal Mode (REGMOD = ‘0’)
Low Power Mode (REGMOD = ‘1’) 65
35 111
61 µA
Dropout Voltage (VDO)31mV/mA
Notes:
1. Input range specified for regulation. When an external regulator is used, should be tied to VDD.
2. Output current is total regulator output, includi ng any current required by the C8051F34x.
3. The minimum input voltage is 2.70 V or VDD + VDO (max load), whichever is greater.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
70 Rev. 1.3
Figure 8.1. REG0 Configuration: USB Bus-Powered
Figure 8.2. REG0 Configuration: USB Self-Powered
Voltage Regulator (REG 0)5 V In
3 V Out
VBUS Sense
REGIN
VBUS
From VBUS
To 3 V
Power Net Device
Power Net
VDD
Voltage Regu lator (REG0)5 V In
3 V O ut
VBUS Sense
REGIN
VBUS
To 3 V
Power Net Device
Power Net
VDD
From 5 V
Power Net
From VBUS
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 71
Figure 8.3. REG0 Configuration: USB Self-Powered, Regulator Disabled
Figure 8.4. REG0 Configuration: No USB Connection
Voltage Regu lator (REG0)5 V In
3 V O ut
VBUS Sense
REGIN
VBUS
From 3 V
Power Net Device
Power Net
VDD
From VBUS
Voltage Regulator (REG 0)5 V In
3 V Out
VBUS Sense
REGIN
VBUS
To 3 V
Power Net Device
Power Net
VDD
From 5 V
Power Net
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
72 Rev. 1.3
SFR Definition 8.1. REG0CN: Voltage Regulator Control
Bit7: REGDIS: Voltage Regulator Disable.
0: Voltage Regulator Enabled.
1: Voltage Regulator Disabled.
Bit6: VBSTAT: VBUS Signal Status.
0: VBUS signal currently absent (device not attached to USB network).
1: VBUS signal currently present (device attached to USB network).
Bit5: VBPOL: VBUS Interrupt Polarity Select.
This bit selects the VBUS interrupt polarity.
0: VBUS interrupt active when VBUS is low.
1: VBUS interrupt active when VBUS is high.
Bit4: REGMOD: Voltage Regulator Mode Select.
This bit selects the Voltage Regulator mode. When REGMOD is set to ‘1’, the voltage regu-
lator operates in low power (suspend) mode.
0: USB0 Voltage Regulator in normal mode.
1: USB0 Voltage Regulator in low power mode.
Bits3–0: Reserved. Read = 0000b. Must Write = 0000b.
R/W R R/W R/W R/W R/W R/W R/W Reset Value
REGDIS VBSTAT VBPOL REGMOD Reserved Reserved Reserved Reserved 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC9
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 73
9. CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop soft-
ware. The MCU family has a superset of all the peripherals included with a standard 8051. Included are
four 16-bit counter/timers (see description in Section 21), an enhanced full-duplex UART (see description
in Section 18), an Enhanced SPI (see description in Section 20), 256 bytes of internal RAM, 128 byte
Sp ecial Function Register (SFR) address space (Section 9.2.6), and 25 Port I/O (see description in Sec-
tion 15). The CIP-51 al so includes on-chip debug hardware (see description in Se ction 23) , and inter faces
directly with the analog and digital subsystems providing a complete data acquisition or control-system
solution in a single integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 9.1 for a block diagram).
The CIP-51 includes the following features:
Figure 9.1. CIP-51 Block Diagram
- Fully Compatible with MCS-51 Instr uc tio n
Set
- 0 to 48 MHz Clock Freq uency
- 256 Bytes of Internal RAM
- 25 Port I/O
- Extended Interrupt Handler
- Reset Input
- Power Management Modes
- On-chip Debug Logic
- Program and Data Memory Security
DATA BUS
TMP1 TMP2
PRGM. ADDRESS REG.
PC INCREMENTER
ALU
PSW
DATA BUS
DATA B US
MEMORY
INTERFACE
MEM_ADDRESS
D8
PIPELINE
BUFFER
DATA POINTER
INTERRUPT
INTERFACE
SYSTEM_IRQs
EMULATION_IRQ
MEM_CONTROL
CONTROL
LOGIC
A16
PROGRAM COUNTER (PC)
STOP
CLOCK
RESET
IDLE POWER CONTROL
REGISTER
DATA BUS
SFR
BUS
INTERFACE
SFR_ADDRESS
SFR_CONTROL
SFR_WRITE_DATA
SFR_READ_DATA
D8
D8
B REGISTER
D8
D8
ACCUMULATOR
D8
D8
D8
D8
D8
D8
D8
D8
MEM_WRITE_DATA
MEM_READ_DATA
D8
SRAM
ADDRESS
REGISTER
SRAM
(256 X 8)
D8
STACK POINTER
D8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
74 Rev. 1.3
Performance
The CIP-51 emplo ys a p ipeli ned architectu re tha t grea tly increases it s instr uction throug hput over the st an-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has
a total of 109 instructions. The table below shows the total number of instructions that for execution time.
Programming and Debugging Support
In-system programming of the Flash program memory and communication with on-chip debug support
logic is accomplished via the Silicon Labs 2-Wire Development Interface (C2). Note that the re-program-
mable Flash can also be read and changed a single byte at a time by the application software using the
MOVC and M OVX instr uctions. This fe ature allows prog ram m emory to be us ed for non-vola tile data stor -
age as well as updating program code under software control.
The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in th e final app lication. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging with-
out occupying package pins. C2 details can be found in Section “23. C2 Interface” on page 271.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs pro-
vides an integrated development environment (IDE) including editor, debugger, and programmer. The
IDE's debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient
in-system device programming and debugging. An 8051 assembler, linker and evaluation ‘C’ compiler are
included in the Development Kit. Many third party macro assemblers and C compilers are also available,
which can be used directly with the IDE.
9.1. Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruc-
tion set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the stan-
dard 8051.
9.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as th ere are program byte s in the instruction. Conditional branch instructions take two fewer clock
cycles to complete when the branch is not taken as opposed to when the branch is taken. Table 9.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
Clocks to Execute 1 2 2/4 33/5 4 5 4/6 6 8
Number of Instructions 26 50 510 752121
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 75
9.1.2. MOVX Instruction and Program Memory
In the CIP-51, the M OVX instruction serves thre e purposes: accessing on-chip XRAM, accessing off-chip
data XRAM (only on C8051F340/1/4/5/8 devices), and accessing on-chip program Flash memory. The
Flash access feature provides a mechanism for user software to update program code and use the pro-
gram memory space for non-volatile data storage (see Section “12. Flash Memory” on page 107). The
External Memory Interface (only on C8051F340/1/4/5/8 devices) provides a fast access interface to
off-chip data XRAM (or memory-mapped peripherals) via the MOVX instruction. Refer to Section
“13. External Data Memory Interface and On-Chip XRAM” on page 114. for details.
Table 9.1. CIP-51 Instruction Set Summary
Mnemonic Description Bytes Clock
Cycles
Arithmetic Operations
ADD A, Rn Add register to A 1 1
ADD A, direct Add direct byte to A 2 2
ADD A, @Ri Add indirect RAM to A 1 2
ADD A, #data Add immediate to A 2 2
ADDC A, Rn Add register to A with carry 1 1
ADDC A, direct Add direct byte to A with carry 2 2
ADDC A, @Ri Add indirect RAM to A with carry 1 2
ADDC A, #data Add immediate to A with carry 2 2
SUBB A, Rn Subtract register fro m A with bo rr ow 1 1
SUBB A, direct Subtract direct byte from A with borrow 2 2
SUBB A, @Ri Subtract indirect RAM from A with borrow 1 2
SUBB A, #data Subtract immedia te fro m A with bo rrow 2 2
INC A Increment A 1 1
INC Rn Increment register 1 1
INC direct Increment direct byte 2 2
INC @Ri Increment indirect RAM 1 2
DEC A Decrement A 1 1
DEC Rn Decrement regis te r 1 1
DEC direct Decrement direc t byt e 2 2
DEC @Ri Decrement indirect RAM 1 2
INC DPTR Increment Data Pointer 1 1
MUL AB Multiply A and B 1 4
DIV AB Divide A by B 1 8
DA A Decimal adjust A 1 1
Logical Operations
ANL A, Rn AND Register to A 1 1
ANL A, direct AND direct byte to A 2 2
ANL A, @Ri AND indirect RAM to A 1 2
ANL A, #data AND immediate to A 2 2
ANL direct, A AND A to direct byte 2 2
ANL direct, #data AND immediate to direct byte 3 3
ORL A, Rn OR Register to A 1 1
ORL A, direct OR direct byte to A 2 2
ORL A, @Ri OR indirect RAM to A 12
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
76 Rev. 1.3
ORL A, #data OR immediate to A 2 2
ORL direct, A OR A to direct byte 2 2
ORL direct, #d ata OR immediate to direct byte 3 3
XRL A, Rn Exclusive-OR Register to A 1 1
XRL A, direct Exclusive-OR direct byte to A 2 2
XRL A, @Ri Exclusive-OR indirect RAM to A 1 2
XRL A, #data Exclusive-OR immediate to A 2 2
XRL direct, A Exclusive-OR A to direct byte 2 2
XRL direct, #data Exclusive-OR immediate to direct byte 3 3
CLR A Clear A 1 1
CPL A Complement A 1 1
RL A Rotate A left 1 1
RLC A Rotate A left through Carry 1 1
RR A Rotate A right 1 1
RRC A Rotate A right through Carry 1 1
SWAP A Swap nibbles of A 1 1
Data Transfer
MOV A, Rn Move Register to A 1 1
MOV A, direct Move direct byte to A 2 2
MOV A, @Ri Move indirect RAM to A 1 2
MOV A, #data Move immediate to A 2 2
MOV Rn, A Move A to Register 1 1
MOV Rn, direct Move direct byte to Register 2 2
MOV Rn, #data Move immediate to Register 2 2
MOV direct, A Move A to direct byte 2 2
MOV direct, Rn Move Register to direct byte 2 2
MOV direct, direct Move direct byte to direct byte 3 3
MOV direct, @Ri Move indirect RAM to direct byte 2 2
MOV direct, #data Move immedi ate to direct byte 3 3
MOV @Ri, A Move A to indirect RAM 1 2
MOV @Ri, direct Move direct byte to indirect RAM 2 2
MOV @Ri, #data Move immediate to indirect RAM 2 2
MOV DPTR, #data16 Load DPTR with 16-bit constant 3 3
MOVC A, @A+DPTR Move code byte relative DPTR to A 1 3
MOVC A, @A+PC Move code byte relative PC to A 1 3
MOVX A, @Ri Move external data (8-bit addre ss) to A 1 3
MOVX @Ri, A Move A to external data (8-bit address) 1 3
MOVX A, @DPTR Move external data (16-bi t address) to A 1 3
MOVX @DPTR, A Move A to external data (16-bit address) 1 3
PUSH direct Push direct byte onto stack 2 2
POP direct Pop direct byte from stack 2 2
XCH A, Rn Exchange Register with A 1 1
XCH A, direct Exchange direct byte with A 2 2
XCH A, @Ri Exchange indirect RAM with A 1 2
XCHD A, @Ri Exchange low nibble of indirect RAM with A 1 2
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic Description Bytes Clock
Cycles
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 77
Boolean Manipulation
CLR C Clear Carry 1 1
CLR bit Clear direct bit 2 2
SETB C Set Carry 1 1
SETB bit Set direct bit 2 2
CPL C Complement Carry 1 1
CPL bit Complement direct bit 2 2
ANL C, bit AND direct bit to Carry 2 2
ANL C, /bit AND complement of direct bit to Carry 2 2
ORL C, bit OR direct bit to carry 2 2
ORL C, /bit OR complement of direct bit to Carry 2 2
MOV C, bit Move direct bit to Carry 2 2
MOV bit, C Move Carry to dir ect bit 2 2
JC rel Jump if Carry is set 22/4
JNC rel Jump if Carry is not set 22/4
JB bit, rel Jump if direct bit is set 33/5
JNB bit, rel Jump if direct bit is not set 33/5
JBC bit, rel Jump if direct bit is set and clear bit 33/5
Program Branch ing
ACALL addr11 Absolute subroutine call 2 4
LCALL addr16 Long subroutine call 3 5
RET Return from subroutine 1 6
RETI Return from interrupt 1 6
AJMP addr11 Absolute jump 2 4
LJMP addr16 Long jump 3 5
SJMP rel Short jump (relative address) 2 4
JMP @A+DPTR Jump indirect relative to DPTR 1 4
JZ rel Jump if A equals zero 22/4
JNZ rel Jump if A does not equal zero 22/4
CJNE A, direct, rel Compare direct byte to A and jump if not equal 33/5
CJNE A, #data, rel Compare immedia te to A and jump if not equal 33/5
CJNE Rn, #data, rel Compare immediate to Register an d jump if not equal 33/5
CJNE @Ri, #data, rel Compare immediate to indirect and jump if not equal 34/6
DJNZ Rn, rel Decrement Register and jump if not zero 22/4
DJNZ direct, rel Decrement direct byte and jump if not zero 33/5
NOP No operation 1 1
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic Description Bytes Clock
Cycles
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
78 Rev. 1.3
Notes on Registers, Oper ands and Addressing Mode s:
Rn - Register R0-R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly th rough R0 or R1.
rel - 8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location
(0x00-0x7F) or an SFR (0x80-0xFF).
#data - 8-bit constant
#data16 - 16-bit constant
bit - Direct-accessed bit in Data RAM or SFR
addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same
2K-byte page of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by L CALL and LJMP. The destination ma y be anywhere within
the 8K-byte program memory sp ace.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 79
9.2. Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same addres s space but are ac cessed via different instruction types. The CIP-51 memory organization is
shown in Figure 9.2 and Figure 9.3.
Figure 9.2. On-Chip Memory Map for 64 kB Devices
PROGRAM/DATA MEMORY
(FLASH)
(Direct and Indirect
Addressing)
0x00
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
0x80
0xFF Special Function
Register's
(Direct Addressing Only)
DATA MEMORY (RAM)
General Purpose
Registers
0x1F
0x20
0x2F Bit Addressable
Lower 128 RAM
(Direct and Indirect
Addressing)
0x30
INTERNAL DATA ADDRESS SPACE
EXTERNAL DATA ADDRESS SPACE
XRAM - 4096 Bytes
(Accessable us ing MOVX
instruction)
0x0000
0x0FFF
Off-Chip XRAM
(Available only on devices
with EMIF)
0x0400
0xFFFF
FLASH
(In-System
Programmable in 512
Byte Sectors)
0x0000
RESERVED
0xFC00
0xFBFF
USB FIFOs
1024 Bytes
0x07FF
0x1000
0xFFFF
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
80 Rev. 1.3
Figure 9.3. On-Chip Memory Map for 32 kB Devices
9.2.1. Program Memory
The CIP-51 core has a 64k-byte program memory space. The C8051F34x implements 64k or 32k bytes of
this program memory space as in-system, re-programmable Flash memory. Note that on the 64k versions
of the C8051F34x, addresses above 0xFBFF are reserved.
Program memory is nor mally assumed to be re ad-only. However, the CIP-51 can wr ite to pro gram m emory
by setting the Program S tore Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature pro-
vides a mechanism for the CIP-51 to update program code and use the program memory space for
non-volatile data storage. Refer to Section “12. Flash Memory” on page 107 for further details.
PROGRAM/DATA M EM O R Y
(FLASH)
(Direct and Indirect
Addressing)
0x00
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
0x80
0xFF Special Function
Register's
(Direct Addressing Only)
DATA MEMORY (RAM)
General Purpose
Registers
0x1F
0x20
0x2F Bit Addressable
Lower 128 RAM
(Direct and Indirect
Addressing)
0x30
INTERNAL DATA ADDRESS SPACE
EXTERNAL DATA ADDRESS SPACE
XRAM - 2048 By tes
(Accessable using MOVX
instruction)
0x0000
0x07FF
Off-Chip XRAM
(Available only on devices
with EMIF)
0x0400
0xFFFF
FLASH
(In-System
Programmable in 512
Byte Sectors)
0x0000
0x7FFF
USB FIFOs
1024 Bytes
0x07FF
0x0800
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 81
9.2.2. Data Memory
The CIP-51 includes 256 of internal RAM mapped into the data memory space from 0x00 through 0xFF.
The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory.
Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations
0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of
eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as
bytes or as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory ar e acce ssible on ly by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFR) but is physically separate from the SFR
space. The addressing mode used by an instruction when accessing locations above 0x7F determines
whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use
direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the
upper 128 bytes of data memory. Figure 9.2 illustrates the data memory organization of the CIP-51.
9.2.3. General Purpose Registers
The lower 32 bytes of dat a memory, locations 0x00 through 0x1F, may be addressed as four b anks of gen-
eral-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only
one of these banks may be enabled at a time. Two bits in the program st atus wo rd , RS0 (PSW.3) and RS1
(PSW.4), select the active register bank (see description of the PSW in SFR Definition 9.4). This allows
fast context switching when entering subr outin es and interrupt se rvice routines. Indir ect addressin g modes
use registers R0 and R1 as index registers.
9.2.4. Bit Addressable Locations
In addition to direct access to d ata memory or gan ized as bytes, the sixteen data memory location s at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of th e byte at 0x20 ha s bit address 0x 00 while bit7 o f the byte at 0x20 has bit addre ss
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destina-
tion).
The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where
XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV C, 22h.3
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
9.2.5. Stack
A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is desig-
nated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of re gister bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for dat a storage . Th e stack depth can exte nd up
to 256 bytes.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
82 Rev. 1.3
9.2.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional
SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 9.2 lists the SFRs imple-
mented in the CIP-51 System Controller.
The SFR regist ers are access ed anytime the direct a ddressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are
bit-addressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied
addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate
effect an d should be avoided . Refer to the cor respond ing pa ges of the dat asheet, as indicated in Table 9.3,
for a detailed description of ea ch reg ist er.
Table 9.2. Special Function Register (SFR) Memory Map
F8 SPI0CN PCA0L PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4 PCA0CPH4 VDM0CN
F0 B P0MDIN P1MDIN P2MDIN P3MDIN P4MDIN EIP1 EIP2
E8 ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3 RSTSRC
E0 ACC XBR0 XBR1 XBR2 IT01CF SMOD1 EIE1 EIE2
D8 PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 P3SKIP
D0 PSW REF0CN SCON1 SBUF1 P0SKIP P1SKIP P2SKIP USB0XCN
C8 TMR2CN REG0CN TMR2RLL TMR2RLH TMR2L TMR2H - -
C0 SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH P4
B8 IP CLKMUL AMX0N AMX0P ADC0CF ADC0L ADC0H -
B0 P3 OSCXCN OSCICN OSCICL SBRLL1 SBRLH1 FLSCL FLKEY
A8 IE CLKSEL EMI0CN - SBCON1 - P4MDOUT PFE0CN
A0 P2 SPI0CFG SPI0CKR SPI0DAT P0MDOUT P1MDOUT P2MDOUT P3MDOUT
98 SCON0 SBUF0 CPT1CN CPT0CN CPT1MD CPT0MD CPT1MX CPT0MX
90 P1 TMR3CN TMR3RLL TMR3RLH TMR3L TMR3H USB0ADR USB0DAT
88 TCON TMOD TL0 TL1 TH0 TH1 CKCON PSCTL
80 P0 SP DPL DPH EMI0TC EMI0CF OSCLCN PCON
0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F)
(bit addressable)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 83
Table 9.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address Description Page
ACC 0xE0 Accumulator 87
ADC0CF 0xBC ADC0 Configuration 50
ADC0CN 0xE8 ADC0 Control 51
ADC0GTH 0xC4 ADC0 Greate r- Th a n Co mpare High 52
ADC0GTL 0xC3 ADC0 Greate r- Th a n Co mpare Lo w 52
ADC0H 0xBE ADC0 High 50
ADC0L 0xBD ADC0 Low 50
ADC0LTH 0xC6 ADC0 Less-Than Compare Word High 53
ADC0LTL 0xC5 ADC0 Less-Than Compare Word Low 53
AMX0N 0xBA AMUX0 Negative Channel Select 49
AMX0P 0xBB AMUX0 Positive Channel Select 48
B0xF0 B Register 88
CKCON 0x8E Clock Control 241
CLKMUL 0xB9 Clock Multiplier 138
CLKSEL 0xA9 Clock Select 140
CPT0CN 0x9B Comparator0 Control 62
CPT0MD 0x9D Comparator0 Mode Selection 64
CPT0MX 0x9F Comparator0 MUX Selection 63
CPT1CN 0x9A Comparator1 Control 65
CPT1MD 0x9C Comparator1 Mode Selection 67
CPT1MX 0x9E Comparator1 MUX Selection 66
DPH 0x83 Data Pointer High 86
DPL 0x82 Data Pointer Low 86
EIE1 0xE6 Extended Interrupt Enable 1 93
EIE2 0xE7 Extended Interrupt Enable 2 95
EIP1 0xF6 Extended Interrupt Priority 1 94
EIP2 0xF7 Extended Interrupt Priority 2 95
EMI0CN 0xAA External Memory Interface Control 117
EMI0CF 0x85 External Memory Interface Configuration 118
EMI0TC 0x84 External Memory Interface Timing 123
FLKEY 0xB7 Flash Lock an d Ke y 112
FLSCL 0xB6 Flash Scale 113
IE 0xA8 Interrupt Enable 91
IP 0xB8 Interrupt Priority 92
IT01CF 0xE4 INT0/INT1 Configuration 96
OSCICL 0xB3 Internal Oscillator Calibration 133
OSCICN 0xB2 Internal Oscillator Control 132
OSCLCN 0x86 Internal Low-Frequency Oscillator Control 134
OSCXCN 0xB1 External Oscillator Control 137
P0 0x80 Port 0 Latch 150
P0MDIN 0xF1 Port 0 Inpu t Mo de Con fig ur at ion 150
P0MDOUT 0xA4 Port 0 Output Mode Configuration 151
P0SKIP 0xD4 Port 0 Skip 151
P1 0x90 Port 1 Latch 152
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
84 Rev. 1.3
P1MDIN 0xF2 Port 1 Inpu t Mo de Con fig ur at ion 152
P1MDOUT 0xA5 Port 1 Output Mode Configuration 152
P1SKIP 0xD5 Port 1 Skip 153
P2 0xA0 Port 2 Latch 153
P2MDIN 0xF3 Port 2 Inpu t Mo de Con fig ur at ion 153
P2MDOUT 0xA6 Port 2 Output Mode Configuration 154
P2SKIP 0xD6 Port 2 Skip 154
P3 0xB0 Port 3 Latch 155
P3MDIN 0xF4 Port 3 Inpu t Mo de Con fig ur at ion 155
P3MDOUT 0xA7 Port 3 Output Mode Configuration 155
P3SKIP 0xDF Port 3Skip 156
P4 0xC7 Port 4 Latch 156
P4MDIN 0xF5 Port 4 Inpu t Mo de Con fig ur at ion 157
P4MDOUT 0xAE Port 4 Output Mode Configuration 157
PCA0CN 0xD8 PCA Control 266
PCA0CPH0 0xFC PCA Captur e 0 H igh 270
PCA0CPH1 0xEA PCA Capture 1 High 270
PCA0CPH2 0xEC PCA Capture 2 High 270
PCA0CPH3 0xEE PCA Capture 3High 270
PCA0CPH4 0xFE PCA Captur e 4 H igh 270
PCA0CPL0 0xFB PCA Captur e 0 Lo w 269
PCA0CPL1 0xE9 PCA Capture 1 Low 269
PCA0CPL2 0xEB PCA Capture 2 Low 269
PCA0CPL3 0xED PCA Capture 3 Low 269
PCA0CPL4 0xFD PCA Captur e 4 Lo w 269
PCA0CPM0 0xDA PCA Module 0 Mode Register 268
PCA0CPM1 0xDB PCA Module 1 Mode Register 268
PCA0CPM2 0xDC PCA Module 2 Mode Register 268
PCA0CPM3 0xDD PCA Module 3 Mode Register 268
PCA0CPM4 0xDE PCA Module 4 Mode Register 268
PCA0H 0xFA PCA Counter High 269
PCA0L 0xF9 PCA Counter Low 269
PCA0MD 0xD9 PCA Mode 267
PCON 0x87 Power Control 98
PFE0CN 0xAF Prefetch Engine Control 99
PSCTL 0x8F Program Store R/W Control 112
PSW 0xD0 Program Status Word 87
REF0CN 0xD1 Voltage Reference Control 58
REG0CN 0xC9 Voltage Regulator Control 72
RSTSRC 0xEF Reset Source Configuration/Status 105
SBCON1 0xAC UART1 Baud Rate Generator Control 220
SBRLH1 0xB5 UART1 Baud Rate Generator High 221
SBRLL1 0xB4 UART1 Baud Rate Generator Low 221
SBUF1 0xD3 UART1 Data Buffer 220
SCON1 0xD2 UART1 Contro l 218
Table 9.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address Description Page
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 85
SBUF0 0x99 UART0 Data Buffer 211
SCON0 0x98 UART0 Control 210
SMB0CF 0xC1 SMBus Configuration 194
SMB0CN 0xC0 SMBus Control 196
SMB0DAT 0xC2 SMBus Data 198
SMOD1 0xE5 UART1 Mode 219
SP 0x81 Stack Pointer 86
SPI0CFG 0xA1 SPI Configuration 229
SPI0CKR 0xA2 SPI Clock Rate Control 231
SPI0CN 0xF8 SPI Control 230
SPI0DAT 0xA3 SPI Data 231
TCON 0x88 Timer/Counter Control 239
TH0 0x8C Timer/Counter 0 High 242
TH1 0x8D Timer/Counter 1 High 242
TL0 0x8A Timer/Counter 0 Low 242
TL1 0x8B Timer/Counter 1 Low 242
TMOD 0x89 Timer/Counter Mode 240
TMR2CN 0xC8 Timer/Counter 2 Control 247
TMR2H 0xCD Timer/Counter 2 High 248
TMR2L 0xCC Timer/Counter 2 Low 248
TMR2RLH 0xCB Timer/Counter 2 Reload High 248
TMR2RLL 0xCA Timer/Counter 2 Reload Low 248
TMR3CN 0x91 Timer/Counter 3Control 253
TMR3H 0x95 Timer/Counter 3 High 254
TMR3L 0x94 Timer/Counter 3Low 254
TMR3RLH 0x93 Timer/Counter 3 Reload High 254
TMR3RLL 0x92 Timer/Counter 3 Reload Low 254
VDM0CN 0xFF VDD Monitor Control 102
USB0ADR 0x96 USB0 Indirect Address Register 163
USB0DAT 0x97 USB0 Data Register 164
USB0XCN 0xD7 USB0 Transceiver Control 161
XBR0 0xE1 Port I/O Crossbar Control 0 148
XBR1 0xE2 Port I/O Crossbar Control 1 149
XBR2 0xE3 Port I/O Crossbar Control 2 149
All Other Addresses Reserved
Table 9.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address Description Page
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
86 Rev. 1.3
9.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic l. Future product version s may use these bits to implement new feature s in which
case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of
the remaining SFRs are included in the sections of the datasheet associated with their corresponding sys-
tem function.
SFR Definition 9.1. DPL: Data Pointer Low Byte
SFR Definition 9.2. DPH: Data Pointer High Byte
SFR Definition 9.3. SP: Stack Pointer
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed memory.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x82
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed memory.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x83
Bits7–0: SP: Stack Pointer.
The S tack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x81
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 87
SFR Definition 9.4. PSW: Program Status Word
SFR Definition 9.5. ACC: Accumulator
Bit7: CY: Ca rry Flag .
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to logic 0 by all other arithmetic operations.
Bit6: AC: Auxiliary Carry Flag
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the h igh order nibble. It is cle ared to logic 0 by all othe r arithmetic operation s.
Bit5: F0: User Flag 0.
This is a bit-addressable, general purpo se flag for use under software control.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
Bit2: OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 b y the ADD, ADDC, SUBB, MUL, and DIV inst ructions in all other
cases.
Bit1: F1: User Flag 1.
This is a bit-addressable, general purpo se flag for use under software control.
Bit0: PARITY: Parity Flag.
This bit is set to logic 1 if the sum of the eight bi ts in the accumulator is odd and cleared if the
sum is even.
R/W R/W R/W R/W R/W R/W R/W R Reset Value
CY AC F0 RS1 RS0 OV F1 PARITY 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xD0
RS1 RS0 Register Bank Address
0 0 0 0x00 - 0x07
0 1 1 0x08 - 0x0F
1 0 2 0x10 - 0x17
1 1 3 0x18 - 0x1F
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xE0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
88 Rev. 1.3
SFR Definition 9.6. B: B Register
9.3. Interrupt Handler
The CIP-51 includes an extended interrupt system supporting multiple interrupt sources with two priority
levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies
according to the specific version of the device. Each interrupt source has one or more associated inter-
rupt-pending flag( s) located in an SFR. When a peripher al or external source mee t s a valid interrupt condi-
tion, the associated interrupt-pending flag is set to logic 1.
If interrupt s are ena bled for the sour ce, an interrupt req uest is generated when the inter rupt-pending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a prede-
termined address to begin executio n of an interrupt service ro utine (ISR). Each ISR must end with an RETI
instruction, which returns program execution to the next instruction that would have been executed if the
interrupt requ est had not occurred. If inter rupt s are not enabled, the inter rupt-pending flag is ignored by the
hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regard-
less of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in an SFR (IE-EIE2). However, interrupts must first be globally enabled by setting the EA bit
(IE.7) to logic 1 before the individual interr upt enables a re re cognized. Setting the EA bi t to logic 0 disab les
all interrupt sources regardless of the individual interrupt-enable settings.
Some interrupt-pending flags ar e auto matically cleare d by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by sof twar e before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
9.3.1. MCU Interrupt Sources and Vectors
The MCU supports multiple interrupt sources. Software can simulate an interrupt by setting any inter-
rupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and
the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources,
associated vector addresse s, priority order and control bits are summarized in Table 9.4 on page 90. Refer
to the datasheet section associated with a particular on-chip peripheral for information regarding valid
interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
9.3.2. External Interrupts
The INT0 and INT1 external interrupt sources are configurable as active high or low, edge or level sensi-
tive. The IN0PL (INT0 Polarity) and IN1PL (INT1 Polarity) bits in the IT01CF register select active high or
active low; the IT0 and IT 1 bits in TCON (Section “21.1. Timer 0 and Timer 1” on page 235) select level
or edge sensitive. The following table lists the possible configurations.
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
B.7 B.6 B.5 B.4 B.3 B.2 B.1 B.0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xF0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 89
INT0 and INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 9.13). Note
that INT0 and INT0 Port pin assignments are independent of any Crossbar assignments. INT0 and INT1
will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin via the
Crossbar. To assign a Port pin only to INT0 and/or INT1, configure the Crossba r to skip the selected pin(s).
This is accomplished by setting the asso ciated b it in re gister XBR0 (see Sec tion “1 5.1. Prior ity Crossbar
Decoder” on page 144 for complete details on configuring the Crossbar). In the typical configuration, the
external interrupt pin should be skipped in the crossbar and configured as open-drain with the pin latch set
to '1'.
IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the INT0 and INT1 external inter-
rupts, respectively. If an INT0 or INT1 external interrupt is co nfigu red as edge- se nsitive , the corre spon din g
interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When
configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined
by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The
external interrupt source must hold the input active until the interrupt request is recognized. It must then
deactivate the interrupt request before execution of the ISR completes or another interrupt request w ill be
generated.
9.3.3. Interrupt Priorities
Each interrupt source can be in dividua lly prog ra mmed to one of two priority levels: low or high. A low prior-
ity interrupt service routine can be pree mpted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP2) used to configure
its priority level. Low priority is the defa ult. If two interrupt s are recognize d simultane ously, the interr upt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 9.4.
9.3.4. Interrupt Latency
Interrupt response time depen ds on the state of the CPU whe n the inte rr upt occurs. Pen ding inter rupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 6
system clock cyc les: 1 clock cycle to detect the interrupt and 5 clock cycles to complete the LCALL to the
ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL
is made to serv ice the pendin g inte rrup t. Th eref ore, the maxim um r espo nse tim e for an int errupt (when no
other interrupt is currently being serviced or the ne w interrupt is of greater priority) occurs when the CPU is
performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is
20 system clock cycles: 1 clock cycle to detect the interrupt, 6 clock cycles to execute the RETI, 8 clock
cycles to complete the DIV instruction and 5 clock cycles to execute the LCALL to the ISR. If the CPU is
executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the
current ISR completes, including the RETI and following instruction.
Note that the CPU is stalled during Flash write/erase operations and USB FIFO MOVX accesses (see
Section “13.2. Accessing USB FIFO S pace” on page 115). Interrupt service latency will be increased for
interrupts occurring while the CPU is stalled. The latency for these situations will be determined by the
standar d interrupt service procedure (as described above) and the amount of time the CPU is stalled.
IT0 IN0PL INT0 Interrupt IT1 IN1PL INT1 Interrupt
10
Active low, edge sensitive 10Active low, edge sensitive
11Active high, edge sensitive 11Active high, edge sensitive
00Active low, level sensitive 00Active low, level sensitive
01Active high, level sensitive 01Active high, level sensitive
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
90 Rev. 1.3
9.3.5. Interrupt Register Descriptions
The SFRs used to enable th e inte rrupt sources an d set their priori ty level ar e descr ibed be low. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for th e perip h er al an d th e be ha vior of its interrupt -pen d ing flag (s) .
Table 9.4. Interrupt Summary
Interrupt Source Interrupt
Vector Priority
Order Pending Flag
Bit addressable ?
Cleared by HW?
Enable
Flag Priority
Control
Reset 0x0000 Top None N/A N/A Always
Enabled Always
Highest
External Interrupt 0
(INT0)0x0003 0IE0 (TCON.1) Y Y EX0 (IE.0) PX0 (IP.0)
Timer 0 Overflow 0x000B 1TF0 (TCON.5) Y Y ET0 (IE.1) PT0 (IP.1)
External Interrupt 1
(INT1)0x0013 2IE1 (TCON.3) Y Y EX1 (IE.2) PX1 (IP.2)
Timer 1 Overflow 0x001B 3TF1 (TCON.7) Y Y ET1 (IE.3) PT1 (IP.3)
UART0 0x0023 4RI0 (SCON0.0)
TI0 (SCON0.1) Y N ES0 (IE.4) PS0 (IP.4)
Timer 2 Overflow 0x002B 5TF2H (TMR2CN.7)
TF2L (TMR2CN.6) Y N ET2 (IE.5) PT2 (IP.5)
SPI0 0x0033 6
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4 )
Y N ESPI0
(IE.6)PSPI0
(IP.6)
SMB0 0x003B 7SI (SMB0CN.0) Y N ESMB0
(EIE1.0) PSMB0
(EIP1.0)
USB0 0x0043 8Special N N EUSB0
(EIE1.1) PUSB0
(EIP1.1)
ADC0 Window
Compare 0x004B9AD0WINT
(ADC0CN.3) Y N EWADC0
(EIE1.2) PWADC0
(EIP1.2)
ADC0 Conversion
Complete 0x0053 10 AD0INT (ADC0CN.5) Y N EADC0
(EIE1.3) PADC0
(EIP1.3)
Programmable Counter
Array 0x005B 11 CF (PCA0CN.7)
CCFn (PCA0CN.n) Y N EPCA0
(EIE1.4) PPCA0
(EIP1.4)
Comparator0 0x0063 12 CP0FIF (CPT0CN.4)
CP0RIF (CPT0CN.5) N N ECP0
(EIE1.5) PCP0
(EIP1.5)
Comparator1 0x006B 13 CP1FIF (CPT1CN.4)
CP1RIF (CPT1CN.5) N N ECP1
(EIE1.6) PCP1
(EIP1.6)
Timer 3 Overflow 0x0073 14 TF3H (TMR3CN.7)
TF3L (TMR3CN.6) N N ET3
(EIE1.7) PT3
(EIP1.7)
VBUS Level 0x007B 15 N/A N/A N/A EVBUS
(EIE2.0) PVBUS
(EIP2.0)
UART1 0x0083 16 RI1 (SCON1.0)
TI1 (SCON1.1) N N ES1
(EIE2.1) PS1
(EIP2.1)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 91
SFR Definition 9.7. IE: Interrupt Enable
Bit7: EA: Enable All Interrupts.
This bit globally enables/disables all interr upts. It overrides the individual interrupt mask set-
tings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
Bit6: ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of the SPI0 interrupts.
0: Disable all SPI0 interrupts.
1: Enable interrupt requests generated by SPI0.
Bit5: ET2: Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt reque sts generated by the TF2L or TF2H flags.
Bit4: ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
Bit3: ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupt.
1: Enable interrupt requests generated by the TF1 flag.
Bit2: EX1: Enable External Inte rrupt 1.
This bit sets the mask ing of External Interrupt 1.
0: Disable extern al inte r ru pt 1.
1: Enable interrupt requests generated by the INT1 input.
Bit1: ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
Bit0: EX0: Enable External Inte rrupt 0.
This bit sets the mask ing of External Interrupt 0.
0: Disable extern al inte r ru pt 0.
