PIC16F946T-I/PT - Microchip Technology, Inc.

PIC16F946

Data Sheet

64-Pin Flash-Based, 8-Bit

CMOS Microcontrollers with

LCD Driver and nanoWatt Technology

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PIC16F946

64-Pin Flash-Based, 8-Bit CMOS Microcontrollers with

LCD Driver and nanoWatt Technology

High-Performance RISC CPU:

• Only 35 instructions to learn:

- All single-cycle instructions except branches

• Operati ng spe ed:

- DC – 20 MHz oscillator/clock input

- DC – 200 ns instruction cycle

• Program Memory Read (PMR) capability

• Interrupt capability

• 8-level deep hardware stack

• Direct, Indirect and Relative Addressing modes

Special Microcontroller Features:

• Precision Internal Oscillator:

- Factory calibrated to ±1%

- Software selectable frequency range of

8 MHz to 32 kHz

- Software tunable

- Two-Speed Start-up mode

- Crystal fail detect for critical applications

- Clock mode switching during operation for

power saving s

• Power-saving Sleep mode

• Wide operating voltage range (2.0V-5.5V)

• Industri al and Extend ed tem pera t ure range

• Power-on Reset (POR )

• Power-up Timer (PWRT) and Oscillator Start-up

Timer (OST)

• Brown-out Reset (BOR) with software contro l

option

• Enhanced Low-Current Watchdog Timer (WDT)

with on-chip oscillator (software selectable

nominal 268 seconds with full prescaler) with

software enable

• Multiplexed Master Clear with pull-up/input pin

• Programmable code protection

• High-Endurance Flash/EEPROM cell:

- 100,000 write Flash end uran ce

- 1,000,000 write EEPROM endurance

- Flash/Data EEPROM retention: > 40 years

Low-Power Features:

• Standby Current:

- <100 nA @ 2.0V, typi cal

• Operating Current:

-8.5μA @ 32 kHz, 2.0V, typical

-100μA @ 1 MHz, 2.0V, typical

• Watchdog Timer Current:

-1μA @ 2.0V, typical

Peripheral Feat ures:

• Liquid Cr ystal Display module:

- Up to 168 pixel drive cap ab ili ty

- Select ab le cl ock source

- Four commons

• Up to 53 I/O pins and 1 input-only pin:

- High-current source/sink for direct LED drive

- Interrupt-on-pin change

- Individually programmable weak pull-ups

• In-Circuit Serial Programming™ (ICSP™) via two

pins

• Analog comparator module with:

- Two anal og compar ators

- Programmable on-chip voltage reference

(CVREF) module (% of VDD)

- Comparator inputs and outputs externally

accessible

• A/D Converter:

- 10-bit resolution and 8 channels

• Timer0: 8-bit timer/counter with 8-bit

progra mmab le pres caler

• Enhanced Timer1:

- 16-bit timer/counter with prescaler

- External Gate Input mode

- Option to use OSC1 and OSC2 as Timer1

oscillator if INTOSCIO or LP mode is

selected

• Timer2: 8-bit timer/counter with 8-bit period

• Addressable Universal Synchronous

Asynchronous Receiver Transmitter (AUSART)

• 2 Capture, Com p are , PWM module s:

- 16-bit Capture, max. resolut ion 12.5 ns

- 16-bit Compare, max. resolution 200 ns

- 10-bit PWM, max. frequency 20 kHz

• Synchronous Serial Port (SSP) with I2C™

PIC16F946

Pin Diagram – PIC16F946

Device

Program

Memory Data Memory

I/O 10-bit A/D

(ch)

LCD

(segment

drivers) CCP Timers

8/16-bit

Flash

(words) SRAM

(bytes) EEPROM

(bytes)

PIC16F946 8K 336 256 53 8 42 2 2/1

PIC16F946

50 49

17 18 19 20 21 22 23 24 25 26

RD6/SEG19

RD5/SEG18

RD4/SEG17

RC7/RX/DT/SDI/SDA/SEG8

RC6/TX/CK/SCK/SCL/SEG9

RC5/T1CKI/CCP1/SEG10

RC4/T1G/SDO/SEG11

VDD

VSS

RD3/SEG16

RD2/CCP2

RD1

RD0/COM3

RC3/SEG6

RC2/VLCD3

RC1/VLCD2

RD7/SEG20

RG5/SEG41

RG4/SEG40

RG3/SEG39

RG2/SEG38

RG1/SEG37

RG0/SEG36

VSS

VDD

RF1/SEG33

RF0/SEG32

RB0/INT/SEG0

RB1/SEG1

RB2/SEG2

RC0/VLCD1

RA6/OSC2/CLKO/T1OSO

RA7/OSC1/CLKI/T1OSI

VSS

VDD

RE2/AN7/SEG23

RE1/AN6/SEG22

RE0/AN5/SEG21

RA4/C1OUT/T0CKI/SEG4

RA3/AN3/C1+/VREF+/SEG15

RA5/AN4/C2OUT/SS/SEG5

RA2/AN2/C2+/VREF-/COM2

RA0/AN0/C1-/SEG12

RE3/MCLR/VPP

RE4/SEG24

RB4/COM0

RB3/SEG3

AVDD

AVSS

RB5/COM1

RB6/ICSPCLK/ICDCK/SEG14

RB7/ICSPDAT/ICDDAT/SEG13

RF7/SEG31

VSS

VDD

RF5/SEG29

RF6/SEG30

RF4/SEG28

RE7/SEG27

RE5/SEG25

RE6/SEG26

RA1/AN1/C2-/SEG7

27 28 29 30 32

54 53 52 5158 57 56 5560 5964 63 62 61

TQFP

RF2/SEG34

RF3/SEG35

PIC16F946

Table of Contents

1.0 Device Overview .......................................................................................................................................................................... 5

2.0 Memory O rganization................................................................................................................................................................. 11

3.0 I/O Ports........... ........................ ....................... ....................... ....................... ............................................................................. 27

4.0 Clock Sources............................................................................................................................................................................ 71

5.0 Timer0 Module ........................................................................................................................................................................... 83

6.0 Timer1 Module With Gate Control.............................................................................................................................................. 87

7.0 Timer2 Module ........................................................................................................................................................................... 93

8.0 Comparator Module........................................... .... .... .. .... ....... .... .... .. .... ......... .. .... .... .. ................................................................. 95

9.0 Liquid Crystal Display (LCD) Driver Module..................................... .... ....... .... .. .... .... ....... .... .... .. .............................................. 103

10.0 Programmable Low-Voltage Detect (PLVD) Module.......................... .. ........... .. .... .... ......... .... .... .... .......................................... 131

11.0 Addressable Universal Synchronous Async hronous Receiv er Transmitter (USA RT ).............................................................. 133

12.0 Analog-t o-Digital Converter (A/D) Module................................................................................................................................ 149

13.0 Data EEPROM and Flash Program Memory Control....................... .... ........... .... ...... ......... ...... .... ........... ................................. 159

14.0 SS P Module Overview . ............................................................................................................................................................ 165

15.0 Capture/Compare/PWM Modules ........................... .... .. ......... .. .... .... .. ......... .... .. .... .. ......... .... .. .... .............................................. 183

16.0 Specia l Features of the CPU.............. ................... ................... ................... ................... .......................................................... 191

17.0 Instruction Set Summary.......................................................................................................................................................... 213

18.0 Development Support............................................................................................................................................................... 223

19.0 Electrical Specifications............................................................................................................................................................ 229

20.0 DC and AC Characteristics Graphs and Tables............................. .. .... ......... .... .. .... ......... .... .... .. .... .......................................... 231

21.0 Packagin g In fo rmation........................ ................... ....................... ................... ......................................................................... 255

Appendix A: Data Sheet Revision History............................................ .... .... ......... .... .... .... ......... .... .. .................................................. 259

Appendix B: Migrating From Other PICmicro® Devices ................................ ......... .... .... .... ........... .... .... ............................................ 259

Appendix C: Conversion Considerations ............. ....... .. .... .. .... .. ....... .... .. .... .. ....... .... .. .... .. .... ....... .. .... .................................................. 260

Index .................................................................................................................................................................................................. 261

On-line Support.. .... .... ........... ...... .... ........... .... .... ........... .... .... ........... .... ...... .... ........... .... ..................................................................... 269

Systems Information and Upgrade Hot Line...................................................................................................................................... 269

Reader Response.............................................................................................................................................................................. 270

Product Identification System ............................................................................................................................................................ 271

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Customer Noti fic atio n Syst em

PIC16F946

NOTES:

PIC16F946

1.0 DEVICE OVERVIEW

This do cu me n t conta i ns dev ic e spec if i c in f orm at i on fo r

the PIC1 6F946. Addit ional info rmation ma y be found i n

the “PICmicro® Mid-Range MCU Family Reference

Manual” (DS33023), downloaded from the Microchip

web si te. The Refere nce Ma nual s hould be consi dered

a complementary document to this data sheet and is

highly recommended reading for a better

underst a nding of the dev ice archi tecture and oper atio n

of the peripheral modul es.

The PIC16F946 devices are covered by this data

sheet. It is available in a 64-pin package. Figure 1-1

shows a block diagram of the device and Table 1-1

shows the pinout description.

PIC16F946

FIGURE 1-1: PIC16F946 BLOCK DIAGRAM

Power-up

Timer

Oscillator

Start-up Timer

Power-on

Reset

Watchdog

Timer

Brown-out

Reset

RB0/INT/SEG0

RB1/SEG1

RB2/SEG2

RB3/SEG3

RB4/COM0

RB5/COM1

RB6/ICSPCLK/ICDCK/SEG14

RB7/ICSPDAT/ICDDAT/SEG13

Flash

Program

Memory

13 Data Bus 8

Program

Bus

Instruction Reg

Program Counter

RAM

File

Registers

Direct Addr 7

RAM Addr

Addr MUX

Indirect

Addr

FSR Reg

Status Reg

MUX

ALU

W Reg

Instruction

Decode and

Control

Timing

Generation

OSC1/CLKI

OSC2/CLKO

PORTA

8-L evel Stack (13-bit) 336 x 8 bytes

8k x 14

VSS

RA0/AN0/C1-/SEG12

RA1/AN1/C2-/SEG7

RA2/AN2/C2+/VREF-/COM2

RA3/AN3/C1+/VREF+/SEG15

RA4/C1OUT/T0CKI/SEG4

RA5/AN4/C2OUT/SS/SEG5

RA6/OSC2/CLKO/T1OSO

RA7/OSC1/CLKI/T1OSI

Configuration

Internal

Oscillator VDD

Block

Program Memory Read

PORTC RC0/VLCD1

RC1/VLCD2

RC2/VLCD3

RC3/SEG6

RC4/T1G/SDO/SEG11

RC5/T1CKI/CCP1/SEG10

RC6/TX/CK/SCK/SCL/SEG9

RC7/RX/DT/SDI/SDA/SEG8

PORTD

(PRM)

PORTB

PLVD LCD

Data EEPROM

256 bytes

Comparators SSP

CCP1 CCP2

Timer0 Timer1 Timer2 10-bit A/D

BOR

Addressable

USART

PORTE

PORTF

PORTG

RD0/COM3

RD1

RD2/CCP2

RD3/SEG16

RD4/SEG17

RD5/SEG18

RD6/SEG19

RD7/SEG20

RE0/AN5/SEG21

RE1/AN6/SEG22

RE2/AN7/SEG23

RE3/MCLR/VPP

RE4/SEG24

RE5/SEG25

RE6/SEG26

RE7/SEG27

RF0/SEG32

RF1/SEG33

RF2/SEG34

RF3/SEG35

RF4/SEG28

RF5/SEG29

RF6/SEG30

RF7/SEG31

RG0/SEG36

RG1/SEG37

RG2/SEG38

RG3/SEG39

RG4/SEG40

RG5/SEG41

PIC16F946

TABLE 1-1: PIC16F946 PINOUT DESCRIPTIONS

Name Function Input

Type Output

Type Description

RA0/AN0/C1-/SEG12 RA0 TTL CMOS General purpose I/O.

AN0 AN — Analog inp ut C hannel 0/Co m parator 1 input – negative.

C1- — AN Comparator 1 negative inp ut .

SEG12 — A N LCD an alog output .

RA1/AN1/C2-/SEG7 RA1 TTL CMOS General purpose I/O.

AN1 AN — Analog inp ut C hannel 1/Co m parator 2 input – negative.

C2- — AN Comparator 2 negative inp ut .

SEG7 — AN LCD analog ou tput.

RA2/AN2/C2+/VREF-/COM2 RA2 TTL CMOS General purpose I/O.

AN2 AN — Analog input C hannel 2/Co m parator 2 in put – positive.

C2+ — AN Comparator 2 positive input .

VREF- AN — External Voltage Refer ence – nega tive .

COM2 — AN LCD analog out put.

RA3/AN3/C1+/VREF+/SEG15 RA3 TTL CMOS General purpose I/O.

AN3 AN — Analog input C hannel 3/Co m parator 1 in put – positive.

C1+ — AN Comparator 1 positive input .

VREF+ AN — External Voltage Refer ence – posit ive.

SEG15 — AN LCD analog out put.

RA4/C1OUT/T0CKI/SEG4 RA4 TTL CMOS General purpose I/O.

C1OUT — CMOS Comparator 1 out put.

T0CKI ST — Timer0 clock input.

SEG4 — AN LCD analog ou tput.

RA5/AN4/C2OUT/SS/SEG5 RA5 TTL CMOS General purpose I/O.

AN4 AN — Analog input Channel 4.

C2OUT — CMOS Comparator 2 out put.

SS TTL — Slave se le ct input .

SEG5 — AN LCD analog ou tput.

RA6/OSC2/CLKO/T1OSO RA6 TTL CMOS General purpose I/O.

OSC2 — XTAL Crystal/Resonator.

CLKO — CMOS TOSC/4 reference cloc k.

T1OSO — XTAL Timer1 oscillator output.

RA7/OSC1/CLKI/T1OSI RA7 TTL CMOS General purpose I/O.

OSC1 XTAL — Crystal/Resonator.

CLKI ST — Clock input.

T1OSI XTAL — Timer 1 oscilla to r i npu t.

RB0/INT/SEG0 RB0 TTL CMOS General purpose I/O. Individually enabled pull-up.

INT ST — External interrupt pi n.

SEG0 — AN LCD analog ou tput.

RB1/SEG1 RB1 TTL CMOS General purpose I/O. Individually enabled pull-up.

SEG1 — AN LCD analog ou tput.

RB2/SEG2 RB2 TTL CMOS General purpose I/O. Individually enabled pull-up.

SEG2 — AN LCD analog ou tput.

Legend: AN = Analog input or output CMOS= CMOS compatible input or output D = Direct

TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels

HV = High Voltage XTAL = Crystal

PIC16F946

RB3/SEG3 RB3 TTL CMOS General purpose I/O. Individually enabled pull-up.

SEG3 — AN LCD analog ou tput.

RB4/COM0 RB4 TTL CMOS General purpose I/O. Individually controlled interrupt-on-

change. Individually enabl ed pull-up.

COM0 — AN LCD analog out put.

RB5/COM1 RB5 TTL CMOS General purpose I/O. Individually controlled interrupt-on-

change. Individually enabl ed pull-up.

COM1 — AN LCD analog out put.

RB6/ICSPCLK/ICDCK/SEG14 RB6 TTL CMOS Gene ral p urpo se I/O. Individually controlled interrupt-on-

change. Individually enabl ed pull-up.

ICSPCLK ST — ICSP™ clock.

ICDCK ST — I CD cl ock I/O.

SEG14 — AN LCD analog out put.

RB7/ICSPDAT/ICDDAT/SEG13 RB7 TTL CMOS General purpose I/O. Individually controlled interrupt-on-

change. Individually enabl ed pull-up.

ICSPDAT ST CMOS ICSP Da ta I/O.

ICDDAT ST CMOS ICD Data I/O.

SEG13 — AN LCD analog out put.

RC0/VLCD1 RC0 ST CMOS General purpose I/O.

VLC D 1 AN — LCD anal og inp ut.

RC1/VLCD2 RC1 ST CMOS General purpose I/O.

VLC D 2 AN — LCD anal og inp ut.

RC2/VLCD3 RC2 ST CMOS General purpose I/O.

VLC D 3 AN — LCD anal og inp ut.

RC3/SEG6 RC3 ST CMOS General purpose I/O.

SEG6 — AN LCD analog ou tput.

RC4/T1G/SDO/SEG11 RC4 ST CMOS General purpose I/O.

T1G ST — Timer1 gate input.

SDO — CMOS Serial data output.

SEG11 — AN LCD analog out put.

RC5/T1CKI/CCP1/SEG10 RC5 ST CMOS General purpose I/O.

T1CKI ST — Timer1 clock input.

CCP1 ST CMOS C a pt ur e 1 in put/Compare 1 ou tp ut / PW M 1 out put.

SEG10 — AN LCD analog out put.

RC6/TX/CK/SCK/SCL/SEG9 RC6 ST CMOS General purpose I/O.

TX — CMOS U SART asynchro nous seria l tra nsm it .

CK ST CMOS USART synch ronous serial clock.

SCK ST C M O S SPI™ cl oc k.

SCL ST CMOS I2C ™ cl ock.

SEG9 — AN LCD analog ou tput.

TABLE 1-1: PIC16F946 PINOUT DESCRIPTIONS (CONTINUED)

Name Function Input

Type Output

Type Description

Legend: AN = Analog inp ut or o ut put CMO S = CMOS compatible input or output D = Direct

TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels

HV = High Voltage XTAL = Crystal

PIC16F946

RC7/RX/DT/SDI/SDA/SEG8 RC7 ST CMOS General purpose I/O.

RX ST — U SART asynchronous seria l receive.

DT ST CMO S USA RT syn chronou s serial data.

SDI ST CMOS SPI™ data input.

SDA ST CMOS I2C™ data.

SEG8 — AN LCD analog ou tput.

RD0/COM3 RD0 ST CMOS General purpose I/O.

COM3 — AN LCD analog out put.

RD1 RD1 ST CMOS General purpose I/O.

RD2/CCP2 RD2 ST CMOS General purpose I/O.

CCP2 ST CMOS C a pt ur e 2 in put/Compare 2 ou tp ut / PW M 2 out put.

RD3/SEG16 RD3 ST CMOS General purpose I/O.

SEG16 — AN LCD analog out put.

RD4/SEG17 RD4 ST CMOS General purpose I/O.

SEG17 — AN LCD analog out put.

RD5/SEG18 RD5 ST CMOS General purpose I/O.

SEG18 — AN LCD analog out put.

RD6/SEG19 RD6 ST CMOS General purpose I/O.

SEG19 — AN LCD analog out put.

RD7/SEG20 RD7 ST CMOS General purpose I/O.

SEG20 — AN LCD analog out put.

RE0/AN5/SEG21 RE0 ST CMOS General purpose I/O.

AN5 AN — Analog input Channel 5.

SEG21 — AN LCD analog out put.

RE1/AN6/SEG22 RE1 ST CMOS General purpose I/O.

AN6 AN — Analog input Channel 6.

SEG22 — AN LCD analog out put.

RE2/AN7/SEG23 RE2 ST CMOS General purpose I/O.

AN7 AN — Analog input Channel 7.

SEG23 — AN LCD analog out put.

RE3/MCLR/VPP RE3 ST — Digital input only.

MCLR ST — Master Clear with internal pull-up.

VPP HV — Programming voltage.

RE4/SEG24 RE4 ST CMOS General purpose I/O.

SEG24 — AN LCD analog out put.

RE5/SEG25 RE5 ST CMOS General purpose I/O.

SEG25 — AN LCD analog out put.

RE6/SEG26 RE6 ST CMOS General purpose I/O.

SEG26 — AN LCD analog out put.

RE7/SEG27 RE7 ST CMOS General purpose I/O.

SEG27 — AN LCD analog out put.

RF0/SEG32 RF0 ST CMOS General purpose I/O.

SEG32 — AN LCD analog out put.

TABLE 1-1: PIC16F946 PINOUT DESCRIPTIONS (CONTINUED)

Name Function Input

Type Output

Type Description

Legend: AN = Analog input or output CMOS= CMOS compatible input or output D = Direct

TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels

HV = High Voltage XTAL = Crystal

PIC16F946

RF1/SEG33 RF1 ST CMOS General purpose I/O.

SEG33 — AN LCD analog out put.

RF2/SEG34 RF2 ST CMOS General purpose I/O.

SEG34 — AN LCD analog out put.

RF3/SEG35 RF3 ST CMOS General purpose I/O.

SEG35 — AN LCD analog out put.

RF4/SEG28 RF4 ST CMOS General purpose I/O.

SEG28 — AN LCD analog out put.

RF5/SEG29 RF5 ST CMOS General purpose I/O.

SEG29 — AN LCD analog out put.

RF6/SEG30 RF6 ST CMOS General purpose I/O.

SEG30 — AN LCD analog out put.

RF7/SEG31 RF7 ST CMOS General purpose I/O.

SEG31 — AN LCD analog out put.

RG0/SEG36 RG0 ST CMOS General purpose I/O.

SEG36 — AN LCD analog out put.

RG1/SEG37 RG1 ST CMOS General purpose I/O.

SEG37 — AN LCD analog out put.

RG2/SEG38 RG2 ST CMOS General purpose I/O.

SEG38 — AN LCD analog out put.

RG3/SEG39 RG3 ST CMOS General purpose I/O.

SEG39 — AN LCD analog out put.

RG4/SEG40 RG4 ST CMOS General purpose I/O.

SEG10 — AN LCD analog out put.

RG5/SEG41 RG5 ST CMOS General purpose I/O.

SEG41 — AN LCD analog out put.

VDD VDD D — Power supply for micro con tro ller.

VSS VSS D — Gr ound reference for micr ocontroll er.

TABLE 1-1: PIC16F946 PINOUT DESCRIPTIONS (CONTINUED)

Name Function Input

Type Output

Type Description

Legend: AN = Analog inp ut or o ut put CMO S = CMOS compatible input or output D = Direct

TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels

HV = High Voltage XTAL = Crystal

PIC16F946

2.0 MEMORY ORGANIZATION

2.1 Program Memory Organization

The PIC16F946 has a 13-bit program counter capable

of addressing an 8k x 14 program memory space

(0000h-1FFFh). The Reset vector is at 0000h and the

interrupt vector is at 0004h.

FIGURE 2-1: PROGRAM MEMORY MAP

AND STACK FOR THE

PIC16F946

2.2 Data Memory Organization

The data memory is partitioned into multiple banks

which contain the General Purpose Registers (GPRs)

and the Special Function Registers (SFRs). Bits RP0

and RP1 are bank select bits.

=00:→ Bank 0

=01:→ Bank 1

=10:→ Bank 2

=11:→ Bank 3

Each bank extends up to 7Fh (128 bytes). The lower

locations of each bank are reserved for the Special

Function Registers. Above the Special Function

Registers are the General Purpose Registers,

implemented as static RAM. All implemented banks

contain Special Function Registers. Some frequently

used Special Function Registers from one bank are

mirrored in another bank for code reduction and

quicker access.

2.2. 1 GENERAL PURPOSE REGISTER

FILE

The register file is organized as 336 x 8 in the

PIC16F946. Each register is accessed either directly or

indirectly through the File Select Register (FSR) (see

Section 2.5 “Indirect Addressing, INDF and FSR

Registers”).

2.2.2 SPECIAL FUNCTION REGISTERS

The Special Function Registers are registers used by

the CPU and peripheral functions for controlling the

desired operation of the device (see Tables 2-1,

2-2, 2-3 and 2-4). These registers are static RAM.

The special registers can be classified into two sets:

core and peripheral. The Special Function Registers

assoc iated with th e “core” are d escribed in this sectio n.

Those related to the operation of the peripheral

features are described in the section of that peripheral

feature.

pc<12:0>

0000h

0004h

Stack Lev el 1

Stack Level 8

Reset Vector

Interrupt Vector

CALL, RETURN

RETFIE, RETLW

Stack Level 2

0005h

On-chip

1FFFh

Program

Memory

Page 0

Page 1

Page 2

Page 3

07FFh

0800h

0FFFh

1000h

17FFh

1800h

RP0 RP1 (STATUS<6:5>)

PIC16F946

FIGURE 2-2: PIC16F946 SPECIAL FUNCTION REGISTERS

File File File File

Address Address Address Address

Indirect add r. (1) 00h Indirect addr. (1) 80h Indirect addr. (1) 100h Indirect addr. (1) 180h

TMR0 01h OPTION_REG 81h TMR0 101h OPTION_REG 181h

PCL 02h PCL 82h PCL 102h PCL 182h

STATUS 03h STATUS 83h STATUS 103h STATUS 183h

FSR 04h FSR 84h FSR 104h FSR 184h

PORTA 05h TRISA 85h WDTCON 105h TRISF 185h

PORTB 06h TRISB 86h PORTB 106h TRISB 186h

PORTC 07h TRISC 87h LCDCON 107h TRISG 187h

PORTD 08h TRISD 88h LCDPS 108h PORTF 188h

PORTE 09h TRISE 89h LVDCON 109h PORTG 189h

PCLATH 0Ah PCLATH 8Ah PCLATH 10Ah PCLATH 18Ah

INTCON 0Bh INTCON 8Bh INTCON 10Bh INTCON 18Bh

PIR1 0Ch PIE1 8Ch EEDATL 10Ch EECON1 18Ch

PIR2 0Dh PIE2 8Dh EEADRL 10Dh EECON2(1) 18Dh

TMR1L 0Eh PCON 8Eh EEDATH 10Eh 18Eh

TMR1H 0Fh OSCCON 8Fh EEADRH 10Fh 18Fh

T1CON 10h OSCTUNE 90h LCDDATA0 110h LCDDATA12 190h

TMR2 11h ANSEL 91h LCDDATA1 111h LCDDATA13 191h

T2CON 12h PR2 92h LCDDATA2 112h LCDDATA14 192h

SSPBUF 13h SSPADD 93h LCDDATA3 113h LCDDATA15 193h

SSPCON 14h SSPSTAT 94h LCDDATA4 114h LCDDATA16 194h

CCPR1L 15h WPUB 95h LCDDATA5 115h LCDDATA17 195h

CCPR1H 16h IOCB 96h LCDDATA6 116h LCDDATA18 196h

CCP1CON 17h CMCON1 97h LCDDATA7 117h LCDDATA19 197h

RCSTA 18h TXSTA 98h LCDDATA8 118h LCDDATA20 198h

TXREG 19h SPBRG 99h LCDDATA9 119h LCDDATA21 199h

RCREG 1Ah 9Ah LCDDATA10 11Ah LCDDATA22 19Ah

CCPR2L 1Bh 9Bh LCDDATA11 11Bh LCDDATA23 19Bh

CCPR2H 1Ch CMCON0 9Ch LCDSE0 11Ch LCDSE3 19Ch

CCP2CON 1Dh VRCON 9Dh LCDSE1 11Dh LCDSE4 19Dh

ADRESH 1Eh ADRESL 9Eh LCDSE2 11Eh LCDSE5 19Eh

ADCON0 1Fh ADCON1 9Fh 11Fh 19Fh

General

Purpose

96 Bytes

20h

General

Purpose

80 Bytes

A0h

General

Purpose

80 Bytes

120h General

Purpose

80 Bytes

1A0h

EFh 16Fh 1EFh

accesses

70h-7Fh F0h accesses

70h-7Fh 170h accesses

70h-7Fh 1F0h

7Fh FFh 17Fh 1FFh

Bank 0Bank 1Bank 2Bank 3

Unimple m ented data memory locations, re ad as ‘0’.

Note 1: Not a physical register.

PIC16F946

TABLE 2-1: PIC16F946 SPECIAL REGISTERS SUMMARY BANK 0

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR/BOR

Reset

Value on

all other

Resets(1)

Bank 0

00h INDF Addressing this location uses contents of FSR to address data memory (not a physical register) xxxx xxxx xxxx xxxx

01h TMR0 Timer0 Mo dule Reg ister xxxx xxxx uuuu uuuu

02h PCL Program Counter’s (PC) Least Significant Byte 0000 0000 0000 0000

03h STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 000q quuu

04h FSR Indirect Data Memory Address Pointer xxxx xxxx uuuu uuuu

05h PORTA RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0 xxxx xxxx uuuu uuuu

06h PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 xxxx xxxx uuuu uuuu

07h PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 xxxx xxxx uuuu uuuu

08h PORTD RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 xxxx xxxx uuuu uuuu

09h PORTE RE7 RE6 RE5 RE4 RE3 RE2 RE1 RE0 xxxx xxxx uuuu uuuu

0Ah PCLATH — — — Write Buffer for upper 5 bits of Program Counter ---0 0000 ---0 0000

0Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF— CCP2IF 0000 -0-0 0000 -0-0

0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 xxxx xxxx uuuu uuuu

0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 xxxx xxxx uuuu uuuu

10h T1CON T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

11h TMR2 Timer2 Modul e Regi ster 0000 0000 0000 0000

12h T2CON — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000

13h SSPBUF Synchronous Serial Port Receive Buffer/Transmit Register xxxx xxxx uuuu uuuu

14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

15h CCPR1L Capture/Compare/PWM Register 1 (LSB) xxxx xxxx uuuu uuuu

16h CCPR1H Capture/Compare/PWM Register 1 (MSB) xxxx xxxx uuuu uuuu

17h CCP1CON —— CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

19h TXREG USART Transmit Data Register 0000 0000 0000 0000

1Ah RCREG USART Receive Data Register 0000 0000 0000 0000

1Bh(2) CCPR2L Capture/Compare/PWM Register 2 (LSB) xxxx xxxx uuuu uuuu

1Ch(2) CCPR2H Capture/Compare/PWM Register 2 (MSB) xxxx xxxx uuuu uuuu

1Dh(2) CCP2CON —— CCP2X CCP2Y CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000

1Eh ADRESH A/D Result Register High Byte xxxx xxxx uuuu uuuu

1Fh ADCON0 ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

Legend: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented

Note 1: Other (non Power-up) Resets include MCLR R ese t and Watchdog Timer Re set dur i ng nor ma l opera ti on .

PIC16F946

TABLE 2-2: PIC16F946 SPECIAL FUNCTION REGISTERS SUMMARY BANK 1

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR/BOR

Reset

Value on

all other

Resets(1)

Bank 1

80h INDF Addressing this location uses contents of FSR to address data memory (not a physical

81h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

82h PCL Program Counter’s (PC) Least Significant Byte 0000 0000 0000 0000

83h STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 000q quuu

84h FSR Indirect Data Memory Address Pointer xxxx xxxx uuuu uuuu

85h TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111

86h TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 1111 1111 1111 1111

87h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111

88h TRISD TRISD7 TRISD6 TRISD5 TRISD4 TRISD3 TRISD2 TRISD1 TRISD0 1111 1111 1111 1111

89h TRISE TRISE7 TRISE6 TRISE5 TRISE4 TRISE3(3) TRISE2 TRISE1 TRISE0 1111 1111 1111 1111

8Ah PCLATH ——— Write Buffer for the upper 5 bits of the Program Counter ---0 0000 ---0 0000

8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE— CCP2IE 0000 -0-0 0000 -0-0

8Eh PCON ———SBOREN——PORBOR ---1 --qq ---u --uu

8Fh OSCCON — IRCF2 IRCF1 IRCF0 OSTS(2) HTS LTS SCS -110 q000 -110 x000

90h OSCTUNE ——— TUN4 TUN3 TUN2 TUN1 TUN0 ---0 0000 ---u uuuu

91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

92h PR 2 Timer2 Period Reg ist er 1111 1111 1111 1111

93h SSPADD Synchronous Serial Port (I2 C mode) Address Register 0000 0000 0000 0000

94h SSPSTAT SMP CKE D/A PSR/WUA BF 0000 0000 0000 0000

95h WPUB WPUB7 WPUB6 WPUB5 WPUB4 WPUB3 WPUB2 WPUB1 WPUB0 1111 1111 1111 1111

96h IOCB IOCB7 IOCB6 IOCB5 IOCB4 — — — — 0000 ---- 0000 ----

97h CMCON1 — — — — — — T1GSS C2SYNC ---- --10 ---- --10

98h TXSTA CSRC TX9 TXEN SYNC — BRGH TRMT TX9D 0000 -010 0000 -010

99h SPBRG SPBRG7 SPBRG6 SPBRG5 SPBRG4 SPBRG3 SPBRG2 SPBRG1 SPBRG0 0000 0000 0000 0000

9Ah —Unimplemented — —

9Bh —Unimplemented — —

9Ch CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

9Dh VRCON VREN —VRR— VR3 VR2 VR1 VR0 0-0- 0000 0-0- 0000

9Eh ADRESL A/D Result Register Low Byte xxxx xxxx uuuu uuuu

9Fh ADCON1 — ADCS2 ADCS1 ADCS0 — — — — -000 ---- -000 ---

Legend: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented

Note 1: Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.

2: The value of the OSTS bit is dependent on the value of the Configuration Word (CONFIG) of the device. See Section 4.0 “Clock

Sources”.

3: Bit is read-only; TRISE = 1 always.

PIC16F946

TABLE 2-3: PIC16F946 SPECIAL REGISTERS SUMMARY BANK 2

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR/BOR

Reset

Value on

all other

Resets(1)

Bank 2

100h INDF Addressing this location uses contents of FSR to address data memory (not a physical register) xxxx xxxx xxxx xxxx

101h TMR0 Timer0 Module Register xxxx xxxx uuuu uuuu

102h PCL Program Counter’s (PC) Least Significant Byte 0000 0000 0000 0000

103h STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 000q quuu

104h FSR Indirect Data Memory Address Pointer xxxx xxxx uuuu uuuu

105h WDTCON — — — WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN ---0 1000 ---0 1000

106h PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 xxxx xxxx uuuu uuuu

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

108h LCDPS WFT BIASMD LCDA WA LP3 LP2 LP1 LP0 0000 0000 0000 0000

109h LVDCON ——IRVSTLVDEN— LVDL2 LVDL1 LVDL0 --00 -100 --00 -100

10Ah PCLATH — — — Write Buffer for the upper 5 bits of the Program Counter ---0 0000 ---0 0000

10Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

10Ch EEDATL EEDATL7 EEDATL6 EEDATL5 EEDATL4 EEDATL3 EEDATL2 EEDATL1 EEDATL0 0000 0000 0000 0000

10Dh EEADRL EEADRL7 EEADRL6 EEADRL5 EEADRL4 EEADRL3 EEADRL2 EEADRL1 EEADRL0 0000 0000 0000 0000

10Eh EEDATH —— EEDATH5 EEDATH4 EEDATH3 EEDATH2 EEDATH1 EEDATH0 --00 0000 --00 0000

10Fh EEADRH — — — EEADRH4 EEADRH3 EEADRH2 EEADRH1 EEADRH0 ---0 0000 ---0 0000

110h LCDDATA0 SEG7

COM0 SEG6

COM0 SEG5

COM0 SEG4

COM0 SEG3

COM0 SEG2

COM0 SEG1

COM0 SEG0

COM0 xxxx xxxx uuuu uuuu

111h LCDDATA1 SEG15

COM0 SEG14

COM0 SEG13

COM0 SEG12

COM0 SEG11

COM0 SEG10

COM0 SEG9

COM0 SEG8

COM0 xxxx xxxx uuuu uuuu

112h LCDDATA2 SEG23

COM0 SEG22

COM0 SEG21

COM0 SEG20

COM0 SEG19

COM0 SEG18

COM0 SEG17

COM0 SEG16

COM0 xxxx xxxx uuuu uuuu

113h LCDDATA3 SEG7

COM1 SEG6

COM1 SEG5

COM1 SEG4

COM1 SEG3

COM1 SEG2

COM1 SEG1

COM1 SEG0

COM1 xxxx xxxx uuuu uuuu

114h LCDDATA4 SEG15

COM1 SEG14

COM1 SEG13

COM1 SEG12

COM1 SEG11

COM1 SEG10

COM1 SEG9

COM1 SEG8

COM1 xxxx xxxx uuuu uuuu

115h LCDDATA5 SEG23

COM1 SEG22

COM1 SEG21

COM1 SEG20

COM1 SEG19

COM1 SEG18

COM1 SEG17

COM1 SEG16

COM1 xxxx xxxx uuuu uuuu

116h LCDDATA6 SEG7

COM2 SEG6

COM2 SEG5

COM2 SEG4

COM2 SEG3

COM2 SEG2

COM2 SEG1

COM2 SEG0

COM2 xxxx xxxx uuuu uuuu

117h LCDDATA7 SEG15

COM2 SEG14

COM2 SEG13

COM2 SEG12

COM2 SEG11

COM2 SEG10

COM2 SEG9

COM2 SEG8

COM2 xxxx xxxx uuuu uuuu

118h LCDDATA8 SEG23

COM2 SEG22

COM2 SEG21

COM2 SEG20

COM2 SEG19

COM2 SEG18

COM2 SEG17

COM2 SEG16

COM2 xxxx xxxx uuuu uuuu

119h LCDDATA9 SEG7

COM3 SEG6

COM3 SEG5

COM3 SEG4

COM3 SEG3

COM3 SEG2

COM3 SEG1

COM3 SEG0

COM3 xxxx xxxx uuuu uuuu

11Ah LCDDATA10 SEG15

COM3 SEG14

COM3 SEG13

COM3 SEG12

COM3 SEG11

COM3 SEG10

COM3 SEG9

COM3 SEG8

COM3 xxxx xxxx uuuu uuuu

11Bh LCDDATA11 SEG23

COM3 SEG22

COM3 SEG21

COM3 SEG20

COM3 SEG19

COM3 SEG18

COM3 SEG17

COM3 SEG16

COM3 xxxx xxxx uuuu uuuu

11Ch LCDSE0(2) SE7 SE6 SE5 SE4 SE3 SE2 SE1 SE0 0000 0000 uuuu uuuu

11Dh LCDSE1(2) SE15 SE14 SE13 SE12 SE11 SE10 SE9 SE8 0000 0000 uuuu uuuu

11Eh LCDSE2(2) SE23 SE22 SE21 SE20 SE19 SE18 SE17 SE16 0000 0000 uuuu uuuu

11Fh —Unimplemented — —

Legend: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented

Note 1: Other (non Power-up) Resets include MCLR R ese t and Watchdog Timer Re set dur i ng nor ma l opera ti on .

2: This register is only initialized by a POR or BOR reset and is unchanged by other Resets.

PIC16F946

TABLE 2-4: PIC16F946 SPECIAL FUNCTION REGISTERS SUMMARY BANK 3

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR/BOR

Reset

Value on

all other

Resets(1)

Bank 3

180h INDF Addressing this location uses contents of FSR to address data memory (not a physical

181h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

182h PCL Program Counter (PC) Least Significant Byte 0000 0000 0000 0000

183h STATUS IRP RP1 RP0 TO PD ZDCC0001 1xxx 000q quuu

184h FSR Indirect Data Memory Address Pointer xxxx xxxx uuuu uuuu

185h TRISF TRISF7 TRISF6 TRISF5 TRISF4 TRISF3 TRISF2 TRISF1 TRISF0 1111 1111 1111 1111

186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 1111 1111 1111 1111

187h TRISG —— TRISG5 TRISG4 TRISG3 TRISG2 TRISG1 TRISG0 --11 1111 --11 1111

188h PORTF RF7 RF6 RF5 RF4 RF3 RF2 RF1 RF0 xxxx xxxx uuuu uuuu

189h PORTG —— RG5 RG4 RG3 RG2 RG1 RG0 --xx xxxx --uu uuuu

18Ah PCLATH — — — Write Buffer for the upper 5 bits of the Program Counter ---0 0000 ---0 0000

18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

18Ch EECON1 EEPGD — — — WRERR WREN WR RD 0--- x000 0--- q000

18Dh EECON2 EEPROM Control Register 2 (not a physical register) ---- ---- ---- ----

190h LCDDATA12 SEG31

COM0 SEG30

COM0 SEG29

COM0 SEG28

COM0 SEG27

COM0 SEG26

COM0 SEG25

COM0 SEG24

COM0 xxxx xxxx uuuu uuuu

191h LCDDATA13 SEG39

COM0 SEG38

COM0 SEG37

COM0 SEG36

COM0 SEG35

COM0 SEG34

COM0 SE33

COM0 SEG32

COM0 xxxx xxxx uuuu uuuu

192h LCDDATA14 ——————SEG41

COM0 SEG40

COM0 ---- --xx ---- --uu

193h LCDDATA15 SEG31

COM1 SEG30

COM1 SEG29

COM1 SEG28

COM1 SEG27

COM1 SEG26

COM1 SEG25

COM1 SEG24

COM1 xxxx xxxx uuuu uuuu

194h LCDDATA16 SEG39

COM1 SEG38

COM1 SEG37

COM1 SEG36

COM1 SEG35

COM1 SEG34

COM1 SEG33

COM1 SEG32

COM1 xxxx xxxx uuuu uuuu

195h LCDDATA17 ——————SEG41

COM1 SEG40

COM1 ---- --xx ---- --uu

196h LCDDATA18 SEG31

COM2 SEG30

COM2 SEG29

COM2 SEG28

COM2 SEG27

COM2 SEG26

COM2 SEG25

COM2 SEG24

COM2 xxxx xxxx uuuu uuuu

197h LCDDATA19 SEG39

COM2 SEG38

COM2 SEG37

COM2 SEG36

COM2 SEG35

COM2 SEG34

COM2 SEG33

COM2 SEG32

COM2 xxxx xxxx uuuu uuuu

198h LCDDATA20 ——————SEG41

COM2 SEG40

COM2 ---- --xx ---- --uu

199h LCDDATA21 SEG31

COM3 SEG30

COM3 SEG29

COM3 SEG28

COM3 SEG27

COM3 SEG26

COM3 SEG25

COM3 SEG24

COM3 xxxx xxxx uuuu uuuu

19Ah LCDDATA22 SEG39

COM3 SEG38

COM3 SEG37

COM3 SEG36

COM3 SEG35

COM3 SEG34

COM3 SEG33

COM3 SEG32

COM3 xxxx xxxx uuuu uuuu

19Bh LCDDATA23 ——————SEG41

COM3 SEG40

COM3 ---- --xx ---- --uu

19Ch LCDSE3(2) SE31 SE30 SE29 SE28 SE27 SE26 SE25 SE24 0000 0000 uuuu uuuu

19Dh LCDSE4(2) SE39 SE38 SE37 SE36 SE35 SE34 SE33 SE32 0000 0000 uuuu uuuu

19Eh LCDSE5(2) —————— SE41 SE40 ---- --00 ---- --uu

19Fh —Unimplemented — —

Legend: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented

Note 1: Other (non Power-up) Resets include MCLR R ese t and Watchdog Timer Re set dur i ng nor ma l opera ti on .