1: Enable interrupt requests generated by the INT0 input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EA ESPI0 ET2 ES0 ET1 EX1 ET0 EX0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xA8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
92 Rev. 1.3
SFR Definition 9.8. IP: Interrupt Priority
Bit7: UNUSED. Read = 1, Write = don't care.
Bit6: PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority level.
1: SPI0 interrupt set to high priority level.
Bit5: PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupt set to low priority level.
1: Timer 2 interrupts set to high priority level.
Bit4: PS0: UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupt set to low priority level.
1: UART0 interrupts set to high priority level.
Bit3: PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupt set to low priority level.
1: Timer 1 interrupts set to high priority level.
Bit2: PX1: External Interrupt 1 Priority Control.
This bit sets the pr iority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority level.
1: External In terrupt 1 set to high priority lev el.
Bit1: PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority level.
1: Timer 0 interrupt set to high priority level.
Bit0: PX0: External Interrupt 0 Priority Control.
This bit sets the pr iority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority level.
1: External In terrupt 0 set to high priority lev el.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
- PSPI0 PT2 PS0 PT1 PX1 PT0 PX0 10000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xB8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 93
SFR Definition 9.9. EIE1: Extended Interrupt Enable 1
Bit7: ET3: Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable interrupt reque sts generated by the TF3L or TF3H flags.
Bit6: ECP1: Enable Comparator1 (CP1) Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 interrupts.
1: Enable interrupt requests generated by the CP1RIF or CP1FIF flag s.
Bit5: ECP0: Enable Comparator0 (CP0) Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF or CP0FIF flag s.
Bit4: EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts .
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
Bit3: EADC0: Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interru pt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
Bit2: EWADC0: Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison interrupt.
1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT).
Bit1: E USB0: Enable USB0 Interrupt.
This bit sets the masking of the USB0 interrupt.
0: Disable all USB0 interrupts.
1: Enable interrupt requests generated by USB0.
Bit0: ESMB0: Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 interrupts.
1: Enable interrupt requests generated by SMB0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ET3 ECP1 ECP0 EPCA0 EADC0 EWADC0 EUSB0 ESMB0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xE6
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
94 Rev. 1.3
SFR Definition 9.10. EIP1: Extended Interrupt Priority 1
Bit7: PT3: Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupts set to low priority level.
1: Timer 3 interrupts set to high priority level.
Bit6: PCP1: Comparator1 (CP1) Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 interrupt set to low priority level.
1: CP1 interrupt set to high priority level.
Bit5: PCP0: Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
Bit4: PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority lev el.
1: PCA0 interrupt set to high priority level.
Bit3: PADC0 ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
Bit2: PWADC0: ADC0 Win dow Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrupt.
0: ADC0 Window interrupt set to low priority level.
1: ADC0 Window interrupt set to high priority level.
Bit1: P USB0: USB0 Interrupt Priority Control.
This bit sets the priority of the USB0 interrupt.
0: USB0 interrupt set to low priority lev el.
1: USB0 interrupt set to high priority level.
Bit0: PSMB0: SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
PT3 PCP1 PCP0 PPCA0 PADC0 PWADC0 PUSB0 PSMB0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF6
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 95
SFR Definition 9.11. EIE2: Extended Interrupt Enable 2
SFR Definition 9.12. EIP2: Extended Interrupt Priority 2
Bits7–2: UNUSED. Read = 000000b. Write = don’t care.
Bit1: ES1: Enable UART1 Interrupt.
This bit sets the masking of the UART1 interrupt.
0: Disable UART1 interrupt.
1: Enable UART1 interrupt.
Bit0: EVBUS: Enable VBUS Level Interrupt.
This bit sets the masking of the VBUS interrupt.
0: Disable all VBUS interrupts.
1: Enable interrup t requests ge nerated by VBUS level sense.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - - - ES1 EVBUS 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xE7
Bits7–2: UNUSED. Read = 000000b. Write = don’t care.
Bit1: PS1: UART1 Interrupt Priority Control.
This bit sets the priority of the UART1 interrupt.
0: UART1 interrupt set to low priority level.
1: UART1 interrupts set to high priority level.
Bit0: PVBUS: VBUS Level Interrupt Priority Control.
This bit sets the priority of the VBUS interrupt.
0: VBUS interrupt set to low priority level.
1: VBUS interrupt set to high priority level.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - - - PS1 PVBUS 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
96 Rev. 1.3
SFR Definition 9.13. IT01CF: INT0/INT1 Configuration
Bit7: IN1PL: INT1 Polarity
0: INT1 input is active low.
1: INT1 input is active high.
Bits6–4: IN1SL2–0: INT1 Port Pin Selection Bits
These bits select which Port pin is assigned to INT1. Note that this pin assignment is inde-
pendent of the Crossbar; INT1 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configu red to skip the selected pin (accomplishe d by
setting to ‘1’ the corresponding bit in register P0SKIP).
Bit3: IN0PL: INT0 Polarity
0: INT0 interrupt is active low.
1: INT0 interrupt is active high.
Bits2–0: INT0SL2–0: INT0 Port Pin Selection Bits
These bits select which Port pin is assigned to INT0. Note that this pin assignment is inde-
pendent of the Crossbar. INT0 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configu red to skip the selected pin (accomplishe d by
setting to ‘1’ the corresponding bit in register P0SKIP).
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
IN1PL IN1SL2 IN1SL1 IN1SL0 IN0PL IN0SL2 IN0SL1 IN0SL0 00000001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xE4
Note: Refer to SFR Definition 21.1 for INT0/1 edge- or level-sensitive interrupt selection.
IN1SL2–0 INT1 Port Pin
000 P0.0
001 P0.1
010 P0.2
011 P0.3
100 P0.4
101 P0.5
110 P0.6
111 P0.7
IN0SL2–0 INT0 Port Pin
000 P0.0
001 P0.1
010 P0.2
011 P0.3
100 P0.4
101 P0.5
110 P0.6
111 P0.7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 97
9.4. Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all inter-
rupts, are inactive, and the internal oscillator is stopped (analog peripherals remain in their selected states;
the external oscillator is not affected). Since clocks are running in Idle mode, power consumption is depen-
dent upon the system clock frequency and the number of peripherals left in active mode before entering
Idle. Stop mode consumes the least power. Figure 1.15 describes the Power Control Register (PCON)
used to control the CIP-51's power management modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished through system clock and individual peripheral
management. Each analog peripheral can be disabled when not in use and placed in low power mode.
Digital peripherals, such as timers or serial buses, draw little power when t hey are not in use. Turning off
the oscillators lowers power consumption considerably; however a reset is required to restart the MCU.
The internal oscillator can be placed in Suspend mode (see Section “14. Oscillators” on page 131). In
Suspend mode, the internal oscillator is stopped until a non-idle USB event is detected, or the VBUS input
signal matches the polarity selected by the VBPOL bit in register REG0CN (SFR Definition 8.1).
9.4.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes execution. All internal registers and memory maintain their
original dat a. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an
enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume
operation. The pending interrupt will be serviced and the next instruction to be executed after the return
from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit.
If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence
and begins program execution at address 0x0000.
If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby termi-
nate the Idle mode. This featur e protect s the system from an unintended per manen t shut down in the event
of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by
softwar e prio r to en terin g th e Idle mo de if the WDT was initially configured to allow this operat ion. This pro-
vides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefi-
nitely, waiting for an external stimulus to wake up the system. Refer to Section “11.6. PCA Watchdog
Timer Re set” on page 103 for more information on the use and configuration of the WDT.
9.4.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruc -
tion that sets the bit completes execution. In Stop mode the internal oscillator , CPU, and all digit al peripher-
als are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including
the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can
only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset
sequence and be gin s pr og ra m execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Dete ctor sho uld be d isabled if the CPU is to be put to in STOP mode for longer tha n the
MCD timeout of 100 µsec.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
98 Rev. 1.3
SFR Definition 9.14. PCON: Power Control
Bits7–2: GF5–GF0: General Purpose Flags 5–0.
These are general purpose flags for use under software control.
Bit1: STOP: Stop Mode Select.
Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0.
1: CPU goes into Stop mode (internal oscillator stopped).
Bit0: IDLE: Idle Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial
Ports, and Analog Peripherals are still active.)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
GF5 GF4 GF3 GF2 GF1 GF0 STOP IDLE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x87
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 99
10. Prefetch Engine
The 48 MHz versions of the C8051F34x family of devices incorporate a 2-byte prefetch engine. Be cause
the access time of the FLASH memory is 40 ns, and the minimum instruction time is roughly 20 ns, the
prefetch engine is nece ssa ry for full- spee d cod e ex ec ution. In structions are re ad fr om FLASH memo ry two
bytes at a tim e by the pr efetch engin e, and give n to the CIP-51 processor core to execute. When running
linear code (code without any jumps or branches), the prefetch engine allows instructions to be executed
at full speed. When a code branch occurs, the processor may be stalled for up to two clock cycles while the
next set of code bytes is retrieved from FLASH memory. The FLRT bit (FLSCL.4) determines how many
clock cycles are used to read each set of two code bytes from FLASH. When operating from a system
clock of 25 MHz or less, the F LRT bit should be set to ‘0’ so that the prefetch engine takes only one clock
cycle for each re ad. When opera ting with a system clock o f greater tha n 25 MHz (up to 48 MHz), the FLRT
bit should be set to ‘1’, so that each prefetch code read lasts for two clock cycles.
SFR Definition 10.1. PFE0CN: Prefetch Engine Control
Bits 7–6: Unused. Read = 00b; Write = Don’t Care
Bit 5: PFEN: Prefetch Enable.
This bit enables the pr ef etch engine.
0: Prefetch engine is disabled.
1: Prefetch engine is enabled.
Bits 4–1: Unused. Read = 0000b; Write = Don’t Care
Bit 0: FLBWE: FLASH Block Write Enable.
This bit allows block writes to FLASH memory from software.
0: Each byte of a software FLASH write is written individually.
1: FLASH bytes ar e writ te n in gr ou ps of two.
R R R/W R R R R R/W Reset Value
PFEN FLBWE 00100000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAF
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 100
11. Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
• CIP-51 halts program execution
• Special Function Registers (SFRs) are initialized to their defined reset values
• External Port pins are forced to a known state
• Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost even though the data on the stack is not altered.
The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pull-ups are enabled
during and after the reset. For VDD Monitor and Power-On Resets, the RST pin is driven low until the
device exits the reset state.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the inter-
nal oscillator. Refer to Section “14. Oscillators” on page 131 for infor mation on selecting and co nfiguring
the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock
source (Section “22.3. Watchdog Timer Mode” on page 264 details the use of the Watchdog Timer).
Program execution begins at location 0x0000.
Figure 11.1. Reset Sources
PCA
WDT
Missing
Clock
Detector
(one-
shot) Software Reset (SWRSF)
System Reset
Reset
Funnel
Px.x
Px.x
EN
System
Clock CIP-51
Microcontroller
Core
Extended Interrupt
Handler
Clock Select
EN
WDT
Enable
MCD
Enable
Errant
FLASH
Operation
+
-
Comparator 0
C0RSEF
RST
(wired-OR)
Power On
Reset
+
-
VDD
Supply
Monitor Enable
'0'
Internal HF
Oscillator
XTAL1
XTAL2
External
Oscillator
Drive
Clock
Multiplier
USB
Controller VBUS
Transition
Enable
Internal LF
Oscillator
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
101 Rev. 1.3
11.1. Power-On Reset
During power-up, the device is held in a reset state and the RST pin is driven low until VDD settles above
VRST. A Power-On Reset delay (TPORDelay) occurs before the device is released from reset; this delay is
typically less than 0.3 ms. Figure 11.2. plots the power-on and V DD monitor reset timing.
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. Wh en PORSF is
set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other
resets). Since all resets cause program execution to begin at the same location (0x0000) software can
read the PORSF flag to deter mine if a po we r- up wa s the cause o f re se t. T he co nten t of inter na l data mem -
ory should be assumed to be undefined after a power-on reset. The VDD monitor is enabled following a
power-on reset.
Software can for ce a power-on reset by writing ‘1’ to the PINRSF bit in register RSTSRC.
Figure 11.2. Power-On and VDD Monitor Reset Timing
Power-On
Reset
VDD
Monitor
Reset
RST
t
volts
1.0
2.0
Logic HIGH
Logic LOW TPORDelay
VDD
2.70
2.4 VRST
VDD
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 102
11.2. Power-Fail Reset / VDD Monitor
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply
monitor will drive the RST pin low and hold the CIP-51 in a reset st ate (see Figure 11.2). When VDD returns
to a level above VRST, the CIP-51 will be released from the reset state. Note that even though internal data
memory content s a re not altered by th e power-fail reset, it is impossible to determ ine if VDD dropped below
the level required for data retention. If the PORSF flag reads ‘1’, the data may no longer be valid. The VDD
monitor is enabled af ter power- on resets; however its defined state (enable d/disabled) is not alte red by any
other reset sour ce. F or ex amp le, if the VDD monitor is enabled and a software reset is performed, the VDD
monitor will still be enabled after the reset. It is strongly recommended that the VDD monitor be left enabled
at all times for any system that contains code to write to Flash memory.
Important Note: The VDD monitor must be enabled before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it is enabled and stabilized may cause a system reset. In applica-
tions where this reset is undesirable, a delay can be implemented between enabling the VDD monitor and
selecting it as a reset source. The procedure for configuring the VDD monitor as a reset source is shown
below:
Step 1. Enable the VDD monitor (VDM0CN.7 = ‘1’).
Step 2. If desired, wait for the VDD monitor to stabilize (see Table 11.1 for the VDD Monitor turn-o n
time).
Step 3. Select the VDD monitor as a reset source (RSTSRC.1 = ‘1’).
See Figure 11.2 for VDD monitor timing. See Table 11.1 for complete electrical characteristics of the VDD
monitor.
SFR Definition 11.1. VDM0CN: VDD Monitor Control
Bit7: VDMEN: VDD Monitor Enable.
This bit turns the V DD monitor circuit on/of f. The VDD Monitor cannot generate system re sets
until it is also selected as a reset source in registe r RSTSRC (SFR Definition 11.2). The V DD
Monitor must be allowed to stabilize before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it has stabilized will generate a system reset.
See Table 11.1 for the minimum V DD Monitor turn-on time. The VDD Monitor is enabled fol-
lowing all POR resets.
0: VDD Monitor Disabled.
1: VDD Monitor Enabled.
Bit6: VDDSTAT: VDD Status.
This bit indicates the current power supply status (VDD Monitor output).
0: VDD is at or below the VDD monitor threshold.
1: VDD is above the VDD monitor threshold.
Bits5–0: Reserved. Read = Variable. Write = don’t care.
R/WRRRRRRRReset Value
VDMEN VDDSTAT Reserved Reserved Reserved Reserved Reserved Reserved Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xFF
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
103 Rev. 1.3
11.3. External Reset
The extern al RST pin provides a means for external circuitry to force the device into a reset state. Assert-
ing an active-low signal on the RST pin generates a reset; an external pull-up and/or decoupling of the
RST pin may be necessary to a void erroneous noise-induced resets. See Table 11.1 for complete RST pin
specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
11.4. Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the syst em clock. If more than
100 µs pass between rising edges on the system clock, the one-shot will time out and generate a reset.
After a MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source;
otherwise, this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a
‘0’ disables it. The state of the RST pin is unaffected by this reset.
11.5. Comparator0 Reset
Comparator0 can be configured as a re set source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5). Com -
parator0 should b e enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter
on the output from gene rating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting
input voltage (on CP0+) is less than the inverting input voltage (on CP0-), a system reset is generated.
After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0 as the reset
source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset.
11.6. PCA Watchdog Timer Reset
The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be
used to prevent software from running out of control during a system malfunction. The PCA WDT function
can be enabled or disabled by software as described in Section “22.3. Watchdog Timer Mode” on
page 264; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction
prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is
set to ‘1’. The state of the RST pin is unaffected by this reset.
11.7. Flash Error Reset
If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This
may occur due to any of the following:
• A Flash write or erase is attempted above user code space. This occurs when PSWE is set to “1”, a nd
a MOVX write operatio n is attempted a bove add ress 0x7FFF ( 32 kB Flash devices) or 0xFBFF ( 64 kB
Flash devices).
• A Flash read is attempted above user code space. This occurs when a MOVC operation is attempted
above address 0x7FFF (32 kB Flash devices) or 0xFBFF (64 kB Flash devices).
• A Program read is attempte d above user code sp ac e. This occurs wh en user code attemp t s to branch
to an address above 0x7FFF (32 kB Flash devices) or 0xFBFF (64 kB Flash devices).
• A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section
“12.3. Security Options” on page 109).
• A Flash Write or Erase is attempted when the VDD monitor is not enabled.
The FERROR bit (RSTSRC.6) is set following a Flash error reset. The st ate of the RST p in is unaf fected by
this reset.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 104
11.8. Software Reset
Software may force a reset by writing a ‘1’ to the SWRSF bit (RSTSRC.4). The SWRSF bit will read ‘1’ fol-
lowing a software forced reset. The state of the RST pin is unaffected by this reset.
11.9. USB Reset
Writing ‘1’ to the USBRSF bit in register RSTSRC selects USB0 as a reset source. With USB0 selected as
a reset source, a system reset will be generated when either of the following occur:
1. RESET signaling is detected on the USB network. The US B Function Controller (USB0) must
be enabled for RESET signaling to be detected. See Section “16. Universal Serial Bus Con-
troller (USB0)” on page 159 for information on the USB Function Controller.
2. The voltage on the VBUS pin matches the polarity selected by the VBPOL bit in register
REG0CN. See Section “8. Voltage Regulator (REG0)” on page 69 for details on the VBUS
detection circuit.
The USBRSF bit will read ‘1’ following a USB reset. The state of the RST pin is unaffected by this reset.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
105 Rev. 1.3
SFR Definition 11.2. RSTSRC: Reset Source
Bit7: USBRSF: USB Reset Flag
0: Read: Last reset was not a USB reset; Write: USB resets disabled.
1: Read: Last reset was a USB reset; Write: USB resets enabled.
Bit6: F ERROR: Flash Error Indicator.
0: Source of last reset was not a Flash read/write/erase error.
1: Source of last reset was a Flash read/write/erase error.
Bit5: C0RSEF: Comparator0 Reset Enable and Flag.
0: Read: Source of last reset was not Comparator0; Write: Comparator0 is not a reset
source.
1: Read: Source of last reset was Comparator0; Write: Comparator0 is a reset source
(active-low).
Bit4: SWRSF: Software Reset Force and Flag.
0: Read: Source of last reset was not a write to the SWRSF bit; Write: No Effect.
1: Read: Source of last was a write to the SWRSF bit; Write: Forces a system reset.
Bit3: WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not a WDT timeout.
1: Source of last reset was a WDT timeout.
Bit2: MCDRSF: Missing Clock Detector Flag.
0: Read: Source of last reset was not a Missing Clock Detector timeout; Write: Missing
Clock Detector disabled.
1: Read: Source of last reset was a Missing Clock Detector timeout; Write: Missing Clock
Detector enable d; trigg e rs a rese t if a missing clock condition is detected.
Bit1: PORSF: Power-On / VDD Monitor Reset Flag.
This bit is set anytime a powe r- on res et oc curs. Writing this bit selects/deselects the VDD
monitor as a rese t sour ce. Note: writing ‘1’ to this bit before the VDD monitor is e nabled
and stabilized can cause a system reset. See register VDM0CN (SFR Definition 11.1).
0: Read: Last reset was not a power-on or VDD monitor reset; Write: VDD monitor is not a
reset source.
1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate;
Write: VDD monitor is a reset source.
Bit0: PINRSF: HW Pin Reset Flag.
0: Source of last reset was not RST pin.
1: Source of last reset was RST pin.
Note: For bits that act as both reset source enab les (on a write) and reset indicator flags (on a
read), read-modify-write instructions read and modify the source enable only. This applies to
bits: USBRSF, C0RSEF, SWRSF, MCDRSF, PORSF.
R/W R R/W R/W R R/W R/W R Reset Value
USBRSF FERROR C0RSEF SWRSF WDTRSF MCDRSF PORSF PINRSF Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xEF
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 106
Table 11.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
RST Output Low Voltage IOL = 8.5 mA, VDD = 2.7 to 3.6 V 0.6 V
RST Input High Voltage 0.7 x VDD V
RST Input Low Voltage 0.3 x VDD
RST Input Pull-Up Current RST = 0.0 V 25 40 µA
VDD POR Threshold (VRST)2.40 2.55 2.70 V
Missing Clock Detector Tim-
eout Time from last system clock ris-
ing edge to reset initiation 100 220 500 µs
Reset Time Delay Delay between release of any
reset source and code execution
at location 0x0000 5.0 µs
Minimum RST Low Time to
Generate a System Reset 15 µs
VDD Monitor Turn-on Time 100 µs
VDD Monitor Supply Current 20 50 µA
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 107
12. Flash Memo ry
On-chip, re-programmable Flash memory is included for program code and non-vo latile data storag e. The
Flash memory can be programmed in-system through the C2 interface or by software using the MOVX
instruction. On ce cleared to lo gic 0, a Flash bit mu st be erased to se t it back to logic 1. Flash bytes wou ld
typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automat-
ically timed by hardware for proper execution; data polling to determine the end of the write/erase opera-
tion is not requ ired. Co de exec ution is stalled during a Flash write/erase operation. Refer to Table 12.1 for
complete Flash memory electrical characteristics.
12.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the C2 interface using programming
tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initial-
ized device. For details on the C2 commands to program Flash memory, see Section “23. C2 Interface”
on page 271.
To ensure the integrity of Flash contents, it is strongly recommended that the VDD monitor be left
enabled in any sys tem which wr ites or era ses Flash me mory from code. It is also c rucial t o ensure
that the FLR T bit in register FLSCL be se t to '1' if a clock speed hig her than 25 MHz is being used
for the device.
12.1.1. Flash Lock and Key Functions
Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and
Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations
may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be
written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and
erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash
write or erase is attempted before the key codes have been written properly. The Flash lock resets after
each write or erase; the key codes must be written again before a following Flash operation can be per-
formed. The FLKEY register is detailed in SFR Definition 12.2.
12.1.2. Flash Erase Procedure
The Flash memory can be pr ogrammed by so ftware using the MOVX write instruction with the address and
data byte to be programmed provided as normal operands. Before writing to Flash memory using MOVX,
Flash write oper ation s must be en abled b y: (1) Writing the Flash key codes in sequence to the Flash Lock
register (FLKEY); and (2) Setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1 (this
directs the MOVX writes to target Flash memory). The PSWE bit remains set until cleared by software.
A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits
to logic 1 in Flash. A byte location to be programmed must be erased before a new value is written.
The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting
all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps:
Step 1. Disable interrupts (recommended).
Step 2. Write the first key code to FLKEY: 0xA5.
Step 3. Write the second key code to FLKEY: 0xF1.
Step 4. Set the PSEE bit (register PSCTL).
Step 5. Set the PSWE bit (register PSCTL).
Step 6. Using the MOVX instruction, write a data byte to any location within the 512-byte page to
be erased .
Step 7. Clear the PSWE bit (reg iste r PSCT L ).
Step 8. Clear the PSEE bit (register PSCTI).
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
108 Rev. 1.3
12.1.3. Flash Write Procedure
Bytes in Flash memory can be written one byte at a time, or in groups of two. The FLBWE bit in register
PFE0CN (SFR Definition 10.1) controls whether a single byte or a block of two bytes is written to Flash
during a write operation. When FLBWE is cleared to ‘0’, the Flash will be written one byte at a time. When
FLBWE is set to ‘1’, the Flash will be written in two-byte blocks. Block writes are performed in the same
amount of time as single-byte writes, which can save time when storing large amounts of data to Flash
memory.During a single-byte write to Flash, bytes are written individually, and a Flash write will be per-
formed after each MOVX write instru ction. The recomme nded procedure for writing Flash in single bytes is:
Step 1. Disable interrupts.
Step 2. Clear the FLBWE bit (register PFE0CN) to select single-byte write mode.
Step 3. Set the PSWE bit (register PSCTL).
Step 4. Clear the PSEE bit (register PSCTL).
Step 5. Write the first key code to FLKEY: 0xA5.
Step 6. Write the second key code to FLKEY: 0xF1.
Step 7. Using the MOVX instruction, write a single data byte to the desired location within the
512-byte sector.
Step 8. Clear the PSWE bit.
Step 9. Re-enable interrupts.
Steps 5-7 must be repeated for each byte to be written.
For block Flash writes, the Flash write procedure is only performed after the last byte of each block is writ-
ten with the MOVX write instruction. A Flash write block is two bytes long, from even addresses to odd
addresses. Writes must be performed sequentially (i.e. addresses ending in 0b and 1b must be written in
order). The Flash write will be performed following the MOVX write that targets the address ending in 1b. If
a byte in the block does not need to be updated in Flash, it should be writte n to 0xFF. The r ecommended
procedure for writing Flash in blocks is:
Step 1. Disable interrupts.
Step 2. Set the FLBWE bit (register PFE0CN) to select block write mode.
Step 3. Set the PSWE bit (register PSCTL).
Step 4. Clear the PSEE bit (register PSCTL).
Step 5. Write the first key code to FLKEY: 0xA5.
Step 6. Write the second key code to FLKEY: 0xF1.
Step 7. Using the MOVX instruction, write the first data byte to the even block location (ending in
0b).
Step 8. Write the first key code to FLKEY: 0xA5.
Step 9. Write the second key code to FLKEY: 0xF1.
S t ep 10. Using the MOVX instruction, write the second dat a byte to the o dd block location (e nding
in 1b).
Step 11. Clear the PSWE bit.
Step 12. Re-enable interrupts.
Steps 5–10 must be repeated for each block to be written.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 109
12.2. Non-Volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and read using the MOVC instruction. Note: MOVX read instru ctions always t a rget XRAM.
12.3. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-
ware as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly
set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before
software can erase Flash memory. Additional security features prevent proprietary program code and data
constants from being read or altered across the C2 interface.
A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program
memory from access (re ads, writes, or er ases) by unprotected code or the C2 interface. The Flash security
mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to
0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the
page containing the Flash Security Lock Byte is also locked when any other Flash pages are locked. See
example be low.
Table 12.1. Flash Electrical Characteristics
Parameter Conditions Min Typ Max Units
Flash Size C8051F340/2/4/6/A/C/D*
C8051F341/3/5/7/8/9/B 65536*
32768 Bytes
Bytes
Endurance 20k 100k Erase/Write
Erase Cycle Time 25 MHz System Clock 10 15 20 ms
Write Cycle Time 25 MHz System Clock 40 55 70 µs
*Note: 1024 bytes at location 0xFC00 to 0xFFFF are reserved.
Security Lock Byte: 11111101b
1’s Complement: 00000010b
Flash pages locked: 3 (2 + Flash Lock Byte Page)
Addresses locked: First two pages of Flash: 0x0000 to 0x03FF
Flash Lock Byte Page: (0xFA00 to 0xFBFF for 64k devices; 0x7E00 to
0x7FFF for 32k devices)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
110 Rev. 1.3
Figure 12.1. Flash Program Memory Map and Security Byte
Access limit set
according to the
FLASH security lock
byte
C8051F340/2/4/6/A/C/D
0x0000
0xFBFF
Lock Byte
Reserved
0xFBFE
0xFC00
FLASH memory
organized in 512-byte
pages
0xFA00
Unlocked FLASH Pages
Locked when any
other FLASH pages
are locked C8051F341/3/5/7/8/9/B
0x0000
0x7FFF
Lock Byte
0x7FFE
0x7E00
Unlocked FLASH Pages
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 111
The level of FLASH security depends on the FLASH access method. The three FLASH access methods
that can be restricted a re reads, w rites, and erases from the C2 debug interface, user firmware executing
on unlocked pages, and user firmware executing on locked pages.
Accessing FLASH from the C2 debug interface:
1. Any unlocked page may be read, written, or erased.
2. Locked pages cannot be read, written, or erased.
3. The page containing the Lock Byte may be read, written, or erased if it is unlocked.
4. Reading the contents of the Lock Byte is always permitted.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted .
6. Unlocking FLASH pages (changing ‘0’s to ‘1’s in the Lock Byte) requires the C2 Device Erase
command, which erases all F LASH pag es including the p age cont ainin g the Lock Byte and the
Lock Byte itself.
7. The Reserved Area cannot be read, written, or erased.
Accessing FLASH from user firmware executing on an unlocked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Locked pages cannot be read, written, or erased.
3. The page containing the Lock Byte cannot be erased. It may be read or written only if it is
unlocked.
4. Reading the contents of the Lock Byte is always permitted.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted .
6. Unlocking FLASH pages (changing ‘0’s to ‘1’s in the Lock Byte) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a FLASH Error device reset.
Accessing FLASH from user firmware executing on a locked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Any locked page except the page containing the Lock Byte may be read, written, or erased.
3. The page containing the Lock Byte cannot be erased. It may only be read or written.
4. Reading the contents of the Lock Byte is always permitted.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted .
6. Unlocking FLASH pages (changing ‘0’s to ‘1’s in the Lock Byte) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a FLASH Error device reset.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
112 Rev. 1.3
SFR Definition 12.1. PSCTL: Program Store R/W Control
SFR Definition 12.2. FLKEY: Flash Lock and Key
Bits7–3: Unused: Read = 00000b. Write = don’t care.
Bit2: Reserved. Read = 0b. Must Write = 0b.
Bit1: PSEE: Program Store Erase Enable
Setting this bit (in combination with PSWE) allows an entire page of Flash program memor y
to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to
Flash memory using the MOVX instruction will erase the entire page that contains the loca-
tion addressed by the MOVX instruction. The value of the data byte written does not matter.
0: Flash program memory era sure disabled.
1: Flash program memory erasure enabled.
Bit0: PSWE: Program Store Write Enable
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The Flash location should be erased before writing data.
0: Writes to Flash progra m memo ry disabled.
1: Writes to Flash progra m memo ry enabled; the MOVX write instruction targets Flash
memory.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - - Reserved PSEE PSWE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x8F
Bits–0: FLKEY: Flash Lock and Key Register
Write:
This register must be written to before Flash writes or erases can be performed. Flash
remains locked until this register is written to with the following key codes: 0xA5, 0xF1. The
timing of the writes does not matter , as long as the codes are written in order. The key codes
must be written for each Flash write or erase operation. Flash will be locked until the next
system reset if the wrong codes are written or if a Flash operation is attempted before the
codes have been written correctly.
Read:
When read, bits 1 -0 indicate the current Flash lock state.
00: Flash is write/erase locked.
01: The first key code has been written (0xA5).
10: Flash is unlocked (writes/erases allowed).
11: Flash writes/erases disabled until the next reset.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xB7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 113
SFR Definition 12.3. FLSCL: Flash Scale
Bits7: FOSE: Flash One-shot Enable
This bit enables the Flash read one-shot. When the Flash one-shot disabled, the Flash
sense amps are enabled for a full clock cycle during Flash reads. At system clock frequen-
cies below 10 MHz, disabling the Flash one-shot will increase system power consumption.
0: Flash one-shot disabled.
1: Flash one-shot enabled.
Bits6–5: RESERVED. Read = 00b. Must Write 00b.
Bit 4: FLRT: FLASH Read Time.
This bit should be pr ogrammed to the smalle st allowed value, accordin g to the system clock
speed.
0: SYSCLK <= 25 MHz.
1: SYSCLK <= 48 MHz.
Bits3–0: RESERVED. Read = 0000b. Must Write 0000b.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
FOSE Reserved Reserved FLRT Reserved Reserved Reserved Reserved 10000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xB6
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 114
13. External Data Memory Interface and On-Chip XRAM
4k Bytes (C8051F340/2/4/6/A/C/D) or 2k Bytes (C8051F341/3/5/7/8/9/B) of RAM are included on-chip,
and mapped into the external data memory space (XRAM). The 1k Bytes of USB FIFO space can also be
mapped into XRAM address space for additional general-purpose data storage. Additionally, an External
Memory Interface (EMIF) is available on the C8051F340/1/4/5/8/C devices, which can be used to ac cess
off-chip data memories and memory-mapped devices connected to the GPIO ports. The external memory
space may be accessed using the external m ove instruction (MOVX) and the data p ointer (DPTR), or using
the MOVX indirec t ad dre ssin g m ode u sin g R0 or R1. If th e M OVX instr uc tio n is us ed with an 8 -bi t addr e ss
operand (such as @R1), then the h igh byte of the 16- bit a ddress is provide d by the Extern al Memor y Inte r-
face Control Register (EMI0CN, shown in SFR Definition 13.1). Note: the MOVX instruction can also be
used for writing to the FLASH memory. See Section “12. Flash Memory” on page 107 for details. The
MOVX instruction accesses XRAM by default.
13.1. Accessing XRAM
The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms,
both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit
register which contains the effective address of the XRAM location to be read from or written to. The sec-
ond method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM
address. Examples of both of these methods are given below.
13.1.1. 16-Bit MOVX Example
The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the
DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the
accumulator A:
MOV DPTR, #1234h ; load DPTR with 16-bit address to read (0x1234)
MOVX A, @DPTR ; load contents of 0x1234 into accumulator A
The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately,
the DPTR can be accessed thro ugh th e SFR regi ster s DPH, which contains the upper 8-bits of DPTR, and
DPL, which contains the lower 8-bits of DPTR.
13.1.2. 8-Bit MOVX Example
The 8-bit form of the MOVX instruction uses the content s of the EMI0CN SF R to dete rmine the upp er 8-bit s
of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the
effective address to be accessed. The following series of instructions read the contents of the byte at
address 0x1234 into the accumulator A.
MOV EMI0CN, #12h ; load high byte of address into EMI0CN
MOV R0, #34h ; load low byte of address into R0 (or R1)
MOVX a, @R0 ; load contents of 0x1234 into accumulator A
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
115 Rev. 1.3
13.2. Accessing USB FIFO Space
The C8051F34x devices include 1k of RAM which functions as USB FIFO space. Figure 13.1 shows an
expanded view of the FI FO space and use r XRA M. FIFO space is norm ally acce ss ed via USB FI F O re gis-
ters; see Section “16.5. FIFO Management” on page 167 for more information on accessing these
FIFOs. The MOVX instruction should not be used to load or modify USB data in the FIFO space.
Unused areas of the USB FIFO space may be used as general purpose XRAM if necessary. The FIFO
block operates on the USB clock domain; thus the USB clock must be active when accessing FIFO space.
Note that the number of SYSCLK cycles required by the MOVX instruction is increased when accessing
USB FIFO space.
To access the FIFO RAM directly using MOVX instructions, the following conditions must be met: (1) the
USBFAE bit in register EMI0CF must be set to '1', and (2) the USB clock must be greater than or equal to
twice the SYSCLK (USBCLK > 2 x SYSCLK). When this bit is set, the USB FIFO space is mapped into
XRAM space at addresses 0x0400 to 0x07FF. The normal XRAM (on-chip or external) at the same
addresses cannot be accessed when the USBFAE bit is set to ‘1’.
Important Note: The USB clock must be active when accessing FIFO space.
Figure 13.1. USB FIFO Space and XRAM Memory Map with USBFAE set to ‘1’
On/Off-Chip XRAM
0x0000
Endpoint0
(64 bytes)
Free
(64 bytes)
0x0400
0x043F
0x0440
0x063F
0x0640
0x073F
0x0740
0x07BF
0x07C0
0x07FF
Endpoint1
(128 bytes)
Endpoint2
(256 bytes)
Endpoint3
(512 bytes)
USB FIFO Space
(USB Clock Domain)
0x03FF
On/Off-Chip XRAM
0x0800
0xFFFF
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 116
13.3. Configuring the External Memory Interface
Configuring the External Memory Interface consists of five steps:
1. Configure the Output Modes of the associated port pins as either push-pull or open-drain
(push-pull is most common), and skip the associated pins in the crossbar.
2. Configure Port latches to “park” the EMIF pins in a dormant state (usually by setting them to
logic ‘1’).
3. Select Multiplexed mode or Non-multiplexed mode.
4. Select the memory mode (on-chip only, split mode without bank select, split mode with bank
select, or off-chip only).
5. Set up timing to interface with off-chip memory or peripherals.
Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed
mode selection, and Mode bits are located in th e EMI0CF register shown in SFR Definition 13.2.
13.4. Port Configuration
The External Memory Interface appea rs on Ports 4, 3, 2, and 1 when it is used for of f-chip memory acce ss.
When the EMIF is used, the Crossbar should be configured to skip over the control lines P1.7 (WR), P1.6
(RD), and if multiplexed mode is selected P1.3 (ALE) using the P1SKIP register. For more information
about configuring the Crossbar, see Section “Figure 15.1. Port I/O Functional Block Diagram (Port 0
through Port 3)” on page 142.
The External Memory Interface claims the associated Port pins for memory operations ONLY during the
execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port
pins reverts to the Port latches or to the Crossbar settings for those pins. See Section “15. Port Input/
Output” on page 142 for more information about the Crossbar and Port operation and configuration. The
Port latches should be explicitly configured to ‘park’ the External Memory Interface pins in a dor-
mant state, most commonly by setting them to a logic 1.