2: This register is only initialized by a POR or BOR reset and is unchanged by other Resets.

PIC16F946

2.2.2.1 Status Register

The Status register, shown in Register 2-1, contains:

• the ari thmetic status of the ALU

• the Reset status

• the bank select bits for data memory (SRAM)

The Status register can be the destination for any

instruction, like any other register. If the Status register

is the destination for an instruction that affects the Z,

DC or C bits, then the write to these three bits is

disabl ed. These bit s are set or clea red according to the

device logic. Furthermore, the TO and PD bits are not

writable. Therefore, the result of an instruction with the

Status register as destination may be different than

intended.

For example, CLRF STATUS will clear the upper three

bits and set th e Z bit. Thi s leaves the Status re gister a s

‘000u u1uu’ (where u = unchanged).

It is recommended, therefore, that only BCF, BSF,

SWAPF and MOVWF instructions are used to alter the

S tatus r egister , because these in structions do no t affect

any Status bits. For other instructions not affecting any

Status bits (see Section 17.0 “Instruction Set

Summary”).

Note 1: The C and DC bits operate as a Borrow

and Digit Borrow out bit, respectively, in

subtraction. See the SUBLW and SUBWF

instructions for examples.

R/W-0 R/W-0 R/W-0 R-1 R-1 R/W-x R/W-x R/W-x

IRP RP1 RP0 TO PD ZDCC

bit 7 bit 0

bit 7 IRP: Register Bank Select bit ( used f or in dire ct add ressing)

1 = Bank 2, 3 (100h-1FFh)

0 = Bank 0, 1 (00h-FFh)

bit 6-5 RP<1:0>: Register Bank Select bits (used for direct addressing)

00 = Bank 0 (00h-7Fh)

01 = Bank 1 (80h-FFh)

10 = Bank 2 (100h-17Fh)

11 = Bank 3 (180h-1FFh)

bit 4 TO: Time-out bit

1 = After power-up, CLRWDT instruction or SLEEP instruction

0 = A WDT time-out occurred

bit 3 PD: Power-down bit

1 = After power-up or by the CLRWDT instruction

0 = By execution of the SLEEP instruction

bit 2 Z: Zero bit

1 = The result of an arithmetic or logic operation is zero

0 = The result of an arithmetic or logic operation is not zero

bit 1 DC: Digit Carry/Borrow bit (ADDWF, ADDLW,SUBLW,SUBWF instructions )(1)

1 = A carry-out from the 4th low-order bit of the result occurred

0 = No carry-out from the 4th low-order bit of the result

bit 0 C: Carry/Borrow bit (ADDWF, ADDLW, SUBLW, SUBWF instructions)(1)

1 = A carry-out from the Most Significant bit of the result occurred

0 = No carry-out from the Most Significant bit of the result occurred

Note 1: For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s

complement of the second operand. For rotate (RRF, RLF) instructions, this bit is

loaded with either the high or low-order bit of the source register.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.2.2.2 Option Register

The Option register is a readable and writable register,

which contains various control bits to configure:

• TMR0/WDT prescaler

• External R B0/INT int errupt

•TMR0

• Weak pull-ups on PORTB

Note: To achieve a 1:1 prescaler assignment for

TMR0, assign the prescaler to the WDT by

setting PSA bit to ‘1’ (OPTION_REG<3>).

See Section 5.4 “Prescaler”.

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0

bit 7 bit 0

bit 7 RBPU: PORTB Pull-up Enable bit

1 = PORTB pull-ups are disabled

0 = PORTB pull-ups are enabled by individual port latch values

bit 6 INTEDG: Interrupt Edge Select bit

1 = Interrupt on rising edge of RB0/INT/SEG0 pin

0 = Interrupt on falling edge of RB0/INT/SEG0 pin

bit 5 T0CS: TMR0 Clock Sourc e Sele ct bit

1 = Transition on RA4/C1OU T/T0CKI/SEG4 pin

0 = Internal instruction cycle clock (CLKO)

bit 4 T0SE: TMR0 Source Edge Select bit

1 = Increment on high-to-low transition on RA4/C1OUT/T0CKI/SEG4 pin

0 = Increment on low-to-high transition on RA4/C1OUT/T0CKI/SEG4 pin

bit 3 PSA: Prescaler Assignment bit

1 = Prescaler is assigned to the WDT

0 = Prescaler is assigned to the Timer0 module

bit 2-0 PS<2:0>: Prescaler Rate Select bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

000

001

010

011

100

101

110

111

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

1 : 256

1 : 1

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

Bit Value TMR0 Rate WDT Rate

PIC16F946

2.2.2.3 INTCON Register

The INTCON register is a readable and writable

for TMR0 register overflow, PORTB change and

external RB0/INT/SEG0 pin interrupts.

18Bh)

Note: Interru pt flag bit s are set w hen an interr upt

condition occurs, regardless of the state of

its corresponding enable bit or the global

enable bit, GIE (INTCON<7>). User

software should ensure the appropriate

interrupt flag bits are clear prior to

enabling an interrupt.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-x

GIE PEIE T0IE INTE RBIE T0IF INTF RBIF

bit 7 bit 0

bit 7 GIE: Global Interrupt Enable bit

1 = Enables all unmasked interrupts

0 = Disables all inte rrupts

bit 6 PEIE: Peripheral Interrupt Enable bit

1 = Enables all unmasked peripheral interrupts

0 = Disables all peripheral interrupts

bit 5 T0IE: TMR0 Overflow Interrupt Enable bit

1 = Enables the TMR0 interrupt

0 = Disables the TMR0 interrupt

bit 4 INTE: RB0/INT/SEG0 External Interrupt Enable bit

1 = Enables the RB0/INT/SEG0 external interrupt

0 = Disables the RB0/INT/SEF0 external interrupt

bit 3 RBIE: PORTB Change Interrupt Enable bit(1)

1 = Enables the PORTB change interrupt

0 = Disables the PORTB change interrupt

bit 2 T0IF: TMR0 Overflow Interrupt Flag bit(2)

1 = TMR0 register has overflowed (must be cleared in software)

0 = TMR0 reg i ster did not overflow

bit 1 INTF: RB0/INT/SEG0 External Interrupt Flag bit

1 = The RB0/INT/SEG0 external interrupt occurred (must be cleared in software)

0 = The RB0/INT/SEG0 external interrupt did not occur

bit 0 RBIF: PORTB Change Interrupt Flag bit

1 = When at least one of the PORTB <5:0> pins changed state (must be cleared in software)

0 = None of the PORTB <7:4> pins have changed state

Note 1: IOCB register must also be enabled.

2: T0IF bit is set when Timer0 rolls over. Timer0 is unchanged on Reset and should

be initialized before clearing T0IF bit.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.2.2.4 PIE 1 Register

The PIE1 regis te r con t ai ns th e in terrupt enabl e bi t s, a s

shown in Register 2-1.

Note: Bit PEIE (INTCON<6>) must be set to

enable any peripheral interrupt.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE

bit 7 bit 0

bit 7 EEIE: EE Write Complete Interrupt Enable bit

1 = Enabled

0 = Disabled

bit 6 ADIE: A/D Converter Interrupt Enable bit

1 = Enabled

0 = Disabled

bit 5 RCIE: USART Rece iv e Interru pt Enab le bit

1 = Enabled

0 = Disabled

bit 4 TXIE: USART Transmit Interrupt Enable bit

1 = Enabled

0 = Disabled

bit 3 SSPIE: Synchronous Serial Port (SSP) Interrupt Enable bit

1 = Enabled

0 = Disabled

bit 2 CCP1IE: CCP1 Interrupt Enable bit

1 = Enabled

0 = Disabled

bit 1 TMR2IE: TMR2 to PR2 Match Interrupt Enable bit

1 = Enabled

0 = Disabled

bit 0 TMR1IE: TMR1 Overflow Interrupt Enable bit

1 = Enabled

0 = Disabled

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.2.2.5 PI E2 Regi st er

The PIE2 regis te r con t ai ns th e in terrupt enabl e bi t s, a s

shown in Register 2-5.

Note: Bit PEIE (INTCON<6>) must be set to

enable any peripheral interrupt.

R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0 U-0 R/W-0

OSFIE C2IE C1IE LCDIE —LVDIE— CCP2IE

bit 7 bit 0

bit 7 OSFIE: Oscillator Fail Interrupt Enable bit

1 = Enabled

0 =Disabled

bit 6 C2IE: Comparator 2 Interrupt Enable bit

1 = Enables Comparator 2 interrupt

0 = Disables Comparator 2 interrupt

bit 5 C1IE: Comparator 1 Interrupt Enable bit

1 = Enables Comparator 1 interrupt

0 = Disables Comparator 1 interrupt

bit 4 LCDIE: LCD Module Interrupt Enable bit

1 = LCD interrupt is enabled

0 = LCD interrupt is disabled

bit 3 Unimplemented: Read as ‘0’

bit 2 LVDIE: Low Voltage Detect Interrupt Enable bit

1 = Enables LVD Interrupt

0 = Disa bl es LVD Interrupt

bit 1 Unimplemented: Read as ‘0’

bit 0 CCP2IE: CCP2 Interrupt Enable bit (only available in PIC16F914/917)

1 = Enables the CCP2 interrupt

0 = Disables the CCP2 interrupt

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.2.2.6 PIR1 Register

The PIR1 register contains the interrupt flag bits, as

shown in Register 2-6.

Note: Interrupt flag bits are set when an interrupt

condition occurs, regardless of the state of

its corresponding enable bit or the global

enable bit, GIE (INTCON<7>). User

software should ensure the appropriate

interrupt flag bits are cle ar prior to ena bling

an interrupt.

R/W-0 R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0

EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF

bit 7 bit 0

bit 7 EEIF: EE Write Operation Interrupt Flag bit

1 = The write operation completed (must be cleared in software)

0 = The write operation has not completed or has not started

bit 6 ADIF: A/D Converter Interrupt Flag bit

1 = The A/D conversion completed (must be cleared in software)

0 = The A/D conversion is not complete

bit 5 RCIF: USART Receive Interrupt Flag bit

1 = The USART receive buffer is full (cleared by reading RCREG)

0 = The USART receive buffer is not full

bit 4 TXIF: USART Transmit Interrupt Flag bit

1 = The USART transmit buffer is empty (cleared by writing to TXREG)

0 = The USART transmit buffer is full

bit 3 SSPIF: Synchronous Serial Port (SSP) Interrupt Flag bit

1 = The Transmission/Reception is complete (must be cleared in software)

0 = Waiting to Transmit/Receive

bit 2 CCP1IF: CCP1 Interrupt Flag bit

Capture Mode:

1 = A TMR1 register capture occurred (must be cleared in software)

0 = No TMR1 register capture occurred

Compare Mode:

1 = A TMR1 register compare match occurred (must be cleared in software)

0 = No TMR1 register compare match occurred

PWM mode:

Unused in this mode

bit 1 TMR2IF: TMR2 to PR2 Interrupt Flag bit

1 = A TMR2 to PR2 match occurred (must be cleared in software)

0 = No TMR2 to PR2 match occurred

bit 0 TMR1IF: TMR1 Overflow Interrupt Flag bit

1 = The TMR1 regist er overflowed (must be cleared in software)

0 = The TMR1 register did not overflow

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.2.2.7 PIR2 Register

The PIR2 register contains the interrupt flag bits, as

shown in Register 2-7.

Note: Interrupt flag bits are set when an interrupt

condition occurs, regardless of the state of

its corresponding enable bit or the global

enable bit, GIE (INTCON<7>). User

software should ensure the appropriate

interrupt flag bits are cle ar prior to ena bling

an interrupt.

R/W-0 R/W-0 R-0 R-0 U-0 R/W-0 U-0 R/W-0

OSFIF C2IF C1IF LCDIF —LVDIF— CCP2IF

bit 7 bit 0

bit 7 OSFIF: Oscillator Fail Interrupt Flag bit

1 = System osci llator faile d, clock inpu t has chan ged to IN TOSC (m ust be cleared in software)

0 = System clock operating

bit 6 C2IF: Comparator 2 Interrupt Flag bit

1 = Comparator output (C2OUT bit) has changed (must be cleared in software)

0 = Comparator output (C2OUT bit) has not changed

bit 5 C1IF: Comparator 1 Interrupt Flag bit

1 = Comparator output (C1OUT bit) has changed (must be cleared in software)

0 = Comparator output (C1OUT bit) has not changed

bit 4 LCDIF: LCD Module Interrupt bit

1 = LCD has generated an interrupt

0 = LCD h as not generated an interrupt

bit 3 Unimplemented: Read as ‘0’

bit 2 LVDIF: Low Voltage Detect Interrupt Flag bit

1 = LVD has generated an interrupt

0 = LVD has not generated an interrupt

bit 1 Unimplemented: Read as ‘0’

bit 0 CCP2IF: CCP2 Interrupt Flag bit (only available in PIC16F914/917)

Capture Mode:

1 = A TMR1 register capture occurred (must be cleared in software)

0 = No TMR1 register capture occurred

Compare Mode:

1 = A TMR1 register compare match occurred (must be cleared in software)

0 = No TMR1 register compare match occurred

PWM mode:

Unused in this mode

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.2.2.8 PCON Regi st er

The Power Control (PCON) regist er (See Regist er 2-8)

cont ains flag bit s to differentiate between a:

• Power-on Reset (POR)

• Brown-out Reset (BOR)

• Watchdog Timer Reset (WDT)

• External MCLR Reset

The PCON register also controls the software en able of

the BOR.

The PCON register bits are shown in Register 2-8.

U-0 U-0 U-0 R/W-1 U-0 U-0 R/W-0 R/W-x

— — — SBOREN ——PORBOR

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4 SBOREN: Software BOR Enable bit(1)

1 = BOR enabled

0 = BOR disabled

bit 3-2 Unimplemented: Read as ‘0’

bit 1 POR: Power-on Reset Status bit

1 = No Power-on Reset occurred

0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)

bit 0 BOR: Brown-out Reset Status bit

1 = No Brown-out Reset occurred

0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs)

Note 1: BOREN<1:0> = 01 in the Configuration Word register for this bit to c ontrol the BOR.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

2.3 PCL and PCLATH

The Program Counter (PC) is 13 bits wide. The low

byte comes from the PCL register , which is a readable

and writable register . The high byte (PC<12:8>) is not

directly readable or writable and comes from

PCLA TH. On any Reset, the PC is cleared. Figure 2-3

shows the two situations for the loading of the PC. The

upper example in Figure 2-3 shows how the PC is

loaded on a write to PCL (PCLATH<4:0> → PCH).

The lower example in Figure 2-3 shows how the PC is

loaded during a CALL or GOTO instruction

(PCLATH<4:3> → PCH).

FIGURE 2-3: LOADING OF PC IN

DIFFERENT SITUATIONS

2.3.1 COMPUTED GOTO

A comput ed GOTO is a ccom pli shed by a ddi ng a n offset

to the program counter (ADDWF PCL). When perform-

ing a table read using a computed GOTO method, care

should be ex ercise d if th e t able loca tion c rosse s a PCL

memory boundary (each 256-byte block). Refer to the

Application Note AN556, “Implementing a Table Read”

(DS00556).

2.3.2 STACK

The PIC16F946 has an 8-level x 13-bit wide hardware

stack (see Figure 2-1). The stack space is not part of

either program or data space and the Stack Pointer is

not readable or writable. The PC is PUSHed onto the

stack when a CALL instruction is executed or an

interrupt causes a branch. The stack is POPed in the

event of a RETURN, RETLW or a RETFIE instruction

execution. PCLATH is not affected by a PUSH or POP

operation.

The st ack operates as a circular buf fer . This means that

after the st ack has been PUSHed ei ght times, th e ninth

PUSH overwrites the value that was stored from the

first PUSH. The tenth PUSH overwrites the second

PUSH (and so on).

2.4 Program Memory Paging

The PIC16F946 device is capable of addressing a

continuous 8K word block of program memory. The

CALL and GOTO instructions provide only 11 bits of

address to allow branching within any 2K program

memory page. When doing a CALL or GOTO instruction,

the upper 2 bits of the address are provided by

PCLA TH<4:3>. When doing a CALL or GOTO instruction,

the user must ensure that the page select bits are

programmed so that the desired program memory page

is addressed. If a return from a CALL instruction (or

interrupt) is executed, t he entire 13-bit PC is POPed off

the stack. Therefore, manipulation of the PCLATH<4:3>

bits is not required for the RETURN instructions (which

POPs the address from the stack).

Example 2-1 shows the calling of a subroutine in

page 1 o f the program memory . This examp le assume s

that PCLATH is saved and restored by the Interrupt

Service Routi ne (if interrupts are used).

EXAMPLE 2-1: CALL OF A SUBROUTINE

IN PAGE 1 FROM PAGE 0

12 8 7 0

5PCLATH<4:0>

PCLATH

Instruction wit

ALU Result

GOTO, CALL

OPCODE<10:0>

12 11 10 0

PCLATH<4:3>

PCH PCL

PCLATH

PCH PCL

PCL a

Destinatio

Note 1: There are no Status bits to indicate stack

overflow or stack underflow conditions.

2: There are no instructions/mnemonics

called PUSH or POP. These are actions

that occur from the executi on of the CALL,

RETURN, RETLW and RETFIE instruc-

tions or the vectoring to an interrupt

address.

Note: The contents of the PCLATH register are

unchanged after a RETURN or RETFIE

instruction is executed. The user must

rewrite the contents of the PCLATH regis-

ter for any subsequent subroutine calls or

GOTO instructions.

ORG 0x500

BCF PCLATH,4

BSF PCLATH,3 ;Select page 1

;(800h-FFFh)

CALL SUB1_P1 ;Call subroutine in

: ;page 1 (800h-FFFh)

ORG 0x900 ;page 1 (800h-FFFh)

SUB1_P1

: ;called subroutine

;page 1 (800h-FFFh)

RETURN ;return to

;Call subroutine

;in page 0

;(000h-7FFh)

PIC16F946

2.5 Indirect Addressing, INDF and

FSR Registers

The INDF register is no t a physica l register. Addres sing

the INDF register will cause indirect addressing.

Indirect addressing is possible by using the INDF

actually accesses data pointed to by the File Select

produce 00h. Writing to the INDF register indirectly

results in a no operation (although Status bits may be

affected). An effective 9-bit address is obtained by

concatenating the 8-bit FSR register and the IRP bit

(STATUS<7>), as shown in Figu re 2-4.

A simple pro gram to clear R AM locatio n 20h-2Fh usin g

indirect addressing is shown in Example 2-2.

EXAMPLE 2-2: INDIRECT ADDRESSING

FIGURE 2-4: DIRECT/INDIRECT ADDRESSING PIC16F946

MOVLW 0x20 ;initialize pointer

MOVWF FSR ;to RAM

NEXTCLRF INDF ;clear INDF register

INCF FSR ;inc pointer

BTFSS FSR,4 ;all done?

GOTO NEXT ;no clear next

CONTINUE ;yes continue

Note: For memory map detail, see Figure 2-1.

Data

Memory

Indirect AddressingDirect Addressing

Bank Select Locatio n Select

RP1 RP0 6 0

From Opcode IRP File Select Register

Bank Select Location Se lect

00 01 10 11 180h

1FFh

00h

7Fh

Bank 0 Bank 1 Bank 2 Bank 3

PIC16F946

3.0 I/O P ORTS

This dev ic e i nc lud es four 8 -bi t port registers alo ng w i th

their corresponding TRIS registers and one four bit

port:

• PORTA and TRISA

• PORTB and TRISB

• PORTC and TRISC

• PORTD and TRISD

• PORTE and TRISE

• PORTF and TRISF

• PORTG and TRISG

3.1 PORTA and TRISA Registers

PORTA is a 8-bit wide, bidirectional port. The

corresponding data direction register is TRISA

(Register 3-2). Setting a TRISA bit (= 1) will make the

corresponding PORTA pin an input (i.e., put the

corresponding output driver in a High-impedance mode).

Clearing a TRISA bit (= 0) will make the corresponding

PORTA pin an output (i.e., put the contents of the output

latch on the selected pin). Example 3-1 shows how to

initialize PORTA.

Five o f the p ins o f PORT A c an be con figured as analo g

inputs. These pins, RA5 and RA<3:0>, are configured

as analog inputs on device power-up and must be

reconfigured by the user to be used as I/O’s. This is

done b y w riting the a ppropri ate v alues to the CMCO N0

and ANSEL registers (see Example 3-1).

Reading the PORTA register (Register 3-1) reads the

status of the pins, whereas writing to it will write to the

port latch. All write operations are read-modify-write

operations. Therefore, a write to a port implies that the

port pins are rea d, this value is modified and then w ritten

to the port data la tch.

The TRISA register controls the direction of the

PORTA pins, even when they are being us ed as analog

inputs. The user must ensure the bits in the TRISA

input s. I/O pin s co nfigure d as analo g inpu t alway s rea d

‘0’.

EXAMPLE 3- 1: INITIALI ZING PORTA

Note 1: The CMCON0 (9Ch) register must be

initialized to configure an analog channel

as a digital input. Pins configured as

analog inputs will read ‘0’.

2: Analog lines that carry LCD signals

(i.e., SEGx, COMy, where x and y are

segment and common identifiers) are

shown as direct connectio ns to the device

pins. The signals are outputs from the

LCD module and may be tri-stated,

depending on the configuration of the

LCD mo dul e.

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

CLRF PORTA ;Init PORTA

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW 07h ;Set RA<2:0> to

MOVWF CMCON0 ;digital I/O

CLF ANSEL ;Make all PORTA I/O

MOVLW F0h ;Set RA<7:4> as inputs

MOVWF TRISA ;and set RA<3:0>

; as outputs

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

PIC16F946

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0

bit 7 bit 0

bit 7-0 RA<7:0>: PORTA I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0

bit 7 bit 0

bit 7-0 TRISA<7:0>: PORTA Tri-State Control bits

1 = PORTA pin configured as an input (tri-stated)

0 = PORTA pin configured as an output

Note: TRISA<7:6> always reads ‘1’ in XT, HS and LP OSC modes.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.1.1 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTA pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions,

refer to the appropriate section in this data sheet.

3.1.1.1 RA0/AN0/C1-/SEG12

Figure 3-1 shows the diagram for this pin. The

RA0/AN0/C 1 -/SEG 12 pin is c onf igu rabl e t o fu nc tio n a s

one of the following:

• a general purpose I/O

• an analog input for the A/D

• an analog input for Comparator 1

• an analog output for the LCD

FIGURE 3-1: BLOCK DIAGRAM OF RA0/AN0/C1-/SEG12

Data Latch

TRIS Latch

RD TRISA

RD PORTA

Analog Input or

I/O Pin

TTL

Input Buffer

VDD

To A/D Co nverter or Compar ator

SEG12

SE12 and LCDEN

Data Bus

WR PORTA

WR TRISA

SE12 and LCDEN

PIC16F946

3.1.1.2 RA1/AN1/C2-/SEG7

Figure 3-2 shows the diagram for this pin. The

RA1/AN1/C2-/SEG7 pin is configurable to function as

one of the following:

• a general purpose I/O

• an analog input for the A/D

• an analog input for Comparator 2

• an analog output for the LCD

FIGURE 3-2: BLOCK DIAGRAM OF RA1/AN1/C2-/SEG7

Data Latch

TRIS Latch

RD TRISA

RD PORTA

To A/D Converter or Comparator

SEG7

Data Bus

WR PORTA

WR TRISA

Analog Input or

I/O Pin

TTL

Input Buffer

VDD

SE7 and LCDEN

PIC16F946

3.1.1.3 RA2/AN2/C2+/VREF-/COM2

Figure 3-3 shows the diagram for this pin. The

RA2/AN2/C2+/VREF-/COM2 pin is configurable to

function as one of the following:

• a general purpose I/O

• an analog input for the A/D

• an analog input for Comparator 2

• a voltage reference input for the A/D

• an analog output for the LCD

FIGURE 3-3: BLOCK DIAGRAM OF RA2/AN2/C2+/VREF-/COM2

Data Latch

TRIS Latch

RD TRISA

RD PORTA

To A/D Converter or Comparator

COM2

Data Bus

WR PORTA

WR TRISA

To A/D Module VREF- Input

Analog Input or

I/O Pin

TTL

Input Buffer

VDD

LCDEN and

LMUX<1:0> = 1X

LCDEN and

LMUX<1:0> = 1X

LCDEN and

LMUX<1:0> = 1X

PIC16F946

3.1.1.4 RA3/AN3/C1+/VREF+/SEG15

Figure 3-4 shows the diagram for this pin. The

RA3/AN3/C1+/VREF+/COM3/SEG15 pin is

configurable to function as one of the following:

• a general purpose in put

• an analog input for the A/D

• a voltage reference input for the A/D

• analog outputs for the LCD

FIGURE 3-4: BLOCK DIAGRAM OF RA3/AN3/C1+/VREF+/SEG15

Data Latch

TRIS Latch

RD TRISA

RD PORTA

VSS

TTL

Input Buffer

SEG15

Data Bus

WR PORTA

WR TRISA

To A/D Module VREF+ Input

VDD

Analog Input or

I/O Pin

SE15 and LCDEN

PIC16F946

3.1.1.5 RA4/C1OUT/T0CKI/SEG4

Figure 3-5 shows the diagram for this pin. The

RA4/C1OUT/T0CKI/SEG4 pin is configurable to

function as one of the following:

• a general purpose I/O

• a digital output from Comparator 1

• a clock input for TMR0

• an analog output for the LCD

FIGURE 3-5: BLOCK DIAGRAM OF RA4/C1OUT/T0CKI/SEG4

C1OUT

CM<2:0> = 110 or 101

Schmitt

Trigger

Data Latch

TRIS Latch

RD TRISA

RD PORTA

VSS

VDD

T0CKI

Data Bus

WR PORTA

WR TRISA

SEG4

Analog Input or

I/O Pin

TTL

Input Buffer

SE4 and LCDEN

PIC16F946

3.1.1.6 RA5/AN4/C2OUT/SS/SEG5

Figure 3-6 shows the diagram for this pin. The

RA5/AN4/C2OUT/SS/SEG5 pin is configurable to

function as one of the following:

• a general purpose I/O

• a digital output from Comparator 2

• a slave select input

• an analog output for the LCD

• an analog input for the A/D

FIGURE 3-6: BLOCK DIAGRAM OF RA5/AN4/C2OUT/SS/SEG5

AN4

RD TRISA

RD PORTA

TTL

SEG5

SE5 and LCDEN

Data Bus

WR PORTA

WR TRISA

To SS Input

Analog Input or

SE5 and LCDEN

C2OUT

CM<2:0> = 110 or 101

Data Latch

VSS

VDD

I/O Pin

TRIS Latch

SE5 and LCDEN

PIC16F946

3.1.1.7 RA6/OSC2/CLKO/T1OSO

Figure 3-7 shows the diagram for this pin. The

RA6/OSC2/CLKO/T1OSO pin is configurable to

function as one of the following:

• a general purpose I/O

• a crystal/resonator connection

• a clock output

• a TMR1 oscillator connection

FIGURE 3-7: BLOCK DIAGRAM OF RA6/OSC2/CLKO/T1OSO

CLKO (FOSC/4)

FOSC = 1x1

RD PORTA

TTL

Input Buffer

Data Bus

WR PORTA

WR TRISA

FOSC = 00x, 010

RA6/OSC2/

Oscillator

Circuit

From OSC1

CLKO/T1OSO

RD TRISA

Data Latch

VSS

VDD

TRIS Latch

or T1OSCEN or T1OSCEN

PIC16F946

3.1.1.8 RA7/OSC1/CLKI/T1OSI

Figure 3-8 shows the diagram for this pin. The

RA7/OSC1/CLKI/T1OSI pin is configurable to function

as one of the following:

• a general purpose I/O

• a crystal/resonator connection

• a clock input

• a TMR1 oscillator connection

FIGURE 3-8: BLOCK DIAGRAM OF RA7/OSC1/CLKI/T1OSI

TABLE 3-1: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

V alue on all

other

Resets

05h PORTA RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0 xxxx xxxx uuuu uuuu

10h T1CON T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

1Fh ADCON0 ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

81h/181h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

85h TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111

91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

9Ch CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

11Ch LCDSE0(1) SE7 SE6 SE5 SE4 SE3 SE2 SE1 SE0 0000 0000 uuuu uuuu

11Dh LCDSE1(1) SE15 SE14 SE13 SE12 SE11 SE10 SE9 SE8 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TA.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

Data Latch

TRIS Latch

RD TRISA

RD PORTA

TTL

Input Buff er

Data Bus

WR PORTA

WR TRISA

FOSC = 10x FOSC = 10x

RA7/OSC1/

VDD

CLKI/T1OSI

Oscillator

Circuit

From OSC1

FOSC = 011

PIC16F946

3.2 PORTB and TRISB Registers

PORTB is a general purpose I/O port with similar

functionality as the PIC16F914. All PORTB pins can have

a weak pull-up feature, and PORTB<7:4> implements an

interrupt-on-input change function.

PORTB is also used for the Serial Flash programming

interface.

EXAMPLE 3- 2: INITIALIZING PORTB

3.3 Additional PORTB Pin Functions

RB<7:6> are used as data and clock signals, respectively ,

for both serial programming and the in-circuit debugger

features on the device. Also, RB0 can be configured as an

external interrupt input.

3.3.1 WEAK PULL-UPS

Each of the POR TB pins has an individually configurable

internal weak pull-up. Control bits WPUB<7:0> enable or

disable each pull-up. Refer to Register 3-6. Each weak

pull-up is automatically turned off when the port pin is

configured as an output. The pull-ups are disabled on a

Power-on Reset by the RBPU bit (OPTION_REG<7>).

3.3.2 INTERRUPT-ON-CHANGE

Four of the PORTB pins are individually configurable

as an interrupt-on-change pin. Control bits IOCB<7:4>

enable or disable the interrupt function for each pin.

Refer to Register 3-5. The interrupt-on-change feature

is disabled on a Power-on Reset.

For enabled interrupt-on-change pins, the values are

comp ared with the old val ue latch ed on the la st read of

PORTB. The ‘mismatch’ outputs of the last read are

OR’d toge ther to set th e PORTB Cha nge Interrupt Flag

bit (RBIF) in the INTCON register (Register 2-3).

This interrupt can wake the device from Sleep. The user,

in the Interrupt Service Routine, clears the inte rrupt by:

a) Any read or write of PORTB. This will end the

mismatch condition.

b) Clear the flag bit RBIF.

A mism at c h c ond it i on wi ll co nti n ue to s et f lag bi t RB IF.

Reading or writing PORTB will end the mismatch con-

dition and allow flag bit RBIF to be cleared. The latch

holding the last read value is not affected by a MCLR

nor Brown-out Re set. After these Resets, the RBIF flag

will continue to be set if a mismatch is present.

Note: Analog lines that carry LCD signals

(i.e., SEGx , COMy , whe re x and y are seg-

ment and common identifiers) are shown

as direct connections to the device pins.

The signals are outputs from the LCD

module and may be tri-stated, depending

on the configuration of the LCD module.

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

CLRF PORTB ;Init PORTB

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW FFh ;Set RB<7:0> as inputs

MOVWF TRISB ;

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

Note: If a change on the I/O pin should occur

when the read operation is being executed

(start of the Q2 cycle), then the RBIF

interrupt flag may not get set. Furthermore,

since a read or write on a port af fects all bits

of that port, care mu st be taken when us ing

multiple pins in Interrupt-on-change mode.

Changes on one pin may not be seen while

servicing changes on another pin.

PIC16F946

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0

bit 7 bit 0

bit 7-0 RB<7:0>: PORTB I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0

bit 7 bit 0

bit 7-0 TRISB<7:0>: PORTB Tri-State Control bits

1 = PORTB pin configured as an input (tri-stated)

0 = PORTB pin configured as an output

Note: TRISB<7:6> always reads ‘1’ in XT, HS and LP OSC modes.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-0 R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0

IOCB7 IOCB6 IOCB5 IOCB4 ————

bit 7 bit 0

bit 7-4 IOCB<7:4>: Interrupt-on-Change bits

1 = Interrupt-on-change enabled

0 = Interrupt-on-change disabled

bit 3-0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

WPUB7 WPUB6 WPUB5 WPUB4 WPUB3 WPUB2 WPUB1 WPUB0

bit 7 bit 0

bit 7-0 WPUB<7:0>: Weak Pull-up Register bits

1 = Pull-up enabled

0 = Pull-up disabled

Note 1: Global RBPU must be enabl ed for individual pull-ups to be ena bled.

2: The weak pull-up device is automatically disabled if the pin is in Output mode

(TRISB<7:0> = 0).

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.3.3 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTB pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions

such as the LCD or interrupts, refer to the appropriate

section in this data sheet.

3.3.3.1 RB0/INT/SEG0

Figure 3-9 shows the diagram for this pin. The

RB0/INT/SEG 0 pin is configu rable to function as on e of

the following:

• a general purpose I/O

• an external edge triggered interrupt

• an analog output for the LCD

3.3.3.2 RB1/SEG1

Figure 3-9 shows the diagram for this pin. The

RB1/SEG 1 p in is c onf igu r abl e to f unc tio n as one o f the

following:

• a general purpose I/O

• an analog output for the LCD

3.3.3.3 RB2/SEG2

Figure 3-9 shows the diagram for this pin. The

RB2/SEG 2 p in is c onf igu r abl e to f unc tio n as one o f the

following:

• a general purpose I/O

• an analog output for the LCD

3.3.3.4 RB3/SEG3

Figure 3-9 shows the diagram for this pin. The

RB3/SEG 3 p in is c onf igu r abl e to f unc tio n as one o f the

following:

• a general purpose I/O

• an analog output for the LCD

PIC16F946

FIGURE 3-9: BLOCK DIAGRAM OF RB<3:0>

Data Latch

TRIS Latch

RD TRISB

RD PORTB

TTL

Input Buffer

SE<3:0> and LCDEN

Data Bus

WR PORTB

WR TRISB

VDD

I/O Pin

VDD

Weak

Pull-up

SE<3:0>

SEG<3:0>

INT(2) Schmitt

Trigger

SE0 and LCDEN

RBPU(1)

Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.

2: RB0 only.

SE<3:0> and LCDEN

PIC16F946

3.3.3.5 RB4/COM0

Figure 3-10 shows the diagram for this pin. The

RB4/C OM0 pin is configu rable t o function as one of th e

following:

• a general purpose I/O

• an analog output for the LCD

FIGURE 3-10: BLOCK DIAGRAM OF RB4/COM0

From other

Set RBIF

RB<7:4> pins

LCDEN

COM0

Data Latch

TRIS Latch

RD TRISB

RD PORTB

TTL

Input Buffer

LCDEN

Data Bus

WR PORTB

WR TRISB

VDD

I/O Pin

VDD

Weak

Pull-up

LCDEN

RBPU(1)

Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.

LCDEN

EN RD PORTB

EN FOSC/4

PIC16F946

3.3.3.6 RB5/COM1

Figure 3-11 shows the diagram for this pin. The

RB5/C OM1 pin is configu rable t o function as one of th e

following:

• a general purpose I/O

• an analog output for the LCD

FIGURE 3-11: BLOCK DIAGRAM OF RB5/COM1

COM1

Data Latch

TRIS Latch

RD TRISB

TTL

Input Buffer

Data Bus

WR PORTB

WR TRISB

VDD

I/O Pin

VDD

Weak

Pull-up

LCDEN and LMUX<1:0> ≠ 00

RBPU(1)

Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.

LCDEN and LMUX<1:0> ≠ 00

LCDEN and

LCDEN and LMUX<1:0> ≠ 00

From other

Set RBIF

RB<7:4> pins

RD PORTB D

EN FOSC/4

EN RD PORTB

LMUX<1:0> ≠ 00

PIC16F946

3.3.3.7 RB6/ICSPCLK/ICDCK/SEG14

Figure 3-12 shows the diagram for this pin. The

RB6/ICSPCLK/ICDCK/SEG14 pin is configurable to

function as one of the following:

• a general purpose I/O

• an In-Circuit Serial Programming™ clock

• an ICD clock I/ O

• an analog output for the LCD

FIGURE 3-12: BLOCK DIAGRAM OF RB6/ICSPCLK/ICDCK/SEG14

Prog ram Mode/ICD

PGC

Data Latch

TRIS Latch

RD TRISB

TTL

Input Buffer

SE14 and LCDEN

Data Bus

WR PORTB

WR TRISB

VDD

I/O Pin

VDD

Weak

Pull-up

SE14 and LCDEN

RBPU(1)

Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.

Prog ram Mode/ICD

SEG14

Schmitt

Trigger Buffer

SE14 and LCDEN

From other

Set RBIF

RB<7:4> pins

RD PORTB D

EN RD PORTB

EN FOSC/4

PIC16F946

3.3.3.8 RB7/ICSPDAT/ICDDAT/SEG13

Figure 3-13 shows the diagram for this pin. The

RB7/ICSPDAT/ICDDAT/SEG13 pin is configurable to

function as one of the following:

• a general purpose I/O

• an In-Circuit Serial Programming™ I/O

• an ICD data I/O

• an analog output for the LCD

FIGURE 3-13: BLOCK DIAGRAM OF RB7/ICSPDAT/ICDDAT/SEG13

PGD

Data Latch

TRIS Latch

RD TRISB

TTL

Input Buffer

SE13 and LCDEN

Data Bus

WR PORTB

WR TRISB

VDD

I/O Pin

VDD

Weak

Pull-up

SE13 and LCDEN

RBPU(1)

Note 1: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.

PORT/Program Mode/ICD

SEG13

Schmitt

Trigger Buffer

SE13 and LCDEN

PGD DRVEN

PGD

SE13 and LCDEN

Program Mode/ICD

From other

Set RBIF

RB<7:4> pins

RD PORTB D

EN RD PORTB

FOSC/4

PIC16F946

TABLE 3-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTB

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

V alue on all

other

Resets

06h/106h PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 xxxx xxxx uuuu uuuu

86h/186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 TRISB3 TRISB2 TRISB1 TRISB0 1111 1111 1111 1111

0Bh/8Bh/

10Bh/18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

95h WPUB WPUB7 WPUB6 WPUB5 WPUB4 WPUB3 WPUB2 WPUB1 WPUB0 1111 1111 1111 1111

96h IOCB IOCB7 IOCB6 IOCB5 IOCB4 — — — — 0000 ---- 0000 ----

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

11Ch LCDSE0(1) SE7 SE6 SE5 SE4 SE3 SE2 SE1 SE0 0000 0000 uuuu uuuu

11Dh LCDSE1(1) SE15 SE14 SE13 SE12 SE11 SE10 SE9 SE8 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TB.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

PIC16F946

3.4 PORTC and TRISC Registers

PORTC is an 8-bit bidirectional port. PORTC is

multiplexed with several peripheral functions. PORTC

pins have Schmitt T rigger input buffers.

All PORTC pins have latch bits (PORTC register).

They, when written, will modify the contents of the

PORTC latch; thus, modifying the value driven out on

a pin if the corresponding TRISC bit is configured for

output.

EXAMPLE 3- 3: INITIALI ZING PORTC

Note: Analog lines that carry LCD signals

(i.e., SEGx, VLCDy, where x and y are

segmen t an d LC D b ias v oltage identifiers)

are shown as direct connections to the

device pins. The signals are outputs from

the LCD module and may be tri-stated,

dependi ng on the config uration of th e LCD

module.

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

CLRF PORTC ;Init PORTC

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW FFh ;Set RC<7:0> as inputs

MOVWF TRISC ;

BCF STATUS,RP0 ;Bank 2

BSF STATUS,RP1 ;

CLRF LCDCON ;Disable VLCD<3:1>

;inputs on RC<2:0>

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0

bit 7 bit 0

bit 7-0 RC<7:0>: PORTC I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0

bit 7 bit 0

bit 7-0 TRISC<7:0>: PORTC Tri-State Control bits

1 = PORTC pin configured as an input (tri-stated)

0 = PORTC pin configured as an output

Note: TRISC<7:6> always read s ‘1’ in XT, HS and LP OSC modes.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.4.1 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTC pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions

such as the LCD or SSP, refer to the appropriate section

in this data sheet.

3.4.1.1 RC0/VLCD1

Figure 3-14 shows the diagram for this pin. The

RC0/VLCD1 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog input for the LCD bias voltage

3.4.1.2 RC1/VLCD2

Figure 3-15 shows the diagram for this pin. The

RC1/VLCD2 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog input for the LCD bias voltage

3.4.1.3 RC2/VLCD3

Figure 3-16 shows the diagram for this pin. The

RC2/VLCD3 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog input for the LCD bias voltage

FIGURE 3-14: BLOCK DIAGRAM OF RC0/VLCD1

RD PORTC

VLCD1

RC0/VLCD1

Schmitt

Trigger

VDD

Data Latch

TRIS Latch

RD TRISC

Data Bus

WR PORTC

WR TRISC

(VLCDEN and LMUX<1:0> ≠ 00)

PIC16F946

FIGURE 3-15: BLOCK DIAGRAM OF RC1/VLCD2

FIGURE 3-16: BLOCK DIAGRAM OF RC2/VLCD3

RD PORTC

VLCD2

RC1/VLCD2

Schmitt

Trigger

VDD

Data Latch

TRIS Latch

RD TRISC

Data Bus

WR PORTC

WR TRISC

(VLCDEN and LMUX<1:0> ≠ 00)

RD PORTC

VLCD3

RC2/VLCD3

Schmitt

Trigger

VDD

Data Latch

TRIS Latch

RD TRISC

Data Bus

WR PORTC

WR TRISC

VLCDEN

PIC16F946

3.4.1.4 RC3/SEG6

Figure 3-17 shows the diagram for this pin. The

RC3/SEG6 pin is config urable to functi on as on e of the

following:

• a general purpose I/O

• an analog output for the LCD

FIGURE 3-17: BLOCK DIAGRAM OF RC3/SEG6

RD PORTC

SEG6

RC3/SEG6

Schmitt

Trigger

VDD

Data Latch

TRIS Latch

RD TRISC

Data Bus

WR PORTC

WR TRISC

SE6 and LCDEN

PIC16F946

3.4.1.5 RC4/T1G/SDO/SEG11

Figure 3-18 shows the diagram for this pin. The

RC4//T1G/SDO/SEG11pin is configurable to function

as one of the following:

• a general purpose I/O

• a TMR1 gate input

• a serial data output

• an analog output for the LCD

FIGURE 3-18: BLOCK DIAGRAM OF RC4/T1G/SDO/SEG11

SDO

PORT/SDO Select

RD PORTC

Data Bus

WR PORTC

WR TRISC

RC4/T1G/

RD TRISC

Data Latch

VSS

VDD

TRIS Latch

Schmitt

Trigger

SE11 and LCDEN

Ti me r1 Gate

SEG11 SE11 and LCDEN

SDO/SEG1

EN Q1

PIC16F946

3.4.1.6 RC5/T1CKI/CCP1/SEG10

Figure 3-19 shows the diagram for this pin. The

RC5/T1CKI/CCP1/SEG10 pin is configurable to

function as one of the following:

• a general purpose I/O

•a TMR1 clock input

• a Capture input, Compare output or PWM output

• an analog output for the LCD

FIGURE 3-19: BLOCK DIAGRAM OF RC5/T1CKI/CCP1/SEG10

CCP1 Data Out

(PORT/CCP1 Select) and CCPMX

RD PORTC

Data Bus

WR PORTC

WR TRISC

RC5/T1CKI/

RD TRISC

Data Latch

VSS

VDD

TRIS Latch

Schmitt

Trigger

SE10 and LCDEN

Timer1 Gate

SEG10 SE10 and LCDEN

CCP1/SEG1

PIC16F946

3.4.1.7 RC6/TX/CK/SCK/SCL/SEG9

Figure 3-20 shows the diagram for this pin. The

RC6/TX/CK/SCK/SCL/SEG9 pin is configurable to

function as one of the following:

• a general purpose I/O

• an asynchronous serial output

• a synchronous clock I/O

• a SPI clock I/O

•an I

2C data I/O

• an analog output for the LCD

FIGURE 3-20: BLOCK DIAGRAM OF RC6/TX/CK/SCK/SCL/SEG9

TX/CK Data Out

I2C™ Data Out

RD PORTC

Data Bus

WR PORTC

WR TRISC

RC6/TX/

RD TRISC

Data Latch

VSS

VDD

TRIS Latch

Schmitt

Trigger

SE9 and LCDEN

CK/SCL/SCK Input

SEG9 SE9 and LCDEN

PORT/SCEN/SSP Mode Select(1)

SCEN or I2C™ Drive

Note 1: If all three data output sources are enabled, the following priority order will be used:

• USAR T data

• SSP data

•PORT data

SCK Data Out

CK/SCK/

SCL/SEG

PIC16F946

3.4.1.8 RC7/RX/DT/SDI/SDA/SEG8

Figure 3-21 shows the diagram for this pin. The

RC7/RX/DT/SDI/SDA/SEG8 pin is configurable to

function as one of the following:

• a general purpose I/O

• an asynchronous serial input

• a synchronous serial data I/O

• a SPI data I/O

•an I

2C data I/O

• an analog output for the LCD

FIGURE 3-21: BLOCK DIAGRAM OF RC7/RX/DT/SDI/SDA/SEG8

Data Bus

WR PORTC

WR TRISC

RD PORTC

RX/SDI Input

SEG8

I2C™ Data Out

Schmitt

Trigger

RC7/RX/DT/

VDD

Data Latch

TRIS Latch

I2C™ Drive

SE8 and LCDEN

RD TRISC

PORT/(SCEN or I2C™) Select

SCEN/I2C™ Mode Select(1)

DT Data Out

or SCEN Drive

SE8 and LCDEN

Note 1: If SSP and USAR T ou tput s are bo th enab led, th e USART dat a outpu t will ha ve prio rity over th e

SSP data output. Both SSP and USART data outputs will have priority over the PORT data

output.

SDI/SDA/

SEG8

PIC16F946

TABLE 3-3: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

V alue on all

other

Resets

07h PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 xxxx xxxx uuuu uuuu

10h T1CON T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

17h CCP1CON — — CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

87h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

11Ch LCDSE0(1) SE7 SE6 SE5 SE4 SE3 SE2 SE1 SE0 0000 0000 uuuu uuuu

11Dh LCDSE1(1) SE15 SE14 SE13 SE12 SE11 SE10 SE9 SE8 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TC.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

PIC16F946

3.5 PORTD and TRISD Registers

PORTD is an 8-bit port with Schmitt Trigger input buffers.

Each pin is ind ividual ly c onfigured as an input or output.

PORTD is only available on the PIC16F946 and

PIC16F946.

EXAMPLE 3- 4: INITIALIZI NG PORTD

Note: Analog lines that carry LCD signals

(i.e., SEGx , COMy , whe re x and y are seg-

ment and common identifiers) are shown

as direct connections to the device pins.

The signals are outputs from the LCD

module and may be tri-stated, depending

on the configuration of the LCD module.

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

CLRF PORTD ;Init PORTD

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW FFh ;Set RD<7:0> as inputs

MOVWF TRISD ;

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0

bit 7 bit 0

bit 7-0 RD<7:0>: PORTD I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

TRISD7 TRISD6 TRISD5 TRISD4 TRISD3 TRISD2 TRISD1 TRISD0

bit 7 bit 0

bit 7-0 TRISD<7:0>: PORTD Tri-State Control bits

1 = PORTD pin configured as an input (tri-stated)

0 = PORTD pin configured as an output

Note: TRISD<7:6> always reads ‘1’ in XT, HS and LP OSC modes.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.5.1 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTD pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions

such as the comparator or the A/D, refer to the

appropriate section in this data sheet.

3.5.1.1 RD0/COM3

Figure 3-22 shows the diagram for this pin. The

RD0/C OM3 pin is conf igurable to func tion as one of the

following:

• a general purpose I/O

• an analog input from Comparator 1

3.5.1.2 RD1

Figure 3-23 shows the diagram for this pin. The RD1

pin is configurable to function as one of the following:

• a general purpose I/O

3.5.1.3 RD2/CCP2

Figure 3-24 shows the diagram for this pin. The

RD2/C CP2 pin is config urable to functi on as on e of the

following:

• a general purpose I/O

• a Capture input, Compare output or PWM output

3.5.1.4 RD3/SEG16

Figure 3-25 shows the diagram for this pin. The

RD3/SEG16 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.5.1.5 RD4/SEG17

Figure 3-25 shows the diagram for this pin. The

RD4/SEG17 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.5.1.6 RD5/SEG18

Figure 3-25 shows the diagram for this pin. The

RD5/SEG18 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.5.1.7 RD6/SEG19

Figure 3-25 shows the diagram for this pin. The

RD6/SEG19 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog output for the LCD

3.5.1.8 RD7/SEG20

Figure 3-25 shows the diagram for this pin. The

RD7/SEG20 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog output for the LCD

PIC16F946

FIGURE 3-22: BLOCK DIAGRAM OF RD0/COM3

FIGURE 3-23: BLOCK DIAGRAM OF RD1

Data Bus

WR PORTD

WR TRISD

RD PORTD

COM3

Schmitt

Trigger

RD0/COM3

VDD

Data Latch

TRIS Latch

LCDEN and LMUX<1:0> = 11

RD TRISD

LCDEN and

LMUX<1:0> = 11

Data Bus

WR PORTD

WR TRISD

RD PORTD

Schmitt

Trigger

RD1 Pin

VDD

Data Latch

TRIS Latch

RD TRISD

PIC16F946

FIGURE 3-24: BLOCK DIAGRAM OF RD2/CCP2

FIGURE 3-25: BLOCK DIAGRAM OF RD<7:3>

Data Bus

WR PORTD

WR TRISD

RD PORTD

CCP2 Input

(PORT/CCP2 Select) and CCPMX

CCP2 Data Out

Schmitt

Trigger

RD2/CCP2

VDD

Data Latch

TRIS Latch

RD TR I S D

Data Bus

WR PORTD

WR TRISD

RD PORTD

SEG<20:16>

RD<7:3> Pin

VDD

Data Latch

TRIS Latch

SE<20:16> and LCDEN

RD TR I S D Schmitt

Trigger

SE<20:16> and LCDEN

PIC16F946

TABLE 3-4: SUMMARY OF REGISTERS ASSOCIATED WITH PORTD

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

V alue on all

other

Resets

08h PORTD RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 xxxx xxxx uuuu uuuu

1Dh(2) CCP2CON — — CCP2X CCP2Y CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000

88h TRISD TRISD7 TRISD6 TRISD5 TRISD4 TRISD3 TRISD2 TRISD1 TRISD0 1111 1111 1111 1111

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

11Eh LCDSE2(1) SE23 SE22 SE21 SE20 SE19 SE18 SE17 SE16 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TD.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

PIC16F946

3.6 PORTE and TRISE Registers

PORT E is a 4-bit port with Schmitt T rigger input buf fers.

RE<7:0> are individually configured as inputs or out-

puts. RE3 is only available as an input if MCLRE is ‘0’

in Confi g uration Word (Register 16-1) ..

EXAMPLE 3- 5: INITIALIZI NG PORTE

Note: Analog lines that carry LCD signals

(i.e., SEGx, where x are segment identifi-

ers) are shown as direct connections to

the device pins. The signals are outputs

from the LCD module and may be

tri-stated, depending on the configuration

of the LCD module.

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

CLRF PORTE ;Init PORTE

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW 0Fh ;Set RE<3:0> as inputs

MOVWF TRISE ;

CLRF ANSEL ;Make RE<2:0> as I/O’s

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

RE7 RE6 RE5 RE4 RE3 RE2 RE1 RE0

bit 7 bit 0

bit 7-0 RE<7:0>: PORTE I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-1 R/W-1 R/W-1 R/W-1 R-1 R/W-1 R/W-1 R/W-1

TRISE7 TRISE6 TRISE5 TRISE4 TRISE3 TRISE2 TRISE1 TRISE0

bit 7 bit 0

bit 7-4 TRISE<7:4>: Data Direction bits

bit 3 TRISE3: Data Direction bit. RE3 is always an input, so this bit always reads as a ‘1’

bit 2-0 TRISE<2:0>: Data Direction bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.6.1 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTE pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions

such as the comparator or the A/D, refer to the

appropriate section in this data sheet.

3.6.1.1 RE0/AN5/SEG21

Figure 3-26 shows the diagram for this pin. The

RE0/AN5/SEG 21 pin is configur able to fu nction as one

of the following:

• a general purpose I/O

• an analog input for the A/D

• an analog output for the LCD

3.6.1.2 RE1/AN6/SEG22

Figure 3-26 shows the diagram for this pin. The

RE1/AN6/SEG 22 pin is configur able to fu nction as one

of the following:

• a general purpose I/O

• an analog input for the A/D

• an analog output for the LCD

3.6.1.3 RE2/AN7/SEG23

Figure 3-26 shows the diagram for this pin. The

RE2/AN7/SEG 23 pin is configur able to fu nction as one

of the following:

• a general purpose I/O

• an analog input for the A/D

• an analog output for the LCD

3.6.1.4 RE3/MCLR/VPP

Figure 3-27 shows the diagram for this pin. The

RE3/MCLR/VPP pin is configurable to function as one

of the following:

• a digital input only

• as Master Clear Reset with weak pull-up

• a programming voltage reference input

3.6.1.5 RE4/SEG24

Figure 3-26 shows the diagram for this pin. The

RE4/SEG24 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.6.1.6 RE5/SEG25

Figure 3-26 shows the diagram for this pin. The

RE5/SEG25 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.6.1.7 RE6/SEG26

Figure 3-26 shows the diagram for this pin. The

RE6/SEG26 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog output for the LCD

3.6.1.8 RE7/SEG27

Figure 3-26 shows the diagram for this pin. The

RE7/SEG27 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog output for the LCD

PIC16F946

FIGURE 3-26: BLOCK DIAGRAM OF RE<7:4, 2:0>

Data Bus

WR PORTE

WR TRISE

RD PORTE

SEG<27:21>

Schmitt

Trigger

RE<7:4,2:0>

VDD

Data Latch

TRIS Latch

Analog Mode or

RD TRISE

AN<7:5>(1)

SE<27:21> an d LCDEN

Note 1: Analog input for A/D apply to RE<2:0> pins only.

Pins

PIC16F946

FIGURE 3-27: BLOCK DIAGRAM OF RE3/MCLR/VPP

TABLE 3-5: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lu e on:

POR, BOR

V alue on all

other

Resets

09h PORTE RE7 R6 RE5 RE4 RE3 RE2 RE1 RE0 xxxx xxxx uuuu uuuu

1Fh ADCON0 ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

89h TRISE TRISE7 TRISE6 TRISE5 TRISE4 TRISE3(2) TRISE2 TRISE1 TRISE0 1111 1111 1111 1111

91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

11Eh LCDSE2(1) SE23 SE22 SE21 SE20 SE19 SE18 SE17 SE16 0000 0000 uuuu uuuu

19Ch LCDSE3(1) SE31 SE30 SE29 SE28 SE27 SE26 SE25 SE24 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TE.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

2: Bit is read-only; TRISE = 1 always.

HV Detect

MCLR Filter

RE3/MCLR/VPP(1)

RE PORTE

MCLR cir cuit

Programm ing mode

Data Bus

RE TRISE

MCLRE

Note 1: RE3 will read ‘0’ when pin is MCLR.

Buffer

Schmitt Trigger

Buffer

Schmitt Trigger

PIC16F946

3.7 PORTF and TRISF Registers

PORTF is an 8-bit port with Schmitt Trigger input

buffers. RF<7:0> are individually configured as inputs

or out put s, depe nding on the st ate o f the po rt direc tio n.

The port bits are also multiplexed with LCD segment

functions.

EXAMPLE 3- 6: INITIALIZI NG PORTF

Note: Analog lines that carry LCD signals

(i.e., SEGx, where x are segment identifiers)

are shown as direct connections to the

device pins. The signals are outputs from

the LCD module and may be tri-stated,

depending on the configur ation of the LCD

module.

BCF STATUS,RP0 ;Bank 3

BCF STATUS,RP1 ;

CLRF PORTF ;Init PORTF

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW 0Fh ;Set RF<3:0> as inputs

MOVWF TRISF ;

CLRF ANSEL ;Make RF<2:0> as I/O’s

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

RF7 RF6 RF5 RF4 RF3 RF2 RF1 RF0

bit 7 bit 0

bit 7-0 RF<7:0>: PORTF I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

TRISF7 TRISF6 TRISF5 TRISF4 TRISF3 TRISF2 TRISF1 TRISF0

bit 7 bit 0

bit 7-0 TRISF<7:0>: Data Direction bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.7.1 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTF pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions,

refer to the appropriate section in this data sheet.

3.7.1.1 RF0/SEG32

Figure 3-28 shows the diagram for this pin. The

RF0/SEG32 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.7.1.2 RF1/SEG33

Figure 3-28 shows the diagram for this pin. The

RF1/SEG33 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.7.1.3 RF2/SEG34

Figure 3-28 shows the diagram for this pin. The

RF2/SEG34 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.7.1.4 RF3/SEG35

Figure 3-28 shows the diagram for this pin. The

RF3/SEG35 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.7.1.5 RF4/SEG28

Figure 3-28 shows the diagram for this pin. The

RF4/SEG28 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.7.1.6 RF5/SEG29

Figure 3-28 shows the diagram for this pin. The

RF5/SEG29 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.7.1.7 RF6/SEG30

Figure 3-28 shows the diagram for this pin. The

RF6/SEG30 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog output for the LCD

3.7.1.8 RF7/SEG31

Figure 3-28 shows the diagram for this pin. The

RF7/SEG31 pin is configurable to function as one of

the following:

• a general purpo se I/O

• an analog output for the LCD

PIC16F946

FIGURE 3-28: BLOCK DIAGRAM OF RF<7:0>

TABLE 3-6: SUMMARY OF REGISTERS ASSOCIATED WITH PORTF

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lu e on:

POR, BOR

Value on all

other

Resets

1Fh ADCON0 ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

185h TRISF TRISF7 TRISF6 TRISF5 TRISF4 TRISF3 TRISF2 TRISF1 TRISF0 1111 1111 1111 1111

188h PORTF RF7 RF6 RF5 RF4 RF3 RF2 RF1 RF0 xxxx xxxx uuuu uuuu

19Ch LCDSE3(1) SE31 SE30 SE29 SE28 SE27 SE26 SE25 SE24 0000 0000 uuuu uuuu

19Dh LCDSE4(1) SE39 SE38 SE37 SE36 SE35 SE34 SE33 SE32 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TF.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

Data Bus

WR PORTF

WR TRISF

RD PORTF

SEG<31:28, 35:32>

Schmitt

Trigger

RF<7:0>

VDD

Data Latch

TRIS Latch

Analog Mode or

RD TRISF SE<31:28, 35:32> and LCDEN

SE<31:28, 35 :32> and LCDEN

PIC16F946

3.8 PORTG and TRISG Registers

PORTG is an 8-bit port with Schmitt Trigger input

buffers. RG<5:0> are individually configured as inputs

or out put s, depe nding on the st ate o f the po rt direc tion.

The port bits are also multiplexed with LCD segment

functions.

EXAMPLE 3- 7: INITIALIZI NG PORTG

Note: Analog lines that carry LCD signals

(i.e., SEGx, where x are segment identifiers)

are shown as direct connections to the

device pins. The signals are outputs from

the LCD module and may be tri-stated,

depending on the configur ation of the LCD

module.

BCF STATUS,RP0 ;Bank 3

BCF STATUS,RP1 ;

CLRF PORTG ;Init PORTG

BSF STATUS,RP0 ;Bank 1

BCF STATUS,RP1 ;

MOVLW 0Fh ;Set RG<3:0> as inputs

MOVWF TRISF ;

CLRF ANSEL ;Make RG<2:0> as I/O’s

BCF STATUS,RP0 ;Bank 0

BCF STATUS,RP1 ;

U-0 U-0 R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

—— RG5 RG4 RG3 RG2 RG1 RG0

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 RG<5:0>: PORTG I/O Pin bits

1 = Port pin is >VIH

0 = Port pin is <VIL

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

U-0 U-0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

—— TRISG5 TRISG4 TRISG3 TRISG2 TRISG1 TRISG0

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 TRISG<5:0>: Data Direction bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

3.8.1 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTG pin is multiplexed with other functions. The

pins and their combined functions are briefly described

here. For specific information about individual functions,

refer to the appropriate section in this data sheet.

3.8.1.1 RG0/SEG36

Figure 3-29 shows the diagram for this pin. The

RG0/SEG36 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.8.1.2 RG1/SEG37

Figure 3-29 shows the diagram for this pin. The

RG1/SEG37 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.8.1.3 RG2/SEG38

Figure 3-29 shows the diagram for this pin. The

RG2/SEG38 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.8.1.4 RG3/SEG39

Figure 3-29 shows the diagram for this pin. The

RG3/SEG39 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.8.1.5 RG4/SEG40

Figure 3-29 shows the diagram for this pin. The

RG4/SEG40 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

3.8.1.6 RG5/SEG41

Figure 3-29 shows the diagram for this pin. The

RG5/SEG41 pin is configurable to function as one of

the following:

• a general purpose I/O

• an analog output for the LCD

PIC16F946

FIGURE 3-29: BLOCK DIAGRAM OF RG<5:0>

TABLE 3-7: SUMMARY OF REGISTERS ASSOCIATED WITH PORTG

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lu e on:

POR, BOR

V alue on all

other

Resets

1Fh ADCON0 ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

187h TRISG —— TRISG5 TRISG4 TRISG3 TRISG2 TRISG1 TRISG0 --11 1111 --11 1111

189h PORTG —— RG5 RG4 RG3 RG2 RG1 RG0 --xx xxxx --uu uuuu

19Dh LCDSE4(1) SE39 SE38 SE37 SE36 SE35 SE34 SE33 SE32 0000 0000 uuuu uuuu

19Eh LCDSE5(1) — — — — — — SE41 SE40 ---- --00 ---- --uu

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by POR TG.

Note 1: This register is only initialized by a POR or BOR and is unchanged by other Resets.

Data Bus

WR PORTG

WR TRISG

RD PORTG

SEG<41:36>

Schmitt

Trigger

RG<5:0>

VDD

Data Latch

TRIS Latch

Analog Mode or

RD TRISG SE<41:36> and LCDEN

SE<41:36> and LCDEN

PIC16F946

4.0 CLOCK SOURCES

4.1 Overview

The PIC16F946 has a wide variety of clock sources

and selection features to allow it to be used in a wide

range of applications while maximizing performance

and minimizing power consumption. Figure 4-1

illustrates a block diagram of the PIC16F946 clock

sources.

Clock sources can be configured from external oscillators,

quartz crystal resonators, ceramic resonators, and

Resistor-Capacitor (RC) circuits. In addition, the system

clock source can b e configured f rom one of tw o internal

oscillators, with a choice of speeds selectable via

software. Additional clock features include:

• Selectable system clock source between external

or internal via software.

• Two-Speed Clock Start-up mode, which

minimizes latency between external oscillator

start-up and code exe cu tio n.

• Fail-Safe Clock Monitor (FSCM) designed to

detect a failure of the external clock source (LP,

XT, HS, EC or RC modes) and switch to the

Internal Os cillator.

The PI C16F946 ca n be conf igured in one of eight cl ock

modes.

1. EC – External clock with I/O on RA6.

2. LP – Low-gain Crystal or Ceramic Resonator

Oscillator mode.

3. XT – Medium-gain Crystal or Ceramic Resonator

Oscillator mode.

4. HS – High-gain Crystal or Ceramic Resonator

mode.

5. RC – External Resistor-Capacitor (RC) with

FOSC/4 output on RA6.

6. RCIO – External Resistor-Capacitor with I/O on

RA6.

7. INTOSC – Internal oscillator with FOSC/4 output

on RA6 and I/O on RA7.

8. INTOSCIO – Internal oscillator with I/O on RA6

and RA7.

Clock s ource m odes are configu red by t he FOSC <2:0>

bits in the Configuration Word register (see

Section 16.0 “Special Features of the CPU”). The

internal clock can be generated by two oscillators. The

HFINTOSC is a high-frequency calibrated oscillator.

The LFINTOSC is a low-frequency uncalibrated

oscillator.

FIGURE 4-1: PIC16F94 6 SYST EM CLOCK BLOCK DIAGRAM

(CPU and Peripherals)

OSC1

OSC2

Sleep

External Oscillator

LP, XT, HS, RC, RCIO, EC

System Clock

Postscaler

MUX

8 MHz

4 MHz

2 MHz

1 MHz

500 kHz

125 kHz

250 kHz

IRCF<2:0>

111

110

101

100

011

010

001

000

31 kHz

LCD Module

FOSC<2:0>

(Configuration Word)

SCS

(OSCCON<0>)

Internal Oscillator

(OSCCON<6:4>)

Watchdog Timer (WDT)

Fail-Safe Clock Monitor (FSCM)

HFINTOSC

8 MHz

LFINTOSC

31 kHz

Power-up Timer (PWRT)

PIC16F946

U-0 R/W-1 R/W-1 R/W-0 R-q R-0 R-0 R/W-0

— IRCF2 IRCF1 IRCF0 OSTS(1) HTS LTS SCS

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6-4 IRCF<2:0>: Internal Oscillator Frequency Select bits

000 =31kHz

001 =125kHz

010 =250kHz

011 =500kHz

100 =1MHz

101 =2MHz

110 =4MHz

111 =8MHz

bit 3 OSTS: Oscillator Start-up Time-out Status bit

1 = Device is running from the external system clock defined by FOSC<2:0>

0 = Device is running from the internal system clock (HFINTOSC or LFINTOSC)

bit 2 HTS: HFINTOSC (High Frequency – 8 MHz to 125 kHz) Status bit

1 =HFINTOSC is stable

0 = HFINTOSC is not stable

bit 1 LTS: LFINTOSC (Low Frequency – 31 kHz) Stable bit

1 = LFINTOSC is stable

0 = LFINTOSC is not stable

bit 0 SCS: System Cloc k S ele ct bit

1 = Internal oscillator is used for system clock

0 = Clock source de fined by F OSC<2:0>

Note 1: The value of the OSTS bit on device power-up is dependent on the value of the

Configuration Word (CONFIG) of the device. The value of the OSTS bit will be ‘0’

on a de vice Power- on Reset ( POR) or any automatic c lock swit ch, which m ay occur

from Two-Speed Start-up or Fail-Safe Clock Mo nitor, if the follow i ng co ndi tio ns are

true:

OSTS = 0 if:

FOSC<2:0> = 000 (LP) or 001 (XT) or 010 (HS)

and

IESO = 1 or FSCM = 1

(IESO will be enabled automatically if FSCM is enabled)

If any of the above conditions are not met, the value of the OSTS bit will be ‘1’ on

a device POR. See Section 4.6 “Two-Speed Clock Start-up Mode” and

Section 4.7 “Fail-Safe Clock Monitor” for more details.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

q = value depends on condition

PIC16F946

4.2 Clock Source Modes

Clock source modes can be classified as external or

internal.

• Extern al c lock mo des rely on external circuitry for

the clock source. Example s are oscillator modules

(EC mode), quartz crystal resonators or ceramic

resonators (LP, XT and HS modes), and

Resistor-Capacitor (RC mode) circuits.

• Internal clock sources are contained internally

within the PIC16F946. The PIC16F946 has two

internal oscillators: the 8 MHz High-Frequency

Internal Os ci llator (HFINTOSC) and 31 kHz

Low-Frequency Internal Oscillator (LFINTOSC).

The syste m cl oc k ca n be selected betw ee n ex tern al or

inte rnal clock sour ces via t he Syste m Clock Sele ction

(SCS) bit (see Section 4.5 “Clock Switching”).

4.3 External Clock Modes

4.3.1 O SCILLA TOR START-UP TIMER

(OST)

If the PIC16F 946 is co nfigured for LP, XT or HS modes,

the Oscillator Start-up Timer (OST) counts 1024 oscil-

lations from the OSC 1 pin, follow ing a Power -on Res et

(POR), and the Power-up T imer (PWRT) has expired (if

configu red ), or a wake -up from Sleep. During th is tim e,

the program counter does not increment and program

execution is suspended. The OST ensures that the

oscillator circuit, using a quartz crystal resonator or

cerami c resona tor , has st arted an d is provid ing a st able

system clock to the PIC16F946. When switching

between clock sources a delay is required to allow the

new clock to stabilize. These oscillator delays are

shown in Table 4-1.

4.3.1.1 Special Case

An exception to this is when the device is put to Sleep

while the followi ng con di tion s are true:

• LP is the selected primary oscillator mode.

• T1OSCEN = 1 (Timer1 oscillator is enabled).

•SCS = 0 (oscillator mode is defined by

FOSC<2:0>).

• OSTS = 1 (device is running from primary system

clock).

For this case, the OST is not necessary after a wake-u p

from Slee p, since T imer1 conti nues to r un duri ng Sleep

and uses the same LP oscillator circuit as its clock

source. For these devices, this case is typically seen

when the LCD module is running during Sleep.

In applic ations where the OSCT UNE register is use d to

shift the FINTOSC frequency, the application should not

expect the FINTOSC frequency to stabilize immediately.

In this case, the frequency may shift gradually toward

the new value. The time for this frequency shift is less

than eight cycles of the base frequency.

Table 4-1 shows example s where the oscilla tor delay is

invoked.

In order to mi nimize laten cy between externa l oscillator

start-up and code execution, the Two-Speed Clock

Start-up mode can be selected (see Section 4.6

“Two-Speed Clock Start-up Mode”).

Note: When the OST is invoked, the WDOG is

held in Reset, because the WDOG ripple

counter is us ed by th e OST to perform th e

oscillator delay count. When the OST

count has expired, the WDOG will begin

counting (if enabled).

PIC16F946

TABLE 4-1: OSCILLATOR DELAY EXAMPLES

Syste m Clock

Source Frequency Switching From Oscillator Delay

(TOST)Comments

LFIOSC 31 kHz Sleep 10 μs internal delay Following a wake-up from Sleep mode

or POR, an interna l dela y is invok ed to

allow the memory bias to stabilize

before program execution can begin.

HFIOSC 125 kHz-8 MHz Sleep 10 μs internal delay Following a wake-up from Sleep mode

or POR, an interna l dela y is invok ed to

allow the memory bias to stabilize

before program execution can begin.

XT or HS 4-20 MHz INTOSC or Sleep 1024 clock cycles Following a change from INTOSC, an

OST of 1024 cy cl es mu st occ ur.

LP 32 kHz INTOSC or Sleep 1024 clock cycles Following a change from INTOSC, an

OST of 1024 cy cl es mu st occ ur. See

Section 4.3.1.1 “Special Case” for

special case conditions.

LP with T1OSC

enabled 32 kHz Sleep 10 μs internal delay Fo llow ing a wake -up fro m Sl eep m ode,

an internal delay is invoked to allow the

memory bias to stabilize before

program execution can begin. See

Section 4.3.1.1 “Special Case” for

details about this special case.

EC, RC 0-20 MHz Sleep 10 μs internal delay Following a wake-up from Sleep mode

or POR, an interna l dela y is invok ed to

allow the memory bias to stabilize

before program execution can begin.

EC, RC 0-20 MHz LFIOSC 10 μs internal delay Following a switch from a LFIOSC or

POR, an internal delay is invoked to

allow the memory bias to stabilize

before program execution can begin.

PIC16F946

4.3.2 EC MODE

The External Clock (EC) mode allows an externally

generated logic level as the system clock source.

When operating in this mode, an external clock source

is connected to the OSC1 pin and the RA6 pin is

availa ble for general purpose I/O. Figure 4-2 shows th e

pin connections for EC mode.

The Oscillator Start-up Timer (OST) is disabled when

EC mode is selected. Therefore, there is no delay in

operation after a Power-on Reset (POR) or wake-up

from Sleep. Because the PIC16F946 design is fully

static, stopping the external clock input will have the

effect of halting the device while leaving all data intact.

Upon restarting the external clock, the device will

resume operation as if no time had elapsed.

FIGURE 4-2: EXTERNAL CLOCK (EC)

MODE OPERATION

4.3.3 LP, XT, HS MODES

The LP, XT and HS modes support the use of quartz

crystal resonators or ceramic resonators connected to

the OSC1 and OSC2 pins (Figures 4-3 and 4-4). The

mode selects a low, medium or high gain setting of the

internal inverter-amplifier to support various resonator

types and speed.

LP Oscillator mode select s the lowest gain setting of the

internal inverter-amplifier . LP mode current consum ption

is the least of the three modes. This mode is bes t suited

to drive resonators with a low drive level specification, for

example, tuning fork type crys tals.

XT Oscillator mode selects the intermediate gain

setting of the internal inverter-amplifier. XT mode

current c onsumption is the medium of the three mo des.

This mode is best suited to drive resonators with a

medium drive level specification, for example,

low-frequency/AT-cut quartz crystal resonators.

HS Oscillator mode selects the highest gain setting of

the internal inverter-amplifier. HS mode current

consumption is the highest of the three modes. This

mode is best suited for resonators that require a high

drive setting, for example, high-frequency/AT-cut

quartz crystal resonators or ceramic resonators .

Figures 4-3 and 4-4 show typical circuits for quartz

crystal and ceramic resonators, respectively.

RA6/OSC2/CLKO/T1OSO

RA6

Clock

PIC16F946

Internal

FOSC

FOSC<2:0> = 011

OSC1/ Clock

CLKIN

(External

System)

Note: In the past, the sources for the LP oscilla-

tor and Timer1 oscillator have been sepa-

rate circuits. In this family of devices, the

LP oscillator and Timer1 oscillator use t he

same oscillator circuitry. When using a

device config ured for the LP osci llator an d

with T1OSCEN = 1, the source of the

clock for each function comes from the

same oscillator block.

PIC16F946

FIGURE 4-3: QUARTZ CRYSTAL

OPERATION (LP, XT OR

HS MODE)

FIGURE 4-4: CERAMIC RESONATOR

OPERATION

(XT OR HS MODE)

Note 1: Quartz crystal characteristics vary

according to type, package and manufac-

turer. The user should consult the

manufacturer data sheets for specifica-

tions and recommended application.

2: Always veri fy os ci lla tor pe rform an ce ov er

the VDD and temperature range that is

expected for the application.

Note 1: A series resistor (RS) may be require d fo r

quartz crystals with low drive level.

2: The v alue of RF va ries wit h the osci llator

mode selected (typically between 2 MΩ to

10 MΩ).

3: If using LP mode and T1OSC in enable,

the LP oscilla tor will c ontinue to run during

Sleep.

Quartz

OSC2

RS(1)

OSC1

RF(2)

Sleep(3)

To Int.

Logic

PIC16F946

Crystal

Note 1: A series res istor (R S) may b e req ui red f or

ceramic resonators with low drive level.

2: The va lue of RF varies with the oscillator

mode sel ected (typically between 2 MΩ to

10 MΩ).

3: An additional parallel feedback resistor

(RP) may be required for proper ceramic

resonator operation (typical value 1 MΩ).

OSC2

RS(1)

OSC1

RF(2)

Sleep

To Int.

Logic

PIC16F946

RF(3)

Ceramic

Resonator

PIC16F946

4.3.4 EX TERN AL RC MODES

The External Resistor-Capacitor (RC) modes support

the use of an external RC circuit. This allows the

designer maximum flexibility in frequency choice while

keeping costs to a minimum when clock accuracy is not

required. There are two modes, RC and RCIO.

In RC mode, the RC circuit connects to the OSC1 pin.

The OSC2/CLKO pin outputs the RC oscillator

frequency divided by 4. This signal may be used to

provide a clock for external circuitry, synchronization,

calibration, test or other application requirements.

Figure 4-5 shows the RC mode connections.

FIGURE 4-5: RC MODE

In RCIO mode, the RC circuit is connected to the OSC1

pin. The OSC2 pin becomes an additional general

purpose I/O pin. The I/O pin becomes bit 4 of PORTA

(RA4). Figure 4-6 shows the RCIO mode connections.

FIGURE 4-6: RCIO MODE

The RC oscillator frequency is a function of the supply

voltage, the resistor (REXT) and capacitor (CEXT)

values and the operating temperature. In addition to

this, the oscillator frequency will vary from unit to unit

due to normal threshold voltage. Furthermore, the

difference in lead fram e c apacitance betwee n package

types w ill also a ffe ct the oscil lation freque ncy o r for low

CEXT values. The user also needs to take into account

variation due to tolerance of external RC components

used.

4.4 Internal Clock Modes

The PIC16F946 has two independent, internal

oscillators that can be configured or selected as the

system clock source.

1. The HFINTOSC (High-Frequency Internal

Oscillator) is factory calibrated and operates at

8 MHz. The frequ ency of t he H FINT OSC can b e

user adjusted ±12% via software using the

OSCTUNE register (Register 4-2).

2. The LFINTOSC (Low-Frequency Internal

Oscillator) is uncalibrated and operates at

approximately 31 kHz.

The sys tem cloc k speed can b e select ed via soft ware

using the Internal Oscillator Frequency Select (IRCF)

bits.

The syste m cl oc k can be selec t ed betw ee n ext erna l or

inte rnal cloc k sources via the S ystem Clo ck Select ion

(SCS) bit (see Section 4.5 “Clock Switching”).

4.4.1 INTOSC AND INTOSCIO MODES

The INTOSC and INTOSCIO modes configure the

internal oscillators as the sy stem clock source when the

device is programmed using the Oscillator Selection

(FOSC) bits in the Configuration Word register

(Register 16-1).

In INTOSC mode , the OSC1 pin is available for ge neral

purpose I/O. The OSC2/CLKO pin outputs the selected

internal oscillator frequency divided by 4. The CLKO

signal may be used to provide a clock for external

circuitry, synchronization, calibration, test or other

application requirements.

In INTOSCIO mode, the OSC1 and OSC2 pins are

available for general purpose I/O.

4.4.2 HFINTOSC

The High-Fre quency Int ernal Oscil lator (HFINT OSC) is

a factory calibrated 8 MHz internal clock source. The

frequency of the HFINTOSC can be altered

approxi mately ± 12% vi a software using the OSC TUNE

The output of the HFINTOSC connects to a postscaler

and multiplexer (see Figure 4-1). One of seven

frequencies can be selected via software using the

IRCF bits (see Section 4.4.4 “Frequency Select Bits

(IRCF)”).

The HFINTOSC is enabled by selecting any frequency

between 8 MHz and 125 kHz (IRCF ≠ 000) as the

Syst em Clock S ource ( SCS = 1), or when Two-Speed

Start-up is ena ble d (IESO = 1 and IRCF ≠ 000).

The HF Internal Oscillator (HTS) bit (OSCCON<2>)

indicates whether the HFINTOSC is stable or not.

OSC2/CLKO

CEXT

REXT PIC16F946

OSC1

FOSC/4

Internal

Clock

VDD

VSS

Recommended values:3 kΩ ≤ REXT ≤ 100 kΩ

CEXT > 20 pF

I/O (OSC2)

CEXT

REXT PIC16F946

OSC1

RA6

Internal

Clock

VDD

VSS

Recomm ended values :3 kΩ ≤ REXT ≤ 100 kΩ

CEXT > 20 pF

PIC16F946

4.4.2.1 OSCTUNE Register

The HFINTOSC is factory calibrated but can be

adjusted in software by writing to the OSCTUNE

The OSCTUNE register has a tuning range of ±12%.

The default value of the OSCTUNE register is ‘0’. The

value is a 5-bit two’s complement number. Due to

process varia tion, th e mono ton icity and frequen cy ste p

cannot be spe ci fie d.

When the OSCTUNE register is modified, the HFINTOSC

frequency will begin shifting to the new frequency. The

HFINTOSC clock will stabilize within 1 ms. Code

execution continues during this shift. There is no

indication that the shift has occurred.

OSCTUNE does not affect the LFINTOSC frequency.

Operation of features that depend on the LFINTOSC

clock source frequency, such as the Power-up Timer

(PWRT), Watchdog Timer (WDT), Fail-Safe Clock

Monitor (FSCM) and peripherals, are not af fected by the

change in frequency.

U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— — — TUN4 TUN3 TUN2 TUN1 TUN0

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4-0 TUN<4:0>: Frequenc y Tuning bit s

01111 = Maximum frequency

01110 =

•

00001 =

00000 = Center frequency. Oscillator module is running at the calibrated frequency.

11111 =

•

10000 = Minimum frequency

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

4.4.3 LFINTOSC

The Low-Frequency Internal Oscillator (LFINTOSC) is

an uncalibrated (approximate) 31 kHz internal clock

source.

The output of the LFINTOSC connects to a postscaler

and multiplexer (see Figure 4-1). 31 kHz can be

selected via software using the IRCF bits (see

Section 4.4.4 “Frequency Select Bits (IRCF)”). The

LFINTOSC is also the frequency for the Power-up

Timer (PWRT), Watchdog Timer (WDT) and Fail-Safe

Clock Monitor (FSCM).

The LFINTOSC is enabled by selecting 31 kHz

(IRCF = 000) as the Sys tem Cloc k Sour ce ( SCS = 1),

or when any of the following are enabled:

• Two-Speed Start-up (IESO = 1 and IRCF = 000)

• Power-up Timer (PWRT)

• Watchdog Timer (WDT)

• Fail-Safe Clock Monitor (FSCM)

• Selected as LCD module clock source

The LF Internal Oscillator (LTS) bit (OSCCON<1>)

indicates whether the LFINTOSC is stable or not.

4.4.4 FREQUENCY SELECT BITS (IRCF)

The output of the 8 MHz HFINTOSC and 31 kHz

LFINTOSC connect to a postscaler and multiplexer

(see Figure 4-1). The Internal Oscillator Frequency

select bits, IRCF<2:0> (OSCCON<6:4>), select the

frequency output of the internal oscillators. One of eight

frequencies can be selected via software:

•8 MHz

• 4 MHz (Default after Reset)

•2 MHz

•1 MHz

• 500 kHz

• 250 kHz

• 125 kHz

•31 kHz

4.4.5 HF AND LF INTOSC CLOCK

SWITCH TIM ING

When switching between the LFINTOSC and the

HFINTOSC, the new oscillator may already be shut

down to sa ve pow er. If this is the ca se, there is a 10 μs

delay after the IRCF bits are modified before the

frequency selection takes place. The LTS/HTS bits will

reflect the current active status of the LFINTOSC and

the HFINTOSC oscillators. The timing of a frequency

selection is as follows:

1. IRCF bits are modified.

2. If the new clock is shut down, a 10 μs clock

start-up delay is started.

3. Clock switch circuitry waits for a falling edge of

the current clock.

4. CLKO is held low and the clock switch circuitry

waits for a rising edge in the new clock.

5. CLKO is now connected with the new clock.

HTS/LTS bits are updated as required.

6. Clock switch is complete .

If the internal oscillator speed selected is between

8 MHz and 125 kHz, there is no start-up delay before

the new frequency is selected. This is because the old

and the new frequencies are derived from the

HFINTOSC via the postscaler and multiplexer.

4.5 Clock Switching

The system clock source can be switched between

external and internal clock sources via software using

the System C lock Select (SCS) bit.

4.5.1 SYS TEM CLOCK SELECT (SCS) BIT

The System Clock Select (SCS) bit (OSCCON<0>)

selects the system clock source that is used for the

CPU and peripherals.

• When SCS = 0, the system clock source is

determined by configuration of the FOSC<2:0>

bits in the Configuration Word register (CONFIG).

• When SCS = 1, the system clock source is

chosen by the internal oscillator frequency

selected by the IRCF bits. After a Reset, SCS is

always cleared.