During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the driv-
ers on all Port pins that are actin g as Inpu ts (Dat a[ 7:0] during a READ ope ra tion, for example). The Output
mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the
External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases,
the output modes of all EMIF pins should be configured for push-pull mode.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
117 Rev. 1.3
SFR Definition 13.1. EMI0CN: External Memory Interface Control
Bits7–0: PGSEL[7:0]: XRAM Page Select Bits.
The XRAM Page Select Bits provide the high byte of the 16-bit exter n al da ta memor y
address when using an 8-bit MOVX command, effectively selecting a 256-byte page of
RAM.
0x00: 0x0000 to 0x00FF
0x01: 0x0100 to 0x01FF
...
0xFE: 0xFE 0 0 to 0xFEFF
0xFF: 0xFF00 to 0xFFFF
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PGSEL7 PGSEL6 PGSEL5 PGSEL4 PGSEL3 PGSEL2 PGSEL1 PGSEL0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAA
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 118
SFR Definition 13.2. EMI0CF: External Memory Configuration
Bit7: Unused. Read = 0b. Write = don’t care.
Bit6: USBFAE: USB FIFO Access Enable.
0: USB FIFO RAM not available through MOVX instruction s.
1: USB FIFO RAM available using MOVX instructions. The 1k of USB RAM will be mapped
in XRAM space at addresses 0x 0400 to 0x07FF. The USB clock must be active and
greater than or equal to twice the SYSCLK (USBCLK > 2 x SYSCLK) to access this
area with MOVX instructions.
Bit5: Unused. Read = 0b. Write = don’t care.
Bit4: EMD2: EMIF Multiplex Mode Select.
0: EMIF operates in multiplexed addre ss/data mode.
1: EMIF operates in non-mu ltiplexed mode (separate address and data pins).
Bits3–2: EMD1–0: EMIF Operating Mode Select.
These bits control the operating mo de of the External Memory Interface.
00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to
on-chip memory space.
01: Split Mode without Bank Select: Accesses below the on-chip XRAM boundary are
directed on-chip. Accesses above the on-chip XRAM boundary are directed off-chip. 8-bit
off-chip MOVX operations use the current contents of the Address High port latches to
resolve upper address byte. Note that in order to access off-chip space, EMI0CN must be
set to a page that is not contained in the on-chip address space.
10: Split Mode with Bank Select: Accesses below the on-chip XRAM boundary are directed
on-chip. Access es ab o ve the on -c hip XRAM bo u nd ar y ar e dir ec ted off-chip. 8-bit off-chip
MOVX operations use the contents of EMI0CN to determine the high-byte of the address.
11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to the
CPU.
Bits1–0: EALE1–0: ALE Pulse-Width Select Bits (only has effect when EMD2 = 0).
00: ALE high and ALE low pulse width = 1 SYSCLK cycle.
01: ALE high and ALE low pulse width = 2 SYSCLK cycles.
10: ALE high and ALE low pulse width = 3 SYSCLK cycles.
11: ALE high and ALE low pulse width = 4 SYSCLK cycles.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- USBFAE - EMD2 EMD1 EMD0 EALE1 EALE0 00000011
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x85
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
119 Rev. 1.3
13.5. Multiplexed and Non-multiplexed Selection
The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode,
depending on the state of the EMD2 (EMI0CF.4) bit.
13.5.1. Multiplexed Configuration
In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins:
AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits
of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is
driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in
Figure 13.2.
In Multiplexed m ode, the extern al MOVX ope ration c an be broken into two phases delineated by the state
of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are pre-
sented to AD[7:0]. During this phase, the address latch is configured such that the ‘Q’ outputs reflect the
states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch
outputs remain fixed and are no longer dependent o n the latch inputs. Later in the second phase, the Data
Bus controls the state of the AD[7:0] port at the time RD or WR is asserted.
See Section “13.7.2. Multiplexed Mode” on page 127 for more information.
Figure 13.2. Multiplexed Configuration Example
ADDRESS/DATA BUS
ADDRESS BUS
E
M
I
F
A[15:8]
AD[7:0]
WR
RD
ALE
64K X 8
SRAM
OE
WE
I/O[7:0]
74HC373
G
DQ
A[15:8]
A[7:0]
CE
VDD
8(Optional)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 120
13.5.2. Non-multiplexed Configuration
In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a
Non-multiplexed Configuration is shown in Figure 13.3. See Section “13.7.1. Non-multiplexed Mode” on
page 124 for more information about Non-multiplexed operation.
Figure 13.3. Non-multiplexed Configuration Example
13.6. Memory Mode Selection
The extern a l d ata me mo r y space ca n be co n fig ur ed in o ne o f fo ur m o de s, sh ow n in Figure 13.4, based on
the EMIF Mode bits in the EMI0CF register (SFR Definition 13.2). These modes are summarized below.
More information about the different modes can be found in Section “13.7. Timing” on page 122.
Figure 13.4. EMIF Operating Modes
ADDRESS BUS
E
M
I
F
A[15:0]
64K X 8
SRAM
A[15:0]
DATA BUSD[7:0] I/O[7:0]
VDD
8
WR
RD OE
WE
CE
(Optional)
EMI0CF[3:2] = 00 0xFFFF
0x0000
EMI0CF[3:2] = 11 0xFFFF
0x0000
EMI0CF[3:2] = 01 0xFFFF
0x0000
EMI0CF[3:2] = 10
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
Off-Chip
Memory
(No Bank Select)
On-Chip XRAM
0xFFFF
0x0000
Off-Chip
Memory
(Bank Select)
On-Chip XRAM
Off-Chip
Memory
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
121 Rev. 1.3
13.6.1. Internal XRAM Only
When EMI0CF.[3:2] are set to ‘00’, all MOVX instructions will target the internal XRAM space on the
device. Memory accesses to addresses beyond the populated space will wrap on 2k or 4k boundaries
(depending on the RAM available on the device). As an example, the addresses 0x1000 and 0x2000 both
evaluate to address 0x0000 in on-chip XRAM space.
• 8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the e ffective address
and R0 or R1 to determine the low-byte of the effective address.
• 16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address.
13.6.2. Split Mode without Bank Select
When EMI0CF.[3:2] are set to ‘01’, the XRAM memory map is split into two areas, on-chip space and
off-chip space.
• Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.
• Effective addresses above the internal XRAM size boundary will access off-chip space.
• 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is
on-chip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the
upper 8-bits A[15:8] of the Addre ss Bus du ring an off-chip acces s. Th is allo ws th e use r to ma nip ulate
the upper address bits at will by setting the Port state directly via the port latches. This behavior is in
contrast with “Split Mode with Bank Select” described below. The lower 8-bits of the Address Bus
A[7:0] are driven, determined by R0 or R1.
• 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is
on-chip or off-chip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are
driven during the off-chip transaction.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 122
13.6.3. Split Mode with Bank Select
When EMI0CF.[3:2] are set to ‘10’, the XRAM memory map is split into two areas, on-chip space and
off-chip space.
• Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.
• Effective addresses above the internal XRAM size boundary will access off-chip space.
• 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is
on-chip or off-chip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the
lower 8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus
A[15:0] are driven in “B ank Select” mode.
• 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is
on-chip or off-chip, and the fu ll 16- bits of the Addres s Bus A [15:0 ] ar e dr ive n du rin g the off-chip trans -
action.
13.6.4. External Only
When EMI0CF[3:2] are set to ‘11’, all MOVX operations are directed to off-chip space. On-chip XRAM is
not visible to the CPU. This mode is useful for accessing off-chip memory lo cated between 0x0000 and the
internal XRAM size boundary.
• 8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven
(identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This
allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower
8-bits of the effective address A[7:0] are determined by the contents of R0 or R1.
• 16-bit MOVX operations use th e content s o f DPTR to determin e the effective addre ss A[15:0]. T he fu ll
16-bits of the Address Bus A[15:0 ] ar e dr ive n du rin g the off-chip trans act ion .
13.7. Timing
The timing parameters of the External Memory Interface can be configured to enable connection to
devices having different setup and hold time requirements. The Address Setup time, Address Hold time,
RD and WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in
units of SYSCLK periods through EMI0TC, shown in SFR Definition 13.3, and EMI0CF[1:0].
The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing
parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution
time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for RD or WR pulse + 4 SYSCLKs).
For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional
SYSCLK cycles. Therefore, the minimum execution time for an off-chip XRAM operation in multiplexed
mode is 7 SYSCLK cycles (2 for ALE + 1 for RD or WR + 4). The programmable setup and hold times
default to the maximum delay settings after a reset. Table 13.1 lists the AC parameters for the External
Memory Interface, and Figure 13.5 through Figure 13.10 show the timing diagrams for the different Exter-
nal Memory Interface modes and MOVX operations.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
123 Rev. 1.3
SFR Definition 13.3. EMI0TC: External Memory Timing Control
Bits7–6: EAS1–0: EMIF Address Setup Time Bits.
00: Address setup time = 0 SYSCLK cycles.
01: Address setup time = 1 SYSCLK cycle.
10: Address setup time = 2 SYSCLK cycles.
11: Address setup time = 3 SYSCLK cycles.
Bits5–2: EWR3–0: EMIF WR and RD Pulse-Width Control Bits.
0000: WR and RD pulse width = 1 SYSCLK cycle.
0001: WR and RD pulse width = 2 SYSCLK cycles.
0010: WR and RD pulse width = 3 SYSCLK cycles.
0011: WR and RD pulse width = 4 SYSCLK cycles.
0100: WR and RD pulse width = 5 SYSCLK cycles.
0101: WR and RD pulse width = 6 SYSCLK cycles.
0110: WR and RD pulse width = 7 SYSCLK cycles.
0111: WR and RD pulse width = 8 SYSCLK cycles.
1000: WR and RD pulse width = 9 SYSCLK cycles.
1001: WR and RD pulse width = 10 SYSCLK cycles.
1010: WR and RD pulse width = 11 SYSCLK cycles.
1011: WR and RD pulse width = 12 SYSCLK cycles.
1100: WR and RD pulse width = 13 SYSCLK cycles.
1101: WR and RD pulse width = 14 SYSCLK cycles.
1110: WR and RD pulse width = 15 SYSCLK cycles.
1111:WR and RD pulse wid th = 16 SYSCLK cycles.
Bits1–0: EAH1–0: EMIF Address Hold Ti me Bits.
00: Address hold time = 0 SYSCLK cycles.
01: Address hold time = 1 SYSCLK cycle.
10: Address hold time = 2 SYSCLK cycles.
11: Address hold time = 3 SYSCLK cycles.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EAS1 EAS0 EWR3 EWR2 EWR1 EWR0 EAH1 EAH0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x84
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 124
13.7.1. Non-multiplexed Mode
13.7.1.1.16-bit MOVX: EMI0CF[4:2] = ‘101’, ‘110’, or ‘111’.
Figure 13.5. Non-multiplexed 16-bit MOVX Timing
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPLP3
P2
P1.7
P1.6
P4 EMIF WRITE DATA
P3
P2
P1.7
P1.6
P4
TACH
TWDH
TACW
TACS
TWDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
WR
RD
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPLP3
P2
P1.6
P1.7
P4
P3
P2
P1.6
P1.7
P4
TACH
TRDH
TACW
TACS
TRDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
RD
WR
EMIF R EAD DATA
Nonmuxed 1 6-bit WRITE
Nonmuxed 16-bit READ
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
125 Rev. 1.3
13.7.1.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘101’ or ‘111’.
Figure 13.6. Non-multiplexed 8-bit MOVX without Bank Select Timing
EMIF ADDRESS (8 LSBs) from R0 or R1P3
P2
P1.7
P1.6
P4 EMIF WRITE DATA
P3
P1.7
P1.6
P4
TACH
TWDH
TACW
TACS
TWDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
WR
RD
EMIF ADDRESS (8 LSBs) from R0 or R1P3
P2
P1.6
P1.7
P4
P3
P1.6
P1.7
P4
TACH
TRDH
TACW
TACS
TRDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
RD
WR
EMIF READ DATA
Nonmuxed 8-bit WRITE without Bank Select
Nonmuxed 8-bit READ without Bank Select
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 126
13.7.1.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘110’.
Figure 13.7. Non-multiplexed 8-bit MOVX with Bank Select Timing
P4
P3
P4
ADDR[15:8]
AD[7:0]
P3
P1.7
P1.6
P1.3
P1.7
P1.6
P1.3
TACH
TWDH
TACW
TACS
TWDS
ALE
WR
RD
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF WRITE DATA
EMIF ADDRESS (8 LSBs) from
R0 or R1
TALEH TALEL
P4
P3
P4
ADDR[15:8]
AD[7:0]
P3
P1.6
P1.7
P1.3
P1.6
P1.7
P1.3
TACH
TACW
TACS
ALE
RD
WR
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
TALEH TALEL TRDH
TRDS
EMIF READ DATA
Muxed 8-bit WRITE with Bank Select
Muxed 8-bit READ with Bank Select
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
127 Rev. 1.3
13.7.2. Multiplexed Mode
13.7.2.1.16-bit MOVX: EMI0CF[4:2] = ‘001’, ‘010’, or ‘011’.
Figure 13.8. Multiplexed 16-bit MOVX Timing
P4
P3
P4
ADDR[15:8]
AD[7:0]
P3
P1.7
P1.6
P1.3
P1.7
P1.6
P1.3
TACH
TWDH
TACW
TACS
TWDS
ALE
WR
RD
EMIF ADDRESS (8 MSBs) from DPH
EMIF WRIT E DATA
EMIF ADDRESS (8 LSBs) from
DPL
TALEH TALEL
P4
P3
P4
ADDR[15:8]
AD[7:0]
P3
P1.6
P1.7
P1.3
P1.6
P1.7
P1.3
TACH
TACW
TACS
ALE
RD
WR
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from
DPL
TALEH TALEL TRDH
TRDS
EMIF READ DATA
Muxed 16-bit WRITE
Muxed 16-bit READ
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 128
13.7.2.2.8-bit MOVX without Bank Select: EMI0CF [4:2] = ‘001’ or ‘011’.
Figure 13.9. Multiplexed 8-bit MOVX without Bank Select Timing
P4
P3
P4
ADDR[15:8]
AD[7:0]
P1.7
P1.6
P1.3
P1.7
P1.6
P1.3
TACH
TWDH
TACW
TACS
TWDS
ALE
WR
RD
EMIF WRITE DATA
EMIF ADDRESS (8 LSBs) from
R0 or R1
TALEH TALEL
P4
P3
P4
ADDR[15:8]
AD[7:0]
P1.6
P1.7
P1.3
P1.6
P1.7
P1.3
TACH
TACW
TACS
ALE
RD
WR
EMIF ADDRESS (8 LSBs) from
R0 or R1
TALEH TALEL TRDH
TRDS
EMIF READ DATA
Muxed 8-bit WRITE Without Bank Select
Muxed 8-bit READ Without Bank Select
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
129 Rev. 1.3
13.7.2.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘010’.
Figure 13.10. Multiplexed 8-bit MOVX with Bank Select Timing
P4
P3
P4
ADDR[15:8]
AD[7:0]
P3
P1.7
P1.6
P1.3
P1.7
P1.6
P1.3
TACH
TWDH
TACW
TACS
TWDS
ALE
WR
RD
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF WRITE DATA
EMIF ADDRESS (8 LSBs) from
R0 or R1
TALEH TALEL
P4
P3
P4
ADDR[15:8]
AD[7:0]
P3
P1.6
P1.7
P1.3
P1.6
P1.7
P1.3
TACH
TACW
TACS
ALE
RD
WR
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
TALEH TALEL TRDH
TRDS
EMIF READ DATA
Muxed 8-bit WRITE with Bank Select
Muxed 8-bit READ with Bank Select
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 130
Table 13.1. AC Parameters for External Memory Interface
Parameter Description Min* Max* Units
TACS Address / Control Setup Time 03 x TSYSCLK ns
TACW Address / Control Pulse Width 1 x TSYSCLK 16 x TSYSCLK ns
TACH Address / Control Hold Time 03 x TSYSCLK ns
TALEH Addres s Latc h Ena b l e High Time 1 x TSYSCLK 4 x TSYSCLK ns
TALEL Address Latch Enable Low Time 1 x TSYSCLK 4 x TSYSCLK ns
TWDS Write Data Setup Time 1 x TSYSCLK 19 x TSYSCLK ns
TWDH W rite Data Hold Time 03 x TSYSCLK ns
TRDS Read Data Setup Time 20 ns
TRDH Read Data Hold Time 0ns
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 131
14. Oscillators
C8051F34x devices include a programmable internal high-frequency oscillator, a programmable internal
low-frequency oscillator (C8051F340/1/2/3/4/5/8/9/A/B/C/D), an external oscillator drive circuit, and a 4x
Clock Multiplier. The internal high-frequency and low-frequency oscillators can be enabled/disabled and
adjusted using the special function registers, as shown in Figure 14.1. The system clock (SYSCLK) can be
derived from either of the internal oscillators, the external oscillator circuit, or the 4x Clock Multiplier divided
by 2. The USB clock (USBCLK) can be derived from the internal oscillator, external oscillator, or 4x Clock
Multiplier. Oscillator electrical specifications are given in Table 14.1.
Figure 14.1. Oscillator Diagram
Clock Multiplier
OSC
Input
Circuit
XTLVLD
XTAL1
XTAL2
Option 2
VDD
XTAL2
Option 1
10MΩ
Option 3
XTAL2
Option 4
XTAL2
OSCXCN
XTLVLD
XOSCMD2
XOSCMD1
XOSCMD0
XFCN2
XFCN1
XFCN0
CLKMUL
MULEN
MULINIT
MULRDY
MULSEL1
MULSEL0
Programma ble High-
Frequency Oscillator
EN
OSCICL OSCICN
IOSCEN
IFRDY
SUSPEND
IFCN1
IFCN0
EXOSC / 2
x 2 x 2EXOSC
IOSC
SYSCLK
EXOSC
EXOSC / 2
EXOSC / 3
EXOSC / 4
IOSC / 2
USBCLK
USBCLK2-0
CLKSEL
USBCLK2
USBCLK1
USBCLK0
CLKSL2
CLKSL1
CLKSL0
IOSC
Programmab le Low-
Frequency Oscillator
(C8051F340/1/2/3/4/5/8/9/
A/B/C/D)
EN
EXOSC
OSCLCN
OSCLEN
OSCLRDY
OSCLF3
OSCLF2
OSCLF1
OSCLF0
OSCLD1
OSCLD0
n
n
OSCLF3-0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
132 Rev. 1.3
14.1. Programmable Internal High-Frequency (H-F) Oscillator
All C8051F34x device s inc lud e a programmable internal oscillator th at def au lts as the syst em c loc k after a
system reset. The internal oscillator period can be programmed via the OSCICL register shown in SFR
Definition 14.2. The OSCICL register is factory calibrated to obtain a 12 MHz internal oscillator frequency.
Electrical specifications for the precision internal oscillator are given in Table 14.1 on page 141. Note that
the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as
defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset.
14.1.1. Internal H-F Oscillator Suspend Mode
The internal high-frequency oscillator may be placed in Suspend mode by writing ‘1’ to the SUSPEND bit in
register OSCICN. In Suspend mode, the internal H-F oscillator is stopped until a non-idle USB event is
detected (Section 16) or VBUS matches the polarity selected by the VBPOL bit in register REG0CN (Sec-
tion 8.2). Note that the USB transceiver can still detect USB events when it is disabled.
SFR Definition 14.1. OSCICN: Internal H-F Oscillator Control
Bit7: IOSCEN: Internal H-F Oscillator Enable Bit.
0: Internal H-F Oscillator Disabled.
1: Internal H-F Oscillator Enabled.
Bit6: IFRDY: Internal H-F Oscillator Frequency Ready Flag.
0: Internal H-F Oscillator is not running at programmed frequency.
1: Internal H-F Oscillator is running at programmed frequency.
Bit5: SUSPEND: Force Suspend
Writing a ‘1’ to this bit will force the internal H-F oscillator to be stopped. The oscillator will be
re-started on the next non-idle USB event (i.e., RESUME signaling) or VBUS interrupt event
(see SFR Definition 8.1).
Bits4–2: UNUSED. Read = 000b, Write = don't care.
Bits1–0: IFCN1–0: Internal H-F Oscillator Frequency Control.
00: SYSCLK derived from Internal H-F Oscillator divided by 8.
01: SYSCLK derived from Internal H-F Oscillator divided by 4.
10: SYSCLK derived from Internal H-F Oscillator divided by 2.
11: SYSCLK derived from Internal H-F Oscillator divided by 1.
R/W R R/W R R/W R/W R/W R/W Reset Value
IOSCEN IFRDY SUSPEND - - - IFCN1 IFCN0 10000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xB2
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 133
SFR Definition 14.2. OSCICL: Internal H-F Oscillator Calibration
14.2. Programmable Internal Low-Frequency (L-F) Oscillator
The C8051F340/1/2/3/4/5/8/9/C/D devices include a programmable internal oscillator which operates at a
nominal frequency of 80 kHz. The low-frequency oscillator circuit includes a divider that can be changed to
divide the clock by 1, 2, 4, or 8, using the OSCLD bits in the OSCLCN regi ster (see SFR Definition 14.3).
Additionally, the OSCLF bits (OSCLCN5:2) can be used to adjust the oscillator’s output frequency.
14.2.1. Calibrating the Internal L-F Oscillator
Timers 2 and 3 include capture functions that can be used to capture the oscillator frequency, when run-
ning from a known time base. When either Timer 2 or Timer 3 is configured for L-F Oscillator Capture
Mode, a falling edge (Timer 2) or rising edge (Timer 3) of the low-frequency oscillator’s output will cause a
capture event on the corresponding timer. As a capture event occurs, the current timer value
(TMRnH:TMRnL) is copied into the timer reload registers (TMRnRLH:TMRnRLL). By recording the differ-
ence between two successive timer capture values, the low-frequency oscillator’s period can be calcu-
lated. The OSCLF bits can then be adjusted to produce the desired oscillator period.
Bits4–0: OSCCAL: Oscillator Calibration Value
These bits determine the internal H-F oscillator period. When set to 00000b, the oscillator
operates at its fastest setting. When set to 11111b, the oscillator operates at is slowest set-
ting. The contents of this register are factory calibrated to produce a 12 MHz internal oscilla-
tor frequency.
Note: The contents of this register are undefined when Clo ck Recovery is enabled. See Section
“16.4. USB Clock Configuration” on page 166 for details on Clock Recovery.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
--- OSCCAL Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xB3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
134 Rev. 1.3
SFR Definition 14.3. OSCLCN: Internal L-F Oscillator Control
Bit7: OSCLEN: Internal L-F Oscillator Enable.
0: Internal L-F Oscillator Disabled.
1: Internal L-F Oscillator Enabled.
Bit6: OSCLRDY: Internal L-F Oscillator Ready Flag.
0: Internal L-F Oscillator frequency not stabilized.
1: Internal L-F Oscillator frequency stabilized.
Bits5–2: OSCLF[3:0]: Internal L-F Oscillator Frequency Control bits.
Fine-tune control bits for the internal L-F Oscillator frequency. When set to 0000b, the L-F
oscillator operates at its fastest setting. When set to 1111b, the L-F oscillator operates at its
slowest setting.
Bits1–0: OSCLD[1:0]: Internal L-F Oscillator Divider Select.
00: Divide by 8 selected.
01: Divide by 4selected.
10: Divide by 2 selected.
11: Divide by 1 selected.
R/W R R/W R R/W R/W R/W R/W Reset Value
OSCLEN OSCLRDY OSCLF3 OSCLF2 OSCLF1 OSCLF0 OSCLD1 OSCLD0 00vvvv00
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x86
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 135
14.3. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock m ay also provide a clock inp ut. For a crystal or ceramic resonator configuration, the crystal/
resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 14.1. A 10 MΩ
resistor also must be wired across the XTAL1 and XTAL2 pins for the crystal/resonator configuration. In
RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as shown
in Option 2, 3, or 4 of Figure 14.1. The type of external oscillator must be selected in the OSCXCN register,
and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 14.4)
Important Note on External Oscillator Usage: Port pins must be configured when using the external
oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins
P0.6 and P0.7 (C8051F340/1/4/5/8) or P0.2 and P0.3 (C8051F342/3/6/7/9/A/B) are used as XTAL1 and
XTAL2 respectively. When the external oscillator drive circuit is enabled in capacitor, RC, or CMOS clock
mode, Port pi n P0.7 (C80 51F340/ 1/4/5/8) or P0.3 (C8 051F342/3/6/7/9/A/B) is used as XTAL2. The Port I/
O Crossbar should be configured to skip the Port pins used by the oscillator circuit; see Section
“15.1. Priority Crossbar Decoder” on page 144 for Crossbar configuration. Additionally, when using the
external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be
configured as analog inputs. In CMOS clock mode, the associated pin should be configured as a digital
input. See Section “15.2. Port I/O Initialization” on page 147 for details on Port input mode selection.
14.3.1. Clocking Timers Directly Through the External Oscillator
The external oscillator source divided by eight is a clock option for the timers (Section “21. Timers” on
page 235) and the Programmable Counter Array (PCA) (Section “22. Programmable Counter Array
(PCA0)” on page 255). When the external oscillator is used to clock these peripherals, but is not used as
the system clock, the external oscillator frequency must be less than or equal to the system clock fre-
quency. In this configuration, the clock supplied to the peripheral (external oscillator / 8) is synchronized
with the system clock; the jitter associated with this synchronization is limited to ±0.5 system clock cycles.
14.3.2. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 14.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 14.4 (OSCXCN register). For
example, a 12 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The rec-
ommended procedure is:
Step 1. Enable the external oscillator.
Step 2. Wait at least 1 ms.
Step 3. Poll for XTLVLD => ‘1’.
Step 4. Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
136 Rev. 1.3
14.3.3. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 14.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-
mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 kΩ and C = 50 pF:
Referring to the table in SFR Definition 14.4, the required XFCN setting is 010b. Programming XFCN to a
higher setting in RC mode will improve frequency accuracy at an increased external oscillator supply cur-
rent.
14.3.4. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 14.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-
tor to be used and find the frequency of oscillation from the equati ons below. Assume VDD = 3. 0 V and C =
50 pF:
If a frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 14.4 as
KF = 22:
Therefore, the XFCN value to use in this example is 011b.
f1.23 103
()
RC
------------------------1.23 103
()
246 50×[]
--------------------------0.1 MHz 100 kHz== ==
fKF
CV
DD
×()
------------------------- KF
50 x 3()MHz
--------------------------------
==
fKF
150 MHz
----------------------
=
f22
150
---------0.146 MHz, or 146 kHz==
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 137
SFR Definition 14.4. OSCXCN: External Oscillator Control
Bit7: XTLVLD: Crystal Oscillator Va lid Flag.
(Read only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clo ck Mode .
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode.
101: Capacitor Oscillator Mode.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3: RESERVED. Read = 0, Write = don't care.
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000-111: See table below:
CRYSTAL MODE (Circuit from Figure 14.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal or resonator frequency.
RC MODE (Circuit from Figur e 14.1, Option 2; XOSCMD = 10x )
Choose XFCN value to match frequency range:
f = 1.23(103) / (R x C), where
f = frequency of clock in MHz
C = capacitor value in pF
R = Pull-up resistor value in kΩ
C MODE (Circuit from Figure 14.1, Option 3 ; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x VDD), where
f = frequency of clock in MHz
C = capacitor value the XTAL2 pin in pF
VDD = Power Supply on MCU in volts
R R/W R/W R/W R R/W R/W R/W Reset Value
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0 - XFCN2 XFCN1 XFCN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xB1
XFCN Crystal (XOSCMD = 11x) RC (XOSCMD = 10x) C (XOSCMD = 10x)
000 f ≤ 32 kHz f ≤ 25 kHz K Factor = 0.87
001 32 kHz < f ≤ 84kHz 25 kHz < f ≤ 50 kHz K Fact or = 2.6
010 84 kHz < f ≤ 225 kHz 50 kHz < f ≤ 100 kHz K Factor = 7.7
011 225 kHz < f ≤ 590 kHz 100 kHz < f ≤ 200 kHz K Factor = 22
100 590 kHz < f ≤ 1.5 MHz 200 kH z < f ≤ 400 kHz K Factor = 65
101 1.5 MHz < f ≤ 4 MHz 400 kHz < f ≤ 800 kHz K Factor = 180
110 4 MHz < f ≤ 10 MHz 800 kHz < f ≤ 1.6 MHz K Factor = 664
111 10 MHz < f ≤ 30 MHz 1.6 MHz < f ≤ 3.2 MHz K Factor = 1590
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
138 Rev. 1.3
14.4. 4x Clock Multiplier
The 4x Clock Multiplier allows a 12 MHz oscillator to generate the 48 MHz clock required for Full Speed
USB communication (see Section “16.4. USB Clock Configuration” on page 166). A divided version of
the Multiplier output can also be used as the system clock. C8051F340/1/2/ 3 devices can use the 48 MHz
Clock Multiplier output as system clock. See Table 3.1, “Global DC Elec trical Charact eristics,” on page 25
for system clock frequency specifications. See Section 14.5 for details on system clock and USB clock
source selection.
The 4x Clock Multiplier is configured via the CLKMUL register. The procedure for configuring and enabling
the 4x Clock Multiplier is as follows:
1. Reset the Multiplier by writing 0x00 to register CLKMUL.
2. Select the Multiplier input source via the MULSEL bits.
3. Enable the Multip lier with th e MU LEN bit (CLKMUL | = 0x80 ).
4. Delay for >5 µs.
5. Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0).
6. Poll for MULRDY => ‘1’.
Important Note: When using an external oscillator as the input to the 4x Clock Multiplier, the exter-
nal source must be enabled and stable before the Multiplier is initialized. See Section 14.5 for
details on selectin g an external oscillator source.
SFR Definition 14.5. CLKMUL: Clock Multiplier Control
Bit7: MULEN: Clock Multiplier Enable
0: Clock Multiplier disabled.
1: Clock Multiplier enabled.
Bit6: MULINIT: Clock Multiplier Initialize
This bit should be a ‘0’ when the Clock Multiplier is enabled. Once enabled, writing a ‘1’ to
this bit will initialize the Clock Multiplier . The MULRDY bit reads ‘1’ when the Clock Multiplier
is stabilized.
Bit5: MULRDY: Clock Multiplier Ready
This read-only bit indicates the status of the Clock Multiplier.
0: Clock Multiplier not ready.
1: Clock Multiplier ready (locked).
Bits4–2: Unused. Read = 000b; Write = don’t care.
Bits1–0: MULSEL: Clock Multiplier Input Select
These bits select the clock su pplied to the Clock Multiplier.
R/W R/W R R/W R/W R/W R/W R/W Reset Value
MULEN MULINIT MULRDY - - - MULSEL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address
0xB9
MULSEL Selected Clock
00 Internal Oscillator
01 External Oscillator
10 External Oscillator / 2
11 RESERVED
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 139
14.5. System and USB Clock Selection
The internal oscillator requires little start-up time and may be selected as the system or USB clock immedi-
ately following the OSCICN write that enables the internal oscillator. External crystals and ceramic resona-
tors typically require a start-up time before they are settled and ready for use. The Crystal Valid Flag
(XTLVLD in register OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid
reading a false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the
external oscillator and checking XTLVLD. RC and C modes typically require no startup time.
14.5.1. System Clock Selection
The CLKSL[1:0] bits in register CLKSEL select which oscillator source is used as the system clock.
CLKSL[1:0] must be set to 01b for the system clock to run from the external oscillator; however the exter-
nal oscillator may still clock certain peripherals (timers, PCA, USB) when the internal oscillator is selected
as the system clock. The system clock may be switched on-the-fly between the internal oscillator, external
oscillator, and 4x Clock Multiplier so long as the selected oscillator is enabled and has settled. C8051F340/
1/2/3 devices can use the 48 MHz Clock Multiplier output as system clock. See Table 3.1, “Global DC Elec-
trical Characteristics,” on page 25 for system clock frequency specifications. When operating with a sys-
tem clock of greater than 25 MHz (up to 48 MHz), the FLRT bit (FLSCL.4) should be set to ‘1’. See
Section “10. Prefetch Engine” on page 99 for more details.
14.5.2. USB Clock Selection
The USBCLK[2:0] bits in register CLKSEL select which oscillator source is used as the USB clock. The
USB clock may be derived from the 4x Clock Multiplier output, a divided version of the internal oscillator, or
a divided version of the external oscillator. Note that the USB clock must be 48 MHz when operating USB0
as a Full Speed Function; t he USB clock must be 6 MHz when operating USB0 as a Low Speed Function.
See SFR Definition 14.6 for USB clock selection options.
Some example USB clock configurations for Full and Low Speed mode are given below:
Internal Oscillator
Clock Signal Input Source Selection Register Bit Settings
USB Clock Clock Multiplier USBCLK = 000b
Clock Multiplier Input Internal Oscillator* MULSEL = 00b
Internal Oscillator Divide by 1 IFCN = 11b
External Oscillator
Clock Signal Input Source Selection Register Bit Settings
USB Clock Clock Multiplier USBCLK = 000b
Clock Multiplier Input External Oscillator MULSEL = 01b
External Oscillator Crystal Oscillator Mode
12 MHz Crystal XOSCMD = 110b
XFCN = 111b
*Note: Clock Recovery must be enabled for this configuration.
Internal Oscillator
Clock Signal Input Source Selection Register Bit Settings
USB Clock Internal Oscillator / 2 USBCLK = 001b
Internal Oscillator Divide by 1 IFCN = 11b
External Oscillator
Clock Signal Input Source Selection Register Bit Settings
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
140 Rev. 1.3
SFR Definition 14.6. CLKSEL: Clock Select
USB Clock External Oscillator / 4 USBCLK = 101b
External Oscillator Crystal Oscillator Mode
24 MHz Crystal XOSCMD = 110b
XFCN = 111b
Internal Oscillator
Clock Signal Input Source Selection Register Bit Settings
Bit 7: Unused. Read = 0b; Write = don’t ca re.
Bits6–4: USBCLK2–0: USB Clock Select
These bit s select the clock supplied to USB0. When op erating USB0 in full-speed mode, th e
selected clock should be 48 MHz. When operating USB0 in low-sp eed mode, the selected
clock should be 6 MHz.
Bit3: Unused. Read = 0b; Write = don’t care.
Bits2–0: CLKSL2–0: System Clock Select
These bits select the system clock source. When operating from a system clock of 25 MHz
or less, the FLR T bit should be set to ‘0’. When operating with a system clock of greater than
25 MHz (up to 48 MHz), the FLRT bit (FLSCL.4) should be set to ‘1’. See Section
“10. Prefetch Engine” on page 99 for more details.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- USBCLK - CLKSL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address
0xA9
USBCLK Selected Clock
000 4x Clock Multiplier
001 Internal Oscillator / 2
010 External Oscillator
011 External Oscillator / 2
100 External Oscillator / 3
101 External Oscillator / 4
110 RESERVED
111 RESERVED
CLKSL Selected Clock
000 Internal Oscillator (as determined by the
IFCN bits in register OSCICN)
001 External Oscillator
010 4x Clock Multiplier / 2
011* 4x Clock Multiplier*
100 Low-Frequency Oscillator
101-111 RESERVED
*Note: This option is only available on 48 MHz devices.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 141
Table 14.1. Oscillator Electrical Characteristics
VDD = 2.7 to 3.6 V; –40 to +85 °C unless otherwise specified
Parameter Conditions Min Typ Max Units
Internal High-Frequency Oscillator (Using Factory-Calibrated Settings)
Oscillator Frequency IFCN = 11b 11.82 12.00 12.18 MHz
Oscillator Supply Current
(from VDD)24 ºC, VDD = 3.0 V,
OSCICN.7 = 1 —685— µA
Internal Low-Frequency Oscillator (Using Factory -Calibrated Settings)
Oscillator Frequency OSCLD = 11b 72 80 99 kHz
Oscillator Supply Current
(from VDD)24 ºC, VDD = 3.0 V,
OSCLCN.7 = 1 —7.0— µA
External USB Clock Requirements
USB Clock Frequency* Full Speed Mode
Low Speed Mode 47.88
5.91 48
648.12
6.09 MHz
*Note: Applies only to external oscillator sources.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 142
15. Port Input/Output
Digital and analog resources are available through 40 I/O pins (48-pin packages) or 25 I/O pins (32-pin
packages). Port pins are organized as shown in Figure 15.1. Each of the Port pin s can b e def ined a s gen -
eral-purpo se I/ O (G PIO) or a nalog inp ut; Port p ins P0 .0-P3.7 can be assigned to one of the internal digital
resources as shown in Figure 15.3. The designer has complete control over which functions are assigned,
limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the
use of a Priority Crossbar Decoder. Note that the state of a Port I/O pin can always be read in the corre-
sponding Port latch, regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 15.3 and Figure 15.4). The registers XBR0, XBR1, and XBR2 defined in SFR Definition 15.1, SFR
Definition 15.2, and SFR Definition 15.3, are used to select internal digital functions.
All Port I/Os are 5 V tolerant (refer to Figure 15.2 for the Port cell circ uit). The Port I/ O c ells ar e c on fig ur ed
as either push-pull or open-drain in the Port Output Mode r egisters (PnMDOUT, where n = 0,1,2,3,4). Com-
plete Electrical Specifications for Port I/O are given in Table 15.1 on page 158.
Figure 15.1. Port I/O Functional Block Diagram (Port 0 through Port 3)
XBR0, XBR1, XBR2,
PnSKIP Re g isters
Digital
Crossbar
Priority
Decoder
2
P0
I/O
Cells
P0.0
P0.7
8
PnMDOUT,
PnMDIN Registers
UART0
(Internal Digital Signals)
Highest
Priority
Lowest
Priority
SYSCLK
2
SMBus
T0, T1 2
6
PCA
CP1
Outputs 2
4
SPI
CP0
Outputs 2P1
I/O
Cells
P1.0
P1.7
8
P2
I/O
Cells
P2.0
P2.7
8
P3
I/O
Cells
P3.0
8
(Port Latches)
P0
8
8
8
8
P1
P2
P3
*P3.1-P3.7 only available on 48-pin
packages
**UART 1 only ava ilable on
C8051F340/1/4/5/8/A/B devices
UART1** 2P3.7*
(P0.0-P0.7)
(P1.0-P1.7)
(P2.0-P2.7)
(P3.0-P3.7*)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
143 Rev. 1.3
Figure 15.2. Port I/O Cell Block Diagram
GND
PORT-OUTENABLE
PORT-OUTPUT
PUSH-PULL VDD VDD
WEAK-PULLUP
(WEAK)
PORT
PAD
ANALOG INPUT
Analog Select
PORT-INPUT
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 144
15.1. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 15.3) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips
that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose
associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that
are to be used for analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to the VREF signal, external oscillator
pins (XTAL1, XTAL2), the ADC’s external conve rsion start signal (CNVSTR), EMIF control signals, and any
selected ADC or Comparator inputs. The PnSKIP registers may also be used to skip pins to be used as
GPIO. The Crossbar skips selected pins as if they were already assigned, and moves to the next unas-
signed pin. Figure 15.3 shows all the possible pins available to each peripheral. Figure 15.4 shows the
Crossbar Decoder priority with no Port pins skipped. Figure 15.5 shows a Crossbar example with pins
P0.2, P0.3, and P1.0 skipped.
Figure 15.3. Peripheral Availability on Port I/O Pins
XTAL1
XTAL2
CNVSTR
VREF
XTAL1
XTAL2
ALE
CNVSTR
VREF
RD
WR
01234567012345670123456701234567
SCK
MISO
MOSI
NSS*
CP0
CP0A
CP1
T1
TX1**
**UA RT1 avail able onl y on C8051F340/ 1/4/ 5/ 8/A /B devi c es
*NS S is onl y pi nned out i n 4-wire SPI mode
CEX3
CEX4
P1
CP1A
CEX2
CEX0
CEX1
SYSCLK
RX0
SDA
P3
SF Signals
(48-pin
Package)
P3.1-P3.7 unavaila ble on
the 32-pin p ackages
P2
SCL
P0
SF Signals
(32-pin
Package)
PIN I/O
TX0
S pec i al F unct i on S i gnals are not as signed by t he Cros sbar. When these si gnals are
enabled, t he Cros sbar m us t be m anual ly configured to ski p t hei r c orres pondi ng port pins.
P ort pi n pot ential l y avai labl e t o peripheral
SF Signals
ECI
T0
RX1**
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
145 Rev. 1.3
Figure 15.4. Crossbar Priority Decoder in Example Configuration
(No Pins Skipped)
XTAL1
XTAL2
CNVSTR
VREF
XTAL1
XTAL2
ALE
CNVSTR
VREF
RD
WR
01234567012345670123456701234567
SCK
MISO
MOSI
NSS* *NSS i s onl y pi nned out i n 4-wire S P I m ode
CP0
CP0A
CP1
T1
TX1** **UA RT1 avail able onl y on C8051F340/ 1/4/5/ 8/A/B devi ces
00000000000000000000000000000000
E x am pl e: XBR0 = 0x07
XB R1 = 0x43
P3
P3SKIP[0:7]
SF S i gnal s
(48-pin
Package)
P 3. 1-P 3. 7 u n ava il able on
the 32-p i n p acka g es
P2
CEX3
CEX4
P1SKIP[0:7]
P1
CP1A
CEX2
CEX0
CEX1
SYSCLK
RX0
SDA
SCL
P0
SF S i gnal s
(32-pin
Package)
PIN I/O
TX0
ECI
T0
RX1**
P2SKIP[0:7]
S pec i al Functi on S i gnals are not assigned by t he Crossbar. When these signals are
SF S i gnal s
P0SKIP[0:7]
P ort pi n as si gned t o peri pheral by t he Cros sbar
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 146
Figure 15.5. Crossbar Priority Decoder in Example Configuration (3 Pins Skipped)
Registers XBR0, XBR1, and XBR2 are used to assign the digital I/O resources to the physical I/O Port
pins. Note that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus
(SDA and SCL); when either UART is selected, the Crossbar assigns both pins associated with the UART
(TX and RX). UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned
to P0.4; UAR T RX0 is always assigne d to P0.5. Standard Port I/Os ap pear contiguously af ter the pr ioritized
functions have been assigned.
Important Note: The SPI can be operated in either 3-wire or 4-wire modes, depending on the state of the
NSSMD1-NSSMD0 bits in register SPI0CN. Accordin g to the SPI mode, the NSS signal may or may not be
routed to a Port pin.
XTAL1
XTAL2
CNVSTR
VREF
XTAL1
XTAL2
ALE
CNVSTR
VREF
RD
WR
01234567012345670123456701234567
SCK
MISO
MOSI
NSS* *NS S is only pinned out in 4-wire S P I m ode
CP0
CP0A
CP1
T1
TX1** **UART1 available only on C805 1F340/ 1/4/ 5/8/ A /B devic es
00110000100000000000000000000000
E xam ple: XB R0 = 0x07
XB R1 = 0x 43
P0SKIP = 0x0C
P1SKIP = 0x01
SDA
SCL
P ort pin as s igned t o peripheral by t he Cros sb ar
CP1A
CEX3
CEX4
CEX2
CEX0
CEX1
SYSCLK
P0 P1
S pec ial F unc tion S ignals are not as s igned by the Cros s bar. When t hes e s ignals are
enabled, the C ros s bar m us t be m an ually c onfigured to s k ip t heir co rresp onding port pins .
P0SKIP[0:7] P1SKIP[0:7]
P2
SF S ignals
ECI
T0
RX1**
P3
P3.1-P3.7 una va ilable on
th e 32 -p i n p a c kag es
SF S ignals
(48-pin
Package)
P2SKIP[0:7] P3SKIP[0:7]
SF S ignals
(32-pin
Package)
PIN I/O
TX0
RX0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
147 Rev. 1.3
15.2. Port I/O Initialization
Port I/O initialization consists of the following steps:
Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode
register (PnMDIN).
Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output
Mode register (PnMDOUT).
Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP).
Step 4. Assign Port pins to desired peripherals (XBR0, XBR1).
Step 5. Enable the Crossbar (XBARE = ‘1’).
All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or
ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its
weak pull-up, digital driver, and digital receiver are disabled. This process saves power and reduces noise
on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this
practice is not recommended. To configure a Port pin for digital input, write ‘0’ to the corresponding bit in
register PnMDOUT, and write ‘1’ to the corresponding Port latch (register Pn).
Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by
setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates
a digital input, and a ‘0’ indicates an analog input. All pins default to digital inputs on reset.
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMD-
OUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings. When the WEAKPUD bit in XBR1 is ‘0’, a weak pull-up is enabled for all Port I/O con-
figured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pull-up is
turned off on an output that is driving a ‘0’ to avoid unnecessary power dissipation.
Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions
required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is
enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register
settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode
Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software will determine the
Port I/O pin-assignments based on the XBRn Register settings.
Important Note: The Crossbar must be enabled to use Ports P0, P1, P2, and P3 as standard Port I/O in
output mode. These Port output drivers are disabled while the Crossbar is disabled. Port 4 always func-
tions as stand ard GPIO.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 148
SFR Definition 15.1. XBR0: Port I/O Crossbar Register 0
Bit7: CP1AE: Comparator1 Asynchro nous Output Enable
0: Asynchronou s C P1 un available at Port pin.
1: Asynchronous CP1 routed to Port pin.
Bit6: CP1E: Comparator1 Output Enable
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
Bit5: CP0AE: Comparator0 Asynchro nous Output Enable
0: Asynchronou s C P0 un available at Port pin.
1: Asynchronous CP0 routed to Port pin.
Bit4: CP0E: Comparator0 Output Enable
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
Bit3: SYSCKE: /SYSCLK Output Enable
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK output routed to Port pin.
Bit2: SMB0E: SMBus I/O Enable
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
Bit1: SPI0E: SPI I/O Enable
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins.
Bit0: URT0E: UART0 I/O Output Enable
0: UART0 I/O unavailable at Port pins.
1: UART0 TX0, RX0 routed to Port pins P0.4 and P0.5.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CP1AE CP1E CP0AE CP0E SYSCKE SMB0E SPI0E URT0E 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xE1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
149 Rev. 1.3
SFR Definition 15.2. XBR1: Port I/O Crossbar Register 1
SFR Definition 15.3. XBR2: Port I/O Crossbar Register 2
Bit7: WEAKPUD: Port I/O Weak Pull-up Disable.
0: Weak Pull-ups enabled (except for Por ts whose I/O are configured as ana log input or
push-pull output).
1: Weak Pull-ups disabled.
Bit6: XBARE: Crossbar Enable.
0: Crossbar disabled; all Port drivers disabled.
1: Crossbar enabled.
Bit5: T1E: T1 Enable
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
Bit4: T0E: T0 Enable
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
Bit3: ECIE: PCA0 External Counter Input Enable
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
Bits2–0: PCA0ME: PCA Module I/O Enable Bits.
000: All PCA I/O unavailable at Port pins.
001: CEX0 routed to Port pin.
010: CEX0, CEX1 routed to Port pins.
011: CEX0, CEX1, CEX2 routed to Port pins.
100: CEX0, CEX1, CEX2, CEX3 routed to Port pins.
101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins.
110: Reserved.
111: Reserved.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
WEAKPUD XBARE T1E T0E ECIE PCA0ME 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xE2
Bits7–1: RESERVED: Always write to 0000000b
Bit0: URT1E: UART1 I/O Output Enable (C8051F340/1/4/5/8/A/B Only)
0: UART1 I/O unavailable at Port pins.
1: UART1 TX1, RX1 routed to Port pins.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
URT1E 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xE3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 150
15.3. General Purpose Port I/O
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for
general purpose I/O. Ports 3-0 are accessed through corresponding special function registers (SFRs) that
are both byte addressable and bit addressable. Port 4 (48-pin packages only) uses an SFR which is
byte-addressable. When writing to a Port, the value written to the SFR is latched to maintain the output
data value at each pin. When reading, the logic levels of the Port's inp ut pins are re turned rega rdless of the
XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can
always read its corresponding Port I/O pin). The exception to this is the execution of the read-modify-write
instructions. The read-modify-write instructions when operating on a Port SFR are the following: ANL,
ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SETB, when the de stination is an ind ividual bit
in a Port SFR. For these in structions, the value of the register (not the pin) is read, modified, and written
back to the SFR.
SFR Definition 15.4. P0: Port0 Latch
SFR Definition 15.5. P0MDIN: Port0 Input Mode
Bits7–0: P0.[7:0]
Write - Output appears on I/O pins per Crossbar Registers (when XBARE = ‘1’).
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P0MDIN. Directly reads Port
pin when configured as digital input.
0: P0.n pin is logic low.
1: P0.n pin is logic high.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0x80
Bits7–0: Analog Input Configuration Bits for P0.7–P0.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled .
0: Corresponding P0.n pin is configured as an an alog input.
1: Corresponding P0.n pin is not configured as an analog input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
151 Rev. 1.3
SFR Definition 15.6. P0MDOUT: Port0 Output Mode
SFR Definition 15.7. P0SKIP: Port0 Skip
Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in regis-
ter P0MDIN is logic 0.
0: Corresponding P0.n Output is open-drain.
1: Corresponding P0.n Output is push -pull.
(Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless
of the value of P0MDOUT).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xA4
Bits7–0: P0SKIP[7:0]: Port0 Crossbar Skip Enable Bits.
These bits select Por t pins to be skipped by the Crossbar Decoder. Port pins used as ana-
log inputs (for ADC or Compa rator) or used as special functions (VREF inpu t, external oscil-
lator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P0.n pin is not skipped by the Crossbar.
1: Corresponding P0.n pin is skipped by the Crossbar.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD4
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 152
SFR Definition 15.8. P1: Port1 Latch
SFR Definition 15.9. P1MDIN: Port1 Input Mode
SFR Definition 15.10. P1MDOUT: Port1 Output Mode
Bits7–0: P1.[7:0]
Write - Output appears on I/O pins per Crossbar Registers (when XBARE = ‘1’).
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P1MDIN. Directly reads Port
pin when configured as digital input.
0: P1.n pin is logic low.
1: P1.n pin is logic high.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0x90
Bits7–0: Analog Input Configuration Bits for P1.7–P1.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled .
0: Corresponding P1.n pin is configured as an an alog input.
1: Corresponding P1.n pin is not configured as an analog input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF2
Bits7–0: Output Configuration Bits for P1.7–P1.0 (respectively): ignored if corresponding bit in regis-
ter P1MDIN is logic 0.
0: Corresponding P1.n Output is open-drain.
1: Corresponding P1.n Output is push -pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xA5
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
153 Rev. 1.3
SFR Definition 15.11. P1SKIP: Port1 Skip
SFR Definition 15.12. P2: Port2 Latch
SFR Definition 15.13. P2MDIN: Port2 Input Mode
Bits7–0: P1SKIP[7:0]: Port1 Crossbar Skip Enable Bits.
These bits select Por t pins to be skipped by the Crossbar Decoder. Port pins used as ana-
log inputs (for ADC or Compa rator) or used as special functions (VREF inpu t, external oscil-
lator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P1.n pin is not skipped by the Crossbar.
1: Corresponding P1.n pin is skipped by the Crossbar.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD5
Bits7–0: P2.[7:0]
Write - Output appears on I/O pins per Crossbar Registers (when XBARE = ‘1’).
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P2MDIN. Directly reads Port
pin when configured as digital input.
0: P2.n pin is logic low.
1: P2.n pin is logic high.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xA0
Bits7-0: Analog Input Configuration Bits for P2.7-P2.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled .
0: Corresponding P2.n pin is configured as an an alog input.
1: Corresponding P2.n pin is not configured as an analog input.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 154
SFR Definition 15.14. P2MDOUT: Port2 Output Mode
SFR Definition 15.15. P2SKIP: Port2 Skip
Bits7–0: Output Configuration Bits for P2.7–P2.0 (respectively): ignored if corresponding bit in regis-
ter P2MDIN is logic 0.
0: Corresponding P2.n Output is open-drain.
1: Corresponding P2.n Output is push -pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xA6
Bits7–0: P2SKIP[7:0]: Port2 Crossbar Skip Enable Bits.
These bits select Por t pins to be skipped by the Crossbar Decoder. Port pins used as ana-
log inputs (for ADC or Compa rator) or used as special functions (VREF inpu t, external oscil-
lator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P2.n pin is not skipped by the Crossbar.
1: Corresponding P2.n pin is skipped by the Crossbar.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD6
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
155 Rev. 1.3
SFR Definition 15.16. P3: Port3 Latch
SFR Definition 15.17. P3MDIN: Port3 Input Mode
SFR Definition 15.18. P3MDOUT: Port3 Output Mode
Bits7–0: P3.[7:0]
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P3MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P3MDIN. Directly reads Port
pin when configured as digital input.
0: P3.n pin is logic low.
1: P3.n pin is logic high.
Note: P3.1–3.7 are only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P3.7 P3.6 P3.5 P3.4 P3.3 P3.2 P3.1 P3.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xB0
Bits7–0: Analog Input Configuration Bits for P3.7–P3.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled .
0: Corresponding P3.n pin is configured as an an alog input.
1: Corresponding P3.n pin is not configured as an analog input.
Note: P3.1–3.7 are only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF4
Bits7–0: Output Configuration Bits for P3.7–P3.0 (respectively); ignored if corresponding bit in regis-
ter P3MDIN is logic 0.
0: Corresponding P3.n Output is open-drain.
1: Corresponding P3.n Output is push -pull.
Note: P3.1–3.7 are only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xA7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 156
SFR Definition 15.19. P3SKIP: Port3 Skip
SFR Definition 15.20. P4: Port4 Latch
Bits7–0: P3SKIP[3:0]: Port3 Crossbar Skip Enable Bits.
These bits select Por t pins to be skipped by the Crossbar Decoder. Port pins used as ana-
log inputs (for ADC or Compa rator) or used as special functions (VREF inpu t, external oscil-
lator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P3.n pin is not skipped by the Crossbar.
1: Corresponding P3.n pin is skipped by the Crossbar.
Note: P3.1–3.7 are only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xDF
Bits7–0: P4.[7:0]
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P4MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P4MDIN. Directly reads Port
pin when configured as digital input.
0: P4.n pin is logic low.
1: P4.n pin is logic high.
Note: P4 is only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P4.7 P4.6 P4.5 P4.4 P4.3 P4.2 P4.1 P4.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xC7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
157 Rev. 1.3
SFR Definition 15.21. P4MDIN: Port4 Input Mode
SFR Definition 15.22. P4MDOUT: Port4 Output Mode
Bits7–0: Analog Input Configuration Bits for P4.7–P4.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled .
0: Corresponding P4.n pin is configured as an an alog input.
1: Corresponding P4.n pin is not configured as an analog input.
Note: P4 is only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF5
Bits7–0: Output Configuration Bits for P4.7–P4.0 (respectively); ignored if corresponding bit in regis-
ter P4MDIN is logic 0.
0: Corresponding P4.n Output is open-drain.
1: Corresponding P4.n Output is push -pull.
Note: P4 is only available on 48-pin devices.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xAE
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 158
Table 15.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified
Parameters Conditions Min Typ Max Units
Output High Voltage
IOH = –3 mA, Port I/O push-pull
IOH = –10 µA, Port I/O push-pull
IOH = –10 mA, Port I/O push-pull
VDD – 0.7
VDD – 0.1 VDD – 0.8 V
Output Low Voltage
IOL = 8.5 mA
IOL = 10 µA
IOL = 25 mA 1.0
0.6
0.1 V
Input High Voltage 2.0 V
Input Low Voltage 0.8 V
Input Leakag e Curr en t Weak Pull-up O ff
Weak Pull-up O n, VIN = 0 V 25 ±1
50 µA
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 159
16. Universal Serial Bus Controller (USB0)
C8051F34x devices include a complete Full/Low Speed USB function for USB peripheral implementa-
tions*. The USB Function Controller (USB0) consists of a Serial Interface Engine (SIE), USB Transceiver
(including matching resistors and configurable pull-up resistors), 1k FIFO block, and clock recovery mech -
anism for crystal-less operation. No external components are required. The USB Function Controller and
Transceiver is Universal Serial Bus Specification 2.0 compliant.
Figure 16.1. USB0 Block Diagram
Important Note: This document assumes a comprehensive understanding of the USB
Protocol. Terms and abbreviations used in this document are defined in the USB Specifi-
cation. We encou rage you to review the latest version of th e USB Specification before pro-
ceeding.
*Note: The C8051F34x cannot be used as a USB Host device.
Transceiver Serial Interface Engi ne (SIE)
USB FIFOs
(1k RAM)
D+
D-
VDD Endpoint0
IN/OUT
Endpoint1
IN OUT
Endpoint2
IN OUT
Endpoint3
IN OUT
Data
Transfer
Control
CIP-51 Core
USB
Control,
Status, and
Interrupt
Registers
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16.1. Endpoint Addressing
A total of eight endpoint pipes are available. The control endpoint (Endpoint0) always functions as a
bi-directional IN/OUT endpoint. The other endpoints are implemented as three pairs of IN/OUT endpoint
pipes:
16.2. USB Transceiver
The USB Transceiver is configured via the USB0XCN register shown in SFR Definition 16.1. This configu-
ration includes Transceiver enable/disable, pull-up resistor enable/disable, and device speed selection
(Full or Low Speed). When bit SPEED = ‘1’, USB0 operates as a Full Speed USB function, and the on-chip
pull-up resistor (if enabled) appears on the D+ pin. When bit SPEED = ‘0’, USB0 operates as a Low S peed
USB function, and the on-chip pull-up resistor (if enabled) appears on the D- pin. Bits4-0 of register
USB0XCN can be us ed fo r Transceiver testing as desc ribed in SFR Definition 16.1. The pu ll-up resistor is
enabled only when VBUS is present (see Section “8.2. VBUS Detection” on page 69 for details on
VBUS detection).
Important Note: The USB clock should be active before the Transceiver is enabled.
Table 16.1. Endpoint Addressing Scheme
Endpoint Associated Pipes USB Protocol Address
Endpoint0 Endpoint0 IN 0x00
Endpoint0 OUT 0x00
Endpoint1 Endpoint1 IN 0x81
Endpoint1 OUT 0x01
Endpoint2 Endpoint2 IN 0x82
Endpoint2 OUT 0x02
Endpoint3 Endpoint3 IN 0x83
Endpoint3 OUT 0x03
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SFR Definition 16.1. USB0XCN: USB0 Transceiver Control
16.3. USB Register Access
The USB0 controller registers listed in Table 16.2 are accessed through two SFRs: USB0 Address
(USB0ADR) and USB0 Data (USB0DAT). The USB0ADR register selects which USB register is targeted
Bit7: PREN: Internal Pull-up Resistor Enable
The location of the pull-up resistor (D+ or D–) is determined by the SPEED bit.
0: Internal pull-up resistor disabled (device effectively detached from the USB network).
1: Internal pull-up resistor enabled when VBUS is present (device attached to the USB net-
work).
Bit6: PHYEN: Physical Layer Enable
This bit enables/disables the USB0 physical layer transceiver.
0: Transceiver disabled (suspend).
1: Transceiver enabled (normal).
Bit5: SPEED: USB0 Speed Select
This bit selects the USB0 speed.
0: USB0 operates as a Low Speed device. If enabled, the internal pull-up resisto r appears
on the D– line.
1: USB0 operates as a Full S p eed device. If enab led, the internal pull-up resistor appears on
the D+ line.
Bits4–3: PHYTST1–0: Physical Layer Test
These bits can be used to test the USB0 transceiver.
Bit2: DFREC: Differential Receiver
The state of this bit indicates the current differential value present on the D+ and D– lines
when PHYEN = ‘1’.
0: Differential ‘0’ signaling on the bus.
1: Differential ‘1’ signaling on the bus.
Bit1: Dp: D+ Signal Status
This bit indicates the current logic level of the D+ pin.
0: D+ signal currently at logic 0.
1: D+ signal currently at logic 1.
Bit0: Dn: D- Signal Status
This bit indicates the current logic level of the D– pin.
0: D– signal currently at logic 0.
1: D– signal currently at logic 1.
R/W R/W R/W R/W R/W R R R Reset Value
PREN PHYEN SPEED PHYTST1 PHYTST0 DFREC Dp Dn 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD7
PHYTST[1:0] Mode D+ D–
00b Mode 0: Normal (non-test mode) X X
01b Mode 1: Differential ‘1’ Forced 1 0
10b Mode 2: Differential ‘0’ Forced 0 1
11b Mode 3: Single-Ended ‘0’ Forced 0 0
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by reads/writes of the USB0DAT register. See Figure 16.2.
Endpoint control/status registers are accessed by first writing the USB register INDEX wi th the target en d-
point number. Once the t arget end point number is written to the INDEX register , the control/status registers
associated with the target endpoint may be accessed. See the “Indexed Registers” section of Table 16.2
for a list of endpoint control/status registers.
Important Note: The USB clock must be active when accessing USB registers.
Figure 16.2. USB0 Register Access Scheme
USB Controller
FIFO
Access
Index
Register
Endpoint0 Control/
Status Registers
Endpoint1 Control/
Status Registers
Endpoint2 Control/
Status Registers
Endpoint3 Control/
Status Registers
Common
Registers
Interrupt
Registers
8051
SFRs
USB0ADR
USB0DAT
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SFR Definition 16.2. USB0ADR: USB0 Indirect Address
Bits7: BUSY: USB0 Register Read Busy Flag
This bit is used during indirect USB0 register accesses. Sof tware should write ‘1’ to this bit to
initiate a read of the USB0 register targeted by the USBADDR bits (USB0ADR.[5-0]). The
target address and BUSY bit may be written in the same write to USB0ADR. After BUSY is
set to ‘1’, hardware will clear BUSY when the targeted register data is ready in the
USB0DAT register. Software shou ld check BUSY for ‘0’ before writing to USB0DAT.
Write:
0: No effect.
1: A USB0 indirect register read is initiated at the address specified by the USBADDR bits.
Read:
0: USB0DAT register data is valid.
1: USB0 is busy accessing an indirect register; USB0DAT register data is invalid.
Bit6: AUTORD: USB0 Register Auto-read Flag
This bit is used for block FIFO re ad s.
0: BUSY must be written manually for each USB0 indirect register read.
1: The next indirect register read will automatically be initiated when software reads
USB0DAT (USBADDR bits will not be changed).
Bits5–0: USBADDR: USB0 Indirect Register Address
These bit s hold a 6-bit address used to indirectly access the USB0 core registers. Table 16.2
lists the USB0 core registers and their indirect addresses. Reads and writes to USB0DAT
will target the register indicated by the USBADDR bits.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
BUSY AUTORD USBADDR 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x96
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SFR Definition 16.3. USB0DAT: USB0 Data
This SFR is used to indirectly read and write USB0 registers.
Write Procedure:
1. Poll for BUSY (USB 0ADR.7) => ‘0’.
2. Load the target USB0 register address into the USBADDR bits in register USB0ADR.
3. Write data to USB0DAT.
4. Repeat (Step 2 may be skipped when wr iting to the same USB0 register).
Read Procedure:
1. Poll for BUSY (USB 0ADR.7) => ‘0’.
2. Load the target USB0 register address into the USBADDR bits in register USB0ADR.
3. Write ‘1’ to the BUSY bit in register USB0ADR (steps 2 and 3 can be performed in the
same write).
4. Poll for BUSY (USB 0ADR.7) => ‘0’.
5. Read data from USB0DAT.
6. Repeat from Step 2 (S tep 2 may be skipped when r eading the same USB0 register; Step 3
may be skipped when the AUTORD bit (USB0ADR.6) is logic 1).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
USB0DAT 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x97
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USB Register Definition 16.4. INDEX: USB0 Endpoint Index
Table 16.2. USB0 Controller Registers
USB Register
Name USB Register
Address Description Page Number
Interrupt Registers
IN1INT 0x02 Endpoint0 and Endpoints1-3 IN Interrupt Flags 173
OUT1INT 0x0 4 Endpoints1-3 OUT Interrupt Flags 173
CMINT 0x06 Common USB Interrupt Flags 174
IN1IE 0x07 Endpoint0 and End points1 -3 IN Interrupt Enables 175
OUT1IE 0x09 Endpoints1-3 OUT Interrupt Enables 175
CMIE 0x0B Common USB Interrupt Enables 176
Common Registers
FADDR 0x00 Function Address 169
POWER 0x01 Power Management 171
FRAMEL 0x0C Frame Number Low Byte 172
FRAMEH 0x0D Frame Number High Byte 172
INDEX 0x0E Endpoint Index Selection 165
CLKREC 0x0F Clock Recovery Control 166
FIFOn 0x20–0x23 Endpoints0-3 FIFOs 168
Indexed Registers
E0CSR 0x11 End point0 Control / Status 179
EINCSRL Endpoint IN Control / Status Low Byte 182
EINCSRH 0x12 Endpoint IN Control / Status High Byte 183
EOUTCSRL 0x14 Endpoint OUT Control / Status Low Byte 185
EOUTCSRH 0x15 Endpoint OUT Control / Status High Byte 186
E0CNT 0x16 Number of Received Bytes in Endpoint0 FIFO 180
EOUTCNTL Endpoint OUT Packet Count Low Byte 186
EOUTCNTH 0x17 Endpoint OUT Packet Count High Byte 186
Bits7–4: Unused. Read = 0000b; W rite = don’t care .
Bits3–0: EPSEL: Endpoint Select
These bits select which endpoint is targeted when indexed USB0 registers are accessed.
R R R R R/W R/W R/W R/W Reset Value
- - - - EPSEL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x0E
INDEX Target Endpoint
0x0 0
0x1 1
0x2 2
0x3 3
0x4–0xF Reserved
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16.4. USB Clock Configuration
USB0 is capable of communication as a Full or Low Speed USB function. Communication speed is
selected via the SPEED bit in SFR USB0XCN. When operating as a Low Speed function, the USB0 clock
must be 6 MHz. When operating as a Full Speed function, the USB0 clock must be 48 MHz. Clock options
are described in Section “14. Oscillators” on page 131. The USB0 clock is selected via SFR CLKSEL
(see SFR Definition 14.6).
Clock Recovery circuitry uses the incoming USB data stream to adjust the internal oscillator; this allows
the internal oscillator (and 4x Clock Multiplier) to meet the requirements for USB clock tolerance. Clock
Recovery should be used in the following configurations:
When operating USB0 as a Low Speed function with Clock Recovery, software must write ‘1’ to the
CRLOW bit to enable Low Speed Clock Recovery. Clock Recovery is typically not necessary in Low Speed
mode.
Single Step Mode can be used to help the Clock Recovery circuitry to lock when h igh noise levels are pres-
ent on the USB network. This mode is not required (or recommended) in typical USB environments.
USB Register Definition 16.5. CLKREC: Clock Recovery Control
Communication Speed USB Clock 4x Clock Multiplier Input
Full Speed 4x Clock Multiplier Internal Oscillator
Low Speed Internal Oscillator / 2 N/A
Bit7: CRE: Clock Recovery Enable.
This bit enables/disables the USB clock recovery feature.
0: Clock recovery disabled.
1: Clock recovery enabled.
Bit6: CRSSEN: Clock Recovery Single Step.
This bit forces the oscillator calibration into ‘single-step’ mode during clock recovery.
0: Normal calibration mode.
1: Single step mode.
Bit5: CRLOW: Low Speed Clock Recovery Mode.
This bit must be set to ‘1’ if clock recovery is used when operating as a Low Speed USB
device.
0: Full Speed Mode.
1: Low Speed Mode.
Bits4–0: Reserved. Read = Variable. Must Write = 01001b.
Note: The USB transceiver must be enabled before en abling Clock Recovery.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CRE CRSSEN CRLOW Reserved 00001001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x0F
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16.5. FIFO Management
1024 bytes of on-chip XRAM are used as FIFO space for USB0. This FIFO space is split between End-
points0-3 as shown in Figure 16.3. FIFO space allocated for Endpoints1-3 is configurable as IN, OUT, or
both (Split Mode: half IN, half OUT).
Figure 16.3. USB FIFO Allocation
16.5.1. FIFO Split Mode
The FIFO space for Endpoints1-3 can be split such that the upper half of the FIFO space is u se d by the IN
endpoint, and the lower half is used by the OUT endpoint. For example: if the En d point3 FIFO is configured
for Split Mode, the upper 256 bytes ( 0x0540 to 0x063F) are used by Endpoint3 IN and the lower 256 bytes
(0x0440 to 0x053F) are used by Endpoint3 OUT.
If an endpoint FIFO is not configured for Split Mode, that endpoint IN/OUT pair’s FIFOs are combined to
form a single IN or O UT FIFO. In this cas e only one dire ction of the endpoint IN/OUT pair may be used at
a time. The e ndpoint direction ( IN/OUT) is determined b y the DIRSEL bit in the corres ponding endpoint’s
EINCSRH register (see SFR Definition 16.20).
Endpoint0
(64 by t es)
Configurable as
IN, OUT, or both (Split
Mode)
Free
(64 by t es)
0x0400
0x043F
0x0440
0x063F
0x0640
0x073F
0x0740
0x07BF
0x07C0
0x07FF
User XRAM
(1024 bytes)
0x0000
0x03FF
USB Clock Domain
System Clock D omain
Endpoint1
(128 bytes)
Endpoint2
(256 bytes)
Endpoint3
(512 bytes)
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16.5.2. FIFO Double Buffering
FIFO slots for Endpoints1-3 can be configured for double-buffered mode. In this mode, the maximum
packet size is halved and the FIFO may contain two packets at a time. This mode is available for End-
points1- 3. When a n endpoint is config ured fo r Split Mode, double b uffering may be enable d for the IN End-
point and/or the OUT endpoint. When Split Mode is not enabled, double-buffering may be enabled for the
entire endpoint FIFO. Se e Table 16.3 for a list of maximum packet sizes for each FIFO configuration.
16.5.1. FIFO Access
Each endpoint FIFO is accessed through a corresponding FIFOn register. A read of an endpoint FIFOn
register unload s one byte from the FIFO; a write of an end point FIFOn register loads one byte into the end-
point FIFO. When an endpoint FIFO is configured for Split Mode, a read of the endpoint FIFOn register
unloads one by te from the OUT endpoint FI FO; a write of the endpoint FIFO n register loads one byte into
the IN endpoint FIFO.
USB Register Definition 16.6. FIFOn: USB0 Endpoint FIFO Access
Table 16.3. FIFO Configurations
Endpoint
Number Split Mode
Enabled? Maximum IN Packet Size (Dou-
ble Buffer Disabled / Enabled) Maximum OUT Packet Size
(Double Buffer Disabled /
Enabled)
0N/A 64
1N 128 / 64
Y 64 / 32 64 / 32
2N 256 / 128
Y 128 / 64 128 / 64
3N 512 / 256
Y 256 / 128 256 / 128
USB Addresses 0x20–0x23 provide access to the 4 pairs of endpoint FIFOs:
Wri ting to the FIFO address loads data into the IN FIFO for the corresponding endpoint.
Reading from the FIFO address unloads data from the OUT FIFO for the corresponding
endpoint.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
FIFODATA 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x20 - 0x23
IN/OUT Endpoint FIFO USB Address
00x20
10x21
20x22
30x23
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16.6. Function Addressing
The FADDR register holds the current USB0 function address. Software should write the host-assigned
7-bit function address to the FADDR register when received as part of a SET_ADDRESS command. A new
address written to FADDR will not take effect (USB0 will not respond to the new address) until the end of
the current transfer (typically following the status phase of the SET_ADDRESS command transfer). The
UPDATE bit (FADDR.7) is set to ‘1’ by hardware when software writes a new address to the FADDR regis-
ter. Hardware clears the UPDATE bit when the new address takes effect as described above.
USB Register Definition 16.7. FADDR: USB0 Function Address
16.7. Function Configuration and Control
The USB register POWER (SFR Definition 16.8) is used to configure and control USB0 at the device level
(enable/disable, Reset/Suspend/Resume handling, etc.).
USB Reset: The USBRST bit (POWER.3) is set to ‘1’ by hardware when Reset signaling is detected on
the bus. Upon this detection, the following occur:
1. The USB0 Address is reset (FADDR = 0x00).
2. Endpoint FIFOs are flushed.
3. Control/status registers are reset to 0x00 (E0CSR, EINCSRL, EINCSRH, EOUTCSRL,
EOUTCSRH).
4. USB register INDEX is reset to 0x00.
5. All USB interrup t s (exclud ing the Suspend inter rupt) are enab led and the ir corr esponding flags
cleared.
6. A USB Reset interrupt is generated if ena bled.
Writing a ‘1’ to the USBRST bit will generate an asynchronous USB0 reset. All USB registers are reset to
their default values following this asynchronous reset.
Suspend Mode: With Suspend Detection enabled (SUSEN = ‘1’), USB0 will enter Suspend Mode when
Suspend signaling is detected on the bus. An interrupt will be generated if enabled (SUSINTE = ‘1’). The
Suspend Interrupt Service Routine (ISR) should perform application-specific configuration tasks such as
disabling appropriate peripherals and/or configuring clock sources for low power modes. See Section
“14. Oscillators” on page 131 for more details on internal oscillator configuration, including the Suspend
Bit7: Update: Function Address Update
Set to ‘1’ when soft ware wr ites the FADDR register. USB0 clears this bit to ‘0’ when the n ew
address takes effect.
0: The last address written to FADDR is in effect.
1: The last address written to FADDR is not yet in effect.
Bits6–0: Function Address
Holds the 7-bi t function addr ess for USB0. This ad dress sh ould be written by sof t ware when
the SET_ADDRESS standard device request is received on Endpoint0. The new address
take s effect when the device request completes.
R R/W R/W R/W R/W R/W R/W R/W Reset Value
Update Fu nction Address 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x00
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mode feature of the internal oscillator.
USB0 exits Suspend mode when any of the following occur: (1) Resume signaling is detected or gener-
ated, (2) Reset signaling is detected, or (3) a device or USB reset occurs. If suspended, the internal oscil-
lator will exit Suspend mode upon any of the above listed events.
Resume Signaling: USB0 will exit Suspend mode if Resume signaling is detected on the bus. A Resume
interrupt will be generated upon detection if enabled (RESINTE = ‘1’). Software may force a Remote
Wakeup by writing ‘1’ to the RESUME bit (POWER.2). When forcing a Remote Wakeup, software should
write RESUME = ‘0’ to end Resume signaling 10-15 ms after the Remote Wakeup is initiated (RESUME =
‘1’).
ISO Update: When software writes ‘1’ to the ISOUP bit (POWER.7), the ISO Update function is enab led.