Note: Foll owin g any Reset , t he IRC F bit s are s et

to ‘110’ and the frequency selection is set

to 4 MHz. The user can modify the IRCF

bits to select a different frequency. Note: Any automatic clock switch, which may

occur from Two-Speed Start-up or

Fail-Safe Clock Monitor, does not update

the SCS bit. The user can monitor the

OSTS (OSCCON<3>) to determine the

current system clock source.

PIC16F946

4.5.2 OSCILLATOR START-UP TIME-OUT

STATUS BIT

The Oscillator Start-up Time-out Status (OSTS) bit

(OSCCON<3>) indicates whether the system clock is

running from the external clock source, as defined by

the FOSC bits, or from the internal clock source. In

particular, OSTS indicates that the Oscillator Start-up

Timer (OST) has timed out for LP, XT or HS modes.

4.6 Two-Speed Clock Start-up Mode

Two-Speed Start-up mode provides additional power

savings by minimizing the latency between external

oscillator start-up and code execution. In applications

that make heavy use of the Sleep mode, Two-Speed

Start-up will remove the external oscillator start-up

time from the time spent awake and can reduce the

overall power consumption of the device.

This mode allows the application to wake-up from

Sleep, perform a few instructions using the INTOSC

as the clock source and go back to Sleep without

waiting for the primary oscillator to become stable.

When the PIC16F946 is configured for LP, XT or HS

modes, the Oscillator Start-up Timer (OST) is enabled

(see Section 4.3.1 “Oscillator Start-up Timer

(OST)”). The OST timer will suspend program

execution until 1024 oscillations are counted.

Two-Speed Start- up mode minimize s the del ay in cod e

execution by operating from the internal oscillator as

the OST is counting. When the OST count reaches

1024 and the OSTS bit (OSCC ON <3 >) is se t, pro gra m

execution switches to the external oscillator.

4. 6.1 TWO-SPEED START-UP MODE

CONFIGURATION

Two-Speed Start-up mode is configured by the

following settings:

• IESO = 1 (CONFIG<10>) Internal/External

Switchover bit.

•SCS = 0.

• FOSC configured for LP, XT or HS mode.

Two-Speed Start-up mode is entered after:

• Power-on Reset (POR ) and, if enabled, after

PWRT has expired, or

• Wake -up from Sleep.

If the external clock oscillator is configured to be anything

other than LP, XT or HS mode, then Two-Speed Start-up

is disabled. This is because the external clock oscillator

does not require any stabilization time after POR or an

exit from Sleep.

4.6. 2 TWO-SPEED STAR T-UP

SEQUENCE

1. Wake-up from Power-on Reset or Sleep.

2. Instructions begin execution by the internal

oscillator at the frequency set in the IRCF bits

(OSCCON<6:4>).

3. OST enabled to count 1024 clock cycles.

4. OST timed out, wait for falling edge of the

internal oscillator.

5. OSTS is set.

6. System cloc k held lo w until the next fallin g edge

of new clock (LP, XT or HS mode).

7. System clock is switched to external clock

source.

4.6.3 CHE CKING EXTERNAL/I NTERNAL

CLOCK STATUS

Checking the state of the OSTS bit (OSCCON<3>) will

confirm if the PIC16F946 is running from the external

clock source as defined by the FOSC bits in the

Configuration Word (CONFIG) or the internal oscillator.

Note: Executing a SLEEP instruction will abort

the oscillator start-up time and will cause

the OSTS bit (OSCCON<3>) to remain

clear.

PIC16F946

FIGURE 4-7: TWO-SPEED STAR T-UP

4.7 Fail-Safe Clock Monitor

The Fail-Safe Clock Monitor (FSCM) is designed to

allow the device to continue to operate in the event of

an oscillator failure. The FSCM can detect oscillator

failure at any point after the device has exited a Reset

or Sleep condition and the Oscillator Start-up Timer

(OST) has expired.

FIGURE 4-8: FSCM BLOCK DIAGRAM

The FSCM function is enabled by setting the FCMEN

bit in the Con figuration W ord (CONFIG). It is appl icable

to all external clock options (LP, XT, HS, EC or RC

modes).

In the event of an external clock failure, the FSCM will

set the O SFIF bi t (PIR2< 7>) and g enerate an oscil lator

fail interrupt if the OSFIE bit (PIE2<7>) is set. The

device will then switch the system clock to the internal

oscillator. The system clock will continue to come from

the inte rnal oscillator unless the external clock re covers

and the Fail-Safe condition is exited.

The frequency of the internal oscill ator will depend upon

the value contained in the IRCF bits (OSCCON<6:4>).

Upon entering the Fail-Safe condition, the OSTS bit

(OSCCON<3>) is automatically cleared to reflect that

the internal oscillator is active and the WDT is cleared.

The SCS bit (OSCCON<0>) is not updated. Enabling

FSCM does not affect the LTS bit.

The FSCM sample clock is generated by dividing the

INTOSC clock by 64. This will allow enough time

between FSCM sample clocks for a system clock edge

to occur. Figure 4-8 shows the FSCM block diagram.

On the rising edge of the sample clock, a monitoring

latch ( CM = 0) will be cleared. On a falling edge of the

primary system clock, the monitoring latch will be set

(CM = 1). In th e e ve nt t hat a fal lin g edge o f th e s am pl e

clock occurs, and the monitoring latch is not set, a clock

failure has been detected. The assigned internal

oscillator is enabled when FSCM is enabled as

reflected by the IRCF.

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1

0 1 1022 1023

PC PC + 1 PC + 2

TOSTT

INTOSC

OSC1

OSC2

Progra m Count er

System Clock

Primary

LFINTOSC ÷ 64

Oscillator

Clock Clock

Fail

Detector

Clock

Failure

Detected

Note 1: Two-Speed Start-up is automatically

enabled when t he Fail-Safe Clock Monitor

mode is enabled.

2: Primary clocks with a frequency ≤ ~488

Hz will be cons idered failed by the FSCM .

A slow starting oscillator can cause an

FSCM interrupt.

PIC16F946

4.7.1 FAIL-SAFE CONDITION CLEARING

The Fail-Safe c ondition is cleared after a Reset, the

execution of a SLEEP instruction, or a modification of

the SCS bit. While in Fail-Safe condition, the

PIC16F946 uses the internal oscillator as the system

without exiting the Fail-Safe condition.

The Fail-Safe condition must be cleared before the

OSFIF flag can be cleared.

FIGURE 4-9: FSCM TIMING DIAGRAM

4.7.2 RES E T OR WAKE- UP FROM SLEE P

The FSCM is designed to detect oscillator failure at

any point after the device has exited a Reset or Sleep

condition and the Oscillator Start-up Timer (OST) has

expired. If the external clock is EC or RC mode,

monitoring will begin immediately following these

events.

For LP, XT or HS mode the external oscillator may

require a start-up time considerably longer than the

FSCM sample clock time, a false clock failure may be

detected (see Figure 4-9). To prevent this, the internal

oscillator is automatically configured as the system

clock and functions until the external clock is stable

(the OST has timed out). This is identical to

Two-Speed Start-up mode. Once the external

oscill ato r is st a bl e, the LF INTOSC return s to its role as

the FSCM source.

TABLE 4-2: SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES

OSCFIF

CM Output

System

Clock

Output

Sample Clock

Failure

Detected

Oscillator

Failure

Note: The system clock is normally at a much higher frequency than the sample clock. The relative

frequencies in this example have been chosen for clarity.

(Q)

CM Test CM Test CM Test

Note: Due to the wide range of o scillator start-u p

times, the Fail-Safe circuit is not active

during oscillator start-up (i.e., after exiting

Reset or Sleep). After an appropriate

amount o f time, the use r sho ul d ch ec k th e

OSTS bit (OSCCON<3>) to verify the

oscillator start-up and system clock

switchover has successfully completed.

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

8Fh OSCCON — IRCF2 IRCF1 IRCF0 OSTS(2) HTS LTS SCS -110 q000 -110 x000

90h OSCTUNE — — — TUN4 TUN3 TUN2 TUN1 TUN0 ---0 0000 ---u uuuu

2007h(1) CONFIG CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0 — —

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by oscillators.

Note 1: See Register 16-1 for operation of all Configuration Word bits.

2: See Register 4-1 for details.

PIC16F946

5.0 TIMER0 MODULE

The Timer0 module timer/counter has the following

features:

• 8-bit timer/counter

• Readable and writable

• 8-bit software programmable prescaler

• Internal or external clock select

• Interrupt on overflow from FFh to 00h

• Edge select for external clock

Figure 5-1 i s a block diagram of the T i mer0 module an d

the prescaler shared with the WDT.

5.1 Timer0 Operation

Timer mode is selected by clearing the T0CS bit

(OPTION_REG<5>). In Timer mode, the Timer0

module will increment every instruction cycle (without

prescal er). If TMR0 is written , the incre ment is inhibite d

for the following two instruction cycles. The user can

work around this by writing an adjusted value to the

TMR0 registe r.

Counter mode is selected by setting the T0CS bit

(OPTION_REG<5>). In this mode, the Timer0 module

will increment either on every rising or falling edge of pin

RA4/C1OUT/T0CKI/SEG4. The incrementing edge is

determined by the source edge (T0SE) control bit

(OPTION_REG<4>). Clearing the T0SE bit selects the

rising edge.

5.2 Timer0 Interrupt

A Timer0 interrupt is generated when the TMR0

overflow sets the T0IF bit (INTCON<2>). The interrupt

can be masked by cl eari ng the T0IE bit (INTCO N<5 >).

The T0IF bit must be cleared in softwa re by the T i mer0

module Interrupt Service Routine before re-enabling

this interrupt. The Timer0 interrupt cannot wake the

proce ssor from Sle ep, since th e t im er i s s hu t off during

Sleep.

FIGURE 5-1: BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER

T0CKI

T0SE

CLKO

TMR0

Watchdog

Timer

WDT

Time-out

PS<2:0>

WDTE

Data Bus

Set Flag bit T0IF

on Overflow

T0CS

Note: T0SE, T0CS, PSA and PS<2:0> are bits in the Option register; WDTPS<3:0> are bits in the WDTCON register .

SYNC 2

Cycles

8-bit

Prescaler

(= FOSC/4)

PSA

16-bit

Prescaler 16

WDTPS<3:0>

31 kHz

INTOSC

SWDTEN

PIC16F946

5.3 Using Timer0 with an External

Clock

When no prescaler is used, the external clock input is the

same as the prescaler output. The synchronization of

T0CKI, with the internal phase clocks, is accomplished by

sampling the prescaler output on the Q2 and Q4 cycles of

the internal phase clocks. Therefore, it is necessary for

T0CKI to be high for at least 2 T OSC (and a small RC delay

of 20 ns) and low for at least 2 T OSC (and a small RC delay

of 20 ns). Refer to the electrical specification of the

desired device.

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0

bit 7 bit 0

bit 7 RBPU: PORTB Pull-up Enable bit

1 = PORTB pull-ups are disabled

0 = PORTB pull-ups are enabled by individual port latch values in WPUA register

bit 6 INTEDG: Interrupt Edge Select bit

1 = Interrupt on rising edge of RB0/INT/SEG0 pin

0 = Interrupt on falling edge of RB0/INT/SEG0 pin

bit 5 T0CS: TMR0 Clock Sourc e Sele ct bit

1 = Transition on RA4/C1OUT/T0CKI/SEG4 pin

0 = Internal instruction cycle clock (CLKO)

bit 4 T0SE: TMR0 Source Edge Select bit

1 = Increment on high-to-low transition on RA4/C1OUT/T0CKI/SEG4 pin

0 = Increment on low-to-high transition on RA4/C1OUT/T0CKI/SEG4 pin

bit 3 PSA: Prescaler Assignment bit

1 = Prescaler is assigned to the WDT

0 = Prescaler is assigned to the Timer0 module

bit 2-0 PS<2:0>: Prescaler Rate Select bits

Note 1: A dedicated 16-bit WDT postscaler is available for the PIC16F946. See

Section 16.6 “Watchdog Timer (WDT)” for more information.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

000

001

010

011

100

101

110

111

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

1 : 256

1 : 1

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

Bit Value TMR0 Rate WDT Rate(1)

PIC16F946

5.4 Prescaler

An 8-bit counter is available as a prescaler for the

Timer0 module, or as a postscaler for the Watchdog

Timer. For simplicity, this counter will be referred to as

“prescaler” throughout this data sheet. The prescaler

assignment is controlled in software by the control bit

PSA (OPTION_REG<3>). Clearing the PSA bit will

assign the prescaler to Timer0. Prescale values are

selectable via the PS<2:0> bits (OPTION_REG<2:0>).

The prescaler is not readable or writable. When

assigned to the Timer0 module, all instructions writing

to the TMR0 register (e.g., CLRF 1, MOVWF 1,

BSF 1, x....etc.) will clear the prescaler. When

assigned to WDT, a CLRWDT instruction will clear the

prescaler along with the Watchdog Timer.

5.4.1 SW ITCHIN G PRESCALER

ASSIGNMENT

The prescaler assignment is fully under software control

(i.e., it can be changed “on-the-fly” during program

execution). To avoid an unintended device Reset, the

following instruction sequence (Example 5-1 and

Example 5-2) must be executed when changing the

prescaler assignment from Timer0 to WDT.

EXAMPLE 5-1: CHANGING PRESCALER

(TIMER0 →WDT)

To change prescaler from the WDT to the TMR0

module , use the se quence sh own in Exa mple 5-2. This

preca ution mus t be tak en even if the WDT is dis abled.

EXAMPLE 5-2: CHANGING PRESCALER

(WDT →TIMER0)

TABLE 5-1: REGISTERS ASSOCIATED WITH TIMER0

BCF STATUS,RP0 ;Bank 0

CLRWDT ;Clear WDT

CLRF TMR0 ;Clear TMR0 and

; prescaler

BSF STATUS,RP0 ;Bank 1

MOVLW b’00101111’ ;Required if desired

MOVWF OPTION_REG ; PS2:PS0 is

CLRWDT ; 000 or 001

;

MOVLW b’00101xxx’ ;Set postscaler to

MOVWF OPTION_REG ; desired WDT rate

BCF STATUS,RP0 ;Bank 0

CLRWDT ;Clear WDT and

; prescaler

BSF STATUS,RP0 ;Bank 1

MOVLW b’xxxx0xxx’ ;Select TMR0,

; prescale, and

; clock source

MOVWF OPTION_REG ;

BCF STATUS,RP0 ;Bank 0

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Value on

all other

Resets

01h TMR0 Timer0 Module regist er xxxx xxxx uuuu uuuu

0Bh/10Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

81h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

85h TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111

Legend: – = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the Timer0 module.

PIC16F946

NOTES:

PIC16F946

6.0 TIMER1 MODULE WITH GATE

CONTROL

The PIC16F946 has a 16-bit timer. Figure 6-1 shows

the basic block diagram of the Timer1 module. Timer1

has the follow i ng feat ures :

• 16-bit timer/counter (TMR1H:TMR1L)

• Readable and writable

• Internal or external clock selection

• Synchronous or asynchronous operation

• Interrupt-on-overflow from FFFFh to 0000h

• Wake-up upon overflow (Asynchronous mode)

• Optional exter nal enable input:

- Selectable gate source: T1G or C2 output

(T1GSS)

- Selectable gate po larity ( T1GINV)

• Op tional LP oscil lator

The Timer1 Control register (T1CON), shown in

select the various features of the Timer1 module.

FIGURE 6-1: TIMER1 ON THE PIC16F946 BLOCK DIAGRAM

TMR1H TMR1L

LP OSC

T1SYNC

T1CKPS<1:0> Sleep Input

FOSC/4

Internal

Clock

Prescaler

1, 2, 4, 8 Synchronize

det

Synchronized

Clock Input

OSC1/T1OSI

OSC2/T1OSO

Set Flag bit

TMR1IF on

Overflow TMR1(1)

TMR1ON

T1GE

TMR1ON

T1GE

FOSC = 000

T1OSCEN

FOSC = x00

C2OUT

T1GSS

T1GINV

To C2 Comparator Module

TMR1 Clock

Note 1: Timer1 increments on the rising edge.

2: ST Buffer is low-power type when using LP oscillator or high-speed type when using T1CKI.

RC4/T1G/

RC5/T1CKI/

T1CS

(2)

Clear on special

event trigger

SDO/SEG11

CCP1/SEG10

PIC16F946

6.1 Timer1 Modes of Operation

Timer1 can operate in one of three modes:

• 16-bit timer with prescaler

• 16-bit synchronous counter

• 16-bit asynchronous counter

In Timer mode, Timer1 is incremented on every

instruction cycle. In Counter mode, Timer1 is incremented

on the rising edge of the external clock input T1CKI. In

addition, the Counter mode clock can be synchronized to

the microcontroller system clock or run asynchronously.

In th e Ti mer1 modu le, the m odule cl ock can be g ated

by the T imer1 g ate, whi ch can be select ed as ei ther the

T1G pin or Comparator 2 output.

If an external clock oscillator is needed (and the

microcontroller is using the INTOSC without CLKO),

Timer1 can use the LP oscillator as a clock source.

6.2 Timer1 Interrupt

The Timer1 register pair (TMR1H:TMR1L) increments

to FFFFh and rolls over to 0000h. When Timer1 rolls

over, the Timer1 Interrupt Flag bit (PIR1<0>) is set. To

enable the interrupt on rollo ver , you m ust set th ese bits :

• Timer1 Interrupt Enable bit (PIE1<0>)

• PEIE bit (INTCON<6>)

• GIE bit (INTCON<7>)

The interrupt is cleared by clearing the TMR1IF bit in

the Interrupt Service Routine.

6.3 Timer1 Prescaler

Timer1 has four prescaler options allowing 1, 2, 4 or 8

divisions of the clock input. The T1CKPS bits

(T1CON<5:4>) control the prescale counter. The

prescale counter is not directly readable or writable;

however, the prescaler counter is cleared upon a write

to TMR1H or TMR1L.

6.4 Timer1 Gate

Timer1 gate source is software configurable to be the

T1G pin or th e ou tput of C omparat or 2. This all ows th e

device to directly time external events using T1G or

analog events using Comparator 2. See CMCON1

(Register 8-2) for selecting the Timer1 gate source.

This feature can simplify the software for a Delta-Sigma

A/D converter and many other applications. For more

information on Delta-Sigma A/D converters, see the

Microchip web site (www.microchip.com).

Timer1 gate can be inverted using the T1GINV bit

(T1CON< 7>), wh ether it origin ates from th e T1G pin or

Comparator 2 output. This configures Timer1 to

measure either the active-high or active-low time

between events.

FIGURE 6-2: TIMER1 INCREMENTING EDGE

Note: In Counter mode, a falling edge must be

registered by the counter prior to the first

incr em enti ng ris ing edge.

Note: The T MR1H:TTMR1L register p air and the

TMR1IF bit should be cleared before

enabling interrupts.

Note: T1GE bit (T1CON<6>) must be set to use

either T1G or C2OUT as the Timer1 gate

source. See Register 8-2 for more

information on selecting the Timer1 gate

source.

T1CKI = 1

when TMR1

Enabled

T1CKI = 0

when TMR1

Enabled

Note 1: Arrows indicate counter increments.

2: In Counter mode, a falling edge must be registered by the counter prior to the first incrementing

rising edge of the clock.

PIC16F946

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON

bit 7 bit 0

bit 7 T1GINV: Timer1 Gate Invert bit(1)

1 = Timer1 gate is inverted

0 = Timer1 gate is not inverted

bit 6 T1GE: Timer1 Gate Enable bit(2)

If TMR1ON = 0:

This bit is ignored.

If TMR1ON = 1:

1 = Timer1 gate is enabled

0 = Timer1 gate is disabled

bit 5-4 T1CKPS<1:0>: Timer1 Input Clock Prescale Select bits

11 = 1:8 Prescale Value

10 = 1:4 Prescale Value

01 = 1:2 Prescale Value

00 = 1:1 Prescale Value

bit 3 T1OSCEN: LP Oscillator Enable Control bit

If INTOSC without CLKO oscillator is active:

1 = LP oscillator is enabled for Timer1 clock

0 = LP oscillator is off

Else:

This bit is ignored.

bit 2 T1SYNC: Timer1 External Clock Input Synchronization Control bit

TMR1CS = 1:

1 = Do not synchronize external clock input

0 = Synchronize external clock input

TMR1CS = 0:

This bit is ignored. Timer1 uses the internal clock.

bit 1 TMR1CS: Timer 1 Clock Source Select bit

1 = External clock from RC5/T1CKI/CCP1/SEG10 pin or T1OSC (on the rising edge)

0 = Internal clock (FOSC/4)

bit 0 TMR1ON: Timer1 On bit

1 = Enables Timer1

0 = Stops Timer1

Note 1: T1GINV bit inverts the Timer1 gate logic, regardless of source.

2: T1GE bit must be set to use either T1G pin or C2OUT, as selected by the T1GSS

bit (CMCON1<1>), as a Timer1 gate source.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

6.5 Timer1 Operation in

Asynchronous Counter Mode

If control bit T1SYNC (T1CON<2>) is set, the external

clock input is not synchronized. The timer continues to

increment asynchronous to the internal phase clocks.

The timer will continue to run during Sleep and can

generate an interrupt-on- overflow, which will wake-up

the processor. However, special precautions in

software are needed to read/write the timer (see

Section 6.5.1 “Reading and Writing Timer1 in

Asynchronous Counter Mode”).

6.5.1 READING AND WRITING TIMER1 IN

ASYNCHRONOUS COUNTER

MODE

Reading TMR1H or TMR1L, while the timer is running

from an external asynchronous clock, will ensure a

valid read (taken care of in hardware). However, the

user shoul d keep i n mind that r eadi ng the 16-bit time r

in two 8-b it va lu es i t self, pose s c ertain pro bl em s, s inc e

the timer may overflow between the reads.

For write s, it is re commend ed that the us er simply stop

the timer and write the desired values. A write

contention may occur by writing to the timer registers,

while the register is incrementing. This may pro duce an

unpredictable value in the timer registe r.

Reading the 16-bit value requires some care.

Examples in the “PICmicro® Mid-Range MCU Family

Reference Manual” (DS33023) show how to read and

write Timer1 wh en it i s runni ng in Async hronou s mode.

6.6 TIMER1 OSCILLAT OR

To minimize the multiplexing of peripherals on the I/O

ports, the dedicated TMR1 oscillator, which is normally

used for TMR1 real-time clock applications, is eliminated.

Instead, the TMR1 module can enable the LP oscillator.

If the microcontroller is programmed to run from

INTOSC with no CLKO or LP oscillator:

1. Setting the T1OSCEN and TMR1CS bits to ‘1’

will ena ble the LP osci llator to clock TM R1 while

the microcontroller is clocked from either the

INTOSC or LP oscillator. Note that the T1OSC

and LP oscillators share the same circuitry.

Therefore, when LP oscillator is selected and

T1OS C is enabled, both the micro contro ller and

the Timer1 module share the same clock

source.

2. Sleep mode does not shut off the LP oscillator

operation (i.e., if the INTOSC oscillator runs

the microcontroller, T1OSCEN = 1 and

TMR1CS = 1, TMR1 is running from the LP

oscillator), then the LP oscillator will continue to

run during Sleep mode.

In all oscillator modes except for INTOSC with no

CLKOUT and LP, the T1OSC enable option is unavail-

able and is ignored.

6.7 Resetting Ti me r1 Us ing a CCP

Trigger Output

If the CCP 1 or CCP2 mo dule is config ured in C ompa re

mode to generate a “special event trigger”

(CCP1M<3:0> = 1011), this signal will reset Timer1.

T imer 1 must be c onfigured fo r either T ime r or Synch ro-

nized Counter mode to take advantage of this feature.

If Timer1 is running in Asynchronous Counter mode,

this Reset operation may not work.

In the event that a write to Timer1 coincides with a

special event trigger from CCP1 or CCP2, the write will

take precedence.

In this mode of operation, the CCPRxH:CCPRxL register

pair effectively becomes the period register for Timer1.

Note: The ANSEL (91h) and CMCON0 (9Ch)

analog channel as a digital input. Pins

configured as analog inputs will read ‘0’.

Note: When INTOSC without CLKO oscillator is

selected and T1OSCEN = 1, the LP

oscillator will run continuously independent

of the TMR1ON bit.

Note: The special event triggers from the CCP1

and CCP2 modules will not set interrupt

flag bit, TMR1IF (PIR1<0 >).

PIC16F946

6.8 Resetting of Ti mer1 Register Pair

(TMR1H , TMR1 L)

TMR1H an d TMR1L reg isters are not rese t to 00h on a

POR, or any other Reset, except by the CCP1 and

CCP2 special event triggers.

T1CON register is reset to 00h on a Power-on Reset,

or a Brown-out Reset, which shuts off the timer and

leaves a 1:1 prescale. In all other Resets, the register

is unaffected.

6.9 Timer1 Operation During Sleep

Timer1 can only operate during Sleep when setup in

Asynch ronous Counter mode. In this mode, an external

crystal or clock source can be used to increment the

counter. To set up the timer to wake the device:

• Timer1 must be on (T1CON<0>)

• TMR1IE bit (PIE1<0>) must be set

• PEIE bit (INTCON<6>) must be set

The device will wake-up on an overflow. If the GIE bit

(INTCON<7>) is set, the devi ce will wa ke -up an d jum p

to the Interrupt Service Rout ine (0004h) on an overflow .

If the GIE bit is clear, execution will continue with the

next instruction.

TABLE 6-1: REGISTERS ASSOCIATED WITH TIMER1

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Value on

all other

Resets

0Bh/

8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

10h T1CON T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

97h CMCON1 — — — — — —T1GSSC2SYNC ---- --10 ---- --10

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

Legend: x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the Timer1 module.

PIC16F946

NOTES:

PIC16F946

7.0 TIMER2 MODULE

The Timer2 module timer has the following features:

• 8-bit timer (TMR2 register)

• 8-bit period register (PR2)

• Readable and writable (both registers)

• Software programmable prescaler (1:1, 1:4, 1:16)

• Software programmable postscaler (1:1 to 1:16)

• Interrupt on TMR2 match with PR2

Timer2 has a control register shown in Register 7-1.

TMR2 can be shut-off by clearing control bit TMR2ON

(T2CON<2>) to minimize power consumption.

Figure 7-1 is a simplified block diagram of the Timer2

module. The prescaler and postscaler selection of

Timer2 are controlled by this register.

7.1 Timer2 Operation

Timer2 can be used as the PWM time base for the

PWM mode of the CCP module. The TMR2 register is

readable and writable, and is cleared on any device

Reset. The i npu t clo ck (FOSC/4) has a prescale option

of 1:1, 1:4 or 1:16, selected by control bits T2CKPSx

(T2CON<1:0>). The match output of TMR2 goes

through a 4-bit postscaler (which gives a 1:1 to 1:16

scaling inclusive) to generate a TMR2 interrupt (latche d

in flag bit TMR2IF, (PIR1<1>)).

The prescaler and postscaler counters are cleared

when any of the following occurs:

• A write to the TMR2 register

• A write to the T2CON register

• Any device Reset (Power-on Reset, MCLR Reset,

Watchdog Timer Reset, or Brown-out Reset)

TMR2 is not cleared when T2CON is written.

U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0

bit 7 bit 0

bit 7 Unimplemented: Re ad as ‘0’

bit 6-3 TOUTPS<3:0>: Timer2 Output Postscale Select bits

0000 =1:1 Postscale

0001 =1:2 Postscale

•

1111 =1:16 Postscale

bit 2 TMR2ON: Timer2 On bit

1 = Timer2 is on

0 = Timer2 is off

bit 1-0 T2CKPS<1:0>: Timer2 Clock Prescale Select bits

00 =Prescaler is 1

01 =Prescaler is 4

1x =Prescaler is 16

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

7.2 Timer2 Interrupt

The Timer2 module has an 8-bit period register, PR2.

Timer2 increments from 00h until it matches PR2 and

then resets to 00h on the next increment cycle. PR2 is

a readable and writable register. The PR2 register is

initialized to FFh upon Reset.

7.3 Timer2 Output

The output of TMR2 (before the postscaler) is fed to the

SSP module, which optionally uses it to generate the

shift clock.

FIGURE 7-1: TIMER2 BLOCK DIAGRAM

TABLE 7-1: REGISTERS ASSOCIATED WITH TIMER2

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Value on

all other

Resets

0Bh/

8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

11h TMR2 Holding Register for th e 8-bit TMR2 Register 0000 0000 0000 0000

12h T2CON — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

92h PR2 Timer2 Period Register 1111 1111 1111 1111

Legend: x = unknown, u = unchanged, – = unimplemen ted, read as ‘0’. Shaded cells are not used by the Timer2 module.

Comparator

TMR2 Sets F lag

TMR2

Output(1)

Reset

Postscaler

Prescaler

PR2

FOSC/4

1:1 to 1:16

1:1, 1:4, 1:16

bit TMR2IF

TOUTPS<3:0>

T2CKPS<1:0>

Note 1: TMR2 register ou tput c an be softwa re sel ected by the SSP mod ule as a b aud c lock.

PIC16F946

8.0 COMPARATOR MODULE

The Comparator module contains two analog

comparators. The inputs to the comparators are

multiplexed with I/O port pins RA<3:0>, while the outputs

are multiplexed to pins RA<5:4>. An on-chip Comparator

Voltage Reference (CVREF) can also be applied to the

inputs of the comparators.

The CMCON0 register (Register 8-1) controls the

comparator input and output multiplexers. A block

diagram of the various comparator configurations is

shown in Figure 8-3.

R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0

bit 7 bit 0

bit 7 C2OUT: Comparator 2 Output bit

When C2INV = 0:

1 =C2 V

IN+ > C2 VIN-

0 =C2 V

IN+ < C2 VIN-

When C2INV = 1:

0 =C2 V

IN+ > C2 VIN-

1 =C2 V

IN+ < C2 VIN-

bit 6 C1OUT: Comparator 1 Output bit

When C1INV = 0:

1 =C1 V

IN+ > C1 VIN-

0 =C1 V

IN+ < C1 VIN-

When C1INV = 1:

0 =C1 V

IN+ > C1 VIN-

1 =C1 V

IN+ < C1 VIN-

bit 5 C2INV: Comparator 2 Output Inversion bit

1 = C2 Output inverted

0 = C2 Output not inverted

bit 4 C1INV: Comparator 1 Output Inversion bit

1 = C1 Output inverted

0 = C1 Output not inverted

bit 3 CIS: Comparator Input Switch bit

When CM<2:0> = 010:

1 =C1 V

IN- connects to RA3/AN3/C1+/VREF+/SEG15

C2 VIN- connects to RA2/AN2/C2+/VREF-/COM2

0 =C1 V

IN- connects to RA0/AN0/C1-/SEG12

C2 VIN- connects to RA1/AN1/C2-/SEG7

When CM<2:0> = 001:

1 =C1 V

IN- connects to RA3/AN3/C1+/VREF+/SEG15

0 =C1 V

IN- connects to RA0/AN0/C1-/SEG12

When CM<2:0> = 101:

1 =C2 V

IN+ connects to internal 0.6V reference

0 =C2 V

IN+ connects to RA2/AN2/C2+/VREF-/COM2

bit 2-0 CM<2:0>: Comparator Mode bits(1)

See Figure 8-3 for comparator modes and CM<2:0> bit settings.

Note 1: Setting a pin to an analog input automatically disables the digital input circuitry,

weak pull-ups, and interrupt-on-change, if available. The corresponding TRIS bit

must be se t to Input mode in order to allow e xternal co ntrol of the volt age on the pin.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

8.1 Comparator Operation

A single comparator is shown in Figure 8-1 along with

the relationship between the analog input levels and

the digit al ou tput. When the an alog input a t VIN+ is less

than the analog input VIN-, the o utput of the co mparator

is a digital low level. When the analog input at VIN+ is

greater than the analog input VIN-, the output of the

comparator is a digital high level. The shaded areas of

the output of the comparator in Figure 8-1 represent

the uncertainty due to input offsets and response time.

The polarity of the comparator output can be inverted

by setting the CxINV bits (CMCON0<5:4>). Clearing

CxINV results in a non-inverted output. A complete

table showing the output state versus input conditions

and the polarity bit is shown in Table 8-1.

TABLE 8-1: OUTPUT S TATE VS. INPUT

CONDITIONS

FIGURE 8-1: SINGLE COMPARATOR

8.2 Analog Input Connection

Considerations

A simplified circuit for an analog input is shown in

Figure 8-2. Since the analog pins are connected to a

digital output, they have reverse biased diodes to VDD

and VSS. Th e analog input, th erefore, must be betw een

VSS and VDD. If the input voltage deviates from this

range by more than 0.6V in either direction, one of the

diodes is forward biased and a latch-up may occur. A

maximum sourc e impedance of 10 kΩ is recommended

for the analog sources. Any external component

conne cted to an anal og in put pin , suc h as a capaci tor

or a Zener diode, should have very little leakage.

FIGURE 8-2: ANALOG INPUT MODEL

Note: To use CIN+ and CIN- pins as analog

inputs, the appropriate bits must be

programmed in the CMCON0 (9Ch)

Input Conditions CINV CxOUT

VIN- > VIN+00

VIN- < VIN+01

VIN- > VIN+11

VIN- < VIN+10

IN–

IN+

utput

–

VIN+

VIN-Output

Output

VIN+

VIN-

Rs < 10K

AIN CPIN

5 pF

VDD

VT = 0.6V

RIC

Leakage

±500 nA

Vss

Legend: CPIN= Input Capacitance

VT= Threshold V oltage

ILEAKAGE= Leakage Current at the pin due to various junctions

RIC = Interconnect Resistance

RS= Source Impedance

VA = Analog Voltage

PIC16F946

8.3 Comparator Configuration

There are eight modes of operation for the comparators.

The CMCON0 register is used to select these modes.

Figure 8-3 shows the eight possible modes.

If the Comparator mode is changed, the comparator

output level may not be valid for the specified mode

change delay shown in Section 19.0 “Electrical

Specifications”.

FIGURE 8-3: COMPARATOR I/O OPERATING MODES

Note: Compara tor in terr upts sh ould be dis abled

during a Comparator mode change.

Otherwise, a false interrupt may occur.

RA0/AN0/ VIN-

VIN+

RA3/AN3/ Off (Read as ‘0’)

Comparators Reset (POR Default Value)

CM<2:0> = 000

RA1/AN1/ VIN-

VIN+

RA2/AN2/ Off (Read as ‘0’)

VIN-

VIN+C1OUT

Two Independent Comparators

CM<2:0> = 100

VIN-

VIN+C2OUT

VIN-

VIN+C1OUT

Two Common Reference Comparators

CM<2:0> = 011

VIN-

VIN+C2OUT

VIN-

VIN+Off (Read as ‘0’)

One Independent Comparator with Reference Option

CM<2:0> = 101

VIN-

VIN+C2OUT

VIN-

VIN+Off (Read as ‘0’)

Comparators Off

CM<2:0> = 111

VIN-

VIN+Off (Read as ‘0’)

VIN-

VIN+C1OUT

Four Inputs Multiplexed to Two Comparators

CM<2:0> = 010

VIN-

VIN+C2OUT

From C VREF Module

CIS = 0

CIS = 1

CIS = 0

CIS = 1

VIN-

VIN+C1OUT

Two Com mon Reference Comparators with Outputs

CM<2:0> = 110

VIN-

VIN+C2OUT

VIN-

VIN+C1OUT

Three Inputs Multiplexed to Two Comparators

CM<2:0> = 001

VIN-

VIN+C2OUT

CIS = 0

CIS = 1

RA4

RA5

C1-/SEG12

C1+/VREF+/SEG15

RA0/AN0/

C1-/SEG12

RA3/AN3/

C1+/VREF+/SEG15

C2-/SEG7

C2+/VREF-/COM2

RA1/AN1/

C2-/SEG7

RA2/AN2/

C2+/VREF-/COM2

RA0/AN0/

C1-/SEG12

RA3/AN3/

C1+/VREF+/SEG15

RA1/AN1/

C2-/SEG7

RA2/AN2/

C2+/VREF-/COM2

RA0/AN0/

C1-/SEG12

RA3/AN3/

C1+/VREF+/SEG15

RA1/AN1/

C2-/SEG7

RA2/AN2/

C2+/VREF-/COM2

RA0/AN0/

C1-/SEG12

RA1/AN1/

C2-/SEG7

RA2/AN2/

C2+/VREF-/COM2

RA0/AN0/

C1-/SEG12

RA3/AN3/

C1+/VREF+/SEG15

RA1/AN1/

C2-/SEG7

RA2/AN2/

C2+/VREF-/COM2

RA2/AN2/

C2+/VREF-/COM2

RA1/AN1/

C2-/SEG7

RA3/AN3/

C1+/VREF+/SEG15

RA0/AN0/

C1-/SEG12

CIS = 0

CIS = 1

RA0/AN0/

C1-/SEG12

RA1/AN1/

C2-/SEG7

RA2/AN2/

C2+/VREF-/

COM2 RA5

RA3/AN3/

C1+/VREF+/

SEG15

Inte rn al 0.6 V refe re nce

Legend:

A = Analog Input, port reads zeros always. D = Digital Input. CIS (CMCON0<3>) is the computer Input Switch.

PIC16F946

FIGURE 8-4: COMPARATOR C1 OUTPUT BLOCK DIAGRAM

FIGURE 8-5: COMPARATOR C2 OUTPUT BLOCK DIAGRAM

To C1OUT pin

RD CMCON

Set C1IF bit

MULTIPLEX

Port Pins

NReset

To D a ta B u s

C1INV

RD CMCON

C2SYNC

To C2OUT pin

RD CMCON

Set C2IF bit

MULTIPLEX

Port Pins

RD CMCON

Reset

To D a ta B u s

C2INV

EN TMR1

Clock Source(1)

To TMR1

Note 1: Comparator 2 output is latched on falling edge of T1 clock source.

PIC16F946

8.4 Comparator Outputs

The comparator outputs are read through the

CMCON0 register. These bits are read-only. The

comparator outputs may also be directly output to the

RA4 and RA5 I/O pins. When enabled, multiplexers in

the output path of the RA4 and RA5 pins will switch

and the output of each pin will be the unsynchronized

output of the comparator. The uncertainty of each of

the comparators is related to the input offset voltage

and the response time given in the specifications.

Figure 8-4 and Figure 8-5 show the output block

diagram for Comparator 1 and 2.

The TRIS bits will still function as an output

enable/disable for the RA4 and RA5 pins while in this

mode.

The polarity of the comparator outputs can be changed

using the C1INV and C2INV bits (CMCON0<5:4>).

Timer1 gate source can be configured to use the T1G

pin or Comparator 2 output as selected by the T1GSS

bit (CMCON1<1>). This feature can be used to time

the duration or interval of analog events. The output of

Comparator 2 can also be synchronized with Timer1

by setting the C2SYNC bit (CMCON1<0>). When

enabled, the output of Comparator 2 is lat ched on the

falling edge of Timer1 clock source. If a prescaler is

used with Timer1, Comparator 2 is latched after the

prescaler . To prevent a race condition, the Comp arator

2 output is latched on the falling edge of the Timer1

clock source and T imer1 increments on the rising edge

of its clock source. See (Figure 8-5), Comparator 2

Block Diagram and (Figure 5-1), Timer1 Block

Diagram for more information.

It is recommended to synchronize Comparator 2 with

Timer1 by setting the C2SYNC bit when Comparator 2

is used as the Timer1 gate source. This ensures Timer1

does not miss an increment if Comparator 2 changes

during an inc rement.

8.5 Comparat or Interrupts

The comparator interrupt flags are set whenever there is

a change in the output value of its respective comp arator .

Software will need to maintain information about the

sta tus of the output bi ts, a s read from CMCON0< 7:6>, t o

determine the act ual change that has occurred. The CxIF

bits , PIR2<6 :5>, ar e the Comp arat or In terrupt flags. Th is

bit must be reset in software by clearing it to ‘0’. Si nc e it

is al so po ssi bl e t o w rit e a ‘1’ to this register, a simulated

interrupt may be initiated.

The CxIE bits (PIE2<6:5>) and the PEIE bit

(INTCON<6>) must be set to enable the interrupts. In

addition, the GIE bit must also be set. If any of these

bits are cleared, th e interrupt is n ot enabled, th ough the

CxIF bit s will still be se t if an interru pt condi tion occ urs.

The use r , in the Interru pt Service Routi ne, can clear th e

interr upt in the foll owin g man ner:

a) Any read or write of CMCON0. This will end the

mismatch condition.

b) Clear flag bit CxIF

A mismatch condition will continue to set flag bit CxIF.

Readi ng CMCON0 will end the mis match condi tion and

allow flag bits CxIF to be cleared.

U-0 U-0 U-0 U-0 U-0 U-0 R/W-1 R/W-0

—————— T1GSS C2SYNC

bit 7 bit 0

bit 7-2: Unimplemented: Read as ‘0’

bit 1 T1GSS: Timer1 Gate Source Select bit

1 = Timer1 gate source is T1G pin (RC4 must be configured as digital input)

0 = Timer1 gate source is Comparator 2 Output

bit 0 C2SYNC: Comparator 2 Synchronize bit

1 = C2 output synchronized with falling edge of Timer1 clock

0 = C2 output not synchronized with Timer1 clock

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Note: If a change in the CMCON0 register

(CxOUT) should occur when a read

operatio n is being executed (start of the Q2

cycle), th en the CxIF (PI R2<6:5>) interru pt

flag may not get set.

PIC16F946

8.6 Comparator Reference

The Com parator modul e also allows the sel ection of an

internally generated voltage reference for one of the

comparator inputs. The VRCON register, Register 8-3,

controls the voltage reference module shown in

Figure 8-6.

8.6.1 CONFIGURING THE VOLTAGE

REFERENCE

The voltage reference can output 32 distinct voltage

levels; 16 in a high range and 16 in a low range.

The follow ing equati on determines the output volt ages:

EQUATION 8-1:

8.6.2 VOLTAGE REFERENCE

ACCURACY/ERROR

The ful l range of VSS to VDD cannot be realized due to

the construction of the module. The transistors on th e

top and bottom of the resistor ladder network

(Figure 8-6) keep CVREF from approaching VSS or

VDD. The exception is when the module is disabled by

clearin g the VREN b it (VRCON<7> ). When disa bled,

the reference voltage is VSS when VR<3:0> = 0000.