With ISO Update enabled, new packets written to an ISO IN endpoint will not be transmitted until a new
Start-Of-Frame (SOF) is received. If the ISO IN endpoint receives an IN token before a SOF, USB0 will
transmit a zero-length packet. When ISOUP = ‘1’, ISO Update is enabled for all ISO endp oints.
USB Enable: USB0 is disabled following a Power-On-Reset (POR). USB0 is enabled by clearing the
USBINH bit (POWER.4). On ce written to ‘0’, the U SBINH can only be set to ‘1’ by one of the following: (1)
a Power-On-Reset (POR), or (2) an asynchronous USB0 reset generated by writing ‘1’ to the USBRST bit
(POWER.3).
Software should perform all USB0 configuration before enabling USB0. The configuration sequence
should be performed as follows:
Step 1. Select and enable the USB clock source.
Step 2. Reset USB0 by writing USBRST= ‘1’.
Step 3. Configure and enable the USB Transceiver.
Step 4. Perform any USB0 function configuration (interrup ts, Suspend detect).
Step 5. Enable USB0 by writing USBINH = ‘0’.
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USB Register Definition 16.8. POWER: USB0 Power
Bit7: ISOUD: ISO Update
This bit affects all IN Isochronous endpoints.
0: When software writes INPRDY = ‘1’, USB0 will send the pa cket when the next IN token is
received.
1: When software writes INPRDY = ‘1’, USB0 will wait for a SOF token before sending the
packet. If an IN token is received before a SOF token, USB0 will send a zero-length data
packet.
Bits6–5: Unused. Read = 00b. Write = don’t care.
Bit4: USBINH: USB0 Inhibit
This bit is set to ‘1’ following a power-on reset (POR) or an asynchronous USB0 reset (see
Bit3: RESET). Software should clear this bit after all USB0 and transceiver initialization is
complete. Software cannot set this bit to ‘1’.
0: USB0 enabled.
1: USB0 inhibited. All USB traffic is ignored.
Bit3: USBRST: Reset Detect
Writing ‘1’ to this bit forces an a synchronous USB0 reset. Reading this bit provides bus reset
status information.
Read:
0: Reset signaling is not present on the bus.
1: Reset signaling detected on the bus.
Bit2: RESUME: Force Resume
Software can for ce resum e signaling o n th e bus to wa ke USB0 fr om su spend m ode. W riting
a ‘1’ to this bit while in Suspend mode (SUSMD = ‘1’) forces USB0 to generate Resume sig-
naling on the bus (a remote Wakeup event). Software should write RESUME = ‘0’ after
10 ms to15 ms to end the Resume signaling. An in terrupt is generated, and hardware clear s
SUSMD, when software writes RESUME = ‘0’.
Bit1: SUSMD: Suspend Mode
Set to ‘1’ by hardware when USB0 enters suspend mode. Cleared by hardware when soft-
ware writes RESUME = ‘0’ (following a remote wakeup) or reads the CMINT register after
detection of Resume signaling on the bus.
0: USB0 not in suspend mode.
1: USB0 in suspen d mode.
Bit0: SUSEN: Suspend Detection Enable
0: Suspend detection disabled. USB0 will ignore suspend signaling on the bus.
1: Suspend detection enabled. USB0 will enter suspend mode if it detects suspend signaling
on the bus.
R/W R/W R/W R/W R/W R/W R R/W Reset Value
ISOUD - - USBINH USBRST RESUME SUSMD SUSEN 00010000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x01
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USB Register Definition 16.9. FRAMEL: USB0 Frame Number Low
USB Register Definition 16.10. FRAMEH: USB0 Frame Number High
16.8. Interrupts
The read-only USB0 interrupt flags are located in the USB registers shown in USB Register
Definition 16.11 through USB Register Definition 16.13. The as so cia t ed in te rr up t e n ab le bits are located in
the USB registers shown in USB Register Definition 16.14 through USB Register Definition 16.16. A USB0
interrupt is generated when any of the USB interrupt flags is set to ‘1’. The USB0 interrupt is enabled via
the EIE1 SFR (see Section “9.3. Interrupt Handler” on page 88).
Important Note: Reading a USB interrupt flag register resets all flags in that register to ‘0’.
Bits7-0: Frame Number Low
This register contains bits7-0 of the last received frame number.
RRRRRRRRReset Value
Frame Number Low 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x0C
Bits7-3: Unused. Read = 0. Write = don’t care.
Bits2-0: Frame Number High Byte
This register contains bits10-8 of the last received frame number.
RRRRRRRRReset Value
- - - - - Frame Number High 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x0D
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USB Register Definition 16.11. IN1INT: USB0 IN Endpoint Interrupt
USB Register Definition 16.12. OUT1INT: USB0 Out Endpoint Interrupt
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3: IN3: IN Endpoint 3 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: IN Endpoint 3 interrupt inactive.
1: IN Endpoint 3 interrupt ac tive .
Bit2: IN2: IN Endpoint 2 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: IN Endpoint 2 interrupt inactive.
1: IN Endpoint 2 interrupt ac tive .
Bit1: IN1: IN Endpoint 1 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: IN Endpoint 1 interrupt inactive.
1: IN Endpoint 1 interrupt ac tive .
Bit0: EP0: Endpoint 0 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: Endpoint 0 interrupt inactive.
1: Endpoint 0 interrupt active.
RRRRRRRRReset Value
- - - - IN3 IN2 IN1 EP0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x02
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3: OUT3: OUT Endpoint 3 Interrupt-pending Flag
This bit is cleared when software reads the OUT1INT register.
0: OUT Endpoint 3 interrupt inactive.
1: OUT Endpoint 3 interrupt active.
Bit2: OUT2: OUT Endpoint 2 Interrupt-pending Flag
This bit is cleared when software reads the OUT1INT register.
0: OUT Endpoint 2 interrupt inactive.
1: OUT Endpoint 2 interrupt active.
Bit1: OUT1: OUT Endpoint 1 Interrupt-pending Flag
This bit is cleared when software reads the OUT1INT register.
0: OUT Endpoint 1 interrupt inactive.
1: OUT Endpoint 1 interrupt active.
Bit0: Unused. Read = 0; Write = don’t care.
RRRRRRRRReset Value
----OUT3OUT2OUT1-00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x04
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USB Register Definition 16.13. CMINT: USB0 Common Interrupt
Bits7–4: Unused. Read = 0000b; Write = don’t care.
Bit3: SOF: Start of Frame Interrupt
Set by hardware when a SOF token is received. This interrupt event is synthesized by hard-
ware: an interrupt will be generated when hardware expects to receive a SOF event, even if
the actual SOF signal is missed or corrupted.
This bit is cleared when software reads the CMINT register.
0: SOF interrupt inactive.
1: SOF interrupt active.
Bit2: RSTINT: Reset Interrup t- pe n din g Fla g
Set by hardware when Reset signaling is detected on the bus.
This bit is cleared when software reads the CMINT register.
0: Reset interrupt inactive.
1: Reset interrupt active.
Bit1: RSUINT: Resume Interrupt-pending Flag
Set by hardware when Resume signaling is detected on the bus while USB0 is in suspend
mode.
This bit is cleared when software reads the CMINT register.
0: Resume interrupt inactive.
1: Resume interrupt active.
Bit0: SUSINT: Suspend Interrupt-pending Flag
When Suspend detection is enabled (bit SUSEN in register POWER), this bit is set by hard-
ware when Suspend signa ling is detected on the bus. This bit is cleared when software
reads the CMINT reg ister.
0: Suspend interrupt inactive.
1: Suspend interrupt active .
RRRRRRRRReset Value
- - - - SOF RSTINT RSUINT SUSINT 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x06
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 175
USB Register Definition 16.14. IN1IE: USB0 IN Endpoint Interrupt Enable
USB Register Definition 16.15. OUT1IE: USB0 Out Endpoint Interrupt Enable
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3: IN3E: IN Endpoint 3 Interrupt Enable
0: IN Endpoint 3 interrupt disabled.
1: IN Endpoint 3 interrupt enabled.
Bit2: IN2E: IN Endpoint 2 Interrupt Enable
0: IN Endpoint 2 interrupt disabled.
1: IN Endpoint 2 interrupt enabled.
Bit1: IN1E: IN Endpoint 1 Interrupt Enable
0: IN Endpoint 1 interrupt disabled.
1: IN Endpoint 1 interrupt enabled.
Bit0: EP0E: Endpoint 0 Interrupt Enable
0: Endpoint 0 interrupt disabled .
1: Endpoint 0 interrupt enabled.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - IN3E IN2E IN1E EP0E 00001111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x07
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3: OUT3E: OUT Endpoint 3 Interrupt Enable
0: OUT Endpoint 3 interrupt disabled.
1: OUT Endpoint 3 interrupt enabled.
Bit2: OUT2E: OUT Endpoint 2 Interrupt Enable
0: OUT Endpoint 2 interrupt disabled.
1: OUT Endpoint 2 interrupt enabled.
Bit1: OUT1E: OUT Endpoint 1 Interrupt Enable
0: OUT Endpoint 1 interrupt disabled.
1: OUT Endpoint 1 interrupt enabled.
Bit0: Unused. Read = 0; Write = don’t’ care.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - OUT3E OUT2E OUT1E - 00001110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x09
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USB Register Definition 16.16. CMIE: USB0 Common Interrupt Enable
16.9. The Serial Interface Engine
The Serial Interface Engine (SIE) performs all low level USB protocol tasks, interrupting the processor
when data has successfully been transmitted or received. When receiving data, the SIE will interrupt the
processor when a co mplete data p acket has bee n received; ap propriate h andshaking sig nals ar e automa t-
ically generated by the SIE. When transmitting data, the SIE will interrupt the processor when a complete
data packet has been transmitte d an d th e ap pr o pr iate handshake sig nal has bee n rece ive d.
The SIE will not interrupt the processor when corrupted/erroneous packets are received.
16.10. Endpoint0
Endpoint0 is managed through the USB register E0CSR (USB Register Definition 16.17). The INDEX reg-
ister must be loaded with 0x00 to access the E0CSR registe r.
An Endpoint0 interrupt is generate d when:
1. A data packet (OUT or SETUP) has been received and loaded into the Endpoint0 FIFO. The
OPRDY bit (E0CSR. 0) is set to ‘1’ by hardware.
2. An IN data packet has successfully been unloaded from the Endpoint0 FIFO and transmitted
to the host; INPRDY is reset to ‘0’ by hardware.
3. An IN transaction is completed (th is inter rupt gene ra ted dur ing the st atus stage of the tran sa c -
tion).
4. Hardware sets the STSTL bit (E0CSR.2) after a control transaction ended due to a protocol
violation.
5. Hardware sets the SUEND bit (E0CSR.4) because a control transfer ended before firmware
sets the DATAEND bit (E0CSR.3).
Bits7–4: Unused. Read = 0000b; Write = don’t care.
Bit3: SOFE: Start o f Fr ame Interrupt Enable
0: SOF interrupt disabled.
1: SOF interrupt enabled.
Bit2: RSTINTE: Reset Interrupt Enable
0: Reset interrupt disabled.
1: Reset interrupt enabled.
Bit1: RSUI NTE: Res ume Interrupt Enable
0: Resume interrupt di sabled.
1: Resume interrupt enabled.
Bit0: SUSINTE: Suspend Interrupt Enable
0: Suspend interrupt disab led.
1: Suspend interrupt enabled.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - SOFE RSTINTE RSUINTE SUSINTE 00000110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x0B
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 177
The E0CNT regis ter (USB Register Definition 16.18) holds the number of received data bytes in the End-
point0 FIFO.
Hardware will automatically detect protocol errors and send a STALL condition in response. Firmware may
force a STALL conditio n to abo rt the cu rren t tra nsfer. When a STALL condition is generated, the STSTL bit
will be set to ‘1’ and an interrupt generated. The following conditions will cause hardware to generate a
STALL condition:
1. The host sends an OUT token during a OUT data phase after the DATAEND bit has been set
to ‘1’.
2. The host sends an IN token during an IN data phase after the DATAEND bit has been set to
‘1’.
3. The host send s a packet that exceeds the maximum p acket size for Endpoint0.
4. The host sends a non-zero length DATA1 packet during the status phase of an IN transaction.
5. Firmware sets the SDSTL bit (E0CSR.5) to ‘1’.
16.10.1.Endpoint0 SETUP Transactions
All control transfers must begin with a SETUP p acket. SETUP packets are similar to OUT p ackets, contain-
ing an 8-byte data field sent by the host. Any SETUP packet containing a command field of anything other
than 8 bytes will be automatically rejected by USB0. An Endpoint0 interrupt is generated when the data
from a SETUP packet is loaded into the Endpoint0 FIFO. Software should unload the command from the
Endpoint0 FIFO, decode the command, perform any necessary tasks, and set the SOPRDY bit to indicate
that it has serviced the OUT packet.
16.10.2.Endpoint0 IN Transactions
When a SETUP request is received that requires USB0 to transmit data to the host, one or more IN
requests will be sent by the host. For the first IN transaction, firmware should load an IN packet into the
Endpoint0 FIFO, and set the INPRDY bit (E0CSR.1). An interrupt will be generated when an IN packet is
transmitted successfully. Note that no interrupt will be generated if an IN request is received before firm-
ware has loaded a packet into the Endpoint0 FIFO. If the requested data exceeds the maximum packet
size for Endpoint0 (as reported to the host), the data should be split into multiple packets; each packet
should be of the ma ximum packet size excluding th e last ( residual) packet. If the requested da ta is an inte-
ger multiple of the maximum packet size for End point0, the last dat a p acket shou ld be a zero-len gth packet
signaling the end of the transfer. Firmware should set the DATAEND bit to ‘1’ after loading into the End-
point0 FIFO the last data packet for a transfer.
Upon reception of the first IN token for a particular control transfer, Endpoint0 is said to be in Transmit
Mode. In this mode, only IN tokens sh ou ld be se nt b y th e ho st to Endpoint0. The SUEND bit (E0CSR.4) is
set to ‘1’ if a SETUP or OUT token is received while Endpoint0 is in Transmit Mode.
Endpoint0 will remain in Tr ansmit Mode until any of the following occur:
1. USB0 receives an Endpoint0 SETUP or OUT token.
2. Firmware sends a packet less than the maximum Endpoint0 packet size.
3. Firmware sends a zero-length packe t.
Firmware should set the DATAEND bit (E0CSR.3) to ‘1’ when performing (2) and (3) above.
The SIE will transmit a NAK in response to an IN token if there is no packet ready in the IN FIFO (INPRDY
= ‘0’).
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178 Rev. 1.3
16.10.3.Endpoint0 OUT Transactions
When a SETUP request is received that requires the host to transmit data to USB0, one or more OUT
requests will be sent by the host. When an OUT packet is successfully received by USB0, hardware will set
the OPRDY bit (E0CSR.0) to ‘1’ and generate an Endpoint0 interrupt. Following this interrupt, firmware
should unload the OUT packet from the Endpoint0 FIFO and set the SOPRDY bit (E0CSR.6) to ‘1’.
If the amount of data required for the transfer exceeds the maximum packet size for Endpoint0, the data
will be split into multiple packets. If the requested data is an integer multiple of the maximum packet size
for Endpoint0 (as reported to the host), the host will send a zero-length dat a p acket signaling the end of the
transfer.
Upon reception of the first OUT token for a particular control transfer, Endpoint0 is said to be in Receive
Mode. In this mode, only OUT tokens should be sent by the host to Endpoint0. The SUEND bit (E0CSR.4)
is set to ‘1’ if a SETUP or IN token is received while Endpoint0 is in Receive Mode.
Endpoint0 will remain in Receive mode until:
1. The SIE receives a SETUP or IN toke n.
2. The host sends a packet less than the maximum Endpoint0 packet size.
3. The host se nds a zero-length packet.
Firmware should set the DATAEND bit (E0CSR.3) to ‘1’ when the expected amount of data has been
received. The SIE will transmit a STALL condition if the host sends an OUT packet after the DATAEND bit
has been set by firmware. An interrupt will be generated with the STSTL bit (E0CSR.2) set to ‘1’ after the
STALL is transmitted.
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Rev. 1.3 179
USB Register Definition 16.17. E0CSR: USB0 Endpoint0 Control
Bit7: SSUEND: Serviced Setup End
Write: Software should set this bit to ‘1’ after servicing a Setup End (bit SUEND) event.
Hardware clears the SUEND bit when software writes ‘1’ to SSUEND.
Read: This bit always reads ‘0’.
Bit6: SOPRDY: Serviced OPRDY
Write: Software should write ‘1’ to this bit after servicing a received Endpoint0 packet. The
OPRDY bit will be cleared by a write of ‘1’ to SOPRDY.
Read: This bit always reads ‘0’.
Bit5: SDSTL: Send Stall
Software can write ‘1’ to this bit to terminate the current transfer (due to an error condition,
unexpected transfer request, etc.). Hardware will clear this bit to ‘0’ when the STALL hand-
shake is transmitted .
Bit4: SUEND: Setup End
Hardware sets this read-only bit to ‘1’ when a control transaction ends before soft ware has
written ‘1’ to the DATAEN D bit. Hardware clears this bit when software writes ‘1’ to SSU-
END.
Bit3: DATAE ND: Data End
Software should write ‘1’ to this bit:
1. When writing ‘1’ to INPRDY for the last outgoing data packet.
2. When writing ‘1’ to INPRDY for a zero- length data packet.
3. When writing ‘1’ to SOPRDY after servicing the last incoming data pa cket.
This bit is automatically cleared by hardware.
Bit2: STSTL: Sent Stall
Hardware sets this bit to ‘1’ after transmitting a STALL handshake signal. This flag must be
cleared by software.
Bit1: INPRDY: IN Packet Ready
Software should write ‘1’ to this bit after loading a data packet into the Endpoint0 FIFO for
transmit. Hardware clears this bit and generates an interrupt under either of the following
conditions:
1. The packet is transmitted.
2. The packet is overwritten by an incoming SETUP packet.
3. The packet is overwritten by an incoming OUT packet.
Bit0: OPRDY: OUT Packet Ready
Hardware sets this read-only bit and generates an interrupt when a data packet has been
received. This bit is cleared only when software writes ‘1’ to the SOPRDY bit.
R/W R/W R/W R R/W R/W R/W R Reset Value
SSUEND SOPRDY SDSTL SUEND DATAEND STSTL INPRDY OPRDY 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x11
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
180 Rev. 1.3
USB Register Definition 16.18. E0CNT: USB0 Endpoint 0 Data Count
16.11. Configuring Endpoints1-3
Endpoints1-3 are configured and controlled through their own sets of the following control/status registers:
IN registers EINCSRL and EINCSRH, and OUT registers EOUTCSRL and EOUTCSRH. Only one set of
endpoint control/status registers is mapped into the USB register address space at a time, defined b y the
contents of the INDEX register (USB Register Definition 16.4).
Endpoints1-3 can be configured as IN, OUT, or both IN/OUT (Split Mode) as described in Section 16.5.1.
The endpoint mode (Split/Normal) is selected via the SPLIT bit in register EINCSRH.
When SPLIT = ‘1’, the corresponding en dpoint FIFO is split, and both IN and OUT pipes are available.
When SPLIT = ‘0’, the corresponding endpoint functions as either IN or OUT; the endpoint direction is
selected by the DIRSEL bit in register EINCSRH.
16.12. Controlling Endpoints1-3 IN
Endpoints1-3 IN are managed via USB registers EINCSRL and EINCSRH. All IN endpoints can be used
for Interrupt, Bulk, or Isochronous transfers. Isochron ous (ISO) mode is enabled by writing ‘1’ to the ISO bit
in register EINCSRH. Bulk and Interrupt transfers are handled identically by hardware.
An Endpoint1- 3 IN interrupt is generated by any of the following condition s:
1. An IN packet is successfully tr ansferred to the host.
2. Software writes ‘1’ to the FLUSH bit (EINCSRL.3) when the target FIFO is not empty.
3. Hardware generates a STALL condition.
16.12.1.Endpoints1-3 IN Interrupt or Bulk Mode
When the ISO bit (EI NCSRH.6 ) = ‘0’ the target endpoint oper ates in B ulk or In terr upt M ode . Onc e an en d -
point has been configured to operate in Bulk/Interrupt IN mode (typically following an Endpoint0 SET_IN-
TERFACE command), firmware sh ould load an IN packet into the endpoint IN FIFO and set the INPRDY
bit (EINCSRL.0). Upon reception of an IN token, hardware will transmit the data, clear the INPRDY bit, and
generate an interrupt.
Bit7: Unused. Read = 0; Write = don’t care.
Bits6–0: E0CNT: Endpoint 0 Data Count
This 7-bit number indicates the number of received data bytes in the Endpoint 0 FIFO. This
number is only valid while bit OPRDY is a ‘1’.
RRRRRRRRReset Value
- E0CNT 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x16
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 181
Writing ‘1’ to INPRDY without writing any data to the endpoint FIFO will cause a zero-length packet to be
transmitted upon reception of the next IN token.
A Bulk or Interrupt pipe can be shut down (or Halted) by writing ‘1’ to the SDSTL bit (EINCSRL.4). While
SDSTL = ‘1’, hardware will respond to all IN requests with a STALL condition. Each time hardware gener -
ates a STALL condition, an interrupt will be generated and the STSTL bit (EINCSRL.5) set to ‘1’. The
STSTL bit must be reset to ‘0’ by firmware.
Hardware will automatically reset INPRDY to ‘0’ when a packet slot is open in the endpoint FIFO. Note that
if double buffering is enabled for the target endpoint, it is possible for fir m wa re to lo ad tw o packets into the
IN FIFO at a time. In this case, hardware will reset INPRDY to ‘0’ immediately after firmware loads the first
packet into the FIFO and set s INPRDY to ‘1’. An interrupt will not be generated in this case; an interrupt will
only be generated when a data packet is transmitted.
When firmware writes ‘1’ to the FCDT bit (EINCSRH.3) , the data toggle for each IN packet will be toggled
continuously, regardless of the handshake received from the host. This feature is typically used by Inter-
rupt endpoints functioning as rate feedback communication for Isochronous endpoints. When FCDT = ‘0’,
the data toggle bit will only be toggled when an ACK is sent from the host in response to an IN packet.
16.12.2.Endpoints1-3 IN Isochronous Mode
When the ISO bit (EINCSRH.6) is set to ‘1’, the ta rget endpoint oper ates in Isoc hronous ( ISO) mode. On ce
an endpoint has been configured for ISO IN mode, the host will send one IN token (data request) per
frame; the location of data within each frame may vary. Because of this, it is recommended that double
buffering be enabled for ISO IN endpoints.
Hardware will automatically reset INPRDY (EINCSRL.0) to ‘0’ when a packet slot is open in the endpoint
FIFO. Note that if double buffering is enabled for the target endpoint, it is possible for firmware to load two
packets into the IN FIFO at a time. In this case, hardware will reset INPRDY to ‘0’ immediately after firm-
ware loads the first packet into the FIFO and sets INPRDY to ‘1’. An interrupt will not be generated in this
case; an interrupt will only be generated when a data packet is transmitted.
If there is not a data packet ready in the endpoint FIFO when USB0 receives an IN token from the host,
USB0 will transmit a zero-length data packet and set the UNDRUN bit (EINCSRL.2) to ‘1’.
The ISO Update feat ure ( se e Section 16.7) can be useful in starting a double buffered ISO IN endpoint. If
the host has already set up the ISO IN pipe (has begun transmitting IN tokens) when firmware writes the
first data packet to the endpoint FIFO, the next IN token may arrive and the first data packet sent before
firmware has written the second (double buffered) data packet to the FIFO. The ISO Update feature
ensures that any data packet written to the endpoint FIFO will not be transmitted during the current frame;
the packet will only be sent after a SOF signal has been received.
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182 Rev. 1.3
USB Register Definition 16.19. EINCSRL: USB0 IN Endpoint Control Low Byte
Bit7: Unused. Read = 0; Write = don’t care.
Bit6: CLRDT: Clear Data Toggle.
Write: Software should write ‘1’ to this bit to reset the IN Endpoint data toggle to ‘0’.
Read: This bit always reads ‘0’.
Bit5: STSTL: Sent Stall
Hardware sets this bit to ‘1’ when a STALL handshake signal is transmitted. The FIFO is
flushed, and the INPRDY bit cleared. This flag must be cleared by software.
Bit4: SDSTL: Send Stall.
Software shou ld write ‘1’ to this bit to generate a STALL handshake in response to an IN
token. Software should write ‘0’ to this bit to terminate the STALL signal. This bit has no
effect in ISO mode.
Bit3: FLUSH: FIFO Flush.
Writing a ‘1’ to this bit flushes the next packet to be transmitted from the IN Endpoint FIFO.
The FIFO pointer is reset and the INPRDY bit is cleared. If the FIFO contains multiple pack-
ets, sof tware must write ‘1’ to FLUSH for each packet. Hardware resets the FLUSH bit to ‘0’
when the FIFO flush is complete.
Bit2: UNDRUN: Data Underrun.
The function of this bit depends on the IN Endpoint mode:
Isochronous: Set when a zero-length packet is sent af ter an IN token is received while bit
INPRDY = ‘0’.
Interrupt/Bulk: This bit is not used in these modes and will always read a '0'.
This bit must be cleared by software.
Bit1: FIFONE: FIFO Not Empty.
0: The IN Endpoint FIFO is empty.
1. The IN Endpoint FIFO contains one or more packe ts.
Bit0: INPRDY: In Packet Ready.
Software should write ‘1’ to this bit after loading a data packet into the IN Endpoint FIFO.
Hardware clears INPRDY due to any of the followin g :
1. A data packet is transmitted.
2. Double buff ering is enabled (DBIEN = ‘1’) and there is an open FIFO packet slot.
3. If the endpoint is in Isochronous Mode (ISO = ‘1’) and ISOUD = ‘1’, INPRDY will read ‘0’
until the next SOF is received.
An interrupt (if enabled) will be generated when hardware clears INPRDY as a result
of a packet being transmitted.
R W R/W R/W R/W R/W R/W R/W Reset Value
- CLRDT STSTL SDSTL FLUSH UNDRUN FIFONE INPRDY 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x11
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 183
USB Register Definition 16.20. EINCSRH: USB0 IN Endpoint Control High Byte
16.13. Controlling Endpoints1-3 OUT
Endpoints1-3 OUT are managed via USB registers EOUTCSRL and EOUTCSRH. All OUT endpoints can
be used for In terrupt, Bulk, or Isochronous transfers. Isochronous (ISO) mode is enabled by writing ‘1’ to
the ISO bit in register EOUTCSRH. Bulk and Interrupt transfers are handled identically by hardware.
An Endpoint1-3 OUT interrupt may be generated by the following:
1. Hardware sets the OPRDY bit (EINCSRL.0) to ‘1’.
2. Hardware generates a STALL condition.
16.13.1.Endpoints1-3 OUT Interrupt or Bulk Mode
When the ISO bit (EOUTCSRH.6) = ‘0’ the target endpoint operates in Bulk or Interrupt mode. Once an
endpoint has been configured to operate in Bulk/Interrupt OUT mode (typically following an Endpoint0
SET_INTERFACE command), hardware will set the OPRDY bit (EOUTCSRL.0) to ‘1’ and generate an
interrupt upon reception of an OUT token and data packet. The number of bytes in the current OUT data
packet (the packet ready to be unloaded from the FIFO) is given in the EOUTCNTH and EOUTCNTL reg-
isters. In response to this interrupt, firmware should unload the data packet from the OUT FIFO and reset
the OPRDY bit to ‘0’.
Bit7: DBIEN: IN Endpoint Double-buffer Enable.
0: Double-buffering disabled for the selected IN endpoint.
1: Double-buffering enabled for the selected IN endpoint.
Bit6: ISO: Isochronous Transfer Enable.
This bit enables/disables isochronous transfers on the current end point.
0: Endpoint configured for bulk/interrupt transfers.
1: Endpoint configured for isochronous transfers.
Bit5: DIRSEL: Endpoint Direction Select.
This bit is valid only when the selected FIFO is not split (SPLIT = ‘0’).
0: Endpoint direction selected as OUT.
1: Endpoint direction selected as IN.
Bit4: Unused. Read = ‘0’. Write = don’t care.
Bit3: FCDT: Force Data Toggle.
0: Endpoint data toggle switches only when an ACK is received following a data packet
transmission.
1: Endpoint da t a toggle forced to switch af ter every d at a p a cket is transm itted, regardle ss of
ACK reception.
Bit2: SPLIT: FIFO Split Enable.
When SPLIT = ‘1’, the selected endpoint FIFO is split. The upper half of the selected FIFO is
used by the IN endpoint; the lower half of the selected FIFO is used by the OUT endpoint.
Bits1–0: Unused. Read = 00b; Write = don’t care.
R/W R/W R/W R R/W R/W R R Reset Value
DBIEN ISO DIRSEL - FCDT SPLIT - - 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x12
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
184 Rev. 1.3
A Bulk or Interrupt pi pe ca n be sh ut down ( or Halted ) by writing ‘1’ to the SDSTL bit (EOUTCSRL.5). While
SDSTL = ‘1’, hardware will respond to all OUT requests with a STALL condition. Each time hardware gen-
erates a STALL condition, an interrupt will be generated and the STSTL bit (EOUTCSRL.6) set to ‘1’. The
STSTL bit must be reset to ‘0’ by firmware.
Hardware will automatically set OPRDY when a packet is ready in the OUT FIFO. Note that if double buff-
ering is enabled for the t arget end point, it is possible for two packets to be ready in the OUT FIFO at a time.
In this case, hardware will set OPRDY to ‘1’ immediately after firmware unloads the first packet and resets
OPRDY to ‘0’. A second interrupt will be generated in this case.
16.13.2.Endpoints1-3 OUT Isochronous Mode
When the ISO bit (EOUTCSRH.6) is set to ‘1’, the target endpoint operates in Isochronous (ISO) mode.
Once an endpoint has been configured for ISO OUT mode, the host will send exactly one data per USB
frame; the location of the data packet within each fra me may vary, however. Because of this, it is recom -
mended that double buffering be enabled for ISO OUT endpoints.
Each time a data packet is received, hardware will load the received data packet into the endpoint FIFO,
set the OPRDY bit (EOUTCSRL.0) to ‘1’, and generate an interrupt (if enabled). Firmware would typically
use this interrupt to unload the data packet from the endpoint FIFO and reset the OPRDY bit to ‘0’.
If a data packet is received when there is no room in the endpoint FIFO, an interrupt will be generated and
the OVRUN bit (EOUTCS RL.2) set to ‘1 ’. If USB0 receives an ISO data packet with a CRC error, the data
packet will be loaded into the endpoint FIFO, OPRDY will be set to ‘1’, an interrupt (if enabled) will be gen-
erated, and the DATAERR bit (EOUTCSRL.3) will be set to ‘1’. Software should check the DATAERR bit
each time a data packet is unloaded from an ISO OUT endpoint FIFO.
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Rev. 1.3 185
USB Register Definition 16.21. EOUTCSRL: USB0 OUT Endpoint Control Low Byte
Bit7: CLRDT: Clear Data Toggle
Write: Software should write ‘1’ to this bit to reset the OUT endpoint data toggle to ‘0’.
Read: This bit always reads ‘0’.
Bit6: STSTL: Sent Stall
Hardware sets this bit to ‘1’ when a STALL handshake signal is transmitted. This flag must
be cleared by software.
Bit5: SDSTL: Send Stall
Software should write ‘1’ to this bit to generate a STALL handshake. Software should write
‘0’ to this bit to terminate the STALL signal. This bit has no effect in ISO mode.
Bit4: FLUSH: FIFO Flush
Writin g a ‘1’ to this bit flushes the next packe t to be rea d from the OUT endpoint FIFO. The
FIFO pointer is reset and the OPRDY bit is cleare d. If the FIFO contains multiple packets,
software must write ‘1’ to FLUSH for each packet. Hardware resets the FLUSH bit to ‘0’
when the FIFO flush is complete.
Note: If data for the current packet has already been read from the FIFO, the FLUSH bit should
not be used to flush the packet. Instead, the entire data packet should be read from the
FIFO manually.
Bit3: DATERR: Data Error
In ISO mode, this bit is set by hardware if a received packet has a CRC or bit-stuffing error.
It is cleared when software clears OPRDY. This bit is only valid in ISO mode.
Bit2: OVRUN: Data Overrun
This bit is set by hardware when an incoming data packet cannot be loaded into the OUT
endpoin t FIFO. This bit is only valid in ISO mode, and must be cleared by software.
0: No data overrun.
1: A data packet was lost because of a full FIFO since this flag was last cleared.
Bit1: FIFOFUL: OUT FIFO Full
This bit indicates the contents of the OUT FIFO. If double buffering is enabled for the end-
point (DBIEN = ‘1’), the FIFO is full when the FIFO contains two packets. If DBIEN = ‘0’, the
FIFO is full when the FIFO contains one packet.
0: OUT endpoint FIFO is not full.
1: OUT endpoint FIFO is full.
Bit0: OPRDY: OUT Packet Ready
Hardware sets this bit to ‘1’ and generates an interrupt when a data p acket is available. Soft-
ware should clear this bit after each data packet is unloaded from the OUT endpoint FIFO.
W R/W R/W R/W R R/W R R/W Reset Value
CLRDT STSTL SDSTL FLUSH DATERR OVRUN FIFOFUL OPRDY 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x14
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
186 Rev. 1.3
USB Register Definition 16.22. EOUTCSRH: USB0 OUT Endpoint Control High Byte
USB Register Definition 16.23. EOUTCNTL: USB0 OUT Endpoint Count Low
USB Register Definition 16.24. EOUTCNTH: USB0 OUT Endpoint Count High
Bit7: DBOEN: Double-buffer Enable
0: Double-buffering disabled for the selected OUT endpoint.
1: Double-buffering enabled for the selected OUT endpoint.
Bit6: ISO: Isochronous Transfer Enable
This bit enables/disables isochronous transfers on the current end point.
0: Endpoint configured for bulk/interrupt transfers.
1: Endpoint configured for isochronous transfers.
Bits5–0: Unused. Read = 000000b; Write = don’t care.
R/W R/W R/W R/W R R R R Reset Value
DBOEN ISO - - - - - - 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x15
Bits7–0: EOCL: OUT Endpoint Count Lo w Byte
EOCL holds the lower 8-bits of the 10-bit number of data bytes in the last received packet in
the current OUT endpoint FIFO. This number is only valid while OPRDY = ‘1’.
RRRRRRRRReset Value
EOCL 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x16
Bits7–2: Unused. Read = 00000. Write = don’t care.
Bits1–0: EOCH: OUT Endpoint Count High Byte
EOCH holds th e upper 2-bit s of the 10-b it number of dat a bytes in the last received p acket in
the current OUT endpoint FIFO. This number is only valid while OPRDY = ‘1’.
RRRRRRRRReset Value
- - - - - - E0CH 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 USB Address:
0x17
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 187
Table 16.4. USB Transceiver Electrical Characteristics
VDD = 3.0 to 3.6 V, –40 to +85 °C unless otherwise specified
Parameters Symbol Conditions Min Typ Max Units
Transmitter
Output High Voltage VOH 2.8 V
Output Low Voltage VOL 0.8 V
Output Crossover Point VCRS 1.3 2.0 V
Output Impedance ZDRV Driving High
Driving Low 38
38 Ω
Pull-up Resistance RPU Full Speed (D+ Pull-up)
Low Speed (D– Pull-up) 1.425 1.5 1.575 kΩ
Output Rise Time TRLow Speed
Full Speed 75
4300
20 ns
Output Fall Time TFLow Speed
Full Speed 75
4300
20 ns
Receiver
Differential Input
Sensitivity VDI | (D+) – (D–) | 0.2 V
Differential Input Common
Mode Range VCM 0.8 2.5 V
Input Leakag e Curr en t ILPullups Disabled <1.0 µA
Note: Refer to the USB Specification for timing diagrams and symbol definitions.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 188
17. SMBus
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus interface autonomously controlling
the serial transfer of the data. Data can be transferred at up to 1/20th of the system clock as a master or
slave (this can be faster than allowed by the SMBus specification, dependin g on the system clock used). A
method of extending the clock-low duration is available to accommodate devices with different speed
capabilities on the same bus.
The SMBus interface m ay opera te as a ma ster an d/or slave, and may function on a bus with multiple ma s-
ters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization,
arbitration logic, and START/STOP control and generation. Three SFRs are associated with the SMBus:
SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data
register, used for both transmitting and receiving SMBus data and slave addresses.
Figure 17.1. SMBus Block Diagram
Data Path
Control
SMBUS CONTROL LOGIC
C
R
O
S
S
B
A
R
SCL
FILTER
N
SDA
Control
SCL
Control
Arbitration
SCL Synchronization
IRQ Generation
SCL Generation (Mas ter Mode)
SDA Control
Interrupt
Request
Port I/O
SMB0CN
S
T
A
A
C
K
R
Q
A
R
B
L
O
S
T
A
C
K
S
I
T
X
M
O
D
E
M
A
S
T
E
R
S
T
O
01
00
10
11
T0 Overflow
T1 Overflow
TMR2H Overflow
TMR2L Overflow
SMB0CF
E
N
S
M
B
I
N
H
B
U
S
Y
E
X
T
H
O
L
D
S
M
B
T
O
E
S
M
B
F
T
E
S
M
B
C
S
1
S
M
B
C
S
0
01234567 SMB0DAT SDA
FILTER
N
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
189 Rev. 1.3
17.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor.
2. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor.
3. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
17.2. SMBus Configuration
Figure 17.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage
between 3.0 V and 5.0 V; different de vices on the bus may operate at di f feren t voltag e levels. The bi-direc-
tional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pull-up resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when
the bus is free. The maximum number of devices on the bus is limited only by the requ irem ent that the rise
and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
Figure 17.2. Typical SMBus Configuration
17.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbi tration. Note that it is not necessary to specify one
device as the Master in a system; any device who transmits a START and a slave address becomes the
master for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7-1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STO P condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 17.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowl-
edge), which is a high SDA during a high SCL.
VDD = 5V
Master
Device Slave
Device 1 Slave
Device 2
VDD = 3V VDD = 5V VDD = 3V
SDA
SCL
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 190
The direction bi t (R/W) occupies the least-significan t bit position of the address byte. The d irection bit is set
to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the trans-
action is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer , the master
generates a STOP condition to terminate the transaction and free the bus. Figure 17.3 illustrates a typical
SMBus transaction.
Figure 17.3. SMBus Transaction
17.3.1. Arbitration
A master may star t a transfer on ly if the bus is free. The b us is free af ter a ST OP con dition or af ter the SCL
and SDA lines remain high for a specified time (see Section “17.3.4. SCL High (SMBus Free) Timeout”
on page 191). In the event that two or more devices attempt to begin a transfer at the same time, an arbi-
tration scheme is employed to force one master to give up the bus. The master devices continue transmit-
ting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will
be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The win-
ning master continues its transmission without interruption; the losing master becomes a slave and
receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device
always wins, and no data is lost.
SLA6
SDA SLA5-0 R/W D7 D6-0
SCL
Slave Address + R/W Data ByteSTART ACK NACK STOP
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
191 Rev. 1.3
17.3.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
17.3.3. SCL Low Timeout
If the SCL line is held low b y a slave device on the bus, n o further commun ication is possible . Furthermore,
the master ca nnot for ce the SCL lin e high t o correc t the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi-
cation no later than 10 ms after detecting the timeout condition.
When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low time outs. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset ( disable
and re-enable) the SMBus in the event of an SCL low timeout.
17.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the START will be generated following this timeout. Note that a clock source is required for
free timeout dete ctio n , eve n in a slav e- on ly imp l e men tation.
17.4. Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting con-
trol for serial transfers; higher level protocol is determined by user software. The SMBus interface provides
the following application-independent features:
• Byte-wise serial data transfers
• Clock signal generation on SCL (Master Mode only) and SDA data synchronization
• Timeout/bus error recognition, as defined by the SMB0CF configuration registe r
• START/STOP timing, detection, and generation
• Bus arbitration
• Interrupt generation
• Status information
SMBus interrupt s are genera ted for ea ch data byte or slave address that is tran sferred. When transmitting,
this interrupt is generated after the ACK cycle so that software may read the received ACK value; when
receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing
ACK value. See Section “17.5. SMBus Transfer Modes” on page 198 for more details on transmission
sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section
“17.4.2. SMB0CN Control Register” on page 195; Table 17.4 provides a quick SMB0CN decoding refer-
ence.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 192
SMBus configuration options include:
• Timeout detection (SCL Low Timeout and/or Bus Free Timeou t)
• SDA setup and hold time extensions
• Slave event en ab le /d isable
• Clock source selection
These options are selected in the SMB0CF register, as described in Section “17.4 .1. SMBus Configura-
tion Register” on page 192.
17.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current tra ns fe r) .
The SMBCS1-0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolu te minimum SCL low and high times as defined in Equation 17.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in Section “21. Timers” on page 235.
Equation 17.1. Minimum SCL High and Low Times
The selected clock source should be configured to establish the minimum SCL High and Low times as per
Equation 17.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 17.2.
Equation 17.2. Typical SMBus Bit Rate
Table 17.1. SMBus Clock Source Selection
SMBCS1 SMBCS0 SMBus Clock Source
0 0 T imer 0 Overflow
0 1 T imer 1 Overflow
1 0 Timer 2 High Byte Overflow
1 1 Timer 2 Low Byte Overflow
THighMin TLowMin 1
fClockSourceOverflow
----------------------------------------------
==
BitRate fClockSourceOverflow
3
----------------------------------------------
=
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
193 Rev. 1.3
Figure 17.4 shows the typical SCL generation described by Equation 17.2. Notice that THIGH is typically
twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be
extended low by slower slave devices, or driven low by contending master devices). The bit rate when
operating as a master will never exceed the limits defined by equation Equation 17.1.
Figure 17.4. Typical SMBus SCL Generation
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA
setup time defines the absolute minimum time that SDA is stable before SCL tran sitions from low-to- high.
The minimum SDA hold time de fines the absolute mini mum time that the cur rent SDA value remains stabl e
after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times
meet the SMBus Specification requirements of 250 n s and 300 ns, resp ectively. Table 17.2 shows the min-
imum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically
necessary when SYSCLK is above 10 MHz.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “17.3.3. SCL Low Timeout” on page 191). The SMBus interface will force Timer 3
to reload while SCL is high, and allow T imer 3 to count when SCL is low. The Timer 3 interrupt service r ou-
tine should be used to reset SMBus communication by disabling and re-enabling the SMBus.
SMBus Free T imeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 17.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an
interrupt will be generated, and STO will be set).
Table 17.2. Minimum SDA Setup and Hold Times
EXTHOLD Minimum SDA Setup Time Minimum SDA Hold Time
0
Tlow - 4 system clocks
OR
1 system clock + s/w delay*
3 system clocks
1 11 system clocks 12 system clocks
*Note: Setup Time for ACK bit transmissions and th e MSB of all data transfers. The s/w delay
occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI
is cleared in the same write that defines the outgoing ACK value , s/w delay is zero.
SCL
Timer Source
Overflows
SCL High Ti meoutT
Low
T
High
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 194
SFR Definition 17.1. SMB0CF: SMBus Clock/Configuration
Bit7: ENSMB: SMBus Enable.
This bit enables/disables the SMBus interface. When enab led, the inter face constantly mon-
itors the SDA and SCL pins.
0: SMBus interface disabled.
1: SMBus interface enabled.
Bit6: INH: SMBus Slave Inhibit.
When this bit is set to logic 1, the SMBus does not generate an interr upt when slave events
occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are
not affected.
0: SMBus Slave Mode enabled.
1: SMBus Slave Mode inhibited.
Bit5: BUSY: SMBus Busy Indicator.
This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0
when a STOP or free-timeout is sensed.
Bit4: EXTHOLD: SMBus Setup and Hold Time Extension Enable.
This bit controls the SDA setup and hold times according to.
0: SDA Extended Setup and Hold Times disabled.
1: SDA Extended Setup and Hold Times enabled.
Bit3: SMBTOE: SMBus SCL Timeout Detectio n Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to
reload while SCL is hi gh and allows T imer 3 to count when SCL goes low. T imer 3 should be
programmed to generate interrupts at 25 ms, and the Timer 3 interrupt service routine
should reset SMBus communication.
Bit2: SMBFTE: SMBus Free Timeout Detection Enable.
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for
more than 10 SMBus clock source periods.
Bits1–0: SMBCS1-SMBCS0: SMBus Clock Source Selection.
These two bits select the SMBus clock source, which is used to generate the SMBus bit
rate. The selected device should be configured according to Equation 17.1.
R/W R/W R R/W R/W R/W R/W R/W Reset Value
ENSMB INH BUSY EXTHOLD SMBTOE SMBFTE SMBCS1 SMBCS0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC1
SMBCS1 SMBCS0 SMBus Clock Source
0 0 Ti me r 0 Ov er flow
0 1 Ti me r 1 Ov er flow
1 0 Timer 2 High Byte Overflow
1 1 Timer 2 Low Byte Overflow
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
195 Rev. 1.3
17.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 17.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive
modes, respectively.
STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus
interrupt. STA and STO ar e also used to gene ra te START and STOP conditions when op erating as a ma s-
ter. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mode and generate a START when
the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO
while in Master Mode will cause the interface to generate a STOP and end the current transfer after the
next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be
generated.
As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit
indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating
that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing
value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit
before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit;
however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further
slave events will be ignored until the next START is detected.
The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface
is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condi-
tion. ARBLOST is cleared by hardware e ach time SI is cleared.
The SI bit (SMBus Interrupt Flag) is set at the beginn ing and end of each transfe r, after each byte frame, or
when an arbitration is lost ; see Table 17.3 for more details.
Import ant Note About t he SI Bit : The SMBus interface is st alled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
Table 17.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 17.4 for SMBus sta-
tus decoding using the SMB0CN register.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 196
SFR Definition 17.2. SMB0CN: SMBus Control
Bit7: MASTER: SMBus Master/Slave Indicator.
This read-only bit indicates when the SMBus is operatin g as a master.
0: SMBus operating in Slave Mode.
1: SMBus operating in Master Mode.
Bit6: TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
1: SMBus in Transmitter Mode.
Bit5: STA: SMBus Start Flag.
Write:
0: No Start generated.
1: When operatin g as a master, a START condition is transmitted if the bus is free (If th e bus
is not free, the START is transmitted after a STOP is received or a timeout is detected). If
STA is set by software as an active Master, a repeated START will be generated after the
next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Star t detected.
Bit4: STO: SMBus Stop Flag.
Write:
0: No STOP conditio n is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitte d after the next ACK
cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA
and STO are set, a STOP condition is transmitted followed by a START condition.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending ( i f in Master Mode).
Bit3: ACKRQ: SMBus Acknowledge Request
This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK
bit to be written with the correct ACK response value.
Bit2: ARBLOST: SMBus Arbitration Lost Indicator.
This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a
transmitter. A lost arbitration while a slave indicates a bus error condition.
Bit1: ACK: SMBus Acknowledge Flag.
This bit defines the out-going ACK level and records incoming ACK levels. It should be writ-
ten each time a byte is received (when ACKRQ=1), or read after each byte is transmitted.
0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if
in Receiver Mode).
1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
Bit0: SI: SMBus Interrupt Flag.
This bit is set by hardware under the conditions listed in Table 17.3. SI must be cleared by
software. While SI is set, SCL is held low and the SMBus is stalled.
R R R/W R/W R R R/W R/W Reset Value
MASTER TXMODE STA STO ACKRQ ARBLOST ACK SI 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xC0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
197 Rev. 1.3
Table 17.3. Sources for Hardware Changes to SMB0CN
Bit Set by Hardware When: Cleared by Hardware When:
MASTER • A START is generated. • A STOP is generated.
• Arbitration is lost.
TXMODE
• START is generated.
• SMB0DAT is written before the start of an
SMBus frame.
• A START is detected.
• Arbitration is lost.
• SMB0DAT is not written before the
start of an SMBus frame.
STA • A START followed by an address byte is
received. • Must be cleared by softwa re.
STO • A STOP is detected while addressed as a
slave.
• Arbitration is lost due to a detected STOP.
• A pending STOP is generated.
ACKRQ • A byte has been received and an ACK
response value is needed. • After each ACK cycle.
ARBLOST
• A repeated START is detected as a MASTER
when STA is low (unwanted repeated START).
• SCL is sensed low while attempting to gener-
ate a STOP or repeated START condition.
• SDA is sensed low while transmitting a ‘1’
(excluding ACK bits).
• Each time SI is cleared.
ACK • The incoming ACK value is low (ACKNOWL-
EDGE). • The incoming ACK value is high (NOT
ACKNOWLEDGE).
SI
• A START has been generated.
• Lost arbit ra tio n.
• A byte has been transmitted and an ACK/
NACK received.
• A byte has been received.
• A STAR T or repeated START followed by a
slave address + R/W has been received.
• A STOP has been received.
• Must be cleared by software.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 198
17.4.3. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmi tted or one that has just been
received. Sof tware may safely rea d or write to the da ta register when the SI flag is set. Software should not
attempt to ac cess the SMB0DAT re gister wh en the SMBu s is enabled a nd the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always co ntains the last data byte pre sent on th e bus. In the even t of lost a rbi -
tration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 17.3. SMB0DAT: SMBus Data
17.5. SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be
operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or
Slave Receiver. The SMBus interface enters M aster Mo de a ny time a START is gene rate d, an d remains i n
Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end
of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when opera t-
ing as a receiver, and after the ACK cycle when operating as a transmitter.
17.5.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates
the START condition and transmits the first byte containing the address of the target slave and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits
one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the
slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will
switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt.
Figure 17.5 shows a typical Master Transmitter sequence. Two transmit data bytes ar e shown, though any
number of by tes may be transmitt ed. Notice tha t the ‘data byte tra nsferred ’ interrupts occur after the ACK
cycle in this mode.
Bits7-0: SMB0DAT: SMBus Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial inter-
face or a byte that has just been received on the SMBus serial interface. The CPU can read
from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to
logic 1. The serial data in the register remains stable as long as the SI flag is set. When the
SI flag is not set, the system may be in the process of shifting data in/out and the CPU
should not attempt to access this register.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC2
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
199 Rev. 1.3
Figure 17.5. Typical Master Transmitter Sequence
A AAS W PData Byte Data ByteSLA
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmi tted by
SMBus Interface
Interrupt Interrupt InterruptInterrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 200
17.5.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the
START condition and transmits the first byte containing the address of the target slave and the data direc-
tion bit. In this case the data direction bit (R/W) will be logic 1 (READ). Ser ial dat a is then received from the
slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial
data. After each byte is received, ACKRQ is set to ‘1’ and an interrupt is generated. Software must write
the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a ‘1’ to the ACK bit gen-
erates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last
byte is received, to transmit a NACK. The interface exit s Master Receiver Mode after the ST O bit is set and
a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written
while an active Master Receiver. Figure 17.6 shows a typical Master Receiver sequence. Two received
data bytes ar e sh own, tho ugh a ny numbe r of bytes m ay be r eceived. No tice that the ‘d ata byte transferred’
interrupts occur before the ACK cycle in this mode.
Figure 17.6. Typical Master Receiver Sequence
Data ByteData Byte A NAS R PSLA
S = START
P = STOP
A = ACK
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt InterruptInterrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
201 Rev. 1.3
17.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =
0), the inter face en ters Slav e Rece iver Mo de wh en a START followed by a s lav e addr ess an d dir ectio n bit
(WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the
ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received
slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until
the next START is detected. If the received slave address is acknowledged, zero or more data bytes are
received. Sof tware must write the ACK bit af ter ea ch received byte to ACK or NACK the received byte. The
interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Recei ver. Figure 17.7 shows a typical Sla ve
Receiver sequence. Two received data bytes are shown, though any number of bytes may be received.
Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode.
Figure 17.7. Typical Slave Receiver Sequence
PWSLASData ByteData Byte A AA
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt Interrupt
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 202
17.5.4. Slave Transmitter Mode
Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH
= 0), the interface en ters Slave Receiver Mode ( to receive the sla ve address) when a STAR T followed by a
slave address and direction bit (READ in this case) is received. Upo n entering Sla ve Transmitter Mode, an
interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an
ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave
interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data
should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and trans-
mits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the
acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is
a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition m ay be gener-
ated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface
exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver
Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 17.8 shows a typical Slave
Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be trans-
mitted. Notice that the ‘data byte tran sfe rr e d’ inte rr u pts occur after the ACK cycle in this mode.
Figure 17.8. Typical Slave Transmitter Sequence
17.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS
VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the
shown response options are only the typical responses; application-specific procedures are allowed as
long as they conform to the SMBus specification. Highlighte d resp onse s are allowe d but do no t conform to
the SMBus specification.
PRSLASData ByteData Byte A NA
S = START
P = STOP
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt Interrupt
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
203 Rev. 1.3
Table 17.4. SMBus Status Decoding
Mode
Values Read
Current SMbus State Typical Response Options
Values
Written
Status
Vector
ACKRQ
ARBLOST
ACK
STA
STo
ACK
Master Transmitter
1110 0 0 X A master START was generated. Load slave address + R/W
into SMB0DAT.0 0 X
1100
000
A master data or address byte
was transmitted; NACK received. Set STA to restart transfer. 1 0 X
Abort transfer. 0 1 X
001
A master data or address byte
was transmitted; ACK received.
Load next data byte into
SMB0DAT.0 0 X
End transfer with STOP. 0 1 X
End transfer with STOP and
start an other transfer. 1 1 X
Send repeated START. 1 0 X
Switch to Master Receiver
Mode (clear SI without writ-
ing new data to SMB0DAT). 0 0 X
Master Receiver
1000 1 0 X A master data byte was re ceived;
ACK requested.
Acknowledge received byte;
Read SMB0DAT.001
Send NACK to indicate last
byte, and send STOP. 010
Send NACK to indicate last
byte, and send STOP fol-
lowed by START. 110
Send ACK followed by
repeated START. 101
Send NACK to indicate last
byte, and send repeated
START. 1 0 0
Send ACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0 0 1
Send NACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0 0 0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 204
Slave Transmitter
0100
000
A slave byte was transmitted;
NACK received. No action required (expect-
ing STOP condition). 0 0 X
001
A slave byte was transmitted;
ACK received. Load SMB0DAT with next
data byte to transmit. 0 0 X
01X
A Slave byte was transmitted;
error detected. No action required (expect-
ing Master to end transfer). 0 0 X
0101 0 X X An illegal STOP or bus error was
detected while a Slave Transmis-
sion was in progress. Clear STO. 0 0 X
Slave Receiver
0010
10X
A slave address was received;
ACK requested.
Acknowledge received
address. 001
Do not acknowledge
received address. 000
11X
Lost arbitration as master; slave
address received; ACK
requested.
Acknowledge received
address. 001
Do not acknowledge
received address. 000
Reschedule failed transfer;
do not acknowledge received
address. 100
0010 0 1 X Lost arbitration while attempting a
repeated START. Abort failed transf er. 0 0 X
Reschedule failed transfer. 1 0 X
0001
11X
Lost arbitration while attempting a
STOP.No action required (transfer
complete/aborted). 000
00X
A STOP was detected while
addressed as a Slave T ransmitter
or Slave Receiver. Clear STO. 0 0 X
01X
Lost arbitration du e to a detected
STOP. Abort transfer. 0 0 X
Reschedule failed transfer. 1 0 X
0000 10X
A slave byte was received; ACK
requested.
Acknowledge received byte;
Read SMB0DAT.001
Do not acknowledge
received byte. 000
11X
Lost arbitration while transmitting
a data byte as master. Abort faile d tran sf er. 000
Reschedule failed transfer. 100
Table 17.4. SMBus Status Decoding (Continued)
Mode
Values Read
Current SMbus State Typical Response Options
Values
Written
Status
Vector
ACKRQ
ARBLOST
ACK
STA
STo
ACK
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 205
18. UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate su pport allows a wide r ange o f clock sour ces to gene rate standard baud r ates (det ails
in Section “18.1. Enhanced Baud Rate Generation” on page 206). Received data buffering allows
UART0 to start rece ption of a second incoming dat a byte before sof tware has finished reading the previo us
data byte.
UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).
The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0
always access the Transmit regis te r. Reads of SBUF0 alway s acces s t he buf fe red Receive regist er;
it is not possible to read data from the Transmit register.
With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in
SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not
cleared by hardwa re when the CPU vectors to th e interr upt service routine. They must be cleared manually
by software, allowing software to dete rmine the cause of the UAR T0 interrupt (tr ansmit complete or rece ive
complete).
Figure 18.1. UART0 Block Diagram
UART0 Baud
Rate Generator
RI0
SCON
RI0
TI0
RB80
TB80
REN0
MCE0
S0MODE
Tx Control
Tx Clock Send
SBUF0
(TX Shift)
Start
Data
Write to
SBUF0
Crossbar
TX0
Shift
Zero Detector
Tx IRQ
SET
QD
CLR
Stop Bit
TB80
SFR Bus
Serial
Port
Interrupt
TI0 Port I/O
Rx Control
Start
Rx Clock
Load
SBUF0
Shift 0x1FF RB80
Rx IRQ
Input Shift Register
(9 bits)
Load SBUF0
Read
SBUF0
SFR Bus Crossbar
RX0
SBUF0
(RX Latch)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
206 Rev. 1.3
18.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 18.2), which is not
user-accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud
rates. The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Figure 18.2. UART0 Baud Rate Logic
Timer 1 should be con figured for M ode 2, 8-bit auto-reload (see Section “21.1.3. Mode 2: 8-bit Counter/
Timer with Auto-Reload” on page 237). The Timer 1 reload value should be set so that overflows will
occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six
sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an exter-
nal input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 18.1.
Equation 18.1. UART0 Baud Rate
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “21. Timers” on page 235. A quick
reference for typical baud rates using the internal oscillator is given in Table 18.1. Note that the internal
oscillator may still generate the system clock if an external oscillator is driving Timer 1.
18.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown below.
RX Timer
Start
Detected
Overflow
Overflow
TH1
TL1
TX Clock
2
RX Clock
2
Timer 1 UART
UartBaudRate T1CLK
256 T1H–()
-------------------------------1
2
---
×=
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 207
Figure 18.3. UART Interconnect Diagram
18.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per dat a byte: one st art bit, e ight data bit s (LSB first) , and one stop
bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data
bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins wh en software writes a data byte to the SBUF0 register. The TI0 Transmit Inter-
rupt Flag ( SCON0.1) is set at th e end of the transm ission (the beginning of the stop-bit time). Data recep-
tion can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data over-
run, the first received 8 bits are latched into the SBUF0 r eceive r egister and the following overrun data bits
are lost.
If these condition s are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 is set.
Figure 18.4. 8-Bit UART Timing Diagram
OR
RS-232
C8051Fxxx
RS-232
LEVEL
XLTR
TX
RX
C8051Fxxx
RX
TX
MCU RX
TX
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
208 Rev. 1.3
18.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programma-
ble ninth data bit, and a stop bit. The state of the ninth transmit data bit is deter mined by the value in TB80
(SCON0.3), which is assigned by use r sof t ware. It ca n be assigned the value of the p arity flag (bit P in reg-
ister PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB80 (SCON0.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
(1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to ‘1’. If the above conditions are not met,
SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to ‘1’. A UART0 interrupt will occur if
enabled when either TI0 or RI0 is set to ‘1’.
Figure 18.5. 9-Bit UART Timing Diagram
18.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth dat a bit. When a master proce ssor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set t o logic 0.
Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB8 0 = 1) signifying a n address
byte has been received. In the UART interrupt handler, software will compare the received address with
the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable
interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0
bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the
data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmis-
sions until it receives the next address byte.
Multiple addresses ca n be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE D8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 209
Figure 18.6. UART Multi-Processor Mode Interconnect Diagram
Master
Device Slave
Device
TXRX RX TX
Slave
Device
RX TX
Slave
Device
RX TX
V+
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
210 Rev. 1.3
SFR Definition 18.1. SCON0: Serial Port 0 Control
Bit7: S0MODE: Serial Port 0 Operation Mode.
This bit selects the UART0 Operation Mode.
0: 8-bit UAR T with Variable Baud Rate.
1: 9-bit UAR T with Variable Baud Rate.
Bit6: UNUSED. Read = 1b. Write = don’t care.
Bit5: MCE0: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode.
S0MODE = 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
S0MODE = 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1.
Bit4: REN0: Receive Enable.
This bit enables/disables the UART receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
Bit3: TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
Bit2: RB80: Ninth Receive Bit.
RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
Bit1: TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in
8-bit UART Mo de, or at the beginning of the STOP bit in 9-bit UART Mod e). When the
UART0 interrup t is enabled, setting this bit causes the CPU to vector to the UAR T0 interrupt
service routine. This bit must be cleared manually by software.
Bit0: RI0: Receive Interrupt Flag.
Set to ‘1’ by hardware wh en a byte of data ha s been received by UAR T0 (set at the STOP bit
sampling time). When the UART0 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART0 interrupt service routine. This bit must be cleared manually by soft-
ware.
R/W R R/W R/W R/W R/W R/W R /W Reset Value
S0MODE - MCE0 REN0 TB80 RB80 TI0 RI0 01000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0x98
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 211
SFR Definition 18.2. SBUF0: Serial (UART0) Port Data Buffer
Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7–0 (MSB-LSB)
This SFR accesses two registers; a transmit shift register and a receive latch re gister. When
data is written to SBUF0, it goes to the transmit shift register and is held for serial transmis-
sion. Writing a byte to SBUF0 initiates the transmission. A read of SBUF 0 returns the con-
tents of the receive latch.
R/W R/W R/W R /W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x99
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
212 Rev. 1.3
Table 18.1. Timer Settings for Standard Baud Rates Using the Internal Oscillator
Target
Baud
Rate (bps)
Actual
Baud
Rate (bps)
Baud
Rate Error Oscillator
Divide
Factor
Timer Clock
Source SCA1-SCA0
(pre-scale
select*
T1M* Timer 1
Reload
Value (hex)
SYSCLK = 12 MHz
230400 230769 0.16% 52 SYSCLK XX 1 0xE6
115200 115385 0.16% 104 SYSCLK XX 1 0xCC
57600 57692 0.16% 208 SYSCLK XX 1 0x98
28800 28846 0.16% 416 SYSCLK XX 1 0x30
14400 14423 0.16% 832 SYSCLK / 4 01 0 0x98
9600 9615 0.16% 1248 SYSCLK / 4 01 0 0x64
2400 2404 0.16% 4992 SYSCLK / 12 00 0 0x30
1200 1202 0.16% 9984 SYSCLK / 48 10 0 0x98
SYSCLK = 24 MHz
230400 230769 0.16% 104 SYSCLK XX 1 0xCC
115200 115385 0.16% 208 SYSCLK XX 1 0x98
57600 57692 0.16% 416 SYSCLK XX 1 0x30
28800 28846 0.16% 832 SYSCLK / 4 01 0 0x98
14400 14423 0.16% 1664 SYSCLK / 4 01 0 0x30
9600 9615 0.16% 2496 SYSCLK / 12 00 0 0x98
2400 2404 0.16% 9984 SYSCLK / 48 10 0 0x98
1200 1202 0.16% 19968 SYSCLK / 48 10 0 0x30
SYSCLK = 48 MHz
230400 230769 0.16% 208 SYSCLK XX 1 0x98
115200 115385 0.16% 416 SYSCLK XX 1 0x30
57600 57692 0.16% 832 SYSCLK / 4 01 0 0x98
28800 28846 0.16% 1664 SYSCLK / 4 01 0 0x30
14400 14388 0.08% 3336 SYSCLK / 12 00 0 0x75
9600 9615 0.16% 4992 SYSCLK / 12 00 0 0x30
2400 2404 0.16% 19968 SYSCLK / 48 10 0 0x30
X = Don’t care
*Note: SCA1-SCA0 and T1M define the Timer Clock Source. Bit definitions for these values can be found in
Section 21.1.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 213
19. UART1 (C8051F340/1/4/5/8/A/B/C Only)
UART1 is an asynch ronou s, full dup lex serial port offering a variet y of data formatting options. A dedicated
baud rate generator with a 16-bit timer and selectable prescaler is included, which can generate a wide
range of baud rates (details in Section “19.1. Baud Rate Generator” on page 214). A received data
FIFO allows UART1 to receive up to three data bytes before data is lost and an overflow occurs.
UART1 has six associated SFRs. Three are used for the Baud Rate Generator (SBCON1, SBRLH1, and
SBRLL1), two are used for data formatting, control, and status functions (SCON1, SMOD1), and one is
used to send an d receive data (SBUF1). The single SBUF1 location provides acces s to both the transmit
holding register and the receive FIFO. Writes to SBUF1 always access the Transmit Holding Register.
Reads of SBUF1 always access the first byte of the Receive FIFO; it is not possible to read data
from the Transmit Holding Register.
With UART1 interrupts enabled, an interrupt is generated each time a transmit is completed (TI1 is set in
SCON1), or a data byte has been received (RI1 is set in SCON1). The UART1 interrupt flags are not
cleared by hardwa re when the CPU vectors to th e interr upt service routine. They must be cleared manually
by software, allowing software to dete rmine the cause of the UAR T1 interrupt (tr ansmit complete or rece ive
complete). Note that if additional bytes are available in the Receive FIFO, the RI1 bit cannot be cleared by
software.
Figure 19.1. UART1 Block Diagram
SBUF1
TX Holding
Register
RX FIFO
(3 Deep)
TX
Logic
RX
Logic
Write to SBUF1
Read of SBUF1
TX1
RX1
SMOD1
MCE1
S1PT1
S1PT0
PE1
S1DL1
S1DL0
XBE1
SBL1
Data Formatting
SCON1
OVR1
PERR1
THRE1
REN1
TBX1
RBX1
TI1
RI1
Control / Status
UART1
Interrupt
Timer (16-bit) Pre-Scaler
(1, 4, 12, 48)
SYSCLK
SBRLH1 SBRLL1 Overflow
SBCON1
SB1RUN
SB1PS1
SB1PS0
EN
Baud Rate Generator
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
214 Rev. 1.3
19.1. Baud Rate Generator
The UART1 baud rate is generated by a dedicated 16-bit timer which runs from the controller ’s core clock
(SYSCLK), and has prescaler options of 1, 4, 12, or 48. The timer and prescaler options combined allow
for a wide selection of baud rates over many SYSCLK fre quencies.
The baud rate generator is configured using three registers: SBCON1, SBRLH1, and SBRLL1. The
UART1 Baud Rate Generator Control Register (SBCON1, SFR Definition 19.4) enables or disables the
baud rate generator, and selects the prescaler value for the timer. The baud rate generator must be
enabled for UART1 to function. Registers SBRLH1 and SBRLL1 contain a 16-bit reload value for the dedi-
cated 16-bit timer. The internal timer counts up from the reload value on every clock tick. On timer over-
flows (0xFFFF to 0x0000), the timer is reloaded. For reliable UART operation, it is recommended that the
UART baud rate is not configured for baud rates faster than SYSCLK/16. The baud rate for UART1 is
defined in Equation 19.1.
Equation 19.1. UART1 Baud Rate
A quick reference for typical baud rates and system clock frequencie s is given in Table 19.1.
Table 19.1. Baud Rate Generator Settings for Standard Baud Rates
Target Baud
Rate (bps) Actual Baud
Rate (bps) Baud Rate
Error Oscillator
Divide
Factor
SB1PS[1:0]
(Prescaler Bits) Reload Value in
SBRLH1:SBRLL1
SYSCLK = 12 MHz
230400 230769 0.16% 52 11 0xFFE6
115200 115385 0.16% 104 11 0xFFCC
57600 57692 0.16% 208 11 0xFF98
28800 28846 0.16% 416 11 0xFF30
14400 14388 0.08% 834 11 0xFE5F
9600 9600 0.0% 1250 11 0xFD8F
2400 2400 0.0% 5000 11 0xF63C
1200 1200 0.0% 10000 11 0xEC78
SYSCLK = 24 MHz
230400 230769 0.16% 104 11 0xFFCC
115200 115385 0.16% 208 11 0xFF98
57600 57692 0.16% 416 11 0xFF30
28800 28777 0.08% 834 11 0xFE5F
14400 14406 0.04% 1666 11 0xFCBF
9600 9600 0.0% 2500 11 0xFB1E
2400 2400 0.0% 10000 11 0xEC78
1200 1200 0.0% 20000 11 0xD8F0
SYSCLK = 48 MHz
230400 230769 0.16% 208 11 0xFF98
115200 115385 0.16% 416 11 0xFF30
57600 57554 0.08% 834 11 0xFE5F
28800 28812 0.04% 1666 11 0xFCBF
14400 14397 0.02% 3334 11 0xF97D
9600 9600 0.0% 5000 11 0xF63C
2400 2400 0.0% 20000 11 0xD8F0
1200 1200 0.0% 40000 11 0xB1E0
Baud Rate SYSCLK
65536 (SBRLH1:SBRLL1)–()
--------------------------------------------------------------------------- 1
2
---
×1
Prescaler
----------------------
×=
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 215
19.2. Data Format
UART1 has a number of available options for data formatting. Data transfers begin with a start bit (logic
low), followed by the data bits (sent LSB-first), a parity or extra bit (if selected), and end with one or two
stop bits (logic high). The data length is variable between 5 and 8 bits. A parity bit can be appended to the
data, and automatically generated and detected by hardware for even, odd, mark, or space parity. The stop
bit length is selectable between short (1 bit time) and long (1.5 or 2 bit times), and a multi-processor com-
munication mode is available for implementing networked UART buses. All of the data formatting options
can be con figured usin g the SMO D1 regist er, sh own in SFR Definition 19.2. Figure 19.2 shows the timing
for a UART1 transaction without parity or an extra bit enabled. Figure 19.3 shows the timing for a UART1
transaction with parity enabled (PE1 = 1). Figure 19.4 is an example of a UART1 transaction when the
extra bit is enabled (XBE1 = 1). Note that the extra bit feature is not available when parity is enabled, and
the second stop bit is only an option for data lengths of 6, 7, or 8 bits.
Figure 19.2. UART1 Timing Without Parity or Extra Bit
Figure 19.3. UART1 Timing With Parity
Figure 19.4. UART1 Timing With Extra Bit
D1
D0DN-2 DN-1
START
BIT
MARK STOP
BIT 1
BIT TIMES
SPACE
N bits; N = 5, 6, 7, or 8
STOP
BIT 2
Optional
D1
D0DN-2 DN-1 PARITY
START
BIT
MARK STOP
BIT 1
BIT TIMES
SPACE
N bits; N = 5 , 6, 7, o r 8
STOP
BIT 2
Optional
D1
D0DN-2 DN-1 EXTRA
START
BIT
MARK STOP
BIT 1
BIT TIMES
SPACE
N bits; N = 5, 6, 7, or 8
STOP
BIT 2
Optional
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
216 Rev. 1.3
19.3. Configuration and Operation
UART1 provides standard asynchronous, full duplex communication. It can operate in a point-to-point
serial communications application, or as a node on a multi-processor serial interface. To operate in a
point-to-point application, where there are only two devices on the serial bus, the MCE1 bit in SMOD1
should be cleared to ‘0’. For operation as part of a multi-processor communications bus, the MCE1 and
XBE1 bits should both be set to ‘1’. In both types of applications, data is transmitted from the microcontrol-
ler on the TX1 pin, and received on the RX1 pin. The TX1 and RX1 pi ns are configured using the crossbar
and the Port I/O registers, as detailed in Section “15. Port In pu t /O ut p ut ” on page 142.
In typical UART communications, The transmit (TX) output of one device is connected to the receive (RX)
input of the other device, either directly or through a bus transceiver, as shown in Figure 19.5.
Figure 19.5. Typical UART Interconnect Diagram
19.3.1. Data Transmission
Data transmission is double-buffered, and begins when software writes a data byte to the SBUF1 register.
Writing to SBUF1 places data in the Transmit Holding Register, and the Transmit Holding Register Empty
flag (THRE1) will be cleared to ‘0’. If the UARTs shift register is empty (i.e., no transmission is in progress)
the data will be placed in the shift register, and the THRE1 bit will be set to ‘1’. If a transmission is in prog-
ress, the data will remain in the Transmit H olding Register until the current transmission is complete. The
TI1 Transmit Interrupt Flag (SCON1.1) will be set at the end of any transmission (the beginning of the
stop-bit time). If enabled, an interrupt will occur when TI1 is set.
If the extra bit function is enabled (XBE1 = ‘1’) and the parity function is disabled (PE1 = ‘0’), the value of
the TBX1 (SCON1.3) bit will be sent in the extra bit position. When the parity function is enabled (PE1 =
‘1’), hardware will generate the parity bit according to the selected parity type (selected with S1PT[1:0]),
and append it to the data field. Note: when parity is enabled, the extra bit function is not available.
19.3.2. Data Reception
Data rece ption can b egin any tim e af ter the REN1 Receive Ena ble bit (SCON1.4 ) is set to logic 1. Af te r the
stop bit is received, the data byte will be stored in the receive FIFO if the following conditions are met: the
receive FIFO (3 bytes deep) must not be full, and the stop bit(s) must be logic 1. In the event that the
receive FIFO is full, the incoming byte will be lost, and a Receive FIFO Overrun Error will be generated
(OVR1 in register SCON1 will be set to logic 1). If the stop bit(s) were logic 0, the incoming data will not be
stored in the receive FIFO. If the reception conditions are met, the data is stor ed in the re ceive FIFO , and
the RI1 flag will be set. Note: when MCE1 = ‘1’, RI1 will only be set if the extra bit was equal to ‘1’. Data can
be read from the receive FIFO by reading the SBUF1 register. The SBUF1 register represents the oldest
byte in the FIFO. After SBUF1 is read, the next byte in the FIFO is immediately loaded into SBUF1, and
OR
RS-232 C8051Fxxx
RS-232
LEVEL
TRANSLATOR
TX
RX
C8051Fxxx
RX
TX
MCU RX
TX
PC
COM Port
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 217
space is made available in the FIFO for another incoming byte. If enabled, an interrupt will occur when RI1
is set. RI1 can only be cleared to '0' by software when there is no more information in the FIFO. The rec-
ommended procedure to empty the FIFO contents is as follows:
1. Clear RI1 to '0'.
2. Read SBUF1.
3. Check RI1, and repeat at step 1 if RI1 is set to '1'.
If the extra bit functio n is enabled (XBE1 = ‘1’) and the parity function is disabled (PE1 = ‘0’), the extra bit
for the oldest byte in the FIFO can be read from the RBX1 bit (SCON1.2). If the extra bit function is not
enabled, the value of the stop bit for the oldest FIFO byte will be presented in RBX1. When the parity func-
tion is enabled (PE1 = ‘1’), hardware will check the received parity bit against the selected parity type
(selected with S1PT[1:0]) when receiving data. If a byte with pa rity error is received, the PERR1 flag will be
set to ‘1’. This flag must be cleared by software. Note: when parity is enabled, the extra bit function is not
available.