This allows the comparators to detect a zero-crossing

and not con sume CVREF module current.

The volt age reference is VDD derived and theref ore, the

CVREF output changes with fluctuations in VDD. The

tested absolute accuracy of the comparator voltage

reference can be found in Section 19.0 “Electrical

Specifications”.

FIGURE 8-6: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM

VRR = 1 (low range): CVREF = (VR3:VR0/24) x VDD

VRR = 0 (high range):

CVREF = (VDD/4) + (VR3:VR0 x VDD/32)

VRR

VR<3:0>

16-1 Analog

8RRR RR

CVREF to

16 Stages

Comparator

Input

VREN

VDD

MUX

VREN

VR <3:0> = ‘0000’

PIC16F946

8.7 Comparator Response Time

Response time is the minimum time, after selecting a

new reference voltage or input source, before the

comparator output is ensured to have a valid level. If

the internal reference is changed, the maximum delay

of the internal voltage reference must be considered

when using the comparator outputs. Otherwise, the

maximum delay of the comparators should be used

(Table 19-9).

8.8 Operation During Sleep

The comparators and voltage reference, if enabled

before entering Sleep mode, remain active during

Sleep. Thi s results in highe r Sleep currents than shown

in the power-down specifications. The additional

current consumed by the comparator and the voltage

reference is shown separately in the specifications. To

minim ize power consum ption whil e in Sleep mode, tu rn

off the comparator, CM<2:0> = 111, and voltage

reference, VRCON<7> = 0.

While the comparator is enabled during Sleep, an

interrupt will wake-up the device. If the GIE bit

(INTCON<7>) is set, the device will jump to the inter-

rupt vector (0004h), and if clear, continues execution

with the next instruction. If the device wakes up from

Sleep, the contents of the CMCON0, CMCON1 and

VRCON registers are not affected.

8.9 Effect s of a Reset

A device Reset forces the CMCON0, CMCON1 and

VRCON registers to their Reset states. This forces the

Comparator module to be in the Comparator Reset

mode, CM< 2:0> = 000 and the volt a ge re ference to its

OFF state. Thus, all potential inputs are analog inputs

with the comparator and voltage reference disabled to

consume the smallest current possible.

PIC16F946

TABLE 8-2: REGISTERS ASSOCIATED WITH COMPARATOR MODULE

R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

VREN —VRR— VR3 VR2 VR1 VR0

bit 7 bit 0

bit 7 VREN: CVREF Enable bit

1 = CVREF circuit powered on

0 = CVREF circuit powered down, no IDD drain and CVREF = VSS.

bit 6 Unimplemented: Read as ‘0’

bit 5 VRR: CVREF Range Selection bit

1 = Low range

0 = High range

bit 4 Unimplemented: Read as ‘0’

bit 3-0 VR<3:0>: CVREF Value Selection bits 0 ≤ VR<3:0> ≤ 15

When VRR = 1: CVREF = (VR<3:0>/24) * VDD

When VRR = 0: CVREF = VDD/4 + (VR<3:0>/32) * VDD

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Value on

all other

Resets

0Bh/8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF —CCP2IF 0000 -0-0 0000 -0-0

9Ch CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

97h CMCON1 —————— T1GSS C2SYNC ---- --10 ---- --10

85h TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE—CCP2IE 0000 -0-0 0000 -0-0

9Dh VRCON VREN —VRR— VR3 VR2 VR1 VR0 0-0- 0000 0-0- 0000

Legend: x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the comparator or Comparator Voltage

Refere nce mo dule .

PIC16F946

9.0 LIQUID CRYSTAL DISPLAY

(LCD) DRIVER MODULE

The Liquid Crystal Display (LCD) driver module

generates the timing control to drive a static or

multiplexed LCD panel. In the PIC16F946 device, the

module drives the panels of up to four commons and up

to 42 segments. It also provides control of the LCD

pixel data.

The LCD driver module supports:

• Direc t driving of LCD panel

• Three LCD clock sources with selecta ble prescaler

• Up to four commons :

- Static

- 1/2 multiplex

- 1/3 multiplex

- 1/4 multiplex

• 42 segments

• Static, 1/2 or 1/3 LCD Bias

The module has 32 registers:

• LCD Control Register (LCDCON)

• LCD Phase Register (LCDPS)

• Six LCD Segment Enable Registers

(LCDSE<5:0>)

• 24 LCD Data Registers (LCDDATA<11:0>)

The LCDCON register, shown in Register 9-1, controls

the operation of the LCD driver module. The LCDPS

clock source prescaler and the type of waveform;

T ype-A or T ype-B. The LCDSE<2:0> registers c onfigure

the functions of the port pins:

• LCDSE0 SE<7:0>

• LCDSE1 SE<15:8>

• LCDSE2 SE<23:16>

• LCDSE3 SE<31:24>

• LCDSE4 SE<39:32>

• LCDSE5 SE<41:40>

As an example, LCDSEn is detailed in Register 9-3.

Once the module is initialized for the LCD panel, the

individual bits of the LCDDATA<11:0> registers are

cleared/set to represent a clear/dark pixel,

respectively:

• LCDDATA0 SEG7COM0:SEG0COM0

• LCDDATA1 SEG15COM0:SEG8COM0

• LCDDATA2 SEG23COM0:SEG16COM0

• LCDDATA3 SEG7COM1:SEG0COM1

• LCDDATA4 SEG15COM1:SEG8COM1

• LCDDATA5 SEG23COM1:SEG16COM1

• LCDDATA6 SEG7COM2:SEG0COM2

• LCDDATA7 SEG15COM2:SEG8COM2

• LCDDATA8 SEG23COM2:SEG16COM2

• LCDDATA9 SEG7COM3:SEG0COM3

• LCDDATA10 SEG15COM3:SEG8COM3

• LCDDATA11 SEG23COM3:SEG16COM 3

• LCDDATA12 SEG31COM0:SEG24COM0

• LCDDATA13 SEG39COM0:SEG32COM0

• LCDDATA14 SEG41COM0:SEG40COM0

• LCDDATA15 SEG31COM1:SEG24COM1

• LCDDATA16 SEG39COM1:SEG32COM1

• LCDDATA17 SEG41COM1:SEG40COM1

• LCDDATA18 SEG31COM2:SEG24COM2

• LCDDATA19 SEG39COM2:SEG32COM2

• LCDDATA20 SEG41COM2:SEG40COM2

• LCDDATA21 SEG31COM3:SEG24COM3

• LCDDATA22 SEG39COM3:SEG32COM3

• LCDDATA23 SEG41COM3:SEG40COM3

As an example, LCDDATAx is detailed in Register 9-4.

Once the module is configured, the LCDEN

(LCDCON <7>) bit is used to enable or dis able the LCD

module . The LC D p an el c an als o op erate during Slee p

by clearing the SLPEN (LCDCON<6>) bit.

PIC16F946

FIGURE 9-1: LCD DRIVER MODULE BLOCK DIAGRAM

COM<3:0>

Clock Source

Timing Control

Data Bus

Select and

Prescaler

LFINTOSC/32

FOSC/8192

T10SC/32

168

MUX

SEG<42:0>

To I/O Pads(1)

LCDCON

LCDPS

LCDSEn

24 x 8

(= 4 x 24)

LCDDATAx

Registers

Note 1: These signals are connected directly to the I/O pads, but may be tri-stated, depending on the

configuration of the LCD module.

PIC16F946

R/W-0 R/W-0 R/C-0 R/W-1 R/W-0 R/W-0 R/W-1 R/W-1

LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0

bit 7 bit 0

bit 7 LCDEN: LCD Driver Enable bit

1 = LCD driver module is enabled

0 = LCD driver module is disabled

bit 6 SLPEN: LCD Driver Enable in Sleep mode bit

1 = LCD driver module is disabled in Sleep mode

0 = LCD driver module is enabled in Sleep mode

bit 5 WERR: LCD Write Failed Error bit

1 = LCDDATAx register written while LCDPS<WA> = 0 (must be cleared in software)

0 = No LCD write error

bit 4 VLCDEN: LCD Bias Voltage Pins Enable bit

1 = VLCD pins are enabled

0 = VLCD pins are disabled

bit 3-2 CS<1:0>: Clock Sourc e Select bits

00 = FOSC/8192

01 = T1OSC (Timer1)/32

1x = LFINTO SC (31 kHz)/32

bit 1-0 LMUX<1:0>: Comm ons Select bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

C = Only clearable bit ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

- n = Value at POR

LMUX<1:0> Multiplex Maximum Number of Pixels Bias

00 Static (COM0) 42 Static

01 1/2 (COM <1: 0>) 84 1/2 or 1/3

10 1/3 (COM<2:0>) 126 1/2 or 1/3

11 1/4 (COM<3:0>) 168 1 /3

PIC16F946

R/W-0 R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0

WFT BIASMD LCDA WA LP3 LP2 LP1 LP0

bit 7 bit 0

bit 7 WFT: Waveform Type Select bit

1 = Type-B waveform (phase changes on each frame boundary)

0 = Type-A waveform (phase changes within each common type)

bit 6 BIASMD: Bias Mode Select bit

When LMUX<1:0> = 00:

0 = Static Bias mode (do not set this bit to ‘1’)

When LMUX<1:0> = 01:

1 = 1/2 Bias mode

0 = 1/3 Bias mode

When LMUX<1:0> = 10:

1 = 1/2 Bias mode

0 = 1/3 Bias mode

When LMUX<1:0> = 11:

0 = 1/3 Bias mode (do not set this bit to ‘1’)

bit 5 LCDA: LCD Active Status bit

1 = LCD driver module is active

0 = LCD driver module is inactive

bit 4 WA: LCD Wri te Allo w Status bit

1 = Write into the LCDDATA x registers is allowed

0 = Write into the LCDDATAx registers is not allowed

bit 3-0 LP<3:0>: LCD Prescaler Select bits

1111 = 1:16

1110 = 1:15

1101 = 1:14

1100 = 1:13

1011 = 1:12

1010 = 1:11

1001 = 1:10

1000 = 1:9

0111 = 1:8

0110 = 1:7

0101 = 1:6

0100 = 1:5

0011 = 1:4

0010 = 1:3

0001 = 1:2

0000 = 1:1

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

19Dh, OR 19Eh)

190h-199h, 19Ah, OR 19Bh)

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SEn SEn SEn SEn SEn SEn SEn SEn

bit 7 bit 0

bit 7-0 SEn: Segment Enable bits

1 = Segment function of the pin is enabled

0 = I/O function of the pin is enabled

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SEGx-

COMy SEGx-

COMy

bit 7 bit 0

bit 7-0 SEGx-COMy: Pixel On bits

1 = Pixel on ( dark)

0 = Pixel off (clear)

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

9.1 LCD Clock Source Selection

The LCD driver module has 3 possible clock sources:

•F

OSC/8192

•T1OSC/32

• LFINTOSC/32

The first clock source is the system clock divided by

8192 (FOSC/8192). This divider ratio is chosen to

provide about 1 kHz output when the system clock is

8 MHz. The divider is not programmable. Instead, the

LCD prescaler bits, LCDPS<3:0>, are used to set the

LCD frame clock rate.

The second clock source is the T1OSC/32. This also

gives about 1 kHz when a 32.768 kHz crystal is used

with the Timer1 os cilla tor. To use t he Timer1 osc illat or

as a clock source, the T1OSCEN (T1CON<3>) bit

should be set.

The third clock source is the 31 kHz LFINTOSC/32, which

provides approximately 1 kHz output.

The second and third clock sources may be used to

continue running the LCD while the processor is in

Sleep.

Using the bits, CS<1:0> (LCDCON<3:2>), any of these

clock sources can be selected.

9.1.1 LCD PRESCALER

A 16-bit counter is available as a prescaler for the LCD

cloc k. The p rescal er is n ot di rectly readab le or w ritable;

its value is set by the LP<3 :0> bit s (LC DPS<3:0>), which

determ in e the pres c al er as si gn m en t a nd pres ca le rati o.

The prescale values from 1:1 through 1:16.

9.2 LCD Bias Types

The LCD driver module can be configured into three

bias types:

• Static Bias (2 voltage levels: VSS and VDD)

• 1/2 Bias (3 voltage levels: VSS, 1/2 VDD and VDD)

• 1/3 Bias (4 voltage levels: VSS, 1/3 VDD, 2/3 VDD

and VDD)

This module uses an external resistor ladder to

generate the L CD bias voltages.

The exte rnal resistor ladder shoul d be connect ed to the

Bias 1 pin, Bias 2 pin, Bias 3 pin and VSS. The Bias 3

pin should also be connected to VDD.

Figure 9-2 shows the proper way to connect the

resistor ladder to the Bias pins.

FIGURE 9-2: LCD BIAS RESISTOR LADDER CONNECTION DIAGRAM

Note: VLCD pins used to supply LCD bias

voltage are enabled on power-up (POR)

and must be disabled by the user by

clearing LCDCON<4>, the VLCDEN bit,

(see Register 9-1).

VLCD 3

VLCD 2

VLCD 1

VLCD 0(1)

LCD

Driver

Connections for External R-ladder

10 kΩ*10 kΩ*10 kΩ*

LCD Bias 2 L CD Bias 1

LCD Bias 3

* These values are provided for design guidance only and should be optimized for the application by the

designer.

Note 1: Internal connection.

VSS

Static

Bias 1/2 Bias 1/3 Bias

VLCD 0VSS VSS VSS

VLCD 1 —1/2 VDD 1/3 V DD

VLCD 2 —1/2 VDD 2/3 V DD

VLCD 3VDD VDD VDD

10 kΩ*10kΩ*VSS

VDD*

Static Bias

1/2 Bias

1/3 Bias

PIC16F946

9.3 LCD Multiplex Types

The LCD driver module can be configured into four

multiplex types:

• Static (only COM0 used)

• 1/2 multiplex (COM0 and COM1 are used)

• 1/3 multiplex (COM0, COM1 and COM2 are used)

• 1/4 multiplex (all COM0, COM1, COM2 and COM3

are used)

The LMUX<1:0> setting decides the function of RB5,

RA2 and RD0 pins (see Table 9-1 for details).

If the pin is a digital I/O, the corresponding TRIS bit

controls the data direction. If the pin is a COM drive,

then the TRIS setting of that pin is overridden.

TABLE 9-1: RD0, RA2, RB5 FUNCTION

9.4 Segment Enables

The LCDSEn registers are used to select the pin

function for each segment pin. The selection allows

each pin to operate as either an LCD segment driver or

as one of the pin’ s alte rnate fun ction s. To configure the

pin as a segment pin, the corresponding bits in the

LCDS En reg isters mu st be s et to ‘ 1’. See Figures 9-4

and 9-5 for more details.

If the pin is a digital I/O, the corresponding TRIS bit

controls the data direction. Any bit set in the LCDSEn

registers overrides any bit settings in the corresponding

TRIS register.

9.5 Pixel Control

The LCDDATAx registers contain bits which define the

state of each pixel. Each bit defines one unique pixel.

LCDDATAx registers to the respective common and

segment signals.

Any L CD pix el lo catio n not b eing used f or dis play can

be used as general purpose RAM.

9.6 LCD Frame Frequency

The rat e at which the CO M and SEG output s chan ge is

called the LCD frame frequency.

TABLE 9-2: FRAME FREQUENCY

FORMULAS

TABLE 9-3: APPROXIMATE FRAME

FREQUENCY (IN Hz) USING

FOSC @ 8 MHz, TIMER1 @

32.768 kHz OR INTOSC

Note: On a Power-on Reset, the LMUX<1:0>

bits are ‘11’.

LMUX

<1:0> RD0 RA2 RB5

00 Digit al I/O Digital I/O Digital I/O

01 Digital I/O Digital I/O COM1 Driver

10 Digital I/O COM2 Driver COM1 Driver

11 COM3 Driver COM2 Driver COM1 Driver

Note: On a Power-on Reset, these pins are

configured as digital I/O.

Multiplex Frame Frequency =

Static Clock source/ (4 x 1 x (LP<3:0> + 1))

1/2 Clock source/(2 x 2 x (LP<3:0> + 1))

1/3 Clock source/(1 x 3 x (LP<3:0> + 1))

1/4 Clock source/(1 x 4 x (LP<3:0> + 1))

Note: Clock source is FOSC/8192, T1OSC/32 or

LFINTOSC/32.

LP<3:0> Static 1/2 1/3 1/4

2 85 85 114 85

364648564

451516851

543435743

637374937

732324332

PIC16F946

FIGURE 9-3: LCD CLOCK GENERATION

CS<1:0>

T1OSC 32 kHz

Crystal Osc.

LFINTOSC

Nom FRC =31kHz

STAT

DUP

TRIP

QUAD

÷4

LMUX<1:0>

4-bit Prog Presc ÷1, 2, 3, 4

Ring Counter

LMUX<1:0>

COM0

COM1

COM2

COM3

÷8192

FOSC

÷2

÷32

÷32 LP<3:0>

(LCDCON<3:2>) (LCDCON<1:0>)

(LCDCON<1:0>)

(LCDPS<3:0>)

PIC16F946

FIGURE 9-4: LCD SEGMENT MAPPING WORKSHEET (PART 1 OF 2)

LCD

Function COM0 COM1 COM2 COM3 Pin No. PORT Alternate

Functions

LCDDATAx

Address LCD

Segment LCDDATAx

Address LCD

Segment LCDDATAx

Address LCD

Segment LCDDATAx

Address LCD

Segment 28/40-pin

SEG0 LCDDATA0, 0 LCDDATA3, 0 LCDDATA6, 0 LCDDATA9, 0 21/33 RB0 INT

SEG1 LCDDATA0, 1 LCDDATA3, 1 LCDDATA6, 1 LCDDATA9, 1 22/34 RB1

SEG2 LCDDATA0, 2 LCDDATA3, 2 LCDDATA6, 2 LCDDATA9, 2 23/35 RB2

SEG3 LCDDATA0, 3 LCDDATA3, 3 LCDDATA6, 3 LCDDATA9, 3 24/36 RB3

SEG4 LCDDATA0, 4 LCDDATA3, 4 LCDDATA6, 4 LCDDATA9, 4 6/6 RA4 C1OUT/T0CKI

SEG5 LCDDATA0, 5 LCDDATA3, 5 LCDDATA6, 5 LCDDATA9, 5 7/7 RA5 C2OUT/AN4/SS

SEG6 LCDDATA0, 6 LCDDATA3, 6 LCDDATA6, 6 LCDDATA9, 6 14/18 RC3

SEG7 LCDDATA0, 7 LCDDATA3, 7 LCDDATA6, 7 LCDDATA9, 7 3/3 RA1 AN1

SEG8 LCDDATA1, 0 LCDDATA4, 0 LCDDATA7, 0 LCDDATA10, 0 18/26 RC7 RX/DT/SDI/SDA

SEG9 LCDDATA1, 1 LCDDATA4, 1 LCDDATA7, 1 LCDDATA10, 1 17/25 RC6 TX/CK/SCK/SCL

SEG10 LCDDATA1, 2 LCDDATA4, 2 LCDDATA7, 2 LCDDATA10, 2 16/24 RC5 T1CKI/CCP1

SEG11 LCDDATA1, 3 LCDDATA4, 3 LCDDATA7, 3 LCDDATA10, 3 15/23 RC4 T1G/SDO

SEG12 LCDDATA1, 4 LCDDATA4, 4 LCDDATA7, 4 LCDDATA10, 4 2/2 RA0 AN0

SEG13 LCDDATA1, 5 LCDDATA4, 5 LCDDATA7, 5 LCDDATA10, 5 28/40 RB7 ICSPDAT/ICDDAT

SEG14 LCDDATA1, 6 LCDDATA4, 6 LCDDATA7, 6 LCDDATA10, 6 27/39 RB6 ICSPCK/ICDCK

SEG15 LCDDATA1, 7 LCDDATA4, 7 LCDDATA7, 7 LCDDATA10, 7 5/5 RA3 AN3/VREF+

SEG16 LCDDATA2, 0 LCDDATA5, 0 LCDDATA8, 0 LCDDATA11, 0 -/26 RD3

SEG17 LCDDATA2, 1 LCDDATA5, 1 LCDDATA8, 1 LCDDATA11, 1 -/27 RD4

SEG18 LCDDATA2, 2 LCDDATA5, 2 LCDDATA8, 2 LCDDATA11, 2 -/28 RD5

SEG19 LCDDATA2, 3 LCDDATA5, 3 LCDDATA8, 3 LCDDATA11, 3 -/29 RD6

SEG20 LCDDATA2, 4 LCDDATA5, 4 LCDDATA8, 4 LCDDATA11, 4 -/30 RD7

SEG21 LCDDATA2, 5 LCDDATA5, 5 LCDDATA8, 5 LCDDATA11, 5 -/8 RE0 AN5

SEG22 LCDDATA2, 6 LCDDATA5, 6 LCDDATA8, 6 LCDDATA11, 6 -/9 RE1 AN6

SEG23 LCDDATA2, 7 LCDDATA5, 7 LCDDATA8, 7 LCDDATA11, 7 -/10 RE2 AN7

PIC16F946

FIGURE 9-5: LCD SEGMENT MAPPING WORKSHEET (PART 2 OF 2)

LCD

Function COM0 COM1 COM2 COM3 Pin No. PORT Alternate

Functions

LCDDATAx

Address LCD

Segment LCDDATAx

Address LCD

Segment LCDDATAx

Address LCD

Segment LCDDATAx

Address LCD

Segment 28/40-pin

SEG24 LCDDATA12, 0 LCDDATA15, 0 LCDDATA18, 0 LCDDATA21, 0 37 RE4

SEG25 LCDDATA12, 1 LCDDATA15, 1 LCDDATA18, 1 LCDDATA21, 1 42 RE5

SEG26 LCDDATA12, 2 LCDDATA15, 2 LCDDATA18, 2 LCDDATA21, 2 43 RE6

SEG27 LCDDATA12, 3 LCDDATA15, 3 LCDDATA18, 3 LCDDATA21, 3 44 RE7

SEG28 LCDDATA12, 4 LCDDATA15, 4 LCDDATA18, 4 LCDDATA21, 4 45 RF4

SEG29 LCDDATA12, 5 LCDDATA15, 5 LCDDATA18, 5 LCDDATA21, 5 46 RF5

SEG30 LCDDATA12, 6 LCDDATA15, 6 LCDDATA18, 6 LCDDATA21, 6 47 RF6

SEG31 LCDDATA12, 7 LCDDATA15, 7 LCDDATA18, 7 LCDDATA21, 7 48 RF7

SEG32 LCDDATA13, 0 LCDDATA16, 0 LCDDATA19, 0 LCDDATA22, 0 11 RF0

SEG33 LCDDATA13, 1 LCDDATA16, 1 LCDDATA19, 1 LCDDATA22, 1 12 RF1

SEG34 LCDDATA13, 2 LCDDATA16, 2 LCDDATA19, 2 LCDDATA22, 2 13 RF2

SEG35 LCDDATA13, 3 LCDDATA16, 3 LCDDATA19, 3 LCDDATA22, 3 14 RF3

SEG36 LCDDATA13, 4 LCDDATA16, 4 LCDDATA19, 4 LCDDATA22, 4 3 RG0

SEG37 LCDDATA13, 5 LCDDATA16, 5 LCDDATA19, 5 LCDDATA22, 5 4 RG1

SEG38 LCDDATA13, 6 LCDDATA16, 6 LCDDATA19, 6 LCDDATA22, 6 5 RG2

SEG39 LCDDATA13, 7 LCDDATA16, 7 LCDDATA19, 7 LCDDATA22, 7 6 RG3

SEG40 LCDDATA14, 0 LCDDATA17, 0 LCDDATA20, 0 LCDDATA23, 0 7 RG4

SEG41 LCDDATA14, 1 LCDDATA17, 1 LCDDATA20, 1 LCDDATA23, 1 8 RG5

PIC16F946

9.7 LCD W aveform Generation

LCD waveforms are generated so that the net AC

volt age across the d ark p ixe l sh ould b e max imized an d

the net AC voltage across the clear pixel should be

minim ized. The n et DC vo ltage a cross any pixel sh ould

be zero.

The COM signal represents the time slice for each

common, while the SEG contains the pixel data.

The pixel signal (COM-SEG) will have no DC compo-

nent and it can take only one of the two rms values. The

higher rms value will create a dark pixel and a lower

rms value will create a clear pixel.

As the number of commons increases, the delta

between the two rms values decreases. The delta

represents the maximum contrast that the display can

have.

The LCDs can be driven by two types of waveform:

Type-A and Type-B. In Type-A waveform, the phase

changes within ea ch common ty pe, wherea s in Type-B

waveform, the phase changes on each frame

boundary. Thus, Type-A waveform maintains ‘0’V

over a single frame, whereas Type-B waveform takes

two frames.

Figure 9-6 through Figure 9-16 provide waveforms for

static, half-multiplex, one-third-multiplex and

quarter-multiplex drives for Type-A and Type-B

waveforms.

FIGURE 9-6: TYPE-A/TYPE-B WAVEFORMS IN STATIC DRIVE

Note 1: If Sleep has to be executed with LCD

Sleep enabled (LCDCON<SLPEN> is

‘1’), then care must be taken to execute

Sleep only when VDC on all the pixels is

‘0’.

2: When the LCD clock s ource is FOSC/8192,

if Sleep is executed, irrespective of the

LCDCON<SLPEN> setting, the LCD goes

into Sleep. Thus, t ake care to see tha t VDC

on all pixels is ‘0’ when Sleep is executed .

COM0

SEG0

COM0-SEG0

COM0-SEG1

SEG1

-V1

1 Frame

COM0

SEG0

SEG1

SEG2

SEG3

SEG4

SEG5

SEG6

SEG7

PIC16F946

FIGURE 9-7: TYPE-A WAV EFORMS IN 1/2 MUX, 1/2 BIAS DRIVE

-V2

-V1

-V2

-V1

COM0

COM1

SEG0

SEG1

COM0-SEG0

COM0-SEG1

1 Frame

COM1

COM0

SEG0

SEG1

SEG2

SEG3

PIC16F946

FIGURE 9-8: TYPE-B WAV EFORMS IN 1/2 MUX, 1/2 BIAS DRIVE

-V2

-V1

-V2

-V1

COM0

COM1

SEG0

SEG1

COM0-SEG0

COM0-SEG1

COM1

COM0

SEG0

SEG1

SEG2

SEG3

2 Frames

PIC16F946

FIGURE 9-9: TYPE-A WAV EFORMS IN 1/2 MUX, 1/3 BIAS DRIVE

-V3

-V2

-V1

-V3

-V2

-V1

COM0

COM1

SEG0

SEG1

COM0-SEG0

COM0-SEG1

1 Frame

COM1

COM0

SEG0

SEG1

SEG2

SEG3

PIC16F946

FIGURE 9-10: TYPE-B WAVEFORMS IN 1/2 MUX, 1/3 BIAS DRIVE

-V3

-V2

-V1

-V3

-V2

-V1

COM0

COM1

SEG0

SEG1

COM0-SEG0

COM0-SEG1

COM1

COM0

SEG0

SEG1

SEG2

SEG3

2 Frames

PIC16F946

FIGURE 9-11: TYPE-A WAVEFORMS IN 1/3 MUX, 1/2 BIAS DRIVE

-V2

-V1

-V2

-V1

COM0

COM1

COM2

SEG0

SEG1

COM0-SEG0

COM0-SEG1

1 Frame

COM2

COM1

COM0

SEG0

SEG1

SEG2

PIC16F946

FIGURE 9-12: TYPE-B WAVEFORMS IN 1/3 MUX, 1/2 BIAS DRIVE

-V2

-V1

-V2

-V1

COM0

COM1

COM2

SEG0

SEG1

COM0-SEG0

COM0-SEG1

2 Frames

COM2

COM1

COM0

SEG0

SEG1

SEG2

PIC16F946

FIGURE 9-13: TYPE-A WAVEFORMS IN 1/3 MUX, 1/3 BIAS DRIVE

-V3

-V2

-V1

-V3

-V2

-V1

COM0

COM1

COM2

SEG0

SEG1

COM0-SEG0

COM0-SEG1

1 Frame

COM2

COM1

COM0

SEG0

SEG1

SEG2

PIC16F946

FIGURE 9-14: TYPE-B WAVEFORMS IN 1/3 MUX, 1/3 BIAS DRIVE

-V3

-V2

-V1

-V3

-V2

-V1

COM0

COM1

COM2

SEG0

SEG1

COM0-SEG0

COM0-SEG1

2 Frames

COM2

COM1

COM0

SEG0

SEG1

SEG2

PIC16F946

FIGURE 9-15: TYPE-A WAVEFORMS IN 1/4 MUX, 1/3 BIAS DRIVE

-V3

-V2

-V1

-V3

-V2

-V1

COM0

COM1

COM2

COM3

SEG0

SEG1

COM0-SEG0

COM0-SEG1

COM3

COM2

COM1

COM0

1 Frame

SEG0

SEG1

PIC16F946

FIGURE 9-16: TYPE-B WAVEFORMS IN 1/4 MUX, 1/3 BIAS DRIVE

-V3

-V2

-V1

-V3

-V2

-V1

COM0

COM1

COM2

COM3

SEG0

SEG1

COM0-SEG0

COM0-SEG1

COM3

COM2

COM1

COM0

2 Frames

SEG0

SEG1

PIC16F946

9.8 LCD Interrupts

The LCD timing generation provides an interrupt that

defines the LCD frame timing. This interrupt can be

used to co ord ina te the writin g of th e pi xe l data with the

start of a new frame. Writing pixel data at the frame

boundary allow s a v isually c risp tran sition o f the image.

This in terrupt c an als o be us ed to s ynchroni ze externa l

event s to the LCD.

A new frame is defined to begin at the leading edge of

the COM0 common signal. The interrupt will be set

immediately after the LCD controller completes

accessing all pixel data required for a frame. This will

occur at a fixed interval before the frame boundary

(TFINT), as shown in Figure 9-17. The LCD controller

will begin to access data for the next frame within the

interval f r om th e i nte rrup t to when the c on troll er begin s

to access data after the interrupt (TFWR). New data

must be written within TFWR, as this is when the LCD

controller will begin to access the data for the next

frame.

When the LCD driver is running with Type-B waveforms

and the LMUX<1:0> bits are not equal to ‘00’, there are

some additional issues that must be addressed. Since

the DC voltage on the p ixel ta ke s two f rame s to m aintain

zero volts, the pixel data must not change between

subsequent frames. If the pixel data were allowed to

change, the waveform for the odd frames would not

necessarily be the complement of the waveform

generated in the even frames and a DC component

would be introduced into the panel. Therefore, when

using Type-B wa vefo rms, th e user mus t sync hron ize th e

LCD pixel updates to occur within a subframe after the

frame in ter rupt.

To correctly sequence writing while in Type-B, the

interrupt will only occur on complete phase intervals. If the

user attempts to write when the write is disabled, the

WERR (LCDCON<5>) bit is set.

FIGURE 9-17: WAVEFORMS AND INTERRUPT TIMING IN QUARTER-DUTY CYCLE DRIVE

(EXAMPLE – TYPE-B, NON-STATIC)

Note: The interrupt is not generated when the

T ype-A waveform is selected and when the

Type-B with no multiplex (static) is

selected.

Frame

Boundary Frame

Boundary

LCD

Interrupt

Occurs

Controller Accesses

Next Frame Data

TFINT

TFWR

TFWR =TFRAME/2*( LMUX<1:0> + 1) + TCY/2

TFINT =(TFWR/2 – (2 TCY + 40 ns)) →minimum = 1.5(TFRAME/4) – (2 TCY + 40 ns)

(TFWR/2 – (1 TCY + 40 ns)) →maximum = 1.5(TFRAME/4) – (1 TCY + 40 ns)

Frame

Boundary

COM0

COM1

COM2

COM3

2 Frames

PIC16F946

9.9 Operation During Sleep

The LCD m odul e can o perate d uring Sl eep. Th e se lec-

tion is controlled by bit SLPEN (LCDCON<6>). Setting

the SLPEN bit allows the LCD module to go to Sleep.

Clearing the SLPEN bit allows the module to continue

to operate during Sleep.

If a SLEEP instruction is executed and SLPEN = 1, the

LCD module will cease all functions and go into a very

low-current Consumption mode. The module will stop

operation immediately and drive the minimum LCD

voltage on both segment and common lines.

Figure 9-18 shows this operation.

To ensure that no DC component is introduced on the

pane l, the SLEEP instruction sh ould be executed imme-

diately after a LCD frame boundary. The LCD interrupt

can be used to determine the frame boundary. See

Section 9.8 “LCD Interrupts” for the formulas to

calculate the delay.

If a SLEEP instruction is executed and SLPEN = 0, the

module will continue to display the current contents of

the LCDDATA registers. To allow the module to

continue operation while in Sleep, the clock source

must be either the LFINTOSC or T1OSC external

oscillator. While in Sleep, the LCD data cannot be

changed. The LCD module current consumption will

not decrease in this mode; however, the overall

consumption of the device will be lower due to shut

down of the core and other peripheral functions.

Table 9-4 shows the status of the LCD module during

a Sleep while using each of the three available clock

sources:

TABLE 9-4: LCD MODULE STATUS

DURING SLEEP

Clock Source SLPEN Operation

During Sleep?

T1OSC 0Yes

1No

LFINTOSC 0Yes

1No

FOSC/4 0No

1No

Note: The LFINTOSC or external T1OSC

oscillator must be used to operate the LCD

module during Sleep.

PIC16F946

FIGURE 9-18: SLEEP ENTRY/EXIT WHEN SLPEN = 1 OR CS<1:0> = 00

SLEEP Instruction Execution Wake-up

2 Frames

COM0

COM1

COM2

SEG0

PIC16F946

9.10 Configuring the LCD Module

The following is the sequenc e of s teps to configure th e

LCD mo dul e.

1. Select the frame clock prescale using bits

LP<3:0> (LCDPS<3:0>).

2. Configure the appropriate pins to function as

segment drivers using the LCDSEn registers.

3. Configure the LCD module for the following

using the LCDCON register:

-Multiplex and Bias mode, bits LMUX<1:0>

-Timing source, bits CS<1:0>

-Sleep mode, bit SLPEN

4. Write initial values to pixel data registers,

LCDDATA0 through LCDDATA11.

5. Clear LCD Inte rrupt Flag , LCDIF (PIR2<4 >) and

if desired, enable the interrupt by setting bit

LCDIE (PIE2<4>).

6. Enable bias voltage pins (VLCD<3:1>) by

setting VLCDEN (LCDCO N<4>).

7. Enable the LCD module by setting bit LCDEN

(LCDCON<7>).

PIC16F946

TABLE 9-5: REGISTERS ASSOCIATED WITH LCD OPERATION

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Va lue on

all other

Resets

10h T1CON T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

0Bh/8Bh/

10Bh/18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF — CCP2IF 0000 -0-0 0000 -0-0

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE —CCP2IE 0000 -0-0 0000 -0-0

107h LCDCON LCDEN SLPEN WERR VLCDEN CS1 CS0 LMUX1 LMUX0 0001 0011 0001 0011

108h LCDPS WFT BIASMD LCDA WA LP3 LP2 LP1 LP0 0000 0000 0000 0000

110h LCDDATA0 SEG7

COM0 SEG6

COM0 SEG5

COM0 SEG4

COM0 SEG3

COM0 SEG2

COM0 SEG1

COM0 SEG0

COM0 xxxx xxxx uuuu uuuu

111h LCDDATA1 SEG15

COM0 SEG14

COM0 SEG13

COM0 SEG12

COM0 SEG11

COM0 SEG10

COM0 SEG9

COM0 SEG8

COM0 xxxx xxxx uuuu uuuu

112h LCDDATA2 SEG23

COM0 SEG22

COM0 SEG21

COM0 SEG20

COM0 SEG19

COM0 SEG18

COM0 SEG17

COM0 SEG16

COM0 xxxx xxxx uuuu uuuu

113h LCDDATA3 SEG7

COM1 SEG6

COM1 SEG5

COM1 SEG4

COM1 SEG3

COM1 SEG2

COM1 SEG1

COM1 SEG0

COM1 xxxx xxxx uuuu uuuu

114h LCDDATA4 SEG15

COM1 SEG14

COM1 SEG13

COM1 SEG12

COM1 SEG11

COM1 SEG10

COM1 SEG9

COM1 SEG8

COM1 xxxx xxxx uuuu uuuu

115h LCDDATA5 SEG23

COM1 SEG22

COM1 SEG21

COM1 SEG20

COM1 SEG19

COM1 SEG18

COM1 SEG17

COM1 SEG16

COM1 xxxx xxxx uuuu uuuu

116h LCDDATA6 SEG7

COM2 SEG6

COM2 SEG5

COM2 SEG4

COM2 SEG3

COM2 SEG2

COM2 SEG1

COM2 SEG0

COM2 xxxx xxxx uuuu uuuu

117h LCDDATA7 SEG15

COM2 SEG14

COM2 SEG13

COM2 SEG12

COM2 SEG11

COM2 SEG10

COM2 SEG9

COM2 SEG8

COM2 xxxx xxxx uuuu uuuu

118h LCDDATA8 SEG23

COM2 SEG22

COM2 SEG21

COM2 SEG20

COM2 SEG19

COM2 SEG18

COM2 SEG17

COM2 SEG16

COM2 xxxx xxxx uuuu uuuu

119h LCDDATA9 SEG7

COM3 SEG6

COM3 SEG5

COM3 SEG4

COM3 SEG3

COM3 SEG2

COM3 SEG1

COM3 SEG0

COM3 xxxx xxxx uuuu uuuu

11Ah LCDDATA10 SEG15

COM3 SEG14

COM3 SEG13

COM3 SEG12

COM3 SEG11

COM3 SEG10

COM3 SEG9

COM3 SEG8

COM3 xxxx xxxx uuuu uuuu

11Bh LCDDATA11 SEG23

COM3 SEG22

COM3 SEG21

COM3 SEG20

COM3 SEG19

COM3 SEG18

COM3 SEG17

COM3 SEG16

COM3 xxxx xxxx uuuu uuuu

11Ch LCDSE0(2) SE7 SE6 SE5 SE4 SE3 SE2 SE1 SE0 0000 0000 uuuu uuuu

11Dh LCDSE1(2) SE15 SE14 SE13 SE12 SE11 SE10 SE9 SE8 0000 0000 uuuu uuuu

11Eh LCDSE2(2) SE23 SE22 SE21 SE20 SE19 SE18 SE17 SE16 0000 0000 uuuu uuuu

190h LCDDATA12 SEG31

COM0 SEG30

COM0 SEG29

COM0 SEG28

COM0 SEG27

COM0 SEG26

COM0 SEG25

COM0 SEG24

COM0 xxxx xxxx uuuu uuuu

191h LCDDATA13 SEG39

COM0 SEG38

COM0 SEG37

COM0 SEG36

COM0 SEG35

COM0 SEG34

COM0 SE33

COM0 SEG32

COM0 xxxx xxxx uuuu uuuu

192h LCDDATA14 — — — — — — SEG41

COM0 SEG40

COM0 ---- --xx ---- --uu

193h LCDDATA15 SEG31

COM1 SEG30

COM1 SEG29

COM1 SEG28

COM1 SEG27

COM1 SEG26

COM1 SEG25

COM1 SEG24

COM1 xxxx xxxx uuuu uuuu

194h LCDDATA16 SEG39

COM1 SEG38

COM1 SEG37

COM1 SEG36

COM1 SEG35

COM1 SEG34

COM1 SEG33

COM1 SEG32

COM1 xxxx xxxx uuuu uuuu

195h LCDDATA17 — — — — — — SEG41

COM1 SEG40

COM1 ---- --xx ---- --uu

196h LCDDATA18 SEG31

COM2 SEG30

COM2 SEG29

COM2 SEG28

COM2 SEG27

COM2 SEG26

COM2 SEG25

COM2 SEG24

COM2 xxxx xxxx uuuu uuuu

197h LCDDATA19 SEG39

COM2 SEG38

COM2 SEG37

COM2 SEG36

COM2 SEG35

COM2 SEG34

COM2 SEG33

COM2 SEG32

COM2 xxxx xxxx uuuu uuuu

198h LCDDATA20 — — — — — — SEG41

COM2 SEG40

COM2 ---- --xx ---- --uu

Legend: x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the LCD module.

Note 1: These pins may be configured as port pins, depending on the oscillator mode selected.

2: This register is only initialized by a POR or BOR and is unchanged by other Resets.

PIC16F946

199h LCDDATA21 SEG31

COM3 SEG30

COM3 SEG29

COM3 SEG28

COM3 SEG27

COM3 SEG26

COM3 SEG25

COM3 SEG24

COM3 xxxx xxxx uuuu uuuu

19Ah LCDDATA22 SEG39

COM3 SEG38

COM3 SEG37

COM3 SEG36

COM3 SEG35

COM3 SEG34

COM3 SEG33

COM3 SEG32

COM3 xxxx xxxx uuuu uuuu

19Bh LCDDATA23 — — — — — — SEG41

COM3 SEG40

COM3 ---- --xx ---- --uu

19Ch LCDSE3(2) SE31 SE30 SE29 SE28 SE27 SE26 SE25 SE24 0000 0000 uuuu uuuu

19Dh LCDSE4(2) SE39 SE38 SE37 SE36 SE35 SE34 SE33 SE32 0000 0000 uuuu uuuu

19Eh LCDSE5(2) — — — — — — SE41 SE40 ---- --00 ---- --uu

TABLE 9-5: REGISTERS ASSOCIATED WITH LCD OPERATION (CONTINUED)

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lue on

POR, BOR

Va lue on

all other

Resets

Legend: x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the LCD module.

Note 1: These pins may be configured as port pins, depending on the oscillator mode selected.

2: This register is only initialized by a POR or BOR and is unchanged by other Resets.

PIC16F946

NOTES:

PIC16F946

10.0 PROGRAMMABLE

LOW-VOLTAGE DETECT

(PLVD) MODULE

The Programmable Low-Voltage Detect module is an

interrupt driven supply level detection. The voltage

detection monitors the internal power supply.