19.3.3. Multiprocessor Communications
UART1 supports multiproces sor communication between a master processor and one o r more slave pro -
cessors by special use of the extra data bit. When a master processor wants to transmit to one or more
slaves, it first sends an address byte to se lect th e target(s). An add re ss b yte differs from a dat a b yte in th at
its extra bit is logic 1; in a data byte, the extra bit is always set to logic 0.
Setting the MCE1 bit (SMOD1.7) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the extra bit is logic 1 (RBX1 = 1) signifying an
address byte has been received. In the UART interrupt handler, software will compare the received
address with the slave's own assigned address. If the addresses match, the slave will clear its MCE1 bit to
enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their
MCE1 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring
the data. Once the entire message is received, the addressed slave resets its MCE1 bit to ignore all trans-
missions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
Master
Device Slave
Device
TXRX RX TX
Slave
Device
RX TX
Slave
Device
RX TX
V+
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
218 Rev. 1.3
Figure 19.6. UART Multi-Processor Mode Interconnect Diagram
SFR Definition 19.1. SCON1: UART1 Control
Bit7: OVR1: Receive FIFO Overrun Flag.
This bit is used to indicate a re ceive F IF O ove r ru n con d itio n.
0: Receive FIFO Overrun has not occurred.
1: Receive FIFO Overrun has occurred (an incom ing character was discarded due to a full
FIFO).
This bit must be cleared to ‘0’ by software.
Bit6: PERR1: Parity Error Flag.
When parity is enabled, this bit is used to indicate that a p arity error has occurred. It is set to
‘1’ when the parity of the oldest byte in the FIFO does not match the selected Parity Type.
0: Parity Error has not occurred.
1: Parity Error has occurred.
This bit must be cleared to ‘0’ by software.
Bit5: THRE1: Transmit Holding Register Empty Flag.
0: Transmit Holding Register not Empty - do not write to SBUF1.
1: Transmit Holding Register Empty - it is safe to write to SBUF1.
Bit4: REN1: Receive Enable.
This bit enables/disables the UART receiver. When disabled, bytes can still be read from the
receive FIFO.
0: UART1 reception disabled .
1: UART1 reception enabled.
Bit3: TBX1: Extra Transmission Bit.
The logic level of this bit will be assigned to the extra transmission bit when XBE1 is set to
‘1’. This bit is not used when Parity is enabled.
Bit2: RBX1: Extra Receive Bit.
RBX1 is assigned the value of the extra bit when XBE1 is set to ‘1’. If XBE1 is cleared to ‘0’,
RBX1 will be assigned the logic level of the first stop bit. This bit is not valid when Parity is
enabled.
Bit1: TI1: Transmit Interrupt Flag.
Set to a ‘1’ by hardware after data has bee n transmitted, at the beginning of the STOP bit.
When the UART1 interrupt is enabled, setting this bit causes the CPU to vector to the
UART1 interrupt se rvice routine. This bit must be cleared manually by software.
Bit0: RI1: Receive Interrupt Flag.
Set to ‘1’ by hardware wh en a byte of data ha s been received by UAR T1 (set at the STOP bit
sampling time). When the UART1 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART1 interrupt service routine. This bit must be cleared manually by soft-
ware. Note that RI1 will remain set to '1' as long as there is still data in the UART FIFO. After
the last byte has been shifted from the FIFO to SBUF1, RI1 can be cleared.
R/W R/W R R/W R/W R/W R/W R/W Reset Value
OVR1 PERR1 THRE1 REN1 TBX1 RBX1 TI1 RI1 00100000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD2
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 219
SFR Definition 19.2. SMOD1: UART1 Mode
Bit7: MCE1: Multiprocessor Communication Enable.
0: RI will be activated if stop bit(s) are ‘1’.
1: RI will be activated if stop bit(s) and extra bit are ‘1’ (extra bit must be enabled using
XBE1).
Note: This function is not available when hardware parity is enabled.
Bits6–5: S1PT[1:0]: Parity Type.
00: Odd
01: Even
10: Mark
11: Space
Bit4: PE1: Parity Enable.
This bit activates hardware parity generation and checking. The parity type is selected by
bits S1PT1-0 when parity is enabled.
0: Hardware parity is disabled.
1: Hardware parity is enabled.
Bits3–2: S1DL[1:0]: Data Length.
00: 5-bit data
01: 6-bit data
10: 7-bit data
11: 8-bit data
Bit1: XBE1: Extra Bit Enable
When enabled, the value of TBX1 will be appended to the data field.
0: Extra Bit Disabled.
1: Extra Bit Enabled.
Bit0: SBL1: St op Bit Length
0: Short - Stop bit is active for one bit time.
1: Long - Stop bit is active for two bit times (data length = 6, 7, or 8 bits), or 1.5 bit times
(data length = 5 bits).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
MCE1 S1PT1 S1PT0 PE1 S1DL1 S1DL0 XBE1 SBL1 00001100
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xE5
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
220 Rev. 1.3
SFR Definition 19.3. SBUF1: UART1 Data Buffer
SFR Definition 19.4. SBCON1: UART1 Baud Rate Generator Control
Bits7–0: SBUF1[7:0]: Serial Data Buffer Bits 7–0 (MSB-LSB)
This SFR is used to both send data fro m the UART an d to read received data from the
UART1 receive FIFO.
Write: Writing a byte to SBUF1 initiates the transmission. When data is written to SBUF1, it
first goes to the T ransmit Holdin g Register , wher e it is held for serial transmission. When the
transmit shift register is available, data is transferred into the shift register, and SBUF1 may
be written again.
Read: Reading SBUF1 retrieves data from the receive FIFO. When read, the oldest byte in
the receive FIFO is returned, and removed from the FIFO. Up to thre e bytes may be held in
the FIFO. If there are additional bytes available in the FIFO, the RI1 bit will remain at logic
‘1’, even afte r being cleared by soft ware.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xD3
Bit7: RESERVED: Read = 0b; Must write 0b.
Bit6: SB1RUN: Baud Rate Generator Enable.
0: Baud Rate Generator is disabled. UART1 will not function.
1: Baud Rate Generator is enabled.
Bits5–2: RESERVED: Read = 0000b; Must write 0000b.
Bits1–0: SB1PS[1:0]: Baud Rate Prescaler Select.
00: Prescaler = 12
01: Prescaler = 4
10: Prescaler = 48
11: Prescaler = 1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Reserved SB1RUN Reserved Reserved Reserved Reserved SB1PS1 SB1PS0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xAC
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 221
SFR Definition 19.5. SBRLH1: UART1 Baud Rate Generator High Byte
SFR Definition 19.6. SBRLL1: UART1 Baud Rate Generator Low Byte
Bits7–0: SBRLH1[7:0]: High Byte of reload value for UART1 Baud Rate Genera tor.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB5
Bits7–0: SBRLL1[7:0]: Low Byte of reload value for UART1 Baud Rate Generator.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xB4
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 222
20. Enhanced Serial Peripheral Interface (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous
serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and suppo rts mul -
tiple masters and slaves on a single SPI bus. The slave-select (NSS) sig na l ca n be co nf igu re d as an in pu t
to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding
contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can
also be conf igured as a ch ip-select ou tput in master mode , or disable d for 3-wire operation. Add itional gen-
eral purpose port I/O pins can be used to select multiple slave devices in master mode.
Figure 20.1. SPI Block Diagram
SFR Bus
Data Path
Control
SFR Bus
Write
SPI0DAT
Receive Data Buffer
SPI0DAT
01234567
Shift Register
SPI CONTROL LOGIC
SPI0CKR
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
SPI0CFG SPI0CN
Pin Interface
Control
Pin
Control
Logic
C
R
O
S
S
B
A
R
Port I/O
Read
SPI0DAT
SPI IRQ
Tx Data
Rx Data
SCK
MOSI
MISO
NSS
Transmit Data Buffer
Clock Divide
Logic
SYSCLK
CKPHA
CKPOL
SLVSEL
NSSMD1
NSSMD0
SPIBSY
MSTEN
NSSIN
SRMT
RXBMT
SPIF
WCOL
MODF
RXOVRN
TXBMT
SPIEN
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
223 Rev. 1.3
20.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
20.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master dev ice and an inpu t to slav e dev ices. It
is used to serially trans fer data from the ma ster to th e slave. This signal is an output when SPI0 is operat-
ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
20.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat-
ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impeda nce sta te when the SPI module is di sabled and when th e SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
20.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen-
erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
20.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three po ssible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and
NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode.
Since no select signal is present, SPI0 mu st be the only slave on the bus in 3-wire mode. This
is intended for point-to-point communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and
NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When
operating as a master, a 1-to-0 transition of the NSS signal disables the master function of
SPI0 so that multiple master devices can be use d on the same SPI bus.
3. NSSMD[1:0] = 1x : 4-Wire Master Mo de: SPI0 operates in 4- wire mode, and NSS is enabled as
an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This
configuration should only be used when operating SPI0 as a maste r device.
See Figure 20.2, Figure 20.3, and Figure 20.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects t he pinout of the device. Wh en in 3-wir e maste r or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “15. Port Input/Output” on page 142 for general purpose
port I/O and crossbar informati on.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 224
20.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MST EN, SPI0CFG.6). Writing a byte of dat a to the SPI0 dat a re gister (SPI0DAT) when
in master mode writes to the transmit buf fe r. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfer s the content s of its shift register to the SPI master on the MISO line in a full-dup lex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPI0DAT.
When configured as a master, SPI0 can opera te in one of three d iffer ent modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSS-
MD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is
used to disable th e master SPI0 when anothe r master is accessing the bus. When NSS is pulled low in this
mode, MSTEN (SPI0CFG.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a
Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re-enabled in software under these circumst ances. In multi-master systems, devices will
typically default to being sla ve devices while th ey are not a cting as the system master device. In multi-ma s-
ter mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 20.2 shows a conn ection diagram between two master devices in multiple-master mode.
3-wire single-m aster mod e is active wh en NSSMD1 (S PI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, an d is not mapped to an external por t pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 20.3
shows a connection diagram between a master device in 3-wire master mode and a slave device.
4-wire single-master mo de is active when NSSMD1 (SPI0 CN.3) = 1. In this mode, NSS is config ured as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using gene ral-p urpose I/O pins. Figure 20.4 shows a connection diagra m for a master device i n
4-wire master mode and two slave devices.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
225 Rev. 1.3
Figure 20.2. Multiple-Master Mode Connection Diagram
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram
Figure 20.4. 4-Wire Single Master Mode and Slave Mode Connection Diagram
Master
Device 2
Master
Device 1
MOSI
MISO
SCK
MISO
MOSI
SCK
NSS
GPIO NSS
GPIO
Slave
Device
Master
Device
MOSI
MISO
SCK
MISO
MOSI
SCK
Slave
Device
Master
Device
MOSI
MISO
SCK
MISO
MOSI
SCK
NSS NSS
GPIO
Slave
Device
MOSI
MISO
SCK
NSS
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 226
20.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK sig-
nal. A bit coun ter in the SPI0 lo gic counts SCK edges. When 8 bi ts have been shifted thro ugh the shift reg-
ister, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the
receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the
master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are dou-
ble-buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the
transmit buffer will immediately be transferred into the shift register. When the shift register already con-
tains data, the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of
the next (or curr ent) SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS sig-
nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 20.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is no t mapped to an externa l port pin through the crossbar. Since ther e is no way of
uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and
re-enabling SPI0 with the SPIEN bit. Figure 20.3 shows a connection diagram between a slave device in
3-wire slave mod e an d a ma ster device.
20.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master,
and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the
MSTEN and SPIEN bits in SPI0CN are set to logi c 0 to di sable SPI0 a nd a llow a nothe r master
device to access the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed and the receive buffer still holds an unread byte from a previous
transfer. The new byte is not tran sf er re d to th e r ece ive bu ffer, allo win g the p re vio usly received
data byte to be read. The data byte which caused the overrun is lost.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
227 Rev. 1.3
20.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships for master mode are shown in Figure 20.5. For slave mode, the clock and
data relationships are shown in Figure 20.6 and Figure 20.7.
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 20.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum data tran sfer rate (bit s/sec) is o ne-half the syste m clock frequency or 12 .5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in
4-wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and doe s not need to receive data from the slave (i.e. half-du plex oper ation) , the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the seri al inpu t data synchronously with the slave’s
system clock.
Figure 20.5. Master Mode Data/Clock Ti ming
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO/MOSI
NSS (Must Remain High
in Multi-Master Mode)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 228
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0)
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO
NSS (4-Wire Mode)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MOSI
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=0, CK PHA=1)
SCK
(CKPOL=1, CK PHA=1)
M SB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO
N SS (4 -Wire M o de )
MSB Bit 6 Bit 5 B it 4 B it 3 B it 2 B it 1 B it 0MOSI
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
229 Rev. 1.3
20.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
SFR Definition 20.1. SPI0CFG: SPI0 Configuration
Bit 7: SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode).
Bit 6: MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
Bit 5: CKPHA: SPI0 Clock Phase.
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second ed ge of SCK period.*
Bit 4: CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
Bit 3: SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
insta ntaneous value at th e NSS pin, but rather a de-glitched version of the pin input.
Bit 2: NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneous value that is present on the NSS port pin at th e time that
the register is read. Th is input is not de-glitched.
Bit 1: SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift register,
and there is no new information available to read from the transmit buffer or write to the
receive buffer. It returns to logic 0 when a data byte is transferred to the shift regist er from
the transmit buffer or by a transition on SCK.
NOTE: SRMT = 1 when in Master Mode.
Bit 0: RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has be en read and contains no new
information. If there is new information availa ble in the receive buf fer that ha s not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
*Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is
sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device.
See Table 20.1 for timing parameters.
R R/W R/W R/W R R R R Reset Value
SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT 00000111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA1
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 230
SFR Definition 20.2. SPI0CN: SPI0 Control
Bit 7: SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by so ftware.
Bit 6: WCOL: Write Collision Flag.
This bit is set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not
been emptied to the SPI shif t register. When this occurs, the write to SPI0DAT will be
ignored, and the transmit buffer will not be written. This flag can occur in all SPI0 modes. It
must be cleared by software.
Bit 5: MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and genera tes a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not auto-
matically cleared by hardware. It must be cleared by software.
Bit 4: RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buf-
fer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “20.2. SPI0 Master Mode Operation” on p age 224 and Section “20.3. SPI0
Slave Mode Operation” on page 226).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will
assume the value of NSSMD0.
Bit 1: TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the transmit buffer is transferred to the SPI shif t register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buffer.
Bit 0: SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
R/WR/WR/WR/WR/WR/W R R/WReset Value
SPIF WCOL MODF RXOVRN NSSMD1 NSSMD0 TXBMT SPIEN 00000110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xF8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
231 Rev. 1.3
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate
SFR Definition 20.4. SPI0DAT: SPI0 Data
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is give n in th e follo win g equat i on , whe re SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA2
fSCK 2000000
241+()×
--------------------------
=
fSCK 200kHz=
fSCK SYSCLK
2SPI0CKR 1+()×
-------------------------------------------------
=
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A re ad
of SPI0DAT returns the contents of the receive buffer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xA3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 232
Figure 20.8. SPI Master Timing (CKPHA = 0)
Figure 20.9. SPI Master Timing (CKPHA = 1)
SCK*
T
MCKH
T
MCKL
MOSI
T
MIS
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
MIH
SCK*
T
MCKH
T
MCKL
MISO
T
MIH
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
MIS
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
233 Rev. 1.3
Figure 20.10. SPI Slave Timing (CKPHA = 0)
Figure 20.11. SPI Slave Timing (CKPHA = 1)
SCK*
T
SE
NSS
T
CKH
T
CKL
MOSI
T
SIS
T
SIH
MISO
T
SD
T
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
SEZ
T
SDZ
SCK*
T
SE
NSS
T
CKH
T
CKL
MOSI
T
SIS
T
SIH
MISO
T
SD
T
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
SLH
T
SEZ
T
SDZ
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 234
Table 20.1. SPI Slave Timing Parameters
Parameter Description Min Max Units
Master Mode Timing* (See Figure 20.8 and Figure 20.9)
TMCKH SCK High Time 1 x TSYSCLK ns
TMCKL SCK Low Time 1 x TSYSCLK ns
TMIS MISO Va lid to SCK Shift Edge 1 x TSYSCLK + 20 ns
TMIH SCK Shift Edge to MISO Change 0ns
Slave Mode Timing* (See Figure 20.10 and Figure 20.11)
TSE NSS Falling to First SCK Edge 2 x TSYSCLK ns
TSD Last SCK Edge to NSS Rising 2 x TSYSCLK ns
TSEZ NSS Falling to MISO Valid 4 x TSYSCLK ns
TSDZ NSS Rising to MISO High-Z 4 x TSYSCLK ns
TCKH SCK High Time 5 x TSYSCLK ns
TCKL SCK Low Time 5 x TSYSCLK ns
TSIS MOSI Va lid to SCK Sample Edge 2 x TSYSCLK ns
TSIH SCK Sample Edge to MOSI Change 2 x TSYSCLK ns
TSOH SCK Shift Edge to MISO Change 4 x TSYSCLK ns
TSLH Last SCK Edge to MISO Change (CKPHA = 1
ONLY) 6 x TSYSCLK 8 x TSYSCLK ns
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 235
21. Timers
Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the
standard 8051, and two are 16-bit auto-reload timer for use with the ADC, SMBus, USB (frame measure-
ments), Low-Frequency Oscillator (period measurements), or for general purpose use. These timers can
be used to measure time in tervals, count external events and generate periodic inter rupt re qu ests. Timer 0
and Timer 1 are nearly identical and have four primary modes of operation. Timer 2 and Timer 3 offer
16-bit and split 8-bit timer functionality with auto-reload.
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits
(T1M-T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock from
which Timer 0 and/or Timer 1 may be clocked (See SFR Definition 21.3 for pre-scaled clock selection).
Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2 and
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
clock source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incr emented on each hi gh-to-low transition at the sele cted input pin (T0 o r T1). Event s with a fre-
quency of up to one-fourth the system clock's freq uency can be counte d. The input signal need n ot be peri-
odic, but it should be held at a given level for at least two full system clock cycles to ensure the level is
properly sampled.
21.1. Timer 0 and Timer 1
Each timer is implemented as a 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1)
and a high b yte (TH0 or TH1) . The Counter /Timer Control register (TCON) is used to enable Timer 0 and
T imer 1 as well a s indicate status. Timer 0 interrupts can be ena bled by setting the ET0 bit in the IE register
(Section “9.3.5. Interrupt Register Descriptions” on page 90); Timer 1 interrupts can be enabled by
setting the ET1 bit in the IE register (Section 9.3.5). Both counter/timers operate in one of four primary
modes selected by setting the Mode Select bits T1M1-T0M0 in the Counter/Timer Mode register (TMOD).
Each timer can be configured indep endently. Each operating mode is described below.
21.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration
and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same
manner as descr ibed for Timer 0.
The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions
TL0.4-TL0.0. The three upper bits of TL0 (TL0.7-TL0.5) are indeterminate and should be masked out or
ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to
0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are
enabled.
Timer 0 and Timer 1 Modes: Timer 2 Modes: Timer 3 Modes:
13-bit counter/timer 16-bit timer with auto-reload 16-bit timer with auto-reload
16-bit counter/timer
8-bit counter/timer with auto-reload Two 8-bit timers with
auto-reload Two 8-bit timers with
auto-reload
Two 8-bit counter/timers (Timer 0 only)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
236 Rev. 1.3
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low
transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“15.1. Priority Crossbar Decoder” on page 144 for information on selecting and configuring external I/O
pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is
clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock
Scale bits in CKCON (see SFR Definition 21.3).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
INT0 is active as defined by bit IN0PL in register INT01CF (see SFR Definition 9.13). Setting GATE0 to ‘1’
allows the timer to be controlled by the external input signal INT0 (see Section “9.3.5. Interrupt Regist er
Descriptions” on page 90), facilitating pulse width measurements.
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
TL1 and TH1 form the 13-bit re gister for Timer 1 in the same manner as d escribe d above for TL0 a nd TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The
input signal INT1 is used with Timer 1; the INT1 polarity is defined by bit IN1PL in regis ter INT01CF (see
SFR Definition 9.13).
Figure 21.1. T0 Mode 0 Block Diagram
21.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The coun-
ter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
TR0 GATE0 INT0 Counter/Timer
0 X X Disabled
1 0 X Enabled
1 1 0 Disabled
1 1 1 Enabled
X = Don't Care
TCLK TL0
(5 bits ) TH0
(8 b its )
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
TR0
0
1
0
1
SYSCLK
Pre-scaled Clock
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
TMOD
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
GATE0
INT0
T0
Crossbar
INT01CF
I
N
1
S
L
1
I
N
1
S
L
0
I
N
1
S
L
2
I
N
1
P
L
I
N
0
P
L
I
N
0
S
L
2
I
N
0
S
L
1
I
N
0
S
L
0
IN0PL XOR
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 237
21.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configur es Timer 0 and Timer 1 to ope rate as 8- bit counter/time rs with automatic reload of the start
value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from all
ones to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If
Timer 0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is
not changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be
correct. When in Mode 2, Timer 1 operates identically to Timer 0.
Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the
TR0 bit (TCON.4) enables th e timer when either GATE0 (TMOD.3) is logic 0 or when the input signal INT0
is active as defined by bit IN0PL in register INT01CF (see Section “9.3.2. External Interrupts” on
page 88 for details on the external input signals INT0 and INT1).
Figure 21.2. T0 Mode 2 Block Diagram
TCLK
TMOD
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
TL0
(8 bits)
Reload
TH0
(8 bits)
0
1
0
1
SYSCLK
Pre-scaled Clock
INT01CF
I
N
1
S
L
1
I
N
1
S
L
0
I
N
1
S
L
2
I
N
1
P
L
I
N
0
P
L
I
N
0
S
L
2
I
N
0
S
L
1
I
N
0
S
L
0
TR0
GATE0
IN0PL XOR
INT0
T0
Crossbar
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
238 Rev. 1.3
21.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/
timer in TL0 is controlled using the T imer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and
TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is
restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the
Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the
Timer 1 interrupt.
Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0,
1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However,
the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC
conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode set-
tings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1,
configure it for Mode 3.
Figure 21.3. T0 Mode 3 Block Diagram
TL0
(8 b its)
TMOD
0
1
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
Interrupt
0
1
SYSCLK
Pre-scaled Clock TR1 TH0
(8 b its)
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
TR0
GATE0
IN0PL XOR
INT0
T0
Crossbar
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 239
SFR Definition 21.1. TCON: Timer Control
Bit7: TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 1 interrupt service routine.
0: No Timer 1 overflow det ec te d.
1: Timer 1 has overflowed.
Bit6: TR1: Timer 1 Run Control.
0: Timer 1 disabled.
1: Timer 1 enabled.
Bit5: TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 0 interrupt service routine.
0: No Timer 0 overflow det ec te d.
1: Timer 0 has overflowed.
Bit4: TR0: Timer 0 Run Control.
0: Timer 0 disabled.
1: Timer 0 enabled.
Bit3: IE1: External Interrupt 1.
This flag is set by hardware when an edge/leve l of type defined by IT1 is dete cted. It can be
cleared by soft ware but is automatically clea red when the CPU vectors to the External Inter-
rupt 1 service routine if IT1 = 1. When IT1 = 0, this flag is set to ‘1’ when INT1 is active as
defined by bit IN1PL in register INT01CF (see SFR Definition 9.13).
Bit2: IT1: Interrupt 1 Type Select.
This bit select s whether the co nfigured INT1 interrupt will be edge or level sensitive. INT1 is
configured active low or high by the IN1PL bit in th e IT01CF register (see SFR Definition
9.13).
0: INT1 is level triggered.
1: INT1 is edge triggered.
Bit1: IE0: External Interrupt 0.
This flag is set by hardware when an edge/leve l of type defined by IT0 is dete cted. It can be
cleared by soft ware but is automatically clea red when the CPU vectors to the External Inter-
rupt 0 service routine if IT0 = 1. When IT0 = 0, this flag is set to ‘1’ when INT0 is active as
defined by bit IN0PL in register INT01CF (see SFR Definition 9.13).
Bit0: IT0: Interrupt 0 Type Select.
This bit select s whether the co nfigured INT0 interrupt will be edge or level sensitive. INT0 is
configured active low or high by the IN0PL bit in re gister IT01CF (see SFR Defini tion 9.13).
0: INT0 is level triggered.
1: INT0 is edge triggered.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0x88
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
240 Rev. 1.3
SFR Definition 21.2. TMOD: Timer Mode
Bit7: GATE1: Ti mer 1 Gate Control.
0: Timer 1 enabled when TR1 = 1 irres pe ctiv e of INT 1 logic level.
1: T imer 1 enabled on ly when TR1 = 1 AND INT1 is active as defined by bit IN1PL in register
INT01CF (see SFR Def i nit ion 9.1 3) .
Bit6: C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.3).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
(T1).
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
Bit3: GATE0: Ti mer 0 Gate Control.
0: Timer 0 enabled when TR0 = 1 irres pe ctiv e of INT 0 logic level.
1: T imer 0 enabled on ly when TR0 = 1 AND INT0 is active as defined by bit IN0PL in register
INT01CF (see SFR Def i nit ion 9.1 3) .
Bit2: C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.2).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
(T0).
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
GATE1 C/T1 T1M1 T1M0 GATE0 C/T0 T0M1 T0M0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x89
T1M1 T1M0 Mode
0 0 Mode 0: 13-bit counter/timer
0 1 Mode 1: 16-bit counter/timer
10 Mode 2: 8-bit counter/timer with
auto-reload
1 1 Mode 3: Timer 1 inactive
T0M1 T0M0 Mode
0 0 Mode 0: 13-bit counter/timer
0 1 Mode 1: 16-bit counter/timer
10 Mode 2: 8-bit counter/timer with
auto-reload
1 1 Mode 3: Two 8-bit counter/timers
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 241
SFR Definition 21.3. CKCON: Clock Control
Bit7: T3MH: Timer 3 High Byte Clock Select.
This bit selects the clock supplied to the Timer 3 high byte if Timer 3 is configured in split
8-bit timer mode. T3MH is ignored if Timer 3 is in any other mode.
0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: T imer 3 high byte uses the system clock.
Bit6: T3ML: Timer 3 Low Byte Clock Select.
This bit selects the clock supplied to Timer 3. If Timer 3 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 low byte uses the system clock.
Bit5: T2MH: Timer 2 High Byte Clock Select.
This bit selects the clock supplied to the Timer 2 high byte if Timer 2 is configured in split
8-bit timer mode. T2MH is ignored if Timer 2 is in any other mode.
0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: T imer 2 high byte uses the system clock.
Bit4: T2ML: Timer 2 Low Byte Clock Select.
This bit selects the clock supplied to Timer 2. If Timer 2 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 2 low byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 low byte uses the system clock.
Bit3: T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to log ic 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Timer 1 uses the system clock.
Bit2: T0M: Timer 0 Clock Select.
This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to
logic 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Counter/Timer 0 uses the system clock.
Bits1–0: SCA1-SCA0: Timer 0/1 Prescale Bits.
These bits control the division of the clock supplied to Timer 0 and/or Timer 1 if configured
to use prescaled clock inputs.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
T3MH T3ML T2MH T2ML T1M T0M SCA1 SCA0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x8E
SCA1 SCA0 Prescaled Clock
0 0 System clock divided by 12
0 1 System clock divided by 4
1 0 System clock divided by 48
1 1 External clock divided by 8
Note: External clock divided by 8 is synchronized with the
system clock.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
242 Rev. 1.3
SFR Definition 21.4. TL0: Timer 0 Low Byte
SFR Definition 21.5. TL1: Timer 1 Low Byte
SFR Definition 21.6. TH0: Timer 0 High Byte
SFR Definition 21.7. TH1: Timer 1 High Byte
Bits 7–0 : TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x8A
Bits 7–0 : TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x8B
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16- bit Timer 0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x8C
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16- bit Timer 1.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x8D
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 243
21.2. Timer 2
T imer 2 is a 16-bit time r formed by two 8-bi t SFRs: TMR2L (low byte) and TMR2H (high by te). Timer 2 may
operate in 16-bit auto-reload mode, (split) 8-bit auto-reload mode, USB Start-of-Frame (SOF) capture
mode, or Low-Frequency Oscillator (LFO) Falling Edge capture mode. The Timer 2 operation mode is
defined by the T2SPLIT (TMR2CN.3), T2CE (TMR2CN.4) bits, and T2CSS (TMR2CN.1) bits.
Timer 2 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 2 (and/or the PCA) is clocked by an external preci-
sion oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
21.2.1. 16-bit Timer with Auto-Reload
When T2SPLIT = ‘0’ and T2CE = ‘0’, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 2
reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 21.4,
and the Timer 2 High Byte Overflow Flag (T MR2CN.7) is set. If Timer 2 interrupt s are en abled, an inter rupt
will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled and the TF2LEN
bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L) overflow from
0xFF to 0x00 .
Figure 21.4. Timer 2 16-Bit Mode Block Diagram
External Clock / 8
SYSCLK / 12
SYSCLK
TMR2L TMR2H
TMR2RLL TMR2RLH Reload
TCLK
0
1
TR2
TMR2CN
T2SPLIT
T2CSS
T2CE
TF2L
TF2H
T2XCLK
TR2
0
1
T2XCLK
Interrupt
TF2LEN
To ADC,
SMBus
To SMBus
TL2
Overflow
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
244 Rev. 1.3
21.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT = ‘ 1’ and T2CE = ‘0’, Timer 2 operates as two 8-bit timers ( TMR2H and TMR2L) . Both 8-bit
timers operate in auto-reload mode as shown in Figure 21.5. TMR2RLL holds the reload value for TMR2 L;
TMR2RLH holds the re load value for TMR2H. The TR2 bit in TMR2 CN handles the r un control for TMR2H.
TMR2L is always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or
the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows:
The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows
from 0xFF to 0x00. When Timer 2 interrupts ar e enabled, an interrupt is generate d each time TMR2H over-
flows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is generated each
time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the TF2H and
TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags are not
cleared by hardware and must be manua lly cleared by softwar e.
Figure 21.5. Timer 2 8-Bit Mode Block Diagram
T2MH T2XCLK TMR2H Clock Source T2ML T2XCLK TMR2L Clock Source
0 0 SYSCLK / 12 0 0 SYSCLK / 12
0 1 External Clock / 8 0 1 E xternal Clock / 8
1 X SYSCLK 1 X SYSCLK
SYSCLK
TCLK
0
1TR2
External Clock / 8
SYSCLK / 12 0
1
T2XCLK
1
0
TMR2H
TMR2RLH Reload
Reload
TCLK TMR2L
TMR2RLL
Interrupt
TMR2CN
T2SPLIT
T2CSS
T2CE
TF2LEN
TF2L
TF2H
T2XCLK
TR2
To ADC,
SMBus
To SMBus
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 245
21.2.3. Timer 2 Capture Modes: USB Start-of-Frame or LFO Falling Edge
When T2CE = ‘1’, Timer 2 will operate in one of two special capture modes. The capture event can be
selected between a USB Start-of-Frame (SOF) capture, and a Low-Frequency Oscillator (LFO) Falling
Edge capture, using the T2CSS bit. The USB SOF capture mode can be used to calibrate the system clock
or external oscillator against the known USB host SOF clock. The LFO falling-edge capture mode can be
used to calibrate the internal Low-Frequency Oscillator against the internal High-Frequency Oscillator or
an external clock source. When T2SPLIT = ‘0’, Timer 2 counts up and overflows from 0xFFFF to 0x0000.
Each time a capture event is received, the contents of the Timer 2 registers (TMR2H:TMR2L) are latched
into the Timer 2 Reload re gisters (TMR2RLH:TMR2RLL). A Timer 2 interrupt is generated if enabled.
Figure 21.6. Timer 2 Capture Mode (T2SPLIT = ‘0’)
External Clock / 8
SYSCLK / 12
SYSCLK
TMR2L TMR2H
TMR2RLL TMR2RLH
TCLK
0
1
TR2
0
1
Interrupt
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
Capture
USB Start-of -F rame (SOF)
Enable
TMR2CN
T
F
2
H
T
F
2
L
T
2
X
C
L
K
T
2
C
S
S
T
R
2
T
F
2
L
E
N
T
2
C
E
T
2
S
P
L
I
T
0
1
T2CSS
Low-Frequenc y Oscillato r
Falling Edge
To ADC,
SMBus
To SMBus
TL2
Overflow
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
246 Rev. 1.3
When T2SPLIT = ‘1’, the Timer 2 registers (TMR2H and TMR2L) act as two 8-bit counters. Each counter
counts up independe ntly and overflows from 0xFF to 0x00. Each time a capture event is r eceived, the con -
tents of the Timer 2 registers are latched into the Timer 2 Reload registers (T MR2RLH and TMR2 RLL). A
Timer 2 interrupt is generated if enabled.
Figure 21.7. Timer 2 Capture Mode (T2SPLIT = ‘1’)
SYSCLK
TCLK
0
1TR2
External Clock / 8
SYSCLK / 12 0
1
1
0
TMR2H
TMR2RLH
TCLK TMR2L
TMR2RLL
To ADC,
SMBus
To SMBus
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
TMR2CN
T
F
2
H
T
F
2
L
T
2
X
C
L
K
T
2
C
S
S
T
R
2
T
F
2
L
E
N
T
2
C
E
T
2
S
P
L
I
T
Capture
Enable
Capture Interrupt
USB Start-of-Frame ( SOF)
Low-Frequency Oscillator
Falling Edge
0
1
T2CSS
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 247
SFR Definition 21.8. TMR2CN: Timer 2 Control
Bit7: TF2H: Timer 2 High Byte Overflow Flag.
Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when T imer 2 overflows from 0xFFFF to 0x0000. When the T imer 2 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 2 interrupt service routine.
TF2H is not automatically cleared by hardware and must be cleared by software.
Bit6: TF2L: Timer 2 Lo w Byte Overflow Flag.
Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF2LEN is set and Timer 2 interrupts are enabled. TF2L
will set when the low byte overflows regardless of the Timer 2 mode. This bit is not automat-
ically cleared by hardware.
Bit5: TF2LEN: Timer 2 Low Byte Interrupt Enable.
This bit enables/dis abl es Timer 2 Low Byte interrupts. If TF2LEN is set and Timer 2 inter-
rupts are enabled, an interrupt will be generated when the low byte of Timer 2 overflows.
0: Timer 2 Low Byte interrup ts disabl ed .
1: Timer 2 Low Byte interrup ts enable d.
Bit4: T2CE: Timer 2 Capture Enable
0: Capture function disabled.
1: Capture function enabled. The timer is in capture mode, with the capture event selected
by bit T2CSS. Each time a capture event is received, the contents of the Timer 2 re gisters
(TMR2H and TMR2L) are latched into the Timer 2 reload registers (TMR2RLH and
TMR2RLH), and a Timer 2 interrupt is generated (if enabled).
Bit3: T2SPLIT: Timer 2 Split Mode Enable.
When this bit is set, Timer 2 operates as two 8-bit timers with auto-reload.
0: Timer 2 oper ates in 16-bit auto-reload mode.
1: Timer 2 operates as two 8-bit auto-reload timer s.
Bit2: TR2: Timer 2 Run Control.
This bit enables/disables Timer 2. In 8-bit mode, this bit enables/disables TMR2H only;
TMR2L is always enabled in this mode.
0: Timer 2 disabled .
1: Timer 2 enabled.
Bit1: T2CSS: Timer 2 Capture Source Select.
This bit selects the source of a capture event wh en bit T2CE is set to ‘1’.
0: Capture source is USB SOF event.
1: Capture source is falling edge of Low-Frequency Oscillator.
Bit0: T2XCLK: Timer 2 External Clock Select.
This bit selects the external clock source for Timer 2. If Timer 2 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 2 Clock
Select bits (T2MH and T2ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 2 external clock selection is the system clo ck divided by 12.
1: T imer 2 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF2H TF2L TF2LEN T2CE T2SPLIT TR2 T2CSS T2XCLK 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xC8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
248 Rev. 1.3
SFR Definition 21.9. TMR2RLL: Timer 2 Reload Register Low Byte
SFR Definition 21.10. TMR2RLH: Timer 2 Reload Register High Byte
SFR Definition 21.11. TMR2L: Timer 2 Low Byte
SFR Definition 21.12. TMR2H Timer 2 High Byte
Bits 7–0: TMR2RLL: Timer 2 Reload Register Low Byte.