10.1 Voltage Trip Points

The PIC16F946 device supports eight internal PLVD

trip points. See Register 10-1 for available PLVD trip

point voltages.

10.1.1 PLVD CALIBRATION

The PIC16F91X stores the PLVD calibration values in

fuses located in the Calibration Word 2 (2009h). The

Calibration Word 2 is not erased when using the spec-

ified bulk erase sequence in the “PIC16F91X Memory

Programm ing Specific ation” (DS41244) and thus, does

not require reprogramming.

U-0 U-0 R-0 R/W-0 U-0 R/W-1 R/W-0 R/W-0

——IRVSTLVDEN— LVDL2 LVDL1 LVDL0

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5 IRVST: Internal Reference Voltage Stable Status Flag bit(1)

1 = Indicates that the PLVD is stable and PLVD interrupt is reliable

0 = Indicates that the PLVD is not stable and PLVD interrupt should not be enabled

bit 4 LVDEN: Low-Voltage Detect Power Enable bit

1 = Enables PLVD, powers up PLVD circuit and supporting reference circuitry

0 = Disables PLVD, powers down PLVD and supporting circuitry

bit 3 Unimplemented: Read as ‘0’

bit 2-0 LVDL<2:0>: Low-Voltage Detection Limit bits (nominal values)

111 = 4.5V

110 = 4.2V

101 = 4.0V

100 = 2.3V (default)

011 = 2.2V

010 = 2.1V

001 = 2.0V

000 = 1.9V(2)

Note 1: The IRVST bit is usable only when the HFINTOSC is running. When using an

external cry stal to run the microc ont roll er, the PLVD settling time is ex pe cte d to be

<50 μs wh en VDD = 5V and <25 μs when VDD = 3V. Appropriate software delays

should be used after enabling the PLVD module to ensure proper status readings

of the module.

2: Not tested and below minimum VDD.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

TABLE 10-1: REGISTERS ASSOCIATED WITH PROGRAMMABLE LOW-VOLTAGE DETECT

Addres s Name Bit 7 Bit 6 B i t 5 Bit 4 Bit 3 Bit 2 Bit 1 B it 0 Value on

POR, BOR

Value on

all othe r

Resets

0Bh/8Bh/

10Bh/18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF—CCP2IF 0000 -0-0 0000 -0-0

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE—CCP2IE 0000 -0-0 0000 -0-0

109h LVDCON — — IRVST LVDEN — LVDL2 LVDL1 LVDL0 --00 -100 --00 -100

Legend: x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the PLVD module.

PIC16F946

11.0 ADDRESSABLE UNIVERSAL

SYNCHRONOUS

ASYNCHRONOUS RECEIVER

TRANSMITTER (USART)

The Universal Synchronous Asynchronous Receiver

Transmitter (USART) module is one of the two serial

I/O modules. (USART is also known as a Serial

Communications Interface or SCI.) The USART can be

configured as a full-duplex asynchronous system that

can communicate with peripheral devices, such as

CRT terminals and personal computers, or it can be

configured as a half-duplex synchronous system that

can co mmun icate with periph eral de vice s, such as A/D

or D/A integrated circuits, serial EEPROMs, etc.

The USART can be configured in the following modes:

• Asynchronous (full-duplex)

• Synchronous – Master (half-duplex)

• Synchronous – Slave (half-duplex)

Bit SPEN (RCSTA<7>) and bits TRISC<7:6> have to be

set in order to configure pins RC6/TX/CK/SCK/SCL/SEG9

and RC7/RX/DT/SDI/SDA/SEG8 as the Universal

Synchronous Asynchro nous Recei ver T r ansmi tter.

The USART module also has a multi-processor

communic ation capability using 9-bit address detection.

R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0 R-1 R/W-0

CSRC TX9 TXEN SYNC — BRGH TRMT TX9D

bit 7 bit 0

bit 7 CSRC: Cloc k Sourc e Sele ct bit

Asynchronous mode:

Don’t care

Synchronous mode:

1 = Master mode (clock generated internally from BRG)

0 = Slave mode (clock from external source)

bit 6 TX9: 9-bit Transmit Enable bit

1 = Selects 9-bit transmission

0 = Selects 8-bit transmission

bit 5 TXEN: Transmit Enable bit

1 = Transmit enabled

0 = Transmit disabled

Note: SREN/CREN overrides TXEN in Sync mode.

bit 4 SYNC: USART Mode Select bit

1 = Synchronous mode

0 = Asynchronous mode

bit 3 Unimplemented: Read as ‘0’

bit 2 BRGH: High Baud Rate Select bit

Asynchronous mode:

1 = High speed

0 = Low speed

Synchronous mode:

Unused in this mode

bit 1 TRMT: Transmit Shift Register Status bit

1 = TSR empty

0 = TSR full

bit 0 TX9D: 9th bit of Transmit Data, can be Parity bit

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R-0 R-0 R-x

SPEN RX9 SREN CREN ADDEN FERR OERR RX9D

bit 7 bit 0

bit 7 SPEN: Serial Port Enable bit

1 = Serial port enabled (configures RC7/RX/DT/SDI/SDA/SEG8 and

RC6/TX/CK/SCK/SCL/SEG9 pins as serial port pins)

0 = Serial port disabled

bit 6 RX9: 9-bit Receive Enable bit

1 = Selects 9-bit reception

0 = Selects 8-bit reception

bit 5 SREN: Single Receive Enable bit

Asynchronous mode:

Don’t care

Synchronous mode – Master:

1 = Enables single receive

0 = Disables single receive

This bit is cleared after reception is complete

Synchronous mode – Slave:

Don’t care.

bit 4 CREN: Continuous Receive Enable bit

Asynchronous mode:

1 = Enables continuous receive

0 = Disables continuous receive

Synchronous mode:

1 = Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN)

0 = Disables continuous receive

bit 3 ADDEN: Address Detect Enable bit

Asynchronous mode 9-bit (RX9 = 1):

1 = Enables addres s detectio n, enables interrupt and load of the receiv e buffe r when RSR<8 >

is set

0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit

bit 2 FERR: Framing Error bit

1 = Framing error (can be updated by reading RCREG register and receive next valid byte)

0 = No framing error

bit 1 OERR: Overrun Error bit

1 = Overrun error (can be cleared by clearing bit CREN)

0 = No overrun error

bit 0 RX9D: 9th bit of Received Data (can be parity bit but must be calculated by user firmware)

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

11.1 USART Baud Rate Generator

(BRG)

The BRG supports both the Asynchronous and

Synchronous modes of the USART. It is a dedicated

8-bit bau d rate generato r . The SPBRG register con trols

the period of a free running 8-bit timer. In

Asynchronous mode, bit BRGH (TXSTA<2>) also

controls the baud rate. In Synchronous mode, bit

BRGH is ignored. Table 11-1 shows the formula for

computation of the baud rate for different USART

modes which only apply in Master mode (internal

clock).

Given the desired baud rate and FOSC, the nearest

integer value for the SPBRG register can be calculate d

using the formula in Table 11-1. From this, the error in

baud rate can be determined.

It may be advantageous to use the high baud rate

(BRGH = 1) even for slower baud clocks. This is

becaus e the FOSC/(16 (X + 1)) equatio n can reduce the

baud rate error in some cases.

Writing a new value to the SPBRG register causes the

BRG timer to be reset (or cleared). This ensures the

BRG does not wait for a timer overflow before

outputting the new baud rate.

11.1.1 SAMPLING

The data on the RC7/RX/DT/SDI/SDA/SEG8 pin is

sampled three times by a majority detect circuit to

determine if a high or a low level is present at the RX

pin.

TABLE 11-1: BAUD RATE FORMULA

TABLE 11-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR

SYNC BRGH = 0 (Low Speed) BRGH = 1 (High Speed)

(Asy nc hron ous) Baud Ra te = FOSC/(64 (X + 1))

(Synchronous) Baud Rate = FOSC/(4 (X + 1)) Baud Rate = FOSC/(16 (X + 1))

N/A

Legend: X = value in SPBRG (0 to 255)

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimple mented, read as ‘0’. Shaded cells are not used by the BRG.

PIC16F946

TABLE 11-3: BAUD RATES FOR ASYNCHRONOUS MODE (BRGH = 0)

BAUD

RATE

(K)

FOSC = 20 MHz FOSC = 16 MHz FOSC = 10 MHz

KBAUD %

ERROR

SPBRG

value

(decimal) KBAUD %

ERROR

SPBRG

value

(decimal) KBAUD %

ERROR

SPBRG

value

(decimal)

0.3——————— ——

1.2 1.221 1.75 255 1.202 0.17 207 1.202 0.17 129

2.4 2.404 0.17 129 2.404 0.17 103 2.404 0.17 64

9.6 9.766 1.73 31 9.615 0.16 25 9.766 1.73 15

19.2 19.531 1.72 15 19.231 0.16 12 19.531 1.72 7

28.8 31.250 8.51 9 27.778 3.55 8 31.250 8.51 4

33.6 34.722 3.34 8 35.714 6.29 6 31.250 6.99 4

57.6 62.500 8.51 4 62.500 8.51 3 52.083 9.58 2

HIGH 1.221 — 255 0.977 — 255 0.610 — 255

LOW 312.500 — 0 250.000 — 0 156.250 — 0

BAUD

RATE

(K)

FOSC = 4 MHz FOSC = 3.6864 MHz

KBAUD

ERROR

SPBRG

value

(decimal) KBAUD

ERROR

SPBRG

value

(decimal)

0.3 0.300 0 207 0.3 0 191

1.2 1.202 0.17 51 1.2 0 47

2.4 2.404 0.17 25 2.4 0 23

9.6 8.929 6.99 6 9.6 0 5

19.2 20.833 8.51 2 19.2 0 2

28.8 31.250 8.51 1 28.8 0 1

33.6 — — — — — —

57.6 62.500 8.51 0 57.6 0 0

HIGH 0.244 — 255 0.225 — 255

LOW 62.500 — 0 57.6 — 0

TABLE 11-4: BAUD RATES FOR ASYNCHRONOUS MODE (BRGH = 1)

BAUD

RATE

(K)

FOSC = 20 MHz FOSC = 16 MHz FOSC = 10 MHz

KBAUD %

ERROR

SPBRG

value

(decimal) KBAUD %

ERROR

SPBRG

value

(decimal) KBAUD %

ERROR

SPBRG

value

(decimal)

0.3—————————

1.2—————————

2.4 — — — — — — 2.441 1.71 255

9.6 9.615 0.16 129 9.615 0.16 103 9.615 0.16 64

19.2 19.231 0.16 64 19.231 0.16 51 19.531 1.72 31

28.8 29.070 0.94 42 29.412 2.13 33 28.409 1.36 21

33.6 33.784 0.55 36 33.333 0.79 29 32.895 2.10 18

57.6 59.524 3.34 20 58.824 2.13 16 56.818 1.36 10

HIGH 4.883 — 255 3.906 — 255 2.441 - 255

LOW 1250.000 — 0 1000.000 — 0 625.000 - 0

BAUD

RATE

(K)

FOSC = 4 MHz FOSC = 3.6864 MHz

KBAUD

ERROR

SPBRG

value

(decimal) KBAUD

ERROR

SPBRG

value

(decimal)

0.3——————

1.2 1.202 0.17 207 1.2 0 191

2.4 2.404 0.17 103 2.4 0 95

9.6 9.615 0.16 25 9.6 0 23

19.2 19.231 0.16 12 19.2 0 11

28.8 27.798 3.55 8 28.8 0 7

33.6 35.714 6.29 6 32.9 2.04 6

57.6 62.500 8.51 3 57.6 0 3

HIGH 0.977 — 255 0.9 — 255

LOW 250.000 — 0 230.4 — 0

PIC16F946

11.2 USART Asynchronous Mode

In this mode, the USART uses standard

Non-Return-to-Zero (NRZ) format (one Start bit, eight

or nine data bits and one Stop bit). The most common

data format is 8 bits. An on-chip, dedicated, 8-bit Baud

Rate Generator (BRG) can be used to derive standard

baud rate frequencies from the oscillator. The USART

transmits and receives the LSb first. The transmitter

and receiver are functionally independent but use the

same data format and baud rate. The baud rate

generato r produces a cl oc k, eith er x16 or x6 4 of the b it

shift rate, depending on bit BRGH (TXSTA<2>). Parity

is not supported by the hardware, but can be

implemented in software (and stored as the ninth data

bit). Asynchronous mode is stopped during Sleep.

Asynchronous mode is selected by clearing bit SYNC

(TXSTA<4>).

The USART Asynchronous module consists of the

following important elements:

• Baud Rate Ge nerator

• Sampling Circuit

• Asynchronous Transmitter

• Asynchronous Receiver

11.2.1 USART ASYNCHRONOUS

TRANSMITTER

The USART transmitter block diagram is shown in

Figure 11-1. Th e heart of the trans mitter is the T ransm it

(Serial) Shift Register (TSR). The shift register obtains

its data from the Read/Write Transmit Buffer, TXREG.

The TXREG register is loaded with data in software.

The TSR register is not loaded until the Stop bit has

been transmitted from the previous load. As soon as

the Stop bit is transmitted, the TSR is loaded with new

data from the TXREG register (if available). Once the

TXREG register transfers the data to the TSR register

(occurs in one TCY), the TXR EG re giste r i s em pty a nd

flag bit, TXIF (PIR1<4>), is set. This interrupt can be

enabled/disabled by setting/clearing enable bit, TXIE

(PIE1<4>). Flag bit TXIF will be set regardless of the

state of enable bit TXIE and cannot be cleared in soft-

ware. It will re set o nly when ne w dat a i s loaded into the

TXREG register . While flag bit TXIF indicates the status

of the TXREG register , another bit, TRMT (TXSTA<1>),

shows the status of the TSR register. Status bit TRMT

is a read-only bit which is set when the TSR register is

empty. No interrupt logic is tied to this bit so the user

has to poll this bit in order to determine if the TSR

Transmission is enabled by setting enable bit, TXEN

(TXSTA<5>) . The actual transmission w ill not occur until

the TXREG register has been loaded with data and the

Baud Rate Gener ator (BRG) has produced a shift clock

(Figure 11-2). The transmission can also be started by

first loading the TX REG register and then set ting enable

bit TXEN. Normally , when transmission is first started, the

TSR register is empty. At that point, transfer to the

TXREG register will result in an immediate transfer to

TSR, resulting in an empty TXREG. A back-to-back

transfer is thus possible (Figure 11-3). Clearing enable bit

TXEN during a transmission wil l cause the transmission

to be aborted and will reset the transmitter . As a result, the

RC6/TX/CK/SCK/SCL/SEG9 pin will revert to

high-impedance.

In order to select 9-bit transmission, transmit bit TX9

(TXSTA<6>) should be set and the ninth bit should be

written to TX9D (TXSTA<0>). The ninth bit must be

written before writing the 8-bit data to the TXREG reg-

ister. This is because a data write to the TXREG regis-

ter can resu lt in an immediate tra nsfer of the dat a to the

TSR register (if the TSR is empty). In such a case, an

incorrect ninth data bit may be loaded in the TSR

When setting up an Asynchronous Transmission,

follow these steps:

1. Initialize the SPBRG re gister for the ap prop ria te

baud rate. If a high-speed baud rate is desired,

set bit BRGH (Section 11.1 “USART Baud

Rate Generator (BRG)”).

2. Enable the asy nch ron ous seri al port by clearin g

bit SYNC and setting bit SPEN.

3. If interrupt s are desired, then set enable bit TXIE.

4. If 9-bit transmission is desired, then set transmit

bit TX9.

5. Enable the transmission by setting bit TXEN,

which will also set bit TXIF.

6. If 9-bit transmission is selected, the ninth bit

should be loaded in bit TX9D.

7. Load data to the TXREG register (starts

transmission).

8. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

Note 1: The TSR register is not mapped in data

memory, so it is not available to the user.

2: Flag bit T XIF is set when en able bit TXEN

is set. TXIF is cle ared by load ing TXR EG.

PIC16F946

FIGURE 11-1: USART TRANSMIT BLOCK DIAGRAM

FIGURE 11-2: ASYNCHRONOUS MASTER TRANSMISSION

FIGURE 11-3: ASYNCHRONOUS MASTER TRANSMISSION (BACK-TO-BACK)

TXIF

TXIE

Interrupt

TXEN Baud Rate CLK

SPBRG

Baud Rate Generator TX9D

MSb LSb

Data Bus

TXREG Register

TSR Register

(8) 0

TX9

TRMT SPEN

RC6/TX/CK/SCK/

Pin Buffer

and Control

• • •

SCL/SEG9 pin

Word 1 S top bit

Word 1

Transmit Shift Reg

Start bit bit 0 bit 1 bit 7/8

Write to TXREG Word 1

BRG Output

(Shift Clock)

RC6/TX/CK/

TXIF bit

(Transmit Buffer

Reg. Empty Flag)

TRMT bit

(Transmit Shift

Reg. Empty Flag)

SCK/SCL/ SEG9

Transmit Shift Reg.

Write to TXREG

BRG Output

(Shift Clock)

RC6/TX/CK/

TXIF bit

(Interrupt Reg. Flag)

TRMT bit

(Transmit Shift

Reg. Empty Flag)

Word 1 Word 2

S tart bit Stop bit S t art bit

Transmit Shift Reg.

Word 1 Word 2

bit 0 bit 1 bit 7/8 bit 0

Note: This timing diagram shows two consecutive transmissions.

SCK/SCL/SEG9

PIC16F946

TABLE 11-5: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

19h TXREG USART Transmit Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGH TRMT TX9D 0000 -010 0000 -010

99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmiss ion.

PIC16F946

11.2.2 USART ASYNCHRONOUS

RECEIVER

The receiver block diagram is shown in Figure 11-4.

The data is received on the

RC7/RX/DT/SDI/SDA/SEG8 pin and drives the data

recovery block. The data recovery block is actually a

high-speed shifter, operating at x16 times the baud

rate; whereas the main receive serial shifter operates

at the bit rate or at FOSC.

Once Asynchronous mode is selected, reception is

enabled by setti ng bit CRE N (RCSTA<4>).

The heart of the receiver is the Receive (Serial) Shift

received data in the RSR is transferred to the RCREG

bit, R CIF (PI R 1<5> ), i s se t. T he actual i nterr upt can b e

enabled/disabled by setting/clearing enable bit, RCIE

(PIE1<5>). Flag bit RCIF is a read-only bit which is

cleared by the hard ware. It is cleared when the RCREG

double-buffered register (i.e., it is a two-deep FIFO). It

is possible for two bytes of data to be received and

transferred to the RCREG FIFO and a third byte to

begin shifting to the RSR register. On the detection of

the Stop bit of the third byte, if the RCREG register is

still full, the Overrun Error bit, OERR (RCSTA<1>), will

be set. The word in the RSR will be lost. The RCREG

the F IFO. Ov er ru n bi t OE RR ha s to b e cl ear e d in s of t -

ware. Th is is done by resetting the re ceive logi c (CREN

is cleared and then set). If bit OERR is set, transfers

from the RSR register to th e RCREG register are inhib-

ited and n o further dat a will be received. It is , therefor e,

essential to clear error bit OERR if it is set. Framing

error bit, FERR (RCSTA<2>), is set if a Stop bit is

detected as clear. Bit FERR and the 9th receive bit are

buffered the same way as the receive data. Reading

the RCREG will load bits RX9D and FERR with new

values , the refo re, it is essential for th e us er to re ad th e

RCSTA regis ter bef ore reading the RCREG register in

order not to los e t he old FERR a nd R X9D i nformation.

When setting up an Asynchronous Reception, follow

these steps:

1. Initialize the SPBRG re gister for the ap prop ria te

baud rate. If a high-speed baud rate is desired,

set bit BRGH (Section 11.1 “USART Baud

Rate Generator (BRG)”).

2. Enable the asy nch ron ous seri al port by clearin g

bit SYNC and setting bit SPEN.

3. If interrupts are desired, then set enable bit

RCIE.

4. If 9-bit reception is desired, then set bit RX9.

5. Enable the reception by setting bit CREN.

6. Flag bit RCI F wi ll b e se t w he n rec ept ion is com -

plete an d an interru pt will be generate d if enabl e

bit RCIE is set.

7. Read the RCSTA register to get the ninth bit (if

enabled) and determine if any error occurred

during reception.

8. Read the 8-bit received data by reading the

RCREG register.

9. If any error occurred, clear the error by clearing

enable bit CREN.

10. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

PIC16F946

FIGURE 11-4: USART RECEIVE BLOCK DIAGRAM

FIGURE 11-5: ASYNCHRONOUS RECEPTION

TABLE 11-6: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Va lue on:

POR, BOR

Value on

all other

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

1Ah RCREG USART Receive Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010

99h SPBRG Baud Rate Generator Reg ister 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.

x64 Baud Rate CLK

SPBRG

Baud Rate Generator

RC7/RX/DT/

Pin Buffer

and Control

SPEN

Data

Recovery

CREN OERR FERR

RSR Register

MSb LSb

RX9D RCREG Register FIFO

Interrupt RCIF

RCIE Data Bus

÷64

÷16

or Stop Start

(8) 710

RX9

• • •

FOSC

SDI/SDA/SEG8

Start

bit bit 7/8

bit 1bit 0 bit 7/8 bit 0Stop

bit

Start

bit Start

bit

bit 7/8 Stop

bit

RX (pin)

Reg

Rcv Buffer Reg

Rcv Shift

Read Rcv

Buffer Reg

RCREG

RCIF

(Interrupt Flag)

OERR bit

CREN

Word 1

RCREG Word 2

RCREG

Stop

bit

Note: This timing diagram shows three words appearing on the RX input. The RCREG (Receive Buffer) is read after the third word,

causing the OERR (Overrun Error) bit to be set.

PIC16F946

11.2.3 SETTING UP 9-BIT MODE WITH

ADDR ES S DET E CT

When setting up an Asynchronous Reception with

address detect enabled:

• Initialize the SPBRG register for the appropriate

baud rate. If a high-speed baud rate is desired,

set bit BRGH.

• Enable the asynchronous serial port by clearing

bit SYNC and setting bit SPEN.

• If interrupts are desired, then set enable bit RCIE.

• Set bit RX9 to enable 9-bit reception.

• Set ADDEN to enable address detect.

• Enable the reception by setting enable bit CREN.

• Flag bit RCIF will be set when reception is

complete, and an interrupt will be generated if

enable bit RCIE was set.

• Read the RCSTA register to get the ninth bit and

determine if any error occurred during reception.

• Read the 8-bit received data by reading the

RCREG register to determine if the device is

being addressed.

• If any error occurred, clear the error by clearing

enable bit CREN.

• If the device has been addressed, clear the

ADDEN bi t to al low da t a b yte s an d address b yte s

to be read into the receive buf fer and int errupt the

CPU.

FIGURE 11-6: USART RECEIVE BLOCK DIAGRAM

x64 B aud Rate CLK

SPBRG

Baud Rate Generator

RC7/RX/DT

Pin Buffer

and Control

SPEN

Data

Recovery

CREN OERR FERR

RSR Register

MSb LSb

RX9D RCREG Register FIFO

Interrupt RCIF

RCIE Data Bus

÷ 64

÷ 16

or Stop Start(8) 7 10

RX9

• • •

RX9

ADDEN

RX9

ADDEN

RSR<8>

Enable

Load of

Receive

Buffer

FOSC

SDI/SDA/SEG8

PIC16F946

FIGURE 11-7: ASYNCHRONOUS RECEPTION WITH ADDRESS DETECT

FIGURE 11-8: ASYNCHRONOUS RECEPTION WITH ADDRESS BYTE FIRST

TABLE 11-7: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION

Start

bit bit 1bit 0 bit 8 bit 0Stop

bit

Start

bit bit 8 Stop

bit

RC7/RX/DT/

Load RSR

Read

RCIF

Word 1

RCREG

bit 8 = 0, Data Byte bit 8 = 1, Address Byte

Note: This timing diagram shows a data byte followed by an address byte. The data byte is not read into the RCREG (Receive Buffer)

because ADDEN = 1.

SDI/SDA/SEG8

Start

bit bit 1bit 0 bit 8 bit 0Stop

bit

Start

bit bit 8 Stop

bit

Load RSR

Read

RCIF

Word 1

RCREG

bit 8 = 1, Address Byt e bit 8 = 0, Data Byte

Note: This timing diagram shows a data byte followed by an address byte. The data byte is not read into the RCREG (Receive Buffer)

because ADDEN was not updated and still = 0.

RC7/RX/DT/

SDI/SDA/SEG8

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all othe r

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

1Ah RCREG USART Receive Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGHTRMT TX9D 0000 -010 0000 -010

99h SPB RG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.

PIC16F946

11.3 USART Synchronous

Master Mode

In Sync hronous Ma ster mode, the data is transmi tted in

a half-duplex manner (i.e., transmission and reception

do not occur at the same time). When transmitting data,

the reception is inhibited and vice versa. Synchronous

mode is entered by setting bit, SYNC (TXSTA<4>). In

additio n, enabl e bit, SPEN (RCSTA<7>), is set in ord er

to configure the RC6/TX/CK/SCK/SCL/SEG9 and

RC7/RX/DT/SDI/SDA/SEG8 I/O pins to CK (cl ock) and

DT (data) lines, respectively. The Master mode indi-

cates that the processor transmits the master clock on

the CK li ne. Th e M as ter m ode is e nte red by se tti ng bi t,

CSRC (TXSTA<7>).

11.3.1 USART SYNCHRONOUS MASTER

TRANSMISSION

The USART transmitter block diagram is shown in

Figure 11-6. Th e heart of the tra nsmitter is the Trans mit

(Serial) Shift Register (TSR). The shift register obtains

its data from the Read/Write Transmit Buffer register,

TXREG. The TXREG register is loaded with data in

software. The TSR register is not loaded until the last

bit has been transmitted from the previous load. As

soon as the last bit is transmitted, the TSR is loaded

with new data from the TXREG (if available). Once the

TXREG register transfers the data to the TSR register

(occurs in one TCYCLE), the TXREG i s empty an d in ter-

rupt bit, TXIF (PIR1<4>), is set. The interrupt can be

enabled/disabled by setting/clearing enable bit TXIE

(PIE1<4>). Flag bit TXIF will be set regardless of the

state of enable bit TXIE and cannot be cleared in soft-

ware. It will re set o nly when ne w dat a i s loaded into the

TXREG register . While flag bit TXIF indicates the status

of the TXREG register , another bit, TRMT (TXSTA<1>),

shows the status of the TSR register. TRMT is a

read-only bit which is set when the TSR is empty. No

interrupt logic is tied to this bit so the user has to poll

this bit in order to determine if the TSR register is

empty. The TSR is not mapped in data memory so it is

not available to the user.

Transmission is enabled by setting enable bit, TXEN

(TXSTA<5>). The actual transmission will not occur

until the TXREG register has been loaded with data.

The fir st data bit will be shifte d out on the next av ailable

rising edge of the clock on the CK line. Data out is

stab le around the fal ling edge of the sync hronous cloc k

(Figure 11-9). The transmission can also be started by

first loading the TXREG register and then setting bit

TXEN (Figure 11-10). This is advant age ous when s low

baud rate s are selec ted, since th e BRG is kep t in Reset

when bits TXEN, CREN and SREN are clear. Setting

enable bit TXEN will start the BRG, creating a shift

clock immediately. Normally, when transmission is first

started, the TSR register is empty, so a transfer to the

TXREG register will result in an immediate transfer to

TSR, resulting in an empty TXREG. Back-to-back

transfers are possible.

Clearing enable bit TXEN during a transmission will

cause the tra nsm is s ion to be ab orte d a nd wil l re se t th e

transmitter. The DT and CK pins will revert to

high-impedance. If either bit CREN or bit SREN is set

during a transmission, the transmission is aborted and

the DT pin reverts to a high-impedance state (for a

reception). The CK pin will remain an output if bit CSRC

is se t (inte rnal c lock ). The transm itter logic , how ever, is

not reset, although it is disconnected from the pins. In

order to reset the transmitter, the user has to clear bit

TXEN. If b it SREN is set (to inte rrupt an on-goi ng trans-

mission and receive a single word), then after the sin-

gle word is received, bit SREN will be cleared and the

serial port will revert back to transmitting, since bit

TXEN is still set. The DT line will immediately switch

from High-Impedance Receive mode to transmit and

start driving. To avoid this , bit TXEN should be c leared.

In order to select 9-bit transmission, the TX9

(TXSTA<6>) bit should be set and the ninth bit should

be written to bit TX9D (TXSTA<0>). The ninth bit must

be written before writing the 8-bit data to the TXREG

result in an immediate transfer of the data to the TSR

the TXREG was writt en befo re writ ing the “new” T X9D,

the “present” value of bit TX9D is loaded.

Steps to follow when setting up a Synchronous Master

Transmission:

1. Initialize the SPBRG re gister for the ap prop ria te

baud rate (Section 11.1 “USART Baud Rate

Generator (BRG)”).

2. Enable the synchronous master serial port by

setting bits SYNC, SPEN and CSRC.

3. If interrupts are desired, set enable bit TXIE.

4. If 9-bit transmission is desired, set bit TX9.

5. Enable the transmission by setting bit TXEN.

6. If 9-bit transmission is selected, the ninth bit

should be loaded in bit TX9D.

7. S tart transmission by loa ding data to the TXREG

8. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

PIC16F946

TABLE 11-8: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION

FIGURE 11-9: SYNCHRONOUS TRANSMISSION

FIGURE 11-10: SYNCHRONOUS TRANSMISSION (THROUGH TXEN)

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all othe r

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

19h TXREG USART Transmit Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGH TRMT TX9D 0000 -010 0000 -010

99h S PB RG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.

bit 0 bit 1 bit 7

Word 1

Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4 Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4

bit 2 bit 0 bit 1 bit 7

RC6/TX/CK/

Write to

TXREG reg

TXIF bit

(Int errupt Flag )

TXEN bit ‘

’ ‘

’

Word 2

TRMT bit

Write Word 1 Write Word 2

Note: Sync Master mod e; SPBRG = 0. Continuous transmission of two 8-bit words.

SCK/SCL/SEG9

RC7/RX/DT/

SDI/SDA/SEG8

RC7/RX/DT/SDI/SDA/SEG8

RC6/TX/CK/SCK/SCL/SEG9

Write to

TXREG Reg

TXIF bit

TRMT bit

bit 0 bit 1 bit 2 bit 6 bit 7

TXEN b it

PIC16F946

11.3.2 USART SYNCHRONOUS MASTER

RECEPTION

Once Synchronous mode is selected, reception is

enabled by setting either enable bit, SREN

(RCSTA<5>), or enable bit, CREN (RCSTA<4>). Data

is sampled on the RC7/RX/DT/SDI/SDA/SEG8 pin on

the falling edge of the clock. If enable bit SREN is set,

then only a s ing le w ord is rece iv ed. If ena ble bit CRE N

is set, the reception is continuous until CREN is

cleared. If both bits are set, CREN takes precedence.

After clocking the last bit, the received data in the

Receive Shift Register (RSR) is transferred to the

RCREG register (if it is empty). When the transfer is

complete, interrupt flag b it, RCIF (PIR1<5>), is set. The

actual interrupt can be enabled/disabled by set-

ting/cl earing enabl e bit, RCIE (PIE1<5> ). Flag bit RC IF

is a rea d-only bit wh ich i s reset b y the hardw are. In this

case, it is reset when the RCREG register has been

read and is empty. The RCREG is a double-buffered

bytes of data to be received and transferred to the

RCREG FIFO and a third byte to begin shifting into the

RSR register. On the clocking of the last bit of the third

byte, if the RCREG register is still full, then Overrun

Error bit, OERR (RCSTA<1>), is set. The word in the

RSR will be lost. The RCREG register can be read

twice to retrieve the two bytes in the FIFO. Bit OERR

has to be c lea red in s oftwa r e (by cl eari ng b it CR EN) . If

bit OERR is se t, transfers from th e RSR to the RCREG

are inhibited so it is essential to clear bit OERR if it is

set. The ninth receive bit is buffered the same way as

the receive data. Reading the RCREG register will load

bit RX9D with a new value, therefore, it is essential for

the user to read the RCSTA register before reading

RCREG in order not to lose the old RX9D information.

When sett ing up a Synchronous Master Reception:

1. Initialize the SPBRG re gister for the ap prop ria te

baud rate (Section 11.1 “USART Baud Rate

Generator (BRG)”).

2. Enable the synchronous master serial port by

setting bits SYNC, SPEN and CSRC.

3. Ensure bits CREN and SREN are clear.

4. If interrupts are desired, then set enable bit

RCIE.

5. If 9-bit reception is desired, then set bit RX9.

6. If a single reception is required, set bit SREN.

For continuous reception, set bit CREN.

7. Interrupt fla g bit RCIF will be se t when receptio n

is complete and an interrupt will be generated if

enable bit RCIE was set.

8. Read the RCSTA register to get the ninth bit (if

enabled) and determine if any error occurred

during reception.

9. Read the 8-bit received data by reading the

RCREG register.

10. If any error occurred, clear the error by clearing

bit CREN.

11. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

TABLE 11-9: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION

Address Name Bit 7 Bit 6 B it 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

1Ah RCREG USART Receive Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGH TRMT TX9D 0000 -010 0000 -010

99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master reception.

PIC16F946

FIGURE 11-11: SYNCHRONOUS RECEPTION (MASTER MODE, SREN)

11.4 USART Synchronous Slave Mode

Synchronous Slave mode dif fers from the Master mode

in the fact that the shift clock is supplied externally at

the RC6/TX/CK/SCK/SCL/SEG9 pin (instead of being

supplied internally in Master mode). This allows the

device to transfer or receive data while in Sleep mode.

Slave mode is entered by clearing bit, CSRC

(TXSTA<7>).

11.4.1 USART SYNCHRONOUS SLAVE

TRANSMIT

The operation of the Synchronous Master and Slave

modes is identica l, except in the cas e of the Slee p mode.

If two words are written to the TXREG and then the

SLEEP instruction is executed, the following will occur:

a) The first word will immediately transfer to the

TSR register and transmit.

b) The second word will remain in TXREG register.

c) Flag bit TXIF will not be set.

d) When the first word has been shifted out of TSR,

the TXREG register will transfer the second word

to the TSR and flag bit TXIF will now be set.

e) If enable bit TXIE is set, the interrupt will wake

the chip from Sleep and if the global interrupt is

enabled , the p rog ram wil l bran ch to the in terrupt

vector (0004h).

When setting up a Synchronous Slave Transmission,

follow these steps:

1. Enable the synchronou s slave s erial port by se t-

ting bits SYNC and SPEN and clearing bit

CSRC.

2. Clear bits CREN and SREN.

3. If interrupts are desired, then set enable bit

TXIE.

4. If 9-bit transmis si on is des ired , then set bi t TX9.

5. Enable the transmission by setting enable bit

TXEN.

6. If 9-bit transmission is selected, the ninth bit

should be loaded in bit TX9D.

7. S tart transmission by loa ding data to the TXREG

8. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

CREN bit

RC7/RX/DT/

RC6/TX/CK/

Write to

bit SREN

SREN bit

RCIF bit

(Interrupt)

Read

RXREG

Note: Timing diagram demonstrates Sync Master mode with bit SREN = 1 and bit BRG = 0.

Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q2 Q1Q2Q3Q4Q1Q2Q3Q4 Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4

‘

’

bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7

‘

’

Q1Q2Q3Q4

SDI/SDA/SEG8

SCK/SCL/SEG9

PIC16F946

TABLE 11-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION

11.4.2 USART SYNCHRONOUS SLAVE

RECEPTION

The operation of the Synchronous Master and Slave

modes is identical, except in the case of the Sleep

mode. Bit SREN is a “don't care” in Slave mode.

If receive is enabled by setting bit CREN prior to the

SLEEP inst ruction , then a wor d m ay be receiv ed d uring

Sleep. On completely receiving the word, the RSR

and if enabl e bit RCIE bit is set , the interrupt gene rated

will wake the chip from Sleep. If the global interrupt is

enabled , the pro gram wil l branc h to the interru pt vec tor

(0004h).

When setting up a Synchronous Slave Reception,

follow these steps:

1. Enable the synchronous master serial port by

setting bits SYNC and SPEN and clearing bit

CSRC.

2. If interrupts are desired, set enable bit RCIE.

3. If 9-bit reception is desired, set bit RX9.

4. To enable reception, set enable bit CREN.

5. Flag bit RCIF will be set when reception is

complete and an interrupt will be generated if

enable bit RCIE was set.

6. Read the RCSTA register to get the ninth bit (if

enabled) and determine if any error occurred

during reception.

7. Read the 8-bit received data by reading the

RCREG register.

8. If any error occurred, clear the error by clearing

bit CREN.

9. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

TABLE 11-11: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION

Addr e s s Na m e Bit 7 Bit 6 Bit 5 Bit 4 Bi t 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

19h TXREG USART Transmit Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGH TRMT TX9D 0000 -010 0000 -010

99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave transmission.

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Val ue on:

POR, BOR

Value on

all other

Resets

0Bh, 8Bh,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

1Ah RCREG USART Receive Data Register 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h TXSTA CSRC TX9 TXEN SYNC —BRGH TRMT TX9D 0000 -010 0000 -010

99h SPBRG Baud Rate Generator Register 0000 0000 0000 0000

Legend: x = unknown, – = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.

PIC16F946

12.0 ANALOG-TO-DIGITAL

CONVERTER (A/D) MODULE

The Analog-to-Digital converter (A/D) allows conversion

of an analog input signal to a 10-bit binary representation

of that signal. The PIC16F946 has up to eight analog

inputs, multiplexed into one sa mple and ho ld circu it. T he

output of the sample and hold is connected to the input of

the converter . The converter generates a binary result via

successive approximation and stores the result in a 10-bit

software selectable to either VDD o r a voltage applied by

the V REF pin. Figure 12-1 shows the block diagram of the

A/D on the PIC16F946.

FIGURE 12-1: A/D BLOCK DIAGRAM

RA0/AN0/C1-/SEG12

A/D

RA1/AN1/C2-/SEG7

RA2/AN2/C2+/VREF-/COM2

RA5/AN4/C2OUT/SS/SEG5

VDD

VREF+

ADON

GO/DONE

VCFG0 = 1

VCFG0 = 0

CHS<2:0>

ADRESH ADRESL

ADFM

VSS

RE0/AN5/SEG21

RE1/AN6/SEG22

RE2/AN7/SEG23

RA3/AN3/C1+/VREF+/SEG15

VCFG1 = 1

VCFG1 = 0

VREF-

PIC16F946

12.1 A/D Configuration and Operation

There are three registers available to control the

functionality of the A/D module:

1. ANSEL (Register 12-1)

2. ADCON0 (Register 12-2)

3. ADCON1 (Register 12-3)

12.1.1 ANALOG PORT PINS

The ANS<7:0> bits (ANSEL<7:0>) and the TRIS bits

control the operation of the A/D port pins. Set the

corresponding TRIS bits to set the pin output driver to

it s high-imp edance st ate. Likewi se, set the correspond-

ing ANSEL bit to disable the digital input buffer.

12.1.2 CHANNEL SELECTION

There are up to eight analog channels on the PIC16F946,

AN<7:0>. The CHS<2:0> bits (ADCON0<4:2>) control

which channel is connected to the sample and hold

circuit.

12.1.3 VOLTAGE REFERENCE

There are two options for each reference to the A/D

converter , V REF+ a nd VREF-. V REF+ can be connected to

either VDD or an externally applied vol tage. Alternatively ,

VREF- can be connected to either VSS or an externally

applied voltage. VCFG<1:0> bits are used to select the

reference source.

12.1.4 CONVERSION CLOCK

The A/D conversion cycle requires 11 TAD. The source

of the conversion clock is software selectable via the

ADCS bits (ADCON1<6:4>). There are seven possible

clock options:

•F

OSC/2

•F

OSC/4

•FOSC/8

•FOSC/16

•F

OSC/32

•FOSC/64

•FRC (dedicated internal oscillator)

For correct conversion, the A/D conversion clock

(1/TAD) must be sele cted to ensu re a minimu m TAD of

1.6 μs. Table 12-1 shows a few TAD calculations for

selected frequencies.

TABLE 12-1: TAD vs. DEVICE OPERATING FREQUENCIES

Note: Analog voltages on any pin that is defined

as a digital input may cause the input

buffer to conduct excess current.

A/D Clock Source (TAD) Device Frequency

Operation ADCS<2:0> 20 MHz 5 MHz 4 MHz 1 .25 MHz

2 TOSC 000 100 ns(2) 400 ns(2) 500 ns(2) 1.6 μs

4 TOSC 100 200 ns(2) 800 ns(2) 1.0 μs(2) 3.2 μs

8 TOSC 001 400 ns(2) 1.6 μs2.0 μs6.4 μs

16 TOSC 101 800 ns(2) 3.2 μs4.0 μs12.8 μs(3)

32 TOSC 010 1.6 μs6.4 μs8.0 μs(3) 25.6 μs(3)

64 TOSC 110 3.2 μs12.8 μs(3) 16.0 μs(3) 51.2 μs(3)

A/D RC x11 2-6 μs(1,4) 2-6 μs(1,4) 2-6 μs(1,4) 2-6 μs(1,4)

Legend: Shaded cells are outside of recommended range.

Note 1: The A/D RC source has a typical TAD time of 4 μs for VDD > 3.0V.

2: These values violate the minimum required TAD time.

3: For faster conversion times, the selection of another clock source is recommended.

4: When the device frequency is greater than 1 MHz, the A/D RC clock source is only recommended if the

conversion will be perf ormed during Sleep.

PIC16F946

12.1.5 STARTING A CONVERSION

The A/D conversion is initiated by setting the

GO/DONE bi t ( ADCO N0< 1>). Wh en t he c onv ers ion is

complete, the A/D module:

• Clears the GO/DONE bit

• Sets the ADIF flag (PIR1<6 >)

• Generates an interrupt (if enabled)

If the conversion must be aborted, the GO/DONE bit

can be cleared in software. The ADRESH:ADRESL

A/D conversion sample. Instead, the

ADRESH:ADRESL registers wi ll re t ain th e va lue of the

previous conversion. After an aborted conversion, a

AD delay is required before another acquisition can

be initiated. Following the delay, an input acquisition is

automaticall y st arted on the se lec ted chann el .

FIGURE 12-2: A/D CONVERSION TAD CYCLES

12.1.6 CONVERSION OUTPUT

The A/D con version can be supp lied in two forma ts: left

or right shifted. The ADFM bit (ADCON0<7>) controls

the output format. Figure 12-3 shows the output

formats.

FIGURE 12-3: 10-BIT A/D RESULT FORMAT

Note: The GO/DONE bit shou ld not be set in th e

same instru ction that turns on the A/D.

TAD1TAD2 TAD3TAD4TAD5 TAD6 TAD7 TAD8TAD9

Set GO/DONE bit

Holding Capacitor is Disconnected from Analog Input (typically 100 ns)

b9 b8 b7 b6 b5 b4 b3 b2

TAD10 TAD11

b1 b0

TCY TO TAD

Conversion Starts

ADRESH and ADRESL registers are loaded,

GO/DONE bit is cleared,

ADIF bit is set,

Holding Capacitor is Connected to Analog Input

ADRESH ADRESL

(ADFM = 0)MSB LSB

bit 7 bit 0 bit 7 bit 0

10-bit A/D Result Unimplemented: Read as ‘0’

(ADFM = 1)MSB LSB

bit 7 bit 0 bit 7 bit 0

Unimplemented: Read as ‘0’10-bit A/D Result

PIC16F946

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0

bit 7 bit 0

bit 7-0: ANS<7:0>: Analog Select bits

Select between analog or digital function on pins AN<7:0>, respectively.

1 = Analog input. Pin is assigned as analog input.(1)

0 = Digital I/O. Pin is assigned to port or special function.

Note 1: Setting a pin to an analog input automatically disables the digital input circuitry,

weak pull-ups, and interrupt-on-change, if available. The corresponding TRIS bit

must be se t to Input mode in order to allow e xternal co ntrol of the volt age on the pin.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON

bit 7 bit 0

bit 7 ADFM: A/D Result Formed Select bit

1 = Right justified

0 = Left justified

bit 6 VCFG1: Voltage Reference bit

1 = VREF- pin

0 = VSS

bit 5 VCFG0: Voltage Reference bit

1 = VREF+ pin

0 = VDD

bit 4-2 CHS<2:0>: Analog Channel Select bits

000 = Channel 00 (AN0)

001 = Channel 01 (AN1)

010 = Channel 02 (AN2)

011 = Channel 03 (AN3)

100 = Channel 04 (AN4)

101 = Channel 05 (AN5)

110 = Channel 06 (AN6)

111 = Channel 07 (AN7)

bit 1 GO/DONE: A/D Conversion Status bit

1 = A/D conver si on cycle in progress. Set ting this bit starts an A/D co nversion c ycl e.

This bit is automa tically cleared by hardw ar e w hen the A/D conversio n has com pleted.

0 = A/D conver si on completed/ not in progre ss

bit 0 ADON: A/D Conversion Status bit

1 = A/D converter module is operating

0 = A/D conver t er is shut off and con sumes n o ope rating curr ent

Legend:

R = Readable bit W = Writable bi t U = Unimpl em ented bit, read as ‘0’

- n = Value at PO R ‘1’ = Bi t is se t ‘0’ = Bi t is cle ar ed x = Bit is unk now n

PIC16F946

U-0 R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0

— ADCS2 ADCS1 ADCS0 ————

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6-4 ADCS<2:0>: A/D Conversion Clock Select bits

000 =F

OSC/2

001 =F

OSC/8

010 =F

OSC/32

x11 =F

RC (clock derived from a dedicated internal oscillator = 500 kHz max.)

100 =F

OSC/4

101 =F

OSC/16

110 =F

OSC/64

bit 3-0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

12.1.7 CONFIGURING THE A/D

After the A/D module has been configured as desired,

the selected channel must be acquired before the

conversion is started. The analog input channels must

have their corresponding TRIS bits selected as inputs.

To determine sample time, see Section 19.0 “El ectr ical

Specifications”. After this sample time has elapsed, the

A/D conversion can be started.

These s te p s sh ou ld be fol low e d f or a n A/D c onv ersio n:

1. Configure the A/D module:

• Configure analog/digital I/O (ANSEL)

• Configure voltage reference (ADCON0)

• Select A/D input channel (ADCON0)

• Select A/D con ve rsi on cl ock (ADCO N 1)

• Turn on A/D module (ADCON0)

2. Configure A /D interrupt (if desired):

• Clear ADIF bit (PIR1<6>)

• Set ADIE bit (PIE1<6>)

• Set PEIE and GIE bits (I NTCON<7 :6>)

3. Wait the required acquisition time.

4. Start conversion:

• Set GO/DONE bit (ADCON0<1>)

5. Wait for A/D conversion to complete, by either:

• Polling for the GO/DONE bit to be cleared

(with interrupts disabled); OR

• Waiting for the A/D interrupt

6. Read A/D Result register pair

(ADRESH:ADRESL); clear bit ADIF if required.

7. For next conversion, go to step 1 or step 2 as

required. The A/D conversion time per bit is

defined as TAD. A minimum wait of 2 TAD is

required before the next acqu is iti on st a r t s .

EXAMPLE 12-1: A/D CONVERSION

;This code block configures the A/D

;for polling, Vdd reference, R/C clock

;and RA0 input.

;

;Conversion start and wait for complete

;polling code included.

;

BSF STATUS,RP0 ;Bank 1

MOVLW B’01110000’ ;A/D RC clock

MOVWF ADCON1

BSF TRISA,0 ;Set RA0 to input

BSF ANSEL,0 ;Set RA0 to analog

BCF STATUS,RP0 ;Bank 0

MOVLW B’10000001’ ;Right, Vdd Vref, AN0

MOVWF ADCON0

CALL SampleTime ;Wait min sample time

BSF ADCON0,GO ;Start conversion

BTFSC ADCON0,GO ;Is conversion done?

GOTO $-1 ;No, test again

MOVF ADRESH,W ;Read upper 2 bits

MOVWF RESULTHI

BSF STATUS,RP0 ;Bank 1

MOVF ADRESL,W ;Read lower 8 bits

MOVWF RESULTLO

PIC16F946

12.2 A/D Acquisition Requirements

For the A/D converter to meet its specified accuracy,

the charge holding capacitor (CHOLD) must be allowed

to fully charge to the input channel voltage level. The

analog input model is shown in Figure 12-4. The

source impedance (RS) and the internal sampling

switch (RSS) impedance directly affect the time

required to charge the capacitor CHOLD. The sampling

switch (RSS) impedance va rie s over the dev ice vol tag e

(VDD), see Figure 12-4. The maximum recom-

mended impedance for analog sources is 10 kΩ.

As the impedance is decreased, the acquisition time

may be decreased. After the analog input channel is

selected (changed), this acquisition must be done

before the conversion can be started.

To calculate the minimum acquisition time,

Equation 12-1 may be used. This equation assumes

that 1/2 LSb error is used (1024 st eps for the A/D). The

1/2 LSb err or is the ma ximu m error allo wed for the A/D

to meet its specified resolution.

To calculate the minimum acquisition time, TACQ, see

the “PICmicro® Mid-Range MCU Family Reference

Manual” (DS33023).

EQUATION 12-1: ACQUISITION TIME

TACQ Amplifier Settling Time Hold Capacitor Charging Time Temperatu re Co efficient++=

TAMP TCTCOFF++=

2µs TCTemperature - 25°C()0.05µs/°C()[]++=

TCCHOLD RIC RSS RS++() ln(1/2047)–=

10pF 1k

10k

++()– ln(0.0004885)=

1.37

=µs

TACQ 2µS1.37µS50°C- 25°C()0.05µS/°C()[]++=

4.67µS=

VAPPLIED 1e

Tc–

---------

–

⎝⎠

⎜⎟

⎛⎞

VAPPLIED 11

2047

------------

–

⎝⎠

⎛⎞

VAPPLIED 11

2047

------------

–

⎝⎠

⎛⎞

VCHOLD=

VAPPLIED 1e

TC–

----------

–

⎝⎠

⎜⎟

⎛⎞

VCHOLD=

;[1] VCHOLD charged to within 1/2 lsb

;[2] VCHOLD charge response to VAPPLIED

;combin ing [1] and [2]

Where CHOLD is charged to within 1/2 lsb:

Solving for TC:

Therefore:

Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out.

2: The charge holding capacitor (CHOLD) is not discharged after each conversion.

3: The maximum recommended impedance for analog sources is 10 kΩ. This is required to meet the pin

leakage specification.

PIC16F946

FIGURE 12-4: ANALOG INPUT MODEL

12.3 A/D Operation During Sleep

The A/D converter module can operate during Sleep.

This requires the A/D clock source to be set to the

internal oscillator. When the RC clock source is

selected, the A/D waits one instruction before starting

the co nve rsion . This allo ws the SLEEP instruc tion t o b e

execut ed, thus elimin ati ng m uc h o f the swit ching nois e

from the conversion. When the conversion is complete,

the GO/DONE bit is cleared and the result is loaded

into the ADRESH:ADRESL registers. If the A/D

interr upt is enabled, the de vice awa ken s from Sleep. If

the GIE b it (INTCON< 7>) is se t, the progr am count er is

set to the interrupt vector (0004h). If GIE is clear, the

next instruction is executed. If the A/D interrupt is not

enabled, the A/D module is turned off, although the

ADON bit remains set.

When the A/D clock source is something other than

RC, a SLEEP instruction causes the present conversion

to be aborted, and the A/D module is turned off. The

ADON bit remains set.

FIGURE 12-5: A/D TRANSFER FUNCTION

CPIN

RSANx

5 pF

VDD

VT = 0.6V

VT = 0.6V I LEAKAGE

RIC ≤ 1k

Sampling

Switch

SS RSS

CHOLD

= DAC capacitance

VSS

Sampling Switch

567891011

(kΩ)

VDD

= 10 pF

± 500 nA

Legend: CPIN

I LEAKAGE

RIC

CHOLD

= Input Capacitance

= Threshold Voltage

= Leakage current at the pin due to

= Interconnect Resistance

= Sampling Switch

= Sample/Hold Capacit ance (from DAC)

various junctions

RSS

3FFh

3FEh

A/D Output

3FDh

3FCh

004h

003h

002h

001h

000h

Full-Scale

3FBh

1/2 LSB Ideal

Zero-Scale Zero-Scale

Transition

VREF

1/2 LSB Ideal

Transition Center of

Full-Scale Code

1 LSB Ideal

Full-Scale Range

Analog I nput

PIC16F946

12.4 Effects of Reset

A device Reset forces all registers to their Reset state.

Thus, the A/D module is turned off and any pending

conversion is aborted. The ADRESH:ADRESL

registers are unchanged.

TABLE 12-2: SUMMARY OF A/D REGISTERS

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

05h PORTA RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0 xxxx xxxx uuuu uuuu

09h PORTE RE7 RE6 RE5 RE4 RE3 RE2 RE1 RE0 xxxx xxxx uuuu uuuu

0Bh/

8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

1Eh ADRESH Most Significant 8 bits of the left justified A/D result or 2 bits of the right justified result xxxx xxxx uuuu uuuu

1Fh ADCON0 ADFM VCFG1 VCFG0 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

85h TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111

89h TRISE TRISE7 TRISE6 TRISE5 TRISE4 TRISE3 TRISE2 TRISE1 TRISE0 1111 1111 1111 1111

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

9Eh ADRESL Least Significant 2 bits of the left justified A/D result or 8 bits of the right justified result xxxx xxxx uuuu uuuu

9Fh ADCON1 — ADCS2 ADCS1 ADCS0 — — — — -000 ---- -000 ----

Legend: x = unknown , u = unchanged, – = unimplemented read as ‘0’. Shaded cells are not used for A/D module.

PIC16F946

NOTES:

PIC16F946

13.0 DATA EEPROM AND FLASH

PROGRAM MEMORY

CONTROL

Data EEPROM memory is readable and writable and

the Flash program memory is readable during normal

operation (full VDD range). These memories are not

directly m ap ped i n the regi ster file s p ac e. Ins tead, the y

are indirectly addressed through the Special Function

Registers. There are six SFRs used to access these

memories:

• EECON1

• EECON2

• EEDATL

• EEDATH

• EEADRL

• EEADRH

When interfacing the data memory block, EEDATL

holds the 8-bit data for read/write, and EEADRL holds

the address of the EE data location being accessed.

This device has 256 bytes of data EEPROM with an

address range from 0h to 0FFh.

When interfacing the program memory block, the

EEDATL and EEDATH registers form a 2-byte word

that holds the 14-bit data for read, and the EEADRL

and EEADRH registers form a 2-byte word that holds

the 13-bit address of the EEPROM location being

acces sed. This de vice has 4k and 8k words o f program

EEPROM with an address range from 0h-0FFFh and

0h-1FFFh. The program memory allows one-word

reads.

The EEPROM dat a memory allows byte read and write.

A byte write automatically erases the location and

writes the new data (erase before write).

The write time is controlled by an on-chip timer. The

write/erase voltages are generated by an on-chip

charge p ump rated to op erate over the v oltage ran ge of

the device for byte or word operations.

When the device is code-protected, the CPU may

continue to read and write the data EEPROM memory

and r ead th e p rogr am m emor y. W hen co de-pr ot ect ed,

the device programmer can no longer access data or

program memory .

Additional information on the data EEPROM is

available in the “PICmicro® Mid-Range MCU Family

Reference Manual” (DS33023).

13.1 EEADRL and EEADRH Registers

The EEADRL and EEADRH registers can address up

to a maximu m of 256 bytes of dat a EEPROM or up to a

maximum of 8k words of program EEPROM.

When selecting a program address value, the MSB of

the address is written to the EEADRH register and the

LSB is wri tten to the EEAD RL register. When se lec ting

a data address value, only the LSB of the address is

written to the EEADRL register.

13.1.1 EECON1 AND EECON2 REGISTERS

EECON1 is the control register for EE memory

accesses.

Control bit EEPGD determines if the access will be a

program or data memory access. When clear, as it is

when reset, any subsequent operations will operate on

the dat a memory . Wh en set, any subsequent ope rations

will operate on the program memory. Program memory

can only be read.

Control bits RD and WR initiate read and write,

resp ec ti v el y. Th es e bi ts cann o t be clea r e d, on l y s et , in

software. They are cleared in hardware at completion

of the read or write operation. The inability to clear the

WR bit in software prevents the accidental, premature

termination of a write operation.

The WREN bit, when set, w ill allow a write opera tion to

data EEPROM. On power-up, the WREN bit is clear.

The WRERR bit is set when a write operation is

interrupted by a MCLR or a WDT Time-out Reset

during normal operation. In these situations, following

Reset, the user can check the WRERR bit and rewrite

the location. The data and address will be unchanged

in the EEDATL and EEADRL registers.

Interrupt flag bit EEIF (PIR1<7>), is set when write is

complete. It must be cleared in the software.

EECON2 is not a physical register. Reading EECON2

will read all ‘0’s. The EECON2 register is used

exclusively in the data EEPROM write sequence.

PIC16F946

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEDATL7 EEDATL6 EEDATL5 EEDATL4 EEDATL3 EEDATL2 EEDATL1 EEDATL0

bit 7 bit 0

bit 7-0 EEDATL<7:0>: Byte value to Write to or Read from data EEPROM bits or to Read from program memory

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEADRL7 EEADRL6 EEADRL5 EEADRL4 EEADRL3 EEADRL2 EEADRL1 EEADRL0

bit 7 bit 0

bit 7-0 EEADRL<7:0>: Specifies one of 256 locations for EEPROM Read/Write operation bits or low byte for

program memory reads

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = V alue at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

—— EEDATH5 EEDATH4 EEDATH3 EEDATH2 EEDATH1 EEDATH0

bit 7 bit 0

bit 5-0 EEDATH<5:0>: Byte value to Write to or Read from data EEPROM bits or to Read from program memory

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = V alue at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— — — EEADRH4 EEADRH3 EEADRH2 EEADRH1 EEADRH0

bit 7 bit 0

bit 4-0 EEADRH<4:0>: Specifies one of 256 locations for EEPROM Read/Write operation bits or high bits for

program memory reads

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = V alue at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

R/W-0 U-0 U-0 U-0 R/W-x R/W-0 R/S-0 R/S-0

EEPGD — — — WRERR WREN WR RD

bit 7 bit 0

bit 7 EEPGD: Program/Data EEPROM Select bit

1 = A ccesses program mem ory

0 = Accesses data memory

bit 6-4 Unimplemented: Read as ‘0’

bit 3 WRERR: EEPROM Error Flag bit

1 = A write operation is prematurely terminated (any MCLR Reset, any WDT Reset during

normal operation or Brown-out Reset)

0 = The write operation completed

bit 2 WREN: EEPROM Write Enable bit

1 = Allows write cycles

0 = Inhibits write to the data EEPROM

bit 1 WR: Write Control bit

EEPGD = 1:

This bit is ignored

EEPGD = 0:

1 = Initiates a write cycle (The bit is cleared by hardware once write is complete. The WR bit can only be

set, not cleared, in software.)

0 = Write cycle to the data EEPROM is complete

bit 0 RD: Read Control bit

1 = Initiates a memory read (RD is cleared in hardware. The RD bit can only be set, not cleared, in

software.)

0 = D oes not initiate an memory read

Legend:

S = Bit can only be set

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

13.1.2 READING THE DATA EEPROM

MEMORY

To read a data memory location, the user must write th e

address to the EEADRL register, clear the EEPGD

control bit (EECON1<7>), and then set control bit RD

(EECON1<0>). The data is available in the very next

cycle, in the EEDATL register; therefore, it can be rea d

in the ne xt ins tructi on. EEDATL wil l hold this v alue until

another read or until it is written to by the user (during

a write operation).

EXAMPLE 13-1: DATA EEPROM READ

13.1.3 WRITING TO THE DATA EEPROM

MEMORY

To write an EEPROM data location, the user must first

write the add res s to t he EEADRL re gis ter a nd th e da ta

to the EEDATL register. Then the user must follow a

specific sequence to initiate the write for each byte.

The write will not initiate if the sequence described below

is not followed exactly (write 55h to EECON2, write AAh

to EECON2, then set WR bit) for each byte. Interrupts

should be disabled during this code segment.

Additionally, the WREN bit in EECON1 must be set to

enable write. This mechanism prevents accidental

writes to data EEPROM due to errant (unexpected)

code execution (i.e., lost programs). The user should

keep the WREN bit clear at all times, except when

updating EEPROM. The WREN bit is not cleared

by hardware.

After a write sequence has been initiated, clearing the

WREN bit wil l not af fect this wri te cycle. The WR bit wil l

be inhib ited from bei ng set u nle ss the WR EN bit i s set.

At the completion of the write cycle, the WR bit is

cleared in hardware and the EE Write Complete

Interrupt Flag bit (EEIF) is set. The user can either

enable this interrupt or poll this bit. EEIF must be

cleared by software.

The steps to write to EEPROM data memory are:

1. If step 10 is not implemented, check the WR bit

to see if a write is in progress.

2. Write the address to EEADR. Make sure that the

address is not larger than the memory size of

the device.

3. Write the 8-bit data value to be programmed in

the EEDATA register.

4. Clear the EEPGD bit to point to EEPROM data

memory.

5. Set the WREN bit to en able program operations.

6. Disable interrupts (if enabled).

7. Execute the special five instruction sequence:

• Write 55h to EECON2 in two step s (first to W,

then to EECON2)

• Write AAh to EECON2 in two steps (first to

W, then to EECON2)

• Set the WR bit

8. Enable interrupts (if using interrupts).

9. Clear the WREN bit to disable program

operations.

10. At the completion of the write cycle, the WR bit

is cleared and the EEIF interrupt flag bit is set.

(EEIF must be cleared by firmware.) If step 1 is

not implemented, then firmware should check

for EEIF to be set, or WR to clear, to indi cate the

end of the program cycle.

EXAMPLE 13-2: DATA EEPROM WRITE

BSF STATUS,RP1 ;

BCF STATUS,RP0 ; Bank 2

MOVF DATA_EE_ADDR,W ; Data Memory

MOVWF EEADR ; Address to read

BSF STATUS,RP0 ; Bank 3

BCF EECON1,EEPGD ; Point to Data

; memory

BSF EECON1,RD ; EE Read

BCF STATUS,RP0 ; Bank 2

MOVF EEDATA,W ; W = EEDATA

BSF STATUS,RP1 ;

BSF STATUS,RP0

BTFSC EECON1,WR ;Wait for write

GOTO $-1 ;to complete

BCF STATUS,RP0 ;Bank 2

MOVF DATA_EE_ADDR,W;Data Memory

MOVWF EEADR ;Address to write

MOVF DATA_EE_DATA,W;Data Memory Value

MOVWF EEDATA ;to write

BSF STATUS,RP0 ;Bank 3

BCF EECON1,EEPGD ;Point to DATA

;memory

BSF EECON1,WREN ;Enable writes

BCF INTCON,GIE ;Disable INTs.

MOVLW 55h ;

MOVWF EECON2 ;Write 55h

MOVLW AAh ;

MOVWF EECON2 ;Write AAh

BSF EECON1,WR ;Set WR bit to

;begin write

BSF INTCON,GIE ;Enable INTs.

BCF EECON1,WREN ;Disable writes

Required

Sequence

PIC16F946

13.1.4 READING THE FLASH PROGRAM

MEMORY

To read a program memory location, the user must

write two bytes of the address to the EEADRL and

EEADRH registers, set the EEPGD control bit

(EECON1<7>), and then set control bit RD

(EECON1<0>). Once the read control bit is set, the

program memory Flash controller will use the second

instruction cycle to read the data. This causes the

second instruction immediately following the

“BSF EECON1,RD” instruction to be ignor ed. Th e dat a

is available in the very next cycle, in the EEDATL and

EEDATH registers; therefore, it can be read as two

bytes in the following instructions. EEDATL and

EEDATH registers will hold this value u ntil anothe r read

or until it is written to by the user (during a write

operation).

EXAMPLE 13-3: FLASH PROGRAM READ

Note 1: The two instructions following a program

memory read are required to be NOP’s.

This prevents the user from executing a

two-cycle instruction on the next

instruction after the RD bit is set.

2: If the WR bit is set when EEPGD = 1, it

will be immediately reset to ‘0’ and no

operation will take place.

BSF STATUS, RP1 ;

BCF STATUS, RP0 ; Bank 2

MOVLW MS_PROG_EE_ADDR;

MOVWF EEADRH ; MS Byte of Program Address to read

MOVLW LS_PROG_EE_ADDR;

MOVWF EEADR ; LS Byte of Program Address to read

BSF STATUS, RP0 ; Bank 3

BSF EECON1, EEPGD ; Point to PROGRAM memory

BSF EECON1, RD ; EE Read

;

NOP

NOP ; Any instructions here are ignored as program

; memory is read in second cycle after BSF EECON1,RD

;

BCF STATUS, RP0 ; Bank 2

MOVF EEDATA, W ; W = LS Byte of Program EEDATA

MOVWF DATAL ;

MOVF EEDATH, W ; W = MS Byte of Program EEDATA

MOVWF DATAH ;

Required

Sequence

PIC16F946

FIGURE 13-1: FLASH PROGRAM MEMORY READ CYCLE EXECUTION

TABLE 13-1: REGISTERS/BITS ASSOCIATED WITH DATA EEPROM

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Value on

all other

Resets

0Bh/8Bh/

10Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

10Ch EEDATL EEDATL7 EEDATL6 EEDATL5 EEDATL4 EEDATL3 EEDATL2 EEDATL1 EEDATL0 0000 0000 0000 0000

10Dh EEADRL EEADRL7 EEADRL6 EEADRL5 EEADRL4 EEADRL3 EEADRL2 EEADRL1 EEADRL0 0000 0000 0000 0000

10Eh EEDATH — — EEDATH5 EEDATH4 EEDATH3 EEDATH2 EEDATH1 EEDATH0 --00 0000 --00 0000

10Fh EEADRH — — — EEADRH4 EEADRH3 EEADRH2 EEADRH1 EEADRH0 ---0 0000 ---0 0000

18Ch EECON1 EEPGD — — — WRERR WREN WR RD 0--- x000 ---- q000

18Dh EECON2 EEPROM Control Register 2 (not a physical register) ---- ---- ---- ----

Legend: x = unknown, u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition.

Shaded cells are not used by data EEPROM module.

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

BSF EECON1,RD

execut ed her e INSTR(PC + 1)

executed here Forced NOP

execut ed her e

PC + 1 EEADRH,EEADRL PC+3 PC + 5

Flash ADDR

RD bit

EEDATH,EEDATL

PC + 3 PC + 4

INSTR (PC + 1)

INSTR(PC - 1)

executed here INSTR(PC + 3)

executed here INSTR(PC + 4)

executed he re

Flash Data

EEDATH

EEDATL

EERHLT

INSTR (PC) INSTR (PC + 3) INSTR (PC + 4)

PIC16F946

14.0 SSP MODULE OVERVIEW

The Synchronous Serial Port (SSP) module is a serial

inter fac e us ed to c om muni cate wi th o ther peripheral or

microc ontroll er devic es. Thes e periph eral devi ces ma y

be serial EEPROMs, shift registers, display drivers,

A/D converters, etc. The SSP module can operate in

one of two modes:

• Serial Peripheral Interface (SPI™)

• Inter-Integrated Circuit (I2 C™)

An overview of I2C operations and additional information

on the SSP module can be found in the “PICmicro®

Mid-Range MCU Fa mily Reference Manual” (DS33023).

Refer to Application Note AN578, “Use of the SSP

Module in the Multi-Master Environment” (DS00578).

14.1 SPI Mode

This section c ontains register definitions and operational

characteristics of the SPI module. Additional information

on the SPI module can be found in the “PICmicro®

Mid-Range MCU Fa mily Reference Manual” (DS33023).

The SPI mode allows 8 bits of data to be synchronously

transmitted and received simultaneously. To accomplish

communication, typically three pins are used:

• Serial Data Out (SDO) – RC4/T1G/SDO/SEG11

• Serial Data In (SDI) – RC7/RX/DT/SDI/SDA/SEG8

• Serial Clock (SCK) – RC6/TX/CK/SCK/SCL/SEG9

Additionally, a fourth pin may be used when in a Slave

mode of operation:

• Slave Se lect (SS) – RA5/AN4/C2OUT/SS/SEG5

When initializing the SPI, several options need to be

specified. This is done by programming the appropriate

control bits in the SSPCON register (SSPCON<5:0>)

and SSPSTAT<7:6>. These control bits allow the

following to be speci fied:

• Master mode (SCK is the clock output)

• Slave mode (SCK is the clock input)

• Clock Polarity (Idle state of SCK)

• Clock edge (output data on rising/falling edge of

SCK)

• Clock Rate (Master mode only)

• Slave Select mode (Slave mode only)

PIC16F946

R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0

SMP CKE D/A PSR/WUA BF

bit 7 bit 0

bit 7 SMP: SPI™ Data Input Sample Phase bit

SPI Master mode:

1 = Input data sampled at end of data output time

0 = Input data sampled at middle of data output time (Microwire)

SPI Slave mode:

SMP must be cleared when SPI is used in Slave mode

I2 C™ mode:

This bit must be maintained clear

bit 6 CKE: SPI Clock Edge Select bit

SPI mode, CKP = 0:

1 = Data transmitted on falling edge of SCK

0 = Data transmitted on rising edge of SCK (Microwire alternate)

SPI mode, CKP = 1:

1 = Data transmitted on rising edge of SCK

0 = Data transmitted on falling edge of SCK (Microwire default)

I2 C mode:

This bit must be maintained clear

bit 5 D/A: Data/Address bit (I2C mode only)

1 = Indicates that the last byte received or transmitted was data

0 = Indicates that the last byte received or transmitted was address

bit 4 P: Stop bit (I2C mode only)

This bit is cleared when the SSP module is disabled, or when the Start bit is detected last.

SSPEN is cleared.

1 = Indicates that a Stop bit has been detected last (this bit is ‘0’ on Reset)

0 = Stop bit was not detected last

bit 3 S: Start bit (I2C mode only)

This bit is cleared when the SSP module is disabled, or when the Stop bit is detected last.

SSPEN is cleared.

1 = Indicates that a Start bit has been detected last (this bit is ‘0’ on Reset)

0 = Start bit was not detected last

bit 2 R/W: Read/Write bit Information (I2C mode only)

This bit holds the R/W bit information following the last address match. This bit is only valid from

the address match to the next Start bit, Stop bit or ACK bit.

1 = Read

0 = Write

bit 1 UA: Update Address bit (10-bit I2C mode only)

1 = Indicates that the user needs to update the address in the SSPADD register

0 = Address does not need to be updated

bit 0 BF: Buffer Full Status bit

Receive (SPI and I2 C modes ):

1 = Receive complete, SSPBUF is full

0 = Receive not complete, SSPBUF is empty

Transmit (I2 C mode onl y):

1 = Transmit in progress, SSPBUF is full

0 = Transmit complete, SSPBUF is empty

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

R/W-0R/W-0R/W-0R/W-0R/W-0R/W-0R/W-0R/W-0

WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0

bit 7 bit 0

bit 7 WCOL: Write Collision Detect bit

1 = The SSPBUF register is written while it is still transmitting the previous word (must be cleared

in software)

0 = No collision

bit 6 SSPOV: Receive Overflow Indicator bit

In SPI™ mode:

1 = A new byte is rece ived while the SSPBUF reg ister is still holdin g the previou s data. In case of

overflow , the data in SSPSR is lost. Overflow can only occur in Slave mode. The user must read

the SSPBUF, even if only transmitting data, to avoid setting overflow . In Master mode, the over-

flow bit is not set since each new reception (and transmission) is initiated by writing to the

SSPBUF register .

0 = N o overflow

In I2 C™ mode:

1 = A byte is received while the SSPBUF register is still holding the previous byte. SSPOV is a “don’t

care” in Transmit mode. SSPO V m ust be cleare d in soft war e in ei ther mo de.

0 = N o overflow

bit 5 SSPEN: Synch ronous Serial Por t Enable bit

In SPI mode:

1 = Enables ser ia l port and configur es SC K, SDO and SDI as serial por t pins

0 = Disables serial port and configures th ese pins as I/O port pins

In I2 C mode:

1 = Enables the ser ia l por t and configures the SDA and SC L pi ns as serial port pi ns

0 = Disables serial port and configures th ese pins as I/O port pins

In both m odes, whe n enabled, these pins m ust be properl y con f ig ur ed as input or out put.

bit 4 CKP: Clock Po la ri t y Se le ct bi t

In SPI mode:

1 = Idle state for clo ck i s a high level (Microwire default)

0 = Idle state for clock is a low level (Microwire alternate)

In I2 C mode:

SCK rele ase control

1 = Enable cloc k

0 = Holds clock low (clock stretch). (Used to ensure data setup time.)

bit 3-0 SSPM<3:0>: Syn chronous Ser ial P or t Mode Select bits

0000 = SPI Master mode, clock = FOSC/4

0001 = SPI Master mode, clock = FOSC/16

0010 = SPI Master mode, clock = FOSC/64

0011 = SPI Master mode, cl ock = TMR2 output / 2

0100 = SPI Slave mode, clock = SC K pin. SS pin co nt ro l enabled.

0101 = SPI Slave mode, clock = SC K pin. SS pin co nt ro l disabled. SS can be used as I/O pin.

0110 = I2C Slave mode, 7-b it ad dr ess

0111 = I2C Slave mode, 10- bit addr ess

1011 = I2C Firmware Contro lle d Maste r mode (sla ve idle)

1110 = I2C Slave mode, 7-b it address w ith Start and Sto p bi t inter r upts enabled

1111 = I2C Slave mode, 10- bi t addr ess with Start and Stop bit interr upts enabled

Legend:

R = Readable bit W = Writable bi t U = Unimpl em ented bit, read as ‘0’

- n = Value at PO R ‘1’ = Bi t is se t ‘0’ = Bi t is cle ar ed x = Bit is unk nown

PIC16F946

FIGURE 14-1: SSP BLOCK DIAGRAM

(SPI MODE)

To enable the serial port, SSPEN bit (SSPCON<5>)

must be set. To reset or reconfigure SPI mode:

• Clear bit SSPEN

• Re-initialize the SSPCON register

• Set SSPEN bit

This configures the SDI, SDO, SCK and SS pins as

serial port pins. For the pins to behave in a serial port

functio n, they mu st have their dat a direc tion bits (in the

TRISC register) appropriately programmed. This is:

• SDI must have TRISC<7> set

• SDO must have TRISC<4> cleared

• SCK (Master mode) must have TRISC<6>

cleared

• SCK (Slave mode) must have TRISC<6> set

•SS

must have TRISA<5> set.

Read Write

Internal

Data Bus

RC7/RX/

RC4/T1G/

RA5/AN2/

RC6/TX/CK/

SSPSR reg

SSPBUF reg

SSPM<3:0>

bit 0 Shift

Clock

SS Control

Enable

Edge

Select

Clock Select

TMR2 Outpu

TCY

Prescaler

4, 16, 64

TRISC<6>

Edge

Select

SCL/

Peripheral OE

SDA/SEG8

DT/SDI/

SDO/SEG11

C2OUT/SS/

SEG5

SCK/

SEG9

Note 1: When the SPI is in Slave mode with SS

pin control enabled (SSPCON<3:0> =

0100), the SP I modul e will re set if th e SS

pin is set to VDD.

2: If the SPI is used in Slave mode with

CKE = 1, then the SS pin contro l must be

enabled.

3: When the SPI is in Slave mode with SS pin

control enabled (SSPCON<3:0> = 0100),

the state of the SS pin can affect the state

read back from the TRISC<4> bit. The

peripheral OE signa l from the SSP module

into PORTC controls the state that is read

back from the TRISC<4> bit (see

Section 19.4 “DC Characteristics:

PIC16F946-I (Industrial), PIC16F946-E

(Extended)” for information on PORTC).

If read-modify-write instructions, such as

BSF, are performed on the TRISC register

while the SS pin is high, this will cau se the

TRISC<4> bit to be set, thus disabling the

SDO output.

PIC16F946

14.2 Operation

When initializing the SPI, several options need to be

specif ied. This is done by progra mming the ap propriate

control bits (SSPCON<5:0> and SSPSTAT<7:6>).

These control bits allow the following to be specified:

• Master mode (SCK is the clock output)

• Slave mode (SCK is the clock input)

• Clock Polarity (Idle state of SCK)

• Data Input Sample Phase (middle or end of data

output time)

• Clock Edge (output data on rising/falling edge of

SCK)

• Clock Rate (Master mode only)

• Slave Select mode (Slave mode only)

The SSP consists of a transmit/receive shift register

(SSPS R) and a buffer re gist er (S SP BUF) . T he SSP SR

shifts the data i n and out of the device, MS b first. The

SSPBUF holds the data that was written to the SSPSR

until the received data is ready. Once the eight bits of

data have been received, that byte is moved to the

SSPBUF register. Then, the Buffer Full detect bit, BF

(SSPSTAT<0>), and the interrupt flag bit, SSPIF, are

set. This double-buffering of the received data

(SSPBUF) allows the next byte to start reception before

read ing t he dat a tha t wa s j ust rec ei ved . An y w rite to the

SSPBUF register during transmission/reception of data

will be ignored and the Write Collision detect bit, WCOL

(SSPCON<7>), will be set. User software must clear the

WCOL bit so that it can be determined if the following

write(s) to the SSPBUF register completed successfully .

When the application software is expecting to receive

valid da ta, the SSPBUF shoul d be read before th e next

byte o f dat a t o transfe r is written to t he SSPBUF. Buff er

Full bit, BF (SSPSTAT<0>), indicates when SSPBUF

has been loaded with the received data (transmission

is complete). When the SSPBUF is read, the BF bit is

cleared. This data may be irrelevant if the SPI is only a

transmitter. Generally, the SSP interrupt is used to

determine when the transmission/reception has com-

pleted. T he SSPBUF must be rea d and/or written. If the

interrupt method is not going to be used, then software

polling can be d one to ensure that a write collision d oes

not occur. Example 14-1 shows the loading of the

SSPBUF (SSPSR) for data transmission.

The SSPSR is n ot directly reada ble or wri table and can

only be accessed by addressing the SSPBUF register.

Additionally, the SSP Status register (SSPSTAT)

indicates the various status conditions.

EXAMPLE 14-1: LOADING THE SSPBUF (SSPSR) REGISTER

LOOP BTFSS SSPSTAT, BF ;Has data been received(transmit complete)?

BRA LOOP ;No

MOVF SSPBUF, W ;WREG reg = contents of SSPBUF

MOVWF RXDATA ;Save in user RAM, if data is meaningful

MOVF TXDATA, W ;W reg = contents of TXDATA

MOVWF SSPBUF ;New data to xmit

PIC16F946

14.3 Enabling SPI I/O

To enable the serial port, SSP Enable bit, SSPEN

(SSPCON<5>), must be set. To reset or reconfigure

SPI mode, clear the SSPEN bit, re-initialize the

SSPCON registers and then set the SSPEN bit. This

configures the SDI, SDO, SCK and SS pins as serial

port pin s. For the pins t o behave as the serial p ort fun c-

tion, some must have their data direction bits (in the

TRIS register) appropriately programmed. That is:

• SDI is a uto maticall y c on t rol led by the S P I mo dul e

• SDO must have TRISC<4> bit cleared

• SCK (Master mode) must have TRISC<6> bit

cleared

• SCK (Slave mode) must have TRISC<6> bit set

•SS

must have T RISA<5> bit set

Any serial port function that is not desired may be

overridden by programming the corresponding data

direction (TRIS) register to the opposite value.

14.4 Typical Connection

Figure 14-2 shows a typical connection between two

microcontrollers. The master controller (Processor 1)

initiates the data transfer by sending the SCK signal.

Data is shifted out of both shift registers on their

programmed clock edge and latched on the opposite

edge of the clock. Both processors should be

programmed to the same Clock Polarity (CKP), then

both controllers would send and receive data at the

same tim e. Whet her the dat a is meaning ful (or dum m y

data) depends on the application software. This leads

to three scenarios for data transmission:

• Master sends data – Slave sends dumm y data

• Master sends data – Slave sends data

• Master sends dummy data – Slave sen ds data

FIGURE 14-2: SPI™ MASTER/SLAVE CONNECTION

Serial Input Buffer

(SSPBUF)

Shift Register

(SSPSR)

MSb LSb

SDO

SDI

Processor 1

SCK

SPI™ Master SSPM<3:0> = 00xxb

Serial Input Buf fe r

(SSPBUF)

Shift Register

(SSPSR)

LSb

MSb

SDI

SDO

Processor 2

SCK

SPI™ Slave SSPM<3:0> = 010xb

Serial Clock

PIC16F946

14.5 Master Mode

The master can initiate the data transfer at any time

because it controls the SCK. The master determines

when the slave (Processor 2, Figure 14-2) is to

broadcast data by the software protocol.

In Master mode, the data is transmitted/received as

soon as the SSPBUF registe r is written to. If the SPI is

only going to receive, the SDO output could be

disabled (programmed as an input). The SSPSR

SDI pin at the programmed clock rate. As each byte is

received, it will be loaded into the SSPBUF register as

if a normal received byte (interrupts and Status bits

appropriately set). This could be useful in receiver

applications as a “Line Activity Monitor” mode.

The clock pola rity is selected b y appropriately program-

ming the CKP bi t (SSPCON<4>). This then, would giv e

waveforms for SPI communication as shown in

Figure 14-3, Figure 14-5 and Figure 14-6, where the

MSB is t rans m itted first. In M aster mode, the SPI cloc k

rate (bit rate) is user programmable to be one of the

following:

•F

OSC/4 (or TCY)

•FOSC/16 (or 4 • TCY)

•F

OSC/64 (or 16 • TCY)

• Timer2 output/2

This allows a maximum data rate (at 40 MHz) of

10 Mbps.

Figure 14-3 shows the waveforms for Master mode.

When the CKE bit is set, the SDO data is valid before

there is a clock edge on SCK. The change of the input

sample is shown bas ed on the state of the SMP bit. The

time when the SSPBUF is loaded with the received

dat a is shown.

FIGURE 14-3: SPI™ MODE WAVEFORM (MASTER MODE)

SCK

(CKP = 0

SCK

(CKP = 1

SCK

(CKP = 0

SCK

(CKP = 1

4 Clock

Modes

Input

Sample

Input

Sample

SDI

bit 7 bit 0

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

bit 7 bit 0

SDI

SSPIF

(SMP = 1)

(SMP = 0)

(SMP = 1)

CKE = 1)

CKE = 0)

CKE = 1)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

(CKE = 0)

(CKE = 1)

Next Q4 Cycle

after Q2↓

PIC16F946

14.6 Slave Mode

In Slave m ode , the dat a is trans mi tted and rece iv ed a s

the external clock pulses appear on SCK. When the

last bit is latched, the SSPIF interrupt flag bit is set.

While in Slave mode, the external clock is supplied by

the external clock source on the SCK pin. This external

clock must meet the minimum high and low times as

specified in the electrical specifications.

While in Sleep mode, the slave can transmit/receive

data. When a byte is received, the device will wake-up

from Sleep.

14.7 Slave Select Synchronization

The SS pin allows a Synchronous Slave mode. The

SPI must be in Slave mode wit h SS pin control ena bled

(SSPCON<3:0> = 04h). The pin must not be drive n low

for the SS pin to function as an input. The data latch

must be high. When the SS pi n is low , transmissi on and

receptio n are enab led and the SDO pin is driven. When

the SS pin goes high, the SDO pin is no longer driven,

even if in the middle of a transmitted byte, and

becomes a floating output. External pull-up/pull-down

resistors may be desirable, depending on the applica-

tion.

When the SPI module resets, the bit counter is forced

to ‘0’. This can be done by either forcing the SS pin to

a high level or clearing the SSPEN bit.

To emulate two-wire communication, the SDO pin can

be connected to the SDI pin. When the SPI needs to

operate as a receiver, the SDO pin can be configured

as an in put. This d isables transmissi ons from th e SDO.

The SDI can always be left as an input (SDI function)

since it can not cre ate a bus con f li ct .