TMR2RLL holds the low byte of the reload value for Timer 2 when operating in auto-reload
mode, or the captured value of the TMR2L register in capture mode.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xCA
Bits 7–0: TMR2RLH: Timer 2 Reload Register High Byte.
The TMR2RLH holds the high byte of the reload value for Timer 2 when operating in
auto-reload mode, or the captured value of the TMR2H register in capture mode.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xCB
Bits 7–0: TMR2L: Timer 2 Low Byte.
In 16-bit mode, the TMR2L register cont ains the low byte of the 16-bit T imer 2. In 8-bit mode ,
TMR2L cont ains the 8-bit low byte timer va lue.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xCC
Bits 7–0: TMR2H: Timer 2 High Byte.
In 16-bit mode, the TMR2H register contains the hig h byte of the 16-bit Timer 2. In 8-bit
mode, TMR2H contains the 8-bit high byte timer value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xCD
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 249
21.3. Timer 3
T imer 3 is a 16-bit time r formed by two 8-bi t SFRs: TMR3L (low byte) and TMR3H (high by te). Timer 3 may
operate in 16-bit auto-reload mode, (split) 8-bit auto-reload mode, USB Start-of-Frame (SOF) capture
mode, or Low-Frequency Oscillator (LFO) Rising Edge capture mode. The Timer 3 operation mode is
defined by the T3SPLIT (TMR3CN.3), T3CE (TMR3CN.4) bits, and T3CSS (TMR3CN.1) bits.
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external preci-
sion oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
21.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is ‘0’ and T3CE = ‘0’, Timer 3 operates as a 16-bit timer with auto-reload.
Timer 3 can be clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided
by 8. As the 16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the
Timer 3 reload registers (TMR3RLH and TM3RLL) is loaded into the Timer 3 register as shown in
Figure 21.4, and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled,
an interrupt will be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and
the TF3LEN bit is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L) over-
flow from 0xFF to 0x 00 .
Figure 21.8. Timer 3 16-Bit Mode Block Diagram
External Clock / 8
SYSCLK / 12
SYSCLK
TMR3L TMR3H
TMR3RLL TMR3RLH Reload
TCLK
0
1
TR3
TMR3CN
T3SPLIT
T3CSS
T3CE
TF3L
TF3H
T3XCLK
TR3
0
1
T3XCLK
Interrupt
TF3LEN
To ADC
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
250 Rev. 1.3
21.3.2. 8-bit Timers with Auto-Reload
When T3SPLIT is ‘1’ and T3CE = ‘0’, Timer 3 operates as two 8-bi t timers (TMR3H and TMR3L). Both 8-bit
timers operate in auto-reload mode as shown in Figure 21.5. TMR3RLL holds the reload value for TMR3 L;
TMR3RLH holds the re load value for TMR3H. The TR3 bit in TMR3 CN handles the r un control for TMR3H.
TMR3L is always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 3 Clock Select bits (T3MH and T3ML in CKCON) select either SYSCLK or
the clock defined by the Timer 3 External Clock Select bit (T3XCLK in TMR3CN), as follows:
The TF3H bit is set when TMR3H overflows from 0xFF to 0x00; the TF3L bit is set when TMR3L overflows
from 0xFF to 0x00. When Timer 3 interrupts ar e enabled, an interrupt is generate d each time TMR3H over-
flows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each
time either TMR3L or TMR3H overflows. When TF3LEN is enabled, software must check the TF3H and
TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags are not
cleared by hardware and must be manua lly cleared by softwar e.
Figure 21.9. Timer 3 8-Bit Mode Block Diagram
T3MH T3XCLK TMR3H Clock Source T3ML T3XCLK TMR3L Clock Source
0 0 SYSCLK / 12 0 0 SYSCLK / 12
0 1 External Clock / 8 0 1 E xternal Clock / 8
1 X SYSCLK 1 X SYSCLK
SYSCLK
TCLK
0
1TR3
External Cl ock / 8
SYSCLK / 12 0
1
T3XCLK
1
0
TMR3H
TMR3RLH Reload
Reload
TCLK TMR3L
TMR3RLL
Interrupt
TMR3CN
T3SPLIT
T3CSS
T3CE
TF3LEN
TF3L
TF3H
T3XCLK
TR3
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
To ADC
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 251
21.3.3. USB Start-of-Frame Capture
When T3CE = ‘1’, Timer 3 will operate in one of two special capture modes. The capture event can be
selected between a USB Start-of-Frame (SOF) capture, and a Low-Frequency Oscillator (LFO) Rising
Edge capture, using the T3CSS bit. The USB SOF capture mode can be used to calibrate the system clock
or external oscillator against the known USB hos t SOF clock. The LFO rising-edge capture mode can be
used to calibrate the internal Low-Frequency Oscillator against the internal High-Frequency Oscillator or
an external clock source. When T3SPLIT = ‘0’, Timer 3 counts up and overflows from 0xFFFF to 0x0000.
Each time a capture event is received, the contents of the Timer 3 registers (TMR3H:TMR3L) are latched
into the Timer 3 Reload re gisters (TMR3RLH:TMR3RLL). A Timer 3 interrupt is generated if enabled.
Figure 21.10. Timer 3 Capture Mode (T3SPLIT = ‘0’)
External Clock / 8
SYSCLK / 12
SYSCLK
TMR3L TMR3H
TMR3RLL TMR3RLH
TCLK
0
1
TR3
0
1
Interrupt
To ADC
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
Capture
Enable
TMR3CN
T
F
3
H
T
F
3
L
T
3
X
C
L
K
T
3
C
S
S
T
R
3
T
F
3
L
E
N
T
3
C
E
T
3
S
P
L
I
T
USB Start-of-Frame (SOF) 0
1
T3CSS
Low-Frequency Oscillator
Falling Edge
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
252 Rev. 1.3
When T3SPLIT = ‘1’, the Timer 3 registers (TMR3H and TMR3L) act as two 8-bit counters. Each counter
counts up independe ntly and overflows from 0xFF to 0x00. Each time a capture event is r eceived, the con -
tents of the Timer 3 registers are latched into the Timer 3 Reload registers (T MR3RLH and TMR3 RLL). A
Timer 3 interrupt is generated if enabled.
Figure 21.11. Ti mer 3 Capture Mode (T3SPLIT = ‘1’)
SYSCLK
TCLK
0
1TR3
External Clock / 8
SYSCLK / 12 0
1
1
0
TMR3H
TMR3RLH
TCLK TMR3L
TMR3RLL
To ADC
CKCON
T
3
M
H
T
3
M
L
S
C
A
0
S
C
A
1
T
0
M
T
2
M
H
T
2
M
L
T
1
M
TMR3CN
T
F
3
H
T
F
3
L
T
3
X
C
L
K
T
3
C
S
S
T
R
3
T
F
3
L
E
N
T
3
C
E
T
3
S
P
L
I
T
Capture
Enable
Capture Interrupt
USB Start-of-Frame (SOF)
Low-Frequency Oscillator
Falling Edge
0
1
T3CSS
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 253
SFR Definition 21.13. TMR3CN: Timer 3 Control
Bit7: TF3H: Timer 3 High Byte Overflow Flag.
Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when T imer 3 overflows from 0xFFFF to 0x0000. When the T imer 3 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 3 interrupt service routine.
TF3H is not automatically cleared by hardware and must be cleared by software.
Bit6: TF3L: Timer 3 Lo w Byte Overflow Flag.
Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF3LEN is set and Timer 3 interrupts are enabled. TF3L
will set when the low byte overflows regardless of the Timer 3 mode. This bit is not automat-
ically cleared by hardware.
Bit5: TF3LEN: Timer 3 Low Byte Interrupt Enable.
This bit enables/dis abl es Timer 3 Low Byte interrupts. If TF3LEN is set and Timer 3 inter-
rupts are enabled, an interrupt will be generated when the low byte of Timer 3 overflows.
This bit should be cleared when operating Timer 3 in 16-bit mode.
0: Timer 3 Low Byte interrup ts disabl ed .
1: Timer 3 Low Byte interrup ts enable d.
Bit4: T3CE: Timer 3 Capture Enable
0: Capture function disabled.
1: Capture function enabled. The timer is in capture mode, with the capture event selected
by bit T3CSS. Each time a capture event is received, the contents of the Timer 3 re gisters
(TMR3H and TMR3L) are latched into the Timer 3 reload registers (TMR3RLH and
TMR3RLH), and a Timer 3 interrupt is generated (if enabled).
Bit3: T3SPLIT: Timer 3 Split Mode Enable.
When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload.
0: Timer 3 oper ates in 16-bit auto-reload mode.
1: Timer 3 operates as two 8-bit auto-reload timer s.
Bit2: TR3: Timer 3 Run Control.
This bit enables/disables Timer 3. In 8-bit mode, this bit enables/disables TMR3H only;
TMR3L is always enabled in this mode.
0: Timer 3 disabled .
1: Timer 3 enabled.
Bit1: T3CSS: Timer 3 Capture Source Select.
This bit selects the source of a capture event wh en bit T3CE is set to ‘1’.
0: Capture source is USB SOF event.
1: Capture source is rising edge of Low-Frequency Oscillator.
Bit0: T3XCLK: Timer 3 External Clock Select.
This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 3 Clock
Select bits (T3MH and T3ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 3 external clock selection is the system clo ck divided by 12.
1: T imer 3 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF3H TF3L TF3LEN T3CE T3SPLIT TR3 T3CSS T3XCLK 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x91
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
254 Rev. 1.3
SFR Definition 21.14. TMR3RLL: Timer 3 Reload Register Low Byte
SFR Definition 21.15. TMR3RLH: Timer 3 Reload Register High Byte
SFR Definition 21.16. TMR3L: Timer 3 Low Byte
SFR Definition 21.17. TMR3H Timer 3 High Byte
Bits 7–0: TMR3RLL: Timer 3 Reload Register Low Byte.
TMR3RLL holds the low byte of the reload value for Timer 3 when operating in auto-reload
mode, or the captured value of the TMR3L regi ster when operating in capture mode.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x92
Bits 7–0: TMR3RLH: Timer 3 Reload Register High Byte.
The TMR3RLH holds the high byte of the reload value for Timer 3 when operating in
auto-reload mode, or the captured value of the TMR3H register when operating in capture
mode.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x93
Bits 7–0: TMR3L: Timer 3 Low Byte.
In 16-bit mode, the TMR3L register cont ains the low byte of the 16-bit T imer 3. In 8-bit mode ,
TMR3L cont ains the 8-bit low byte timer va lue.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x94
Bits 7–0: TMR3H: Timer 3 High Byte.
In 16-bit mode, the TMR3H register contains the hig h byte of the 16-bit Timer 3. In 8-bit
mode, TMR3H contains the 8-bit high byte timer value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0x95
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 255
22. Programmable Counter Array (PCA0)
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer
and five 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section “15.1. Priority
Crossbar Decoder” on page 144 for details on configuring the Crossbar). The counter/timer is driven by
a programmable time base that can select betwe en six so urces: system clock, system clock divided by four ,
system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or an
external clock signal on the ECI input pin. Each capture/compare module may be configured to operate
independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Fre-
quency Output, 8-Bit PWM, or 16-Bit PWM (each mode is described in Section “22.2. Capture/Compare
Modules” on page 257). The external oscillator clock option is ideal for real-time clock (RTC) functionality,
allowing the PCA to be clocked by a precision external oscillator while the internal oscillator drives the sys-
tem clock. The PCA is configured and controlled through the system controller's Special Function Regis-
ters. The PCA block diagram is shown in Figure 22.1
Import ant Note: The PCA Mod ule 4 may be u sed as a watchdog timer (WDT), and is en abled in this mod e
following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled. See
Section 22.3 for details.
Figure 22.1. PCA Block Diagram
Capture/Compare
Module 1
Capture/Compare
Module 0 Capture/Compare
Module 2 Capture/Compare
Module 3 Capture/Compare
Module 4 / WDT
CEX1
ECI
Crossbar
CEX2
CEX3
CEX4
CEX0
Port I/O
16-Bit Counter/Timer
PCA
CLOCK
MUX
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
256 Rev. 1.3
22.1. PCA Counter/Timer
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte
(MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches
the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register.
Reading the PCA0L Regist er first guaran tees an a ccurate r eading of the entire 16 -bit PCA0 cou nter.
Reading PCA0H or PCA0L does not disturb the counte r operation. The CPS2-CPS0 bits in the PCA0MD
register select the timebase for the counter/timer as shown in Table 22.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by soft-
ware (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 inter-
rupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the
CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle
mode.
Figure 22.2. PCA Counter/Timer Block Diagram
Table 22.1. PCA Timebase Input Options
CPS2 CPS1 CPS0 Timebase
0 0 0 System clock divided by 12
0 0 1 System clock divided by 4
0 1 0 Timer 0 overflow
011
High-to-low transitions on ECI (max rate = system clo ck divided
by 4)
100System clock
1 0 1 External oscillator source divided by 8*
*Note: External oscillator source divided by 8 is synchronized with the system clock.
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
4
C
C
F
3
PCA0MD
C
I
D
L
W
D
T
E
E
C
F
C
P
S
1
C
P
S
0
W
D
L
C
K
C
P
S
2
IDLE
0
1
PCA0H PCA0L
Snapshot
Register
To SFR Bus
Overflow To PCA Interrupt System
CF
PCA0L
read
To PCA Modules
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
000
001
010
011
100
101
SYSCLK
External Clock/8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 257
22.2. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered
Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit
Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the
CIP-51 system controller. These registers are used to exchange data with a module and configure the
module's mode of operation.
Table 22.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA capture/com-
pare module’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's
CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are rec-
ognized. PCA0 interrupts are globally enabled by setting the EA bit and the EPCA0 bit to logic 1. See
Figure 22.3 for details on the PCA interrupt configuration.
Figure 22.3. PCA Interrupt Block Diagram
Table 22.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM CAPP CAPN MAT TOG PWM ECCF Operation Mode
X X 10000X
Capture triggered by positive edge on
CEXn
X X 01000X
Capture triggered by negative edge on
CEXn
X X 1 1 0 0 0 X Capture triggered by transition on CEXn
X 1 0 0 1 0 0 X Software Timer
X 1 0 0 1 1 0 X High Speed Output
X 1 0 0 X 1 1 X Freque ncy Output
0 1 0 0 X 0 1 X 8-Bit Pulse Width Modulator
1 1 0 0 X 0 1 X 16-Bit Pulse Width Modulator
X = Don’t Care
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
4
C
C
F
3
PCA0MD
C
I
D
L
W
D
T
E
E
C
F
C
P
S
1
C
P
S
0
W
D
L
C
K
C
P
S
2
0
1
PCA Module 0
(CCF0)
PCA Module 1
(CCF1)
ECCF1
0
1
ECCF0
0
1
PCA Module 2
(CCF2)
ECCF2
0
1
PCA Module 3
(CCF3)
ECCF3
0
1
PCA Module 4
(CCF4)
ECCF4
PCA Counter/
Timer O ve rflow
0
1
Interrupt
Priority
Decoder
EPCA0
0
1
EA
0
1
PCA0CPMn
(for n = 0 to 4)
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
258 Rev. 1.3
22.2.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA counter/
timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn re giste r are u s ed to sele ct th e type o f tran si-
tion that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge),
or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn)
in PCA0CN is set to logic 1 and an interrupt r equ est is generated if CCF interr upts are enabled . The CCF n
bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and
must be cleared by software. If both CAPPn and CAPNn bits are set to logic 1, then the state of the Port
pin associated with CEXn can be read directly to determine whether a rising-edge or falling-edge caused
the capture.
Figure 22.4. PCA Capture Mode Diagram
Note: The CEXn input signal must rema in high or low fo r at least 2 system clock cycles to be recognized by
the hardware .
PCA0L
PCA0CPLn
PCA
Timebase
CEXn
CrossbarPort I/O
PCA0H
Capture
PCA0CPHn
0
1
0
1
(to CCFn)
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
4
C
C
F
3
PCA Interrupt
0 000xx
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 259
22.2.2. Software Timer (Compare) Mode
In Sof twa re Timer mode, the PCA counter/timer valu e is compared to the module' s 16-bit capture/ comp ar e
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in
PCA0CN is set to logic 1 and an interrupt requ est is generated if CCF interrupt s are enabled. The CCFn bit
is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must
be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 22.5. PCA Software Timer Mode Diagram
Match
16-bit Comparator
PCA0H
PCA0CPHn
Enable
PCA0L
PCA
Timebase
PCA0CPLn
00 00
0
1
x
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
4
C
C
F
3
PCA Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
260 Rev. 1.3
22.2.3. High Speed Output Mode
In High Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs
between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and
PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the
High-Speed Output mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 22.6. PCA High Speed Output Mode Diagram
Match
16-bit Comparator
PCA0H
PCA0CPHn
Enable
PCA0L
PCA
Timebase
PCA0CPLn
0
1
00 0x
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
CEXn
Crossbar Port I/O
Toggle
0
1
TOGn
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
4
C
C
F
3
PCA Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 261
22.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count befor e the out-
put is toggled. The frequency of the squar e wave is then defined by Equation 22.1.
Equation 22.1. Square Wave Frequency Output
Where FPCA is the freque ncy of the clock sele cted by the CPS2-0 bit s in the PCA mode register, PCA0MD.
The lower byte of the capture/compare module is compared to the PCA counter low byte; on a match,
CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn. Fre-
quency Output Mode is enable d by setting the ECOM n, TOGn, and PWMn bits in the PCA0CPM n reg iste r.
Figure 22.7. PCA Frequency Output Mode
FCEXn FPCA
2PCA0CPHn×
-----------------------------------------
=
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equa tion.
8-bit
Comparator
PCA0L
Enable
PCA Timebase
match
PCA0CPHn8-bit AdderPCA0CPLn
Adder
Enable
CEXn
Crossbar Port I/O
Toggle
0
1
TOGn
000 x
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
ENB
ENB
0
1
Writ e to
PCA0CPLn
Write to
PCA0CPHn
Reset
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
262 Rev. 1.3
22.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be u sed inde pende ntly to gen erate a p ulse width mod ulated (PWM ) outp ut on its associ -
ated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register.
When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the value in PCA0CPLn, the
output on the CEXn pin will be set. When the count value in PCA0L overflows, the CEXn output will be
reset (see Figure 22.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00,
PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare high byte
(PCA0CPHn) without sof tware intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register
enables 8-Bit Pulse Wid th Modulator mod e. The duty cycle for 8-Bit PWM Mode is given by Equation 22.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Equation 22.2. 8-Bit PWM Duty Cycle
Using Equation 22.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is
0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
Figure 22.8. PCA 8-Bit PWM Mode Diagram
DutyCycle 256 PCA0CPHn–()
256
---------------------------------------------------
=
8-bit
Comparator
PCA0L
PCA0CPLn
PCA0CPHn
CEXn
Crossbar Port I/O
Enable
Overflow
PCA Timebase
00x0 x
Q
Q
SET
CLR
S
R
match
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 263
22.2.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be o perate d in 16-Bit PWM mod e. In th is m ode , the 16- bit captu re/compare mod-
ule defines the numbe r o f PCA clocks for the low tim e of the PWM signal. When the PCA counter m atches
the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted
low. To output a varying duty cycle, new value writes should be synchronized with PCA CCFn match inter-
rupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn
register. For a varying duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help
synchronize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by
Equation 22.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Equation 22.3. 16-Bit PWM Duty Cycle
Using Equation 22.3, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is
0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
Figure 22.9. PCA 16-Bit PWM Mode
DutyCycle 65536 PCA0CPn–()
65536
-----------------------------------------------------
=
PCA0CPLnPCA0CPHn
Enable
PCA Timebase
00x0 x
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
1
16-bit Comparator
CEXn
Crossbar Port I/O
Overflow
Q
Q
SET
CLR
S
R
match
PCA0H PCA0L
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
264 Rev. 1.3
22.3. Watchdog T i mer Mode
A programmable wa tchdog timer (WDT) function is avail able throu gh the PCA Module 4. The WDT is used
to generate a reset if the time between writes to th e WDT upda te r egi ster ( PCA0 CPH4 ) exceed a spe cifie d
limit. The WDT can be configured and enabled/disabled as needed by software.
With the WDTE and/or WDLCK bits set to ‘1’ in the PCA0MD register, Module 4 operates as a watchdog
timer (WDT). The Module 4 high byte is compared to the PCA counter high byte; the Module 4 low byte
holds the offset to be used when WDT updates are performed. The Watchdog Timer is enabled on
reset. Writes to some PCA registers are restricted while the Watchdog Timer is enabled.
22.3.1. Watchdog Timer Operation
While the WDT is enabled:
• PCA counter is forced on.
• Writes to PCA0L and PCA0H are not allowed.
• PCA clock source bits (CPS2-CPS0) ar e fr oze n.
• PCA Idle control bit (CIDL) is frozen.
• Module 4 is forced into Watchdog Timer mode.
• Write s to the Module 4 mode registe r (PCA0CPM4) are disabled.
While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run
until the WDT is disabled. The PCA counter run control (CR) will read zero if the WDT is enabled but user
software has not enabled the PCA counter. If a match occurs between PCA0CPH4 and PCA0H while the
WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a write
of any value to PCA0CPH4. Upon a PCA0CPH4 write, PCA0H plus the offset held in PCA0CPL4 is loade d
into PCA0CPH4 (See Figure 22.10).
Figure 22.10. PCA Module 4 with Watchdog Timer Enabled
Note that the 8-bit offset held in PCA0CPH4 is compared to the upper byte of the 16-bit PCA counter. This
offset value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the
first PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The
total offset is then given (in PCA clocks) by Equation 22.4, where PCA0L is the value of the PCA0L register
at the time of the update.
PCA0H
Enable
PCA0L Overflow
Reset
PCA0CPL4 8-bit Adder
PCA0CPH4
Adder
Enable
PCA0MD
C
I
D
L
W
D
T
E
E
C
F
C
P
S
1
C
P
S
0
W
D
L
C
K
C
P
S
2
Match
Write to
PCA0CPH4
8-bit
Comparator
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 265
Equation 22.4. Watchdog Timer Offset in PCA Clocks
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH4 and
PCA0H. Software may force a WDT reset by writing a ‘1’ to the CCF4 flag (PCA0CN.4) while the WDT is
enabled.
22.3.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks:
1. Disable the WDT by writing a ‘0’ to the WDTE bit.
2. Select the desired PCA clock source (with the CPS2-CPS0 bits).
3. Load PCA0CPL4 with the desired WDT update offset value.
4. Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in
Idle mode).
5. Enable the WDT by setting the WDTE bit to ‘1’.
6. (optional) Lock the WDT (prevent WDT disable until the next system reset) by setting the
WDLCK bit to ‘1’.
7. Write a value to PCA0CPH4 to reload the WDT.
The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog
timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the
WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing
the WDTE bit.
The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by
12, PCA0L defaults to 0x00, and PCA0CPL4 defaults to 0x00. Using Equation 22.4, this results in a WDT
timeout interval of 256 PCA clocks. Table 22.3 lists some example timeout intervals for typical system
clocks.
Table 22.3. Watchdog Timer Timeout Intervals1
System Clock (Hz) PCA0CPL4 Timeout Interval (ms)
12,000,000 255 65.5
12,000,000 128 33.0
12,000,000 32 8.4
24,000,000 255 32.8
24,000,000 128 16.5
24,000,000 32 4.2
1,500,0002255 524.3
1,500,0002128 264.2
1,500,000232 67.6
32,768 255 24,000
32,768 128 12,093.75
32,768 32 3,093.75
Notes:
1. Assumes SYSCLK / 12 as the PCA clock source, and a PCA0L
value of 0x00 at the update time.
2. System Clock reset frequency.
Offset 256 PCA0CPL4×()256 PCA0L–()+=
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
266 Rev. 1.3
22.4. Register Descriptions for PCA
Following are detailed descriptions of the special function registers related to the operation of the PCA.
SFR Definition 22.1. PCA0CN: PCA Control
Bit7: CF: PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA Counter/T ime r overflows from 0xFFFF to 0x0000 . When the
Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vector
to the PCA interrupt service routine. This bit is not automatically cleared by hardware and
must be cleared by software.
Bit6: CR: PCA Counter/Timer Run Control.
This bit enables/disables the PCA Counter/Timer.
0: PCA Counter/Timer disabled.
1: PCA Counter/Timer enabled.
Bit5: UNUSED. Read = 0b, Write = don't care.
Bit4: CCF4: PCA Module 4 Capture/Compar e Flag.
This bit is set by hardware when a match or capture occurs. When the CCF4 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit3: CCF3: PCA Module 3 Capture/Compar e Flag.
This bit is set by hardware when a match or capture occurs. When the CCF3 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit2: CCF2: PCA Module 2 Capture/Compar e Flag.
This bit is set by hardware when a match or capture occurs. When the CCF2 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit1: CCF1: PCA Module 1 Capture/Compar e Flag.
This bit is set by hardware when a match or capture occurs. When the CCF1 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit0: CCF0: PCA Module 0 Capture/Compar e Flag.
This bit is set by hardware when a match or capture occurs. When the CCF0 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CF CR - CCF4 CCF3 CCF2 CCF1 CCF0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
(bit addressable) 0xD8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 267
SFR Definition 22.2. PCA0MD: PCA Mode
Bit7: CIDL: PCA Counter/Timer Idle Control.
Specifies PCA behavior when CPU is in Idle Mode.
0: PCA continues to function normally while the system controller is in Idle Mode.
1: PCA operation is suspended while the system controller is in Idle Mode.
Bit6: WDTE: Watchdog Timer Enable
If this bit is set, PCA Module 4 is used as the watchdog timer.
0: Watchdog Timer disabled.
1: PCA Module 4 enabled as Watchdog Timer.
Bit5: WDLCK: Watchdog Timer Lock
This bit enables and locks the Watchdog Timer. When WDLCK is set to ‘1’, the Watchdog
Timer may not be disabled until the next system reset.
0: Watchdog Timer unlocked.
1: Watchdog Timer enabled and locked.
Bit4: UNUSED. Read = 0b, Write = don't care.
Bits3–1: CPS2–CPS0: PCA Counter/Timer Pulse Select.
These bits select the timebase source for the PCA counter.
Bit0: ECF: PCA Counter/Timer Overflow Interrupt Enable.
This bit sets the masking of the PCA Counter/Timer Overflo w (CF) interrupt.
0: Disable the CF interru p t.
1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
Note: When the WDTE bit is set to ‘1’, the PCA0MD register cannot be modified. To change the
contents of the PCA0MD re gister, the W atchdog Timer must first be disabled.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
CIDL WDTE WDLCK - CPS2 CPS1 CPS0 ECF 01000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xD9
CPS2 CPS1 CPS0 Timebase
0 0 0 System clock divided by 12
0 0 1 System clock divided by 4
0 1 0 Timer 0 overflow
011
High-to-low transitions on ECI (max rate = system clock
divided by 4)
1 0 0 System clock
1 0 1 External clock divided by 8*
1 1 0 Reserved
1 1 1 Reserved
*Note: External oscillator source divided by 8 is synchronized with the system clock.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
268 Rev. 1.3
SFR Definition 22.3. PCA0CPMn: PCA Capture/Compare Mode
PCA0CPMn Address: PCA0CPM0 = 0xDA (n = 0), PCA0CPM1 = 0xDB (n = 1),
PCA0CPM2 = 0xDC (n = 2), PCA0CPM3 = 0xDD (n = 3),
PCA0CPM4 = 0xDE (n = 4)
Bit7: PWM16n: 16-bit Pulse Width Modulation Ena ble.
This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
Bit6: ECOMn: Comparator Function Enable.
This bit enables/di sables the comparator function for PCA module n.
0: Disabled.
1: Enabled.
Bit5: CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA mo dule n.
0: Disabled.
1: Enabled.
Bit4: CAPNn: Captur e Ne ga tive Function Enable.
This bit enables/disables the negative edge capture for PCA module n.
0: Disabled.
1: Enabled.
Bit3: MATn: Match Function Enable.
This bit enables/disables the match function for PCA module n. When enabled, matches of
the PCA counter with a module's capture/compare register cause the CCFn bit in PCA0MD
register to be set to logic 1.
0: Disabled.
1: Enabled.
Bit2: TOGn: Toggle Function Enable.
This bit enables/disables the toggle function for PCA module n. When enabled, matches of
the PCA counter with a module's capture/compare register cause the logic level on the
CEXn pin to togg le. If the PWMn b it is a lso set to logic 1, the modu le op erat es in Fr eq uency
Output Mode.
0: Disabled.
1: Enabled.
Bit1: PWMn: Pulse Width Modulation Mode Enable.
This bit enables/disables the PWM function for PCA module n. When enabled, a pulse width
modulated signal is outpu t on the CEXn pin. 8-bit PWM is used if PWM16n is cleared; 16-bit
mode is used if PWM16n is set to log ic 1. If the T OGn b it is also set, the modu le operate s in
Frequency Output Mode.
0: Disabled.
1: Enabled.
Bit0: ECCFn: Capture/Compare Flag Interrupt Enable.
This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt.
0: Disable CCFn interrupts.
1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PWM16n ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xDA, 0xDB,
0xDC, 0xDD,
0xDE
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 269
SFR Definition 22.4. PCA0L: PCA Counter/Timer Low Byte
SFR Definition 22.5. PCA0H: PCA Counter/Timer High Byte
SFR Definition 22.6. PCA0CPLn: PCA Capture Module Low Byte
Bits 7–0: PCA0L: PCA Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xF9
Bits 7–0: PCA0H: PCA Counter/Timer High Byte.
The PCA0H register holds the high byte (MSB) of the 16- bit PCA Counter/Timer.
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xFA
PCA0CPLn Address: PCA0CPL0 = 0xFB (n = 0), PCA0CPL1 = 0xE9 (n = 1),
PCA0CPL2 = 0xEB (n = 2), PCA0CPL3 = 0xED (n = 3),
PCA0CPL4 = 0xFD (n = 4)
Bits7–0: PCA0CPLn: PCA Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xFB, 0xE9,
0xEB, 0xED,
0xFD
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
270 Rev. 1.3
SFR Definition 22.7. PCA0CPHn: PCA Capture Module High Byte
PCA0CPHn Address: PCA0CPH0 = 0xFC (n = 0), PCA0CPH1 = 0xEA (n = 1),
PCA0CPH2 = 0xEC (n = 2), PCA0CPH3 = 0xEE (n = 3),
PCA0CPH4 = 0xFE (n = 4)
Bits7–0: PCA0CPHn: PCA Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
0xFC, 0xEA ,
0xEC,0xEE,
0xFE
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 271
23. C2 Interface
C8051F34x devices include an on-chip Silic on Labs 2-Wire (C2) debug interface to allow Flash program-
ming and in-system debugging with the production part installed in the end application. The C2 interface
uses a clock signal (C2CK) and a bi-directional C2 data sign al (C2D) to transfer in formation between the
device and a host sys te m. See th e C2 In te rfa ce Specification for details on the C2 pr ot oco l.
23.1. C2 Interface Registers
The following describes the C2 registers necessary to perform Flash programming functions through the
C2 interface. All C2 registers are accessed through the C2 interface as described in the C2 Interface Spec-
ification.
C2 Register Definition 23.1. C2ADD: C2 Address
C2 Register Definition 23.2. DEVICEID: C2 Device ID
Bits7–0: The C2ADD register is accessed via the C2 interface to select the target Data register for
C2 Data Read and Data Write commands.
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Address Description
0x00 Selects the Device ID register for Data Read instructions
0x01 Selects the Revision ID register for Data Read instructions
0x02 Selects the C2 Flash Programming Control r egister for Data Read /Write instructions
0xAD Selects the C2 Flash Programming Data register for Data Read/Write instructions
This read-only reg ist er retu r ns th e 8- bit devic e ID: 0x0F (C8051F 340/1/2/3/4/5/6/7/8/9/A/B/C/D).
Reset Value
00001111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
272 Rev. 1.3
C2 Register Definition 23.3. REVID: C2 Revision ID
C2 Register Definition 23.4. FPCTL: C2 Flash Programming Control
C2 Register Definition 23.5. FPDAT: C2 Flash Programming Data
This read-only register returns the 8-bit revision ID.
Reset Value
Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0 F PCTL: Flash Programming Control Register.
This register is used to enable Flash programmi ng via the C2 inter face. To enable C2 Flash
programmi ng , th e followin g co de s mu st be writt e n in order: 0x02, 0x01. Note that once C2
Flash programming is enabled, a system reset must be issued to resume normal operation.
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: FPDAT: C2 Flash Programming Data Register.
This register is used to pass Flash commands, addresses, and data during C2 Flash
accesses. Valid commands are listed below.
Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Code Command
0x06 Flash Block Read
0x07 Flash Block Write
0x08 Flash Page Erase
0x03 Device Erase
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 273
23.2. C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and
Flash programming functions may be performed. This is possible because C2 communication is typically
performed when the device is in the halt state, where all on-chip peripherals and user software are stalled.
In this halted state, the C2 interface can safely ‘borrow’ the C2CK (RST) and C2D (P3.0) pins. Note that
the C2D pin is shared on the 32-pin packages only (C8051F342/3/6/7/9/A/B). In most applications, exter-
nal resistors are requ ired to isolate C2 in terface traffi c from the user application. A typical isolat ion configu-
ration is shown in Figure 23.1.
Figure 23.1. Typical C2 Pin Sharing
The configuration in Figure 23.1 assumes the following:
1. The user input ( b) cannot change state while the target device is halted.
2. The RST pin on the target device is used as an input only.
Additional resistors may be necessary depending on the specific applica tion.
C2D
C2CK
RST (a)
Input (b)
Output (c)
C2 Interface Master
C8051Fxxx
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
274 Rev. 1.3
DOCUMENT CHANGE LIST
Revision 0.5 to Revision 1.0
• Updated Table 3.1, “Global DC Electrical Characteristics,” on page 25.
• Updated Table 5.1, “ADC0 Electrical Characteristics,” on page 56.
• Various small text changes.
• Updated Table 8.1, “Voltage Regulator Electrical Specifications,” on page 69.
• Updated Flash security behavior.
Revision 1.0 to Revision 1.1
• Added two new part numbers C8051F348/9 and made associated changes.
• Corrected the entri es "24 kHz" and "48 kHz" to "24 MHz" and "48 MHz" in the "Conditions" column of
Table 3.1, "Global DC Electrical Characteristics," on page 38.
• Added note to co nfigure external interrupt pin as open-dr ain with a “1” in the port latch in Section 9.3.2.
"External Interr upts" on page 96.
• Various small text changes.
• Updated the figures in Section 15.1. "Priority Crossbar Decoder" and added a new figure to clarify
crossbar capabilities.
• Corrected the description of the UNDRUN bit in USB Register Definition 16.19. "EINCSRL: USB0 IN
Endpoint Control Low Byte" on page 19 8 to clarify that this bit works only in Isochronous Mode.
• Corrected the maximum SMBus speed from 1/10th to 1/20th of the system clock in Section 17.
"SMBus" on page 205.
• Corrected the descriptions for the following states and the corresponding typical response options in
Table 17.4. "SMBus Status Decoding" on page 221:
- Slave Transmitter (Status Vector: 0101)
- Slave Receiver (Status Vector: 0001)
• Corrected the bit location of MSTEN fr om SPI0CN.6 to SPI0CFG.6 in Section 20.2. "SPI0 Master
Operation" on page 243.
• Corrected the description of the WCOL bit in SFR Definition 20.2. "SPI0CN: SPI0 Control" on page
249 to match the description in Section 20.4. "SPI0 Interrupt Sources" on p age 245.
• Clarified the following parameters in Table 8.1, “Voltage Regulator Electrical Specifications,” on
page 69:
- VBUS Detection Input High and Low Voltages
- Dropout Voltage
• Updated the package drawings with additional dimensions in Figure 4.2 and Table 4.2, “TQFP-48
Package Dimensions,” on page 32, and Figure 4.4 and Table 4.4, “LQFP-32 Package Dimensions,”
on page 35.
Revision 1.1 to Revision 1.2
• Added two new part numbers C8051F34A/B and made associated changes.
• Corrected references to locations of T0M and T1M in the SFR definition of TMOD on page 240.
• Corrected instances of "8k" to "4k" in the SFR definition of EMI0CF on page 118.
Revision 1.2 to Revision 1.3
• Added QFN-32 package.
Revision 1.3 to Revision 1.4
• Added C8051F34C and C8051F34D devices.
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3 275
NOTES:
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C8051F347-GQ C8051F346-GQ C8051F344-GQ C8051F343-GQ C8051F341-GQ C8051F340-GQ C8051F34A-
GQ C8051F34B-GQ C8051F349-GM C8051F347-GM C8051F343-GM C8051F34B-GM C8051F346-GM
C8051F342-GM C8051F34A-GM C8051F345-GQ C8051F342-GQ C8051F340-TB C8051F342-GMR C8051F343-
GMR C8051F347-GMR C8051F348-GQR C8051F349-GMR C8051F349-GQR C8051F34A-GMR C8051F34A-GQR
C8051F34B-GMR C8051F34B-GQR C8051F345-GQR C8051F343-GQR C8051F340-GQR C8051F344-GQR
C8051F347-GQR C8051F341-GQR C8051F342-GQR C8051F346-GQR C8051F348-GQ C8051F349-GQ
C8051F34C-GQ C8051F34D-GQ