FIGURE 14-4: SLAVE SYNCHRONIZATION WAVEFORM

Note 1: When the SPI is in Slave m ode with SS pin

control enabled (SSPCON<3:0> = 0100),

the SPI module will reset if the SS pin is set

to VDD.

2: If the SPI is us ed in Slave Mo de with CK E

set, then the SS pin control must be

enabled.

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit 7

SDO bi t 7 bit 6 bit 7

SSPIF

Interrupt

(SMP = 0)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

bit 0

bit 7 bit 0

Next Q4 Cycle

after Q2↓

PIC16F946

FIGURE 14-5: SPI™ MODE WAVEFORM (SLAVE MODE WITH CKE = 0)

FIGURE 14-6: SPI™ MODE WAVEFORM (SLAVE MODE WITH CKE = 1)

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit 7 bit 0

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

SSPIF

Interrupt

(SMP = 0)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

Optional

Next Q4 Cycle

after Q2↓

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit 7 bit 0

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

SSPIF

Interrupt

(SMP = 0)

CKE = 1)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

Not Optional

Next Q4 Cycle

after Q2↓

PIC16F946

14.8 Sleep Operation

In Master mode, all module clocks are halted and the

transmission/reception will remain in that state until the

device wakes from Sleep. After the device returns to

normal mode, the module will continue to trans-

mit/r eceive data.

In Slave m ode , th e SP I Transmit/ Receive Sh ift reg is ter

operat es asy nchron ously to the devi ce. Th is al lows the

device to be placed in Sleep mode and data to be

shifted into the SPI Transmit/Receive Shift register.

When all 8 bits have been received, the SSP interrupt

flag bit will be set and if enabled, will wake the device

from Sleep.

14.9 Effects of a Reset

A Reset disables the SSP module and terminates the

current transfer.

14.10 Bus Mode Comp atibility

Table 14-1 shows the compatibility between the

standard SPI modes and the states of the CKP and

CKE control bits.

TABLE 14-1: SPI™ BUS MODES

There is also a SMP bit w hich co ntrols whe n the dat a is

sampled.

TABLE 14-2: REGISTERS ASSOCIATED WITH SPI™ OPERATION

Standard SPI™

Mode Terminology

Control Bits State

CKP CKE

0, 0 0 1

0, 1 0 0

1, 0 1 1

1, 1 1 0

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR,

BOR

Value on

all other

Resets

0Bh,8Bh.

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

13h S SPBUF Synchronous Serial Port Rec eive Buffer/Transmit Register xxxx xxxx uuuu uuuu

14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

87h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

85h TRISA TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111

94h SSPSTAT SMP CKE D/A P S R/W UA BF 0000 0000 0000 0000

Legend: x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not use d by the SSP in SPI mode.

PIC16F946

14.11 SSP I2 C Operation

The SSP module in I2C mode, fully implements all

slave functions, except general call support, and pro-

vides interrupts on Start and Stop bits in hardware to

facilitate firmware implementations of the master func-

tions. The SSP modu le impl ements th e S t andard m ode

specifications, as well as 7-bit and 10-bit addressing.

Two pins are used for data transfer. These are the

RC6/TX/CK/SCK/SCL/SEG9 pin, which is the clock

(SCL), and the RC7/RX/DT/SDI/SDA/SEG8 pin, which

is the data (SDA).

The SSP mod ule fun ctions a re enabl ed by settin g SSP

enable bit SSPEN (SSPCON<5>).

FIGURE 14-7: SSP BLOCK DIAGRAM

(I2 C™ MODE)

The SSP module has five registers for the I2C operation,

which are listed below.

• SSP Control Register (SSPCON)

• SSP Status Register (SSPSTAT )

• Serial Receive/Transmit Buffer (SSPBUF)

• SSP Shift Register (SSPSR) – Not directly

accessible

• SSP Address Register (SSPADD)

The SSPCON register allows control of the I2C

operation. Four mode selection bits (SSPCON<3:0>)

allow one of the following I2C modes to be selected:

•I

2C Slave mode (7-bit address)

•I

2C Slave mode (10-bit address)

•I

2C Slave mode (7-bit add res s), with Start and

Stop bit interrupts enabled to support Firmware

Master mode

•I

2C Slave mode (10-bit address), with Start and

Stop bit interrupts enabled to support Firmware

Master mode

•I

2C Start and Stop bit interrupts enabled to

support Firmware Master mode; Slave is idle

Selection of any I2C mode with the SSPEN bit set

forces the SCL and SDA pins to be open drain, pro-

vided these pins are programmed to inputs by setting

the appropriate TRISC bits. Pull-up resistors must be

provide d external ly to the SCL and SD A pins for proper

operation of the I2C module.

Additional information on SSP I2C operation can be

found in the “PICmicro® Mid-Range MCU Family

Reference Manual” (DS33023).

14.12 Slave Mode

In Slave mod e, the SCL and SDA pin s must be config-

ured as input s (TRISC<7 :6> set). The SSP module will

override the input state with the output data when

required (slave -tran smit ter).

When an add ress is match ed, or the da t a trans fer after

an address match is received, the hardware automati-

cally will generate the Acknowledge (ACK) pulse, and

then load the SSPBUF reg is ter wi th th e re ceive d valu e

currently in the SSPSR register.

There are certain conditions that will cause the SSP

module not to give this ACK pulse. They include (either

or both):

a) The Buffer Full bit BF (SSPSTAT<0>) was set

before the transfer was received.

b) The overf low bit SSPOV (SSPCON<6>) was set

before the transfer was received.

In this case, the SS PSR r egister val ue is no t loa ded int o

the SSPBUF, but bit SSPI F (PIR1<3>) is set. Table 14- 3

shows the results of when a data transfer byte is received,

given the status of bits BF and SSPOV. The shaded cells

show the conditio n where user soft ware did not p roperly

clear the overflow condition. Flag bit BF is cleared by

reading the SSPBUF register, while bit SSPOV is cleared

through software.

The SCL clock input must have a minimum high and low

for proper operation. For high and low times of the I2C

specification, as well as the requirements of the SSP

module, see Section 19.0 “Electrical Specifications”.

Read Write

SSPSR reg

Match Detect

SSPADD reg

Start and

Stop bit Detect

SSPBUF reg

Internal

Data Bus

Addr Match

Set, Reset

S, P bits

(SSPSTAT reg

)

RC6/TX/

RC7/

Shift

Clock

MSb

RX/DT/ LSb

SDI/

CK/SCK/

SCL/SEG9

SDA/

SEG8

PIC16F946

14.12.1 ADDRESSING

Once the SSP module has been enabled, it waits for a

Start condition to occur. Following the Start condition,

the 8-bits are shifted into the SSPSR register. All

incoming bits are sampled with the rising edge of the

clock (SCL) line. The value of register SSPSR<7:1> is

compared to the value of the SSPADD register. The

address is compared on the falling edge of the eighth

clock (SCL) pulse. If the addresses match, and the BF

and SSPOV bits are clear, the following events occur:

a) The SSPSR register value is loaded into the

SSPBUF register.

b) The Buffer Full bit, BF is set.

c) An ACK pulse is generated.

d) SSP Interrupt Flag bit, SSPIF (PIR1<3>) is set

(interrupt is generated if enabled) on the falling

edge of the ninth SCL pulse.

In 10-bit Address mode, two address bytes need to be

received by the slave (Figure 14-8). The five Most

Significant bits (MSbs) of the first address byte specify

if this is a 10-bit address. Bit R/W (SSPSTAT<2>) must

specify a write so the slave device will receive the

second address byte. For a 10-bit address, the first

byte w ould equ al ‘1111 0 A9 A8 0’, where A9 and

A8 are the two MSbs of the address.

The sequence of events fo r 10-bit address is as follows,

with steps 7-9 for slave-transm itter:

1. Receive first (high) byte of address (bits SSPIF,

BF and bit UA (SSPSTAT<1>) are set).

2. Update the SSPADD register with second (low)

byte of address (clears bit UA and releases the

SCL line).

3. Read the SSPBUF register (clears bit BF) and

clear flag bit SSPIF.

4. Receive second (low) byte of address (bits

SSPIF, BF and UA are set).

5. Update t he SSPADD registe r with the f irst (high)

byte of a ddre ss ; if match rele as es SC L li ne, thi s

will clear bit UA.

6. Read the SSPBUF register (clears bit BF) and

clear flag bit SSPIF.

7. Receive repeated Start condition.

8. Receive first (high) byte of address (bits SSPIF

and BF are set).

9. Read the SSPBUF register (clears bit BF) and

clear flag bit SSPIF.

TABLE 14-3: DATA TRANSFER RECEIVED BYTE ACTIONS

Status Bits as Data

Transfer is Received SSPSR → SSPBUF Generate ACK

Pulse

Set bit SSPIF

(SSP Interrupt occurs

if enabled)

BF SSPOV

00 Yes Yes Yes

10 No No Yes

11 No No Yes

0 1 No No Yes

Note: Shaded cells show the conditions where the user software did not properly clear the overflow condition.

PIC16F946

14.12.2 RECEPTION

When the R/W bit of the address byte is clear and an

address match occurs, the R/W bit of the SSPSTAT

the SSPBUF register.

When the address byte overflow condition exists , then

no Acknowledge (ACK) pulse is given. An overflow

condition is defined as either bit BF (SSPSTAT<0>) is

set, or b it SSPOV (SSPCON<6>) is set. This is an e rror

condition due to the user ’s firmware.

An SSP interrupt is generated for each data transfer

byte. Flag bit SSPIF (PIR1<3>) must be cleared in

software. The SSPSTAT register is used to determine

the status of the byte.

FIGURE 14-8: I2 C™ WAVEFORMS FOR RECEPTION (7-BIT ADDRESS)

D3D4

D6D7

A7 A6 A5 A4 A3 A2 A1SDA

SCL 123456789123456789123

Bus Master

terminates

transfer

Bit SSPOV is set because the SSPBUF register is still full.

Cleared in software

SSPBUF register is read

ACK Receiving Data

Receiving Data D0

D3D4

D6D7

ACK

R/W = 0

Receiving Ad dr ess

SSPIF (PIR1<3>)

BF (SSPSTAT<0>)

SSPOV (SSPCON<6>)

ACK

ACK is not sent.

PIC16F946

FIGURE 14-9: I2C™ SLAVE MODE TIMING (RECEPTION, 10-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

S123456789 123456789 12345 789 P

1 1 1 1 0 A9A8 A7 A6A5A4A3A2A1A0 D7 D6D5D4D3 D1D0

Receive Data Byte

ACK

R/W = 0

ACK

Receive First Byte of Address

Clear ed in softwar e

(PIR1<3>) Cleared in software

Receive Second Byte of Address

Clear ed by hard w ar e

when SSPADD is updated

with low byte of address

UA (SSPSTAT<1>)

Clock is held low until

update of SSPADD has

taken place

UA is set indicating

that the SSPADD needs to

be updated

UA is set indicating

that SSPA DD needs to

be updated

Cleared by hardware when

SSPADD is updated with high

byte of address

SSPBUF is written

with contents of SSPSR Dummy read of SSPBUF

to clear BF flag

ACK

CKP

12345 789

D7 D6 D5 D4 D3 D1 D0

Receive Data Byte

Bus maste

terminates

transfer

ACK

Cleared in software Cleared in software

SSPOV (SSPCON<6>)

SSPOV is set

because SSPBUF is

still full. ACK is not sen

(CKP does not reset to ‘0’ when SEN = 0)

Clock is held low until

update of SSPADD has

taken place

PIC16F946

14.12.3 TRANSMISSION

When the R/W bit of the incoming address byte is set

and an address match occurs, the R/W bit of the

SSPSTAT register is set. The received address is

loaded into the SSPBUF register. The ACK pulse will

be sent on the ninth bit, and pin

RC6/TX/CK/SCK/SCL/SEG9 is held low. The transmit

data must be loaded into the SSPBUF register, which

also loads the SSPSR register. Then, pin

RC6/TX/CK/SCK/SCL/SEG9 should be enabled by

setting bit CKP (SSPCON<4>). The maste r m ust mon-

itor the SCL pin prior to asserting another clock pulse.

The slave devices may be holding off the master by

stretching the clock. The eight data bits are shifted out

on the falling edge of the SCL input. This ensures that

the SDA signal is valid during the SCL high time

(Figure 14-10).

An SSP interrupt is generated for each data transfer

byte. Flag bit SSPIF must be cleared in software, and

the SSPSTAT register is used to determine the status

of the byte. Flag bit SSPIF is set on the falling edge of

the ninth clock pulse.

As a slave-transmitter, the ACK pulse from the master

receiver is latched on the rising edge of the ninth SCL

input pulse. If the SDA line was high (not ACK), then

the dat a tran sfer is com plete. When th e ACK is latched

by the slave, the slave logic is reset (resets SSPSTAT

rence of the S tart bit. If the SDA line was lo w (ACK), the

transmit data must be loa ded into the SSPBUF regi ster ,

which also loads the SSPSR register. Then pin

RC6/TX/CK/SCK/SCL/SEG9 should be enabled by

setting bit CKP.

FIGURE 14-10 : I2 C™ WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS)

SDA

SCL

SSPIF (PIR1<3>)

BF (SSPSTAT<0>)

CKP (SSPCON<4>)

A7 A6 A5 A4 A3 A2 A1 ACK D7 D6 D5 D4 D3 D2 D1 D0 ACK

Transmitting DataR/W = 1Receiving Ad dr ess

123456789 123456789 P

Cleared in software

SSPBUF is written in software From SSP Interrupt

Service R out i ne

Set bit after writing to SSPB UF

SData in

sampled SCL held low

while CPU

responds to SSPIF

(the SSPBUF must be written to

before the CKP bit can be set)

PIC16F946

FIGURE 14-11: I2C™ SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

S123456789 123456789 12345 789 P

1 1 1 1 0 A9A8 A7 A6A5A4A3A2A1A0 1 1 1 1 0 A8

R/W = 1

ACK

R/W = 0

ACK

Receive Fir st Byte of Address

Cleared in software

Bus master

terminates

transfer

(PIR1<3>)

Receive Second Byte of Address

Cleared by hardwa re w hen

SSPADD is updated with

low byte of address

UA (SSPSTAT<1>)

Clock is held low until

update of SSPADD has

taken place

UA is set indicating

that the SSPADD

needs to be update d

UA is set indicating

that SSPADD needs

to be updated

Cleared by hardware when

SSPADD is updated with high

byte of address

SSPBUF is written

with contents of Dummy read of SSPBUF

to clear BF flag

Receive Fi rst Byte of Address

12345 789

D7 D6 D5 D4 D3 D1 ACK

Transmitting Data Byte D0

Dummy read of SSPBUF

to clear BF flag

Cleared in software

Write of SSPBUF

initiates transmit

Clear ed in softwar e

Comple tion of

clears BF flag

CKP (SSPCON<4>)

CKP is set in software

CKP is automatically cleared in hardware

Clock is held low until

update of SSPADD has

taken place

data transmission

Clock is held low until

CKP is set to ‘1’

BF flag is clear

third address sequence

at the end of the

holding SCL low

SSPSR

PIC16F946

14.13 Master Mode

Master mode of operation is supported in firmware

using interrupt generation on the detection of the Start

and S t op conditio ns. The S top (P) and S t art (S) bits are

cleared from a Reset or when the SSP module is dis-

abled. The Stop (P) and Start (S) bits will toggle based

on the Start a nd Stop cond itions . Control of the I2C bus

may be t aken whe n the P bit is set or th e bus is idle an d

both the S and P bits are clear.

In Master mode, the SCL and SDA lines are manipu-

lated by cleari ng the c orresp onding TRISC<6 :7> bit(s ).

The output level is always low, irrespective of the

value(s ) i n PO R T C <6:7 >. So w h en tran sm itti ng da t a, a

‘1’ data bit m ust h ave the TRISC<7 > bi t s et (i npu t) an d

a ‘0’ data bi t mus t have the TR I SC< 7> bi t c le ared (o ut-

put). The same scenario is true for the SCL line with the

TRISC<6> bit. Pull-up resistors must be provided

externally to the SCL and SDA pins for proper opera-

tion of the I2C module.

The following events will cause the SSP Interrupt Flag

bit, SSPIF, to be set (SSP Interrupt will occur if

enabled):

• Start condition

• Stop condition

• Data transfer byte transmitted/received

Master mode of operation can be done with either the

Slave mode idle (SSPM<3:0> = 1011), or with the

Slave active. When both Master and Slave modes are

enabled, the software needs to differentiate the

source(s) of the interrupt.

14.14 Multi-Master Mode

In Multi-Master mode, the interrupt generation on the

detection of the Start and Stop conditions, allows the

determination of when the bus is free. The Stop (P)

and Start (S) bi t s are c leared from a Res et or when th e

SSP module is disabled. The Stop (P) and Start (S)

bits will toggle based on the Start and Stop conditions.

Control of the I2C bus may be taken when bit P

(SSPSTAT<4>) is set, or the bus is idle and both the S

and P bits clear. When the bus is busy, enabling the

SSP Interr upt will gen erat e th e in terru pt wh en the Stop

conditi on occ urs .

In Multi-Master operation, the SDA line must be moni-

tored to see if the signal level is the expected output

level. This check only needs to be done when a high

level is output. If a high level is expected and a low

level is present, the device needs to release the SDA

and SCL lines (set TRISC<6:7>). There are two

stages where this arbitration can be lost, these are:

• Address Transfer

• Data Transfer

When the slave logic is enabled, the slave continues

to receive. If arbitration was lost during the address

transfer stage, communication to the device may be in

progress. If addressed, an ACK pulse will be gener-

ated. If arbitration was lost during the data transfer

stage, the device will need to re-transfer the data at a

later time.

14.14.1 CLOCK SYNCHRONIZATION AND

THE CKP BIT

When the CKP bit is cleared, the SCL output is forced

to ‘0’; however, setting the CKP bit will not assert the

SCL outpu t low until the SCL outpu t is already sample d

low. Therefore, the CKP bit will not assert the SCL line

until an external I2C master device has already

asserted the SCL line. The SCL output will remain low

until the CKP bit is set and all other devices on the I2C

bus have deasser t ed SCL. Thi s en sure s tha t a write to

the CKP bit will not violate the minimum high time

requirement for SCL (see Figure 14-12).

PIC16F946

FIGURE 14-12: CLOCK SYNCHRONIZATION TIMING

TABLE 14-4: REGISTERS ASSOCIATED WITH I2 C™ OPERATION

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR,

BOR

Value on

all other

Resets

0Bh, 8Bh ,

10Bh,18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

13h SSPBUF Synch ronous Serial Port Receiv e Buffer/Transmit Register xxxx xxxx uuuu uuuu

14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

87h TRISC POR TC Dat a Directio n Register 1111 1111 1111 1111

93h SSPAD D Synchronous Ser i al Por t (I2C™ mode) Address Register 0000 0000 0000 0000

94h SSPSTAT SMP(1) CKE(1) D/A PSR/WUA BF 0000 0000 0000 0000

Legend: x = unk nown, u = un changed, – = unimple m ent e d lo cations read as ‘0’. Shaded cells are not used by SSP

module in I2C mode.

Note 1: Ma i ntain these bits clear in I2C mode .

SDA

SCL

DX-1DX

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

SSPCON

CKP

Master device

deasserts clock

Master device

asserts clock

PIC16F946

15.0 CAPTURE/COMPARE/PWM

MODULES

Each Capture/Compare/PWM (CCP) module contains

a 16-bit register which can operate as a:

• 16-bit Capture register

• 16-bit Compare register

• PWM Master/Slave Duty Cycle register

Both the CCP1 and CCP2 modules are identical in

operatio n, with th e except ion being the operation of the

special event trigger. Table 15-1 and Table 15-2 show

the resources and interactions of the CCP module(s).

In the following sections, the operation of a CCP

module is described with respect to CCP1. CCP2

operates the same as CCP1, except where noted.

CCP1 Mo dul e:

Capture/Compare/PWM Register1 (CCPR1) is com-

prised of two 8-bit registers: CCPR1L (low byte) and

CCPR1H (high byte). The CCP1CON register controls

the operation of CCP1. The special event trigger is

generated by a compare match and will reset Timer1.

CCP2 Mo dul e:

Capture/Compare/PWM Register2 (CCPR2) is com-

prised of two 8-bit registers: CCPR2L (low byte) and

CCPR2H (high byte). The CCP2CON register controls

the operation of CCP2. The special event trigger is

generated by a compare match and will reset Timer1

and start an A/D conversion (if the A/D module is

enabled).

Additional information on CCP modules is available in

the “PICmicro® Mid-Range MCU Family Reference

Manual” (DS33023) and in Application Note AN594,

“Using the CCP Modules” (DS00594).

TABLE 15-1: CCP MODE – TIMER

RESOURCES REQUIRED

TABLE 15-2: INTERACTION OF TWO CCP MODULES

CCP Mode Timer Resource

Capture Timer1

Compare Timer1

PWM Timer2

CCPx Mode CCPy Mode Interaction

Capture Capture Same TMR1 time base

Capture Compare The compare should be configured for the special event trigger, which clears TMR1

Compare Compare The compare(s) should be configured for the special event trigger, which clears TMR1

PWM PWM The PWMs will have the same frequency and update rate (TMR2 interrupt)

PWM Capture None

PWM Compare None

PIC16F946

U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

—— CCPxX CCPxY CCPxM3 CCPxM2 CCPxM1 CCPxM0

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5-4 CCPxX:CCPxY: PWM Least Significant bits

Capture mode:

Unused

Compare mode:

Unused

PWM mode:

These bits are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPRxL.

bit 3-0 CCPxM<3:0>: CCPx Mode Select bits

0000 = Capture/Compare/PWM disabled (resets CCPx module)

0100 = Capture mode, every falling edge

0101 = Capture mode, every rising edge

0110 = Capture mode, every 4th rising edge

0111 = Capture mode, every 16th rising edge

1000 = Compare mode, set output on match (CCPxIF bit is set)

1001 = Compare mode, clear output on match (CCPxIF bit is set)

1010 = Compare mode, generate software interrupt on match (CCPxIF bit is set, CCPx pin is

unaffected)

1011 = Compare mode, trigger special event (CCPxIF bit is set, CCPx pin is unaffected);

CCP1 resets TMR1; CCP2 resets TMR1 and starts an A/D conversion (if A/D module

is enabled)

11xx =PWM mode

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

15.1 Capture Mode

In Capture mode, CCPR1H:CCPR1L captures the

16-bit value of th e TMR1 r egister wh en an event occurs

on pin RC5/T1CKI/CCP1/SEG10. An event is defined

as one of the following:

• Every falling edge

• Every rising edge

• Every 4th rising edge

• Every 16th rising edge

The type of event is configured by control bits

CCP1M<3:0> (CCPxCON<3:0>). When a capture is

made, the interrupt request flag bit CCP1IF (PIR1<2>)

is set. The interrupt flag must be cleared in software. If

another capture occurs before the value in register

CCPR1 is read, the old captured va lue is overwritten by

the new value.

15.1.1 CCP PIN CONFIGURATION

In Capture mode, the RC5/T1CKI/CCP1/SEG10 pin

should be configured as an input by setting the

TRISC< 5> bit.

FIGURE 15-3: CAPTURE MODE

OPERATION BLOCK

DIAGRAM

15.1.2 TIMER1 MODE SELECTION

Timer1 must be running in Timer mode, or Synchro-

nized Counter mode, for the CCP module to use the

capture feature. In Asynchronous Counter mode, the

capture ope ration may not wo rk.

15.1.3 SOFTWARE INTERRUPT

When the Capture mode is changed, a false capture

interrupt may be generated. The user should keep bit

CCP1IE (PIE1<2>) clear to avoid false interrupts and

should clear the flag bit CCP1IF, following any such

change in Operating mode.

15.1.4 CCP PRESCALER

There are four prescaler settings, specified by bits

CCP1M<3:0>. Whenever the CCP module is turned

off, or the CCP module is not in Capture mode, the

prescaler counter is cleared. Any Reset will clear the

prescaler counter.

Switching from one capture prescaler to another may

generate an interrupt. Also, the prescaler counter will

not be cleare d, therefore , the first cap ture may be from

a non-zero prescaler. Example 15-1 shows the recom-

mended method for switching between capture pre-

scalers . This example also clears the prescaler co unter

and will not generate the “false” interrupt.

EXAMPLE 15-1: CHANGIN G BETWEEN

CAPTURE PRESCALERS

Note: If the RC5/T1CKI/CCP1/SEG10 pin is

configu red as an output, a wr ite to the port

can cause a cap ture cond itio n.

CCPR1H CCPR1L

TMR1H TMR1L

Set Flag bit CCP1IF

(PIR1<2>)

Capture

Enable

Qs CCP1CON<3:0>

RC5/T1CKI/

Prescaler

÷ 1, 4, 16

and

edge detect

CCP1/SEG10

CLRF CCP1CON ; Turn CCP module off

MOVLW NEW_CAPT_PS ; Load the W reg with

; the new prescaler

; move value and CCP ON

MOVWF CCP1CON ; Load CCP1CON with this

; value

PIC16F946

15.2 Compare Mode

In C ompare mo de, t he 16- bit CC PR1 re gist er va lue is

constantly compared against the TMR1 register pair

value. When a match occurs, the

RC5/T1C KI/ CCP1 /SEG 10 pin is:

• Driven high

•Driven low

• Remains unchanged

The action on the pin is based on the value of control

bits CCP1M<3:0> (CCP1CON<3:0>). At the same

time, interrupt flag bit CCP1IF is set.

FIGURE 15-4: COMPARE MODE

OPERATION BLOCK

DIAGRAM

15.2.1 CCP PIN CONFIGURATION

The user m ust configur e the RC5/T1CKI/CC P1/SEG10

pin as an output by clearing the TRISC<5> bit.

15.2.2 TIMER1 MODE SELECTION

Timer1 must be running in Timer mode, or Synchro-

nized Counter mode, if the CCP module is using the

compare feature. In Asynchronous Counter mode, the

compare operation may not work.

15.2.3 SOFTWARE INTERRUPT MODE

When Generate Soft ware Interrupt mode is chosen, the

RC5/T1CKI/CCP1/SEG10 pin is not affected. The

CCPIF bit is set, causing a CCP interrupt (if enabled).

15.2.4 SPECIAL EVENT TRIGGER

In this mod e, an internal hardw are trigger is generated,

which may be used to initiate an action.

The special event trigger output of CCP1 resets the

TMR1 regi ste r pai r. Thi s al lows the CCP R1 r egis ter to

ef fectively b e a 16-bit progra mmable pe riod registe r for

Timer1.

The special event trigger output of CCP2 resets the

TMR1 regis ter pai r and starts an A/D co nv ersi on (if th e

A/D module is enabled).

15.3 PWM Mode (PWM)

In Pulse-Width Modulation mode, the CCPx pin pro-

duces up to a 10-bit resolution PWM output. Since the

RC5/T1CKI/CCP1/SEG10 pin is multiplexed with the

PORTC data latch, the TRISC<5> bit must be cleared

to make the RC5/T1CKI/CCP1/SEG10 pin an output.

Figure 15-5 shows a simplified block diagram of the

CCP module in PWM mode.

For a ste p-by-step proc edure on how to set up the CCP

module for PWM operation, see Section 15.3.3

“Setup for PWM Operation”.

Note: Clearing the CCP1CON register will force

the RC5/T1CKI/CCP1/SEG10 compare

output la tch to the de fault low lev el. This is

not the PORTC I/O data latch.

CCPR1H CCPR1L

TMR1H TMR1L

Comparator

ROutput

Logic

Special Event Trigger

Set Flag bit CCP1IF

(PIR1<2>)

Match

RC5/T1CKI/

TRISC<5> CCP1CON<3:0>

Mode Select

Output Enab le

Special event trigger will:

reset Timer1, but not set interrupt flag bit TMR1IF (PIR1<0>),

and set bit GO/DONE (ADCON0<2>).

CCP1/SEG10

Note: The special event trigger from the

CCP1and CCP2 modules will not set inter-

rupt flag bit TMR1IF (PIR1<0>).

Note: Clearing the CCP1CON register will force

the CCP1 PWM ou tput latch to th e de fault

low level. This is not the PORTC I/O data

latch.

PIC16F946

FIGURE 15-5: SIMPLIFIED PWM BLOCK

DIAGRAM

A PWM output (Figure 15-6) has a time base (period)

and a time that the output stays high (duty cycle). The

frequency of the PWM is the inverse of the period

(1/period).

FIGURE 15-6: PWM OUTP UT

15.3.1 PWM PERIOD

The PWM period is specified by writing to the PR2

following formula:

PWM frequency is defined as 1/[PWM period].

When TM R2 is equal to PR2, t he following three event s

occur on the next increment cycle:

•TMR2 is cleared

• The RC5/T1CKI/CCP1/SEG10 pin is set

(exception: if PWM duty cycle = 0%, the

RC5/T1CKI/CCP1/SEG10 pin will not be set)

• The PWM duty cycle is latched from C CPR1L into

CCPR1H

15.3.2 PWM DUTY CYCLE

The PWM duty cycle is specified by writing to the

CCPR1L register and to the CCP1CON<5:4> bits. Up

to 10- b i t re so l uti on is av ai l ab le. T he CC PR 1 L c ontai ns

the eight MSbs and the CCP1CON<5:4> contains the

two LSbs. This 10-bit value is represented by

CCPR1L:CCP1CON<5:4>. The following equation is

used to calculate the PWM duty cycle in time:

CCPR1L and CCP1CON<5:4> can be written to at any

time, but the duty cycle value is not latched into

CCPR1H until after a match between PR2 and TMR2

occurs (i.e., the period is complete). In PWM mode,

CCPR1H is a read-only register.

The CCPR1H register and a 2-bit internal latch are

used to dou ble buf fer th e PWM duty cycle. Thi s doubl e

buffering is essential for glitch-free PWM operation.

When t he CCP R1H an d 2-bit latch match T MR2, con-

catenate d with an in terna l 2-b it Q clo ck , or 2 bits of the

TMR2 pres caler, the CCP1 pin is cleared.

The maximum PWM resolution (bits) for a given PWM

frequency is given by the formula:

CCPR1L

CCPR1H (Slave)

Comparator

TMR2

Comparator

PR2

(1)

Duty Cycle Registers CCP1CON<5:4>

Clear Time r,

CCP1 pin and

latch D.C.

TRISC<5>

RC5/T1CKI/

Note 1: The 8-b it timer is conc atenate d with 2-bit internal Q

clock, or 2 bits of the pr esca ler, to create 10-bit time

base.

CCP1/SEG1

Period

Duty Cycle

TMR2 = PR2

TMR2 = Duty Cycle

TMR2 = PR 2

PWM period = (PR2) + 1] • 4 • TOSC •

(TMR2 prescale value)

Note: The Timer2 postscaler (see Section 7.0

“Timer2 Module”) is not used in the

determination of the PWM frequency. The

postscaler could be used to have a servo

update rate at a different frequency than

the PWM output.

Note: If the PWM d uty c ycle v alu e i s lon ger tha n

the PWM period, the

RC5/T1CKI/CCP1/SEG10 pin will not be

cleared.

PWM duty cycle =(CCPR1L:CCP1CON<5:4>) •

TOSC • (TMR 2 prescale value)

PWM Resolution

FOSC

FPWM TMR2 Prescaler×

-------------------------------------------------------------

⎝⎠

⎛⎞

log

2()log

--------------------------------------------------------------------------- bits=

PIC16F946

15.3.3 SETUP FOR PWM OPERA TIO N

The following steps should be taken when configuring

the CCP module for PWM operation:

1. Set the PWM period by writing to the PR2

2. Set the PWM duty cycle by writing to the

CCPR1L register and CCP1CON<5:4> bits.

3. Make the RC5/T1CKI/CCP1/SEG10 pin an

output by clearing the TRISC<5> bi t.

4. Set the TMR2 prescale value and enable T imer2

by writing to T2CON.

5. Configure the CCP1 module for PWM o peration.

TABLE 15-1: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 20 MHz

TABLE 15-2: REGISTERS ASSOCIATED WITH CAPTURE, COMPARE AND T IMER1

PWM Frequency 1.22 kHz 4.88 kHz 19.53 kHz 78.12kHz 156.3 kHz 208.3 kHz

Timer Prescaler (1, 4, 16) 16 4 1 1 1 1

PR2 Value 0xFFh 0xFFh 0xFFh 0x3Fh 0x1Fh 0x17h

Maximum Resolution (bits) 10 10 10 8 7 5.5

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR,

BOR

Valu e on

all other

Resets

0Bh,8Bh,

10Bh, 18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF — CCP2IF 0000 -0-0 0000 -0-0

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE — CCP2IE 0000 -0-0 0000 -0-0

87h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111

0Eh TMR1L Holding Register for the Least Signi fic ant Byt e of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

0Fh TMR1H Holding Regist er for the Most Sign ificant Byte of t he 16-bit TMR1 Re gister xxxx xxxx uuuu uuuu

10h T1CON T1GINV T1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

15h CCPR1L Capture/Compare/ PWM Registe r1 (LSB) xxxx xxxx uuuu uuuu

16h CCPR1H Capture/Comp are/PWM Regis ter1 (MSB) xxxx xxxx uuuu uuuu

17h CCP1CON — — CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000

1Bh CCPR2L Capture/Compare/PWM Register 2 (LSB) xxxx xxxx uuuu uuuu

1Ch CCPR2H Capture/Compare/PWM Register 2 (MSB) xxxx xxxx uuuu uuuu

1Dh CCP2CON — — CCP2X CCP2Y CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000

Legend: x = unknown, u = unchanged, – = unimplemen ted, read as ‘0’. Shad e d c e l ls ar e no t used by C a pture an d Timer 1 .

PIC16F946

TABLE 15-3: REGISTERS ASSOCIATED WITH PWM AND TIMER2

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR,

BOR

Value on

all oth er

Resets

0Bh,8Bh,

10Bh, 18Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF —CCP2IF0000 -0-0 0000 -0-0

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE —CCP2IE0000 -0-0 0000 -0-0

87h TRISC PORTC Data Direction Register 1111 1111 1111 1111

11h TMR2 Timer2 Module Register 0000 0000 0000 0000

92h PR2 Timer2 Module Period Register 1111 1111 1111 1111

12h T2CON — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000

15h CCPR1L Capture/Compare/PWM Register 1 (LSB) xxxx xxxx uuuu uuuu

16h CCPR1H Capture/Compare/PWM Register 1 (MSB) xxxx xxxx uuuu uuuu

17h CCP1CON —— CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000

1Bh CCPR2L Capture/Compare/PWM Register 2 (LSB) xxxx xxxx uuuu uuuu

1Ch CCPR2H Capture/Compare/PWM Register 2 (MSB) xxxx xxxx uuuu uuuu

1Dh CCP2CON —— CCP2X CCP2Y CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000

Legend: x = unknown, u = unchanged, – = unimplemen ted, read as ‘ 0’. Shaded c e l ls ar e no t used by PW M an d Timer2.

PIC16F946

NOTES:

PIC16F946

16.0 SPECIAL FEATURES OF THE

CPU

The PIC16F946 has a host of features intended to

maximize system reliability, minimize cost through

elimination of external components, provide power

saving features and offer code protection.

These features are:

• Reset

- Power-on Reset (POR)

- Power-up Timer (PWRT)

- Oscillator Start-up Ti mer (OST)

- Brown-out Reset (BOR)

• Interrupts

• Watchdog Timer (WDT)

• Oscillator Selection

• Sleep

• Code Protection

• ID Locations

• In-Circuit Serial Programming™

The PIC16F946 has two timers that offer necessary

delays on power-up. One is the Oscillator Start-up

Timer (O ST), intende d to keep t he chi p in Res et un til

the crystal oscillator is stable. The other is the

Power-up T imer (PWRT), which provides a fixed delay

of 64 ms (nominal) on power-up only, designed to

keep the part in Reset while the power supply

stabilizes. There is als o circu itry to re set the devi ce if

a brown-out occurs, which can use the Power-up

Timer to provide at least a 64 ms Reset. With these

three functions-on-chip, most applications need no

external Reset circuitry.

The Sleep mode is des igned to of fer a very l ow-c urrent

Power-down mode. The user can wake-up from Sleep

through:

•External Reset

• Watchdog Timer Wake-up

• An interrupt

Several oscillator options are also made available to

allow the p art to f it th e a ppl ic ati on. The INT OSC op tio n

saves system cost, while the LP crystal option saves

power. A set of configuration bits are used to select

various option s (see Register 16-1).

PIC16F946

16.1 Configuration Bits

The configuration bits can be programmed (read as

‘0’), or left unpro grammed (r ead as ‘1’) to select various

device configurations as shown in Register 16-1.

These bits are mapped in program memory location

2007h.

Note: Address 2007h is beyond the user

program memory space. It belongs to the

special configuration memory space

(2000h-3FFFh), which can be accessed

only during programming. See

“PIC16F91X/946 Memory Programming

Specification” (DS41244) for more

information.

—DEBUGFCMEN IESO BOREN1 BOREN0 CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0

bit 13 bit 0

bit 13 Unimplemented: Read as ‘1’

bit 12 DEBUG: In-Circuit Debugger Mode bit

1 = In-Circuit Debugger disabled, RB6/ICSPCLK/ICDCK/SEG14 and RB7/ICSPDAT/ICDDAT/SEG13 are general purpose I/O pins

0 = In-Circuit Debugger enabled, RB6/ICSPCLK/ICDCK/SEG14 and RB7/ICSPDAT/ICDDAT/SEG13 are dedicated to the debugger

bit 11 FCMEN: Fail-Safe Clock Monitor Enabled bit

1 = Fail-Safe Clock Monitor is enabled

0 = Fail-Safe Clock Monitor is disabled

bit 10 IESO: Internal External Switchover bit

1 = Internal External Switchover mode is enabled

0 = Internal External Switchover mode is disabled

bit 9-8 BOREN<1:0>: Brown-out Reset Selection bits(1)

11 = BOR enabled

10 = BOR enabled during operation and disabled in Sleep

01 = BOR controlled by SBOREN bit (PCON<4>)

00 = BOR disabled

bit 7 CPD: Data Code Protection bit(2)

1 = Data memory code protection is disabled

0 = Data memory code protection is enabled

bit 6 CP: Code Protection bit(3)

1 = Program memory code protection is disabled

0 = Program memory code protection is enabled

bit 5 MCLRE: RB3/MCLR/VPP pin function select bit(4)

1 = RB3/MC LR/VPP pin function is MCLR

0 = RB3/MC LR/VPP pin function is digital input, MCLR internally tied to VDD

bit 4 PWRTE: Power-up Timer Enabl e bit

1 = PWRT disabled

0 = PWRT enabled

bit 3 WDTE: Watchdog Timer En able bit

1 = WDT enabled

0 = WDT disabled and can be enabled by SWDTEN bit (WDTCON<0>)

bit 2-0 FOSC<2:0>: Oscillator Selection bits

111 = RC oscillator: CLKO function on RA6/OSC2/CLKO/T1OSO pin, RC on RA7/OSC1/CLKI/T1OSI

110 = RCIO oscillator: I/O function on RA6/OSC2/CLKO/T1OSO pin, RC on RA7/OSC1/CLKI/T1OSI

101 = INTOSC oscillator: CLKO function on RA6/OSC2/CLKO/T1OSO pin, I/O function on RA7/OSC1/CLKI/T1OSI

100 = INTOSCIO oscillator: I/O function on RA6/OSC2/CLKO /T1OS O pin, I/O func tion on RA 7 /OSC1/CLK I/T1OSI

011 = EC: I/O function on RA6/OSC2/CLKO/T1OSO pin, CLKI on RA7/OSC1/CLKI/T1OSI

010 = HS oscillator: High-speed crystal/resonator on RA6/OSC2/CLKO/T1OSO and RA7/OSC1/CLKI/T1OSI

001 = XT oscillator: Crystal/resonator on RA6/OSC2/CLKO/T1OSO and RA7/OSC1/CLKI/T1OSI

000 = LP oscillator: Low-power crystal on RA6/OSC2/CLKO/T1OSO and RA7/OSC1/CLKI/T1OSI

Note 1: Enabling Brown-out Reset does not automatically enable Power-up Timer.

2: The entire data EEPROM will be erased when the code protection is turned off.

3: The entire program memory will be erased when the code protection is turned off.

4: When MCLR is asserted in INTOSC or RC mode, the internal clock oscillator is disabled.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC16F946

16.2 Reset

The PIC1 6F946 diffe rentiates betw een various ki nds of

Reset:

a) P ower-on Reset (PO R)

b) WDT Reset during normal operation

c) WDT Reset during Sleep

d) MCLR Reset during normal operation

e) MCLR Reset during Sleep

f) Brown-out Reset (BOR)

Some regi sters a re not af fected in any Rese t conditio n;

their st at us is un kn ow n o n PO R and un ch anged in an y

other Reset. Most other registers are reset to a “Reset

state” on:

• Power-on Reset

•MCLR

Reset

•MCLR Reset during Sleep

•WDT Reset

• Brown-out Reset (BOR)

They are not affected by a WDT wake-up since this is

viewed as the resump tio n of no rm al op eration. T O an d

PD bits are set or cleared differently in different Reset

situations, as indicated in Table 16-2. These bits are

used in software to determine the nature of the Reset.

See Table 16-5 for a full description of Reset states of

all registers.

A simplif ied block diagra m of the On-Chip Rese t Circu it

is sh own in Figure 16-1 .

The MCLR Reset path has a noise filter to detect and

ignore small pulses. See Section 19.0 “Electrical

Specifications” for pulse width specifications.

FIGURE 16-1: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT

External

Reset

MCLR/VPP pin

VDD

OSC1/

WDT

Module

VDD Rise

Detect

OST/PWRT

LFINTOSC

WDT

Time-out

Power-on Reset

OST

10-bit Ripple Counter

PWRT

Chip_Reset

11-bit Ripple Counter

Reset

Enable OST

Enable PWRT

SLEEP

Brown-out(1)

Reset SBOREN

BOREN

CLKI pin

Note 1: Refer to the Configuration Word register (Register 16-1).

PIC16F946

16.3 Power-on Reset

The on-chip POR circuit holds the chip in Reset until

VDD has reached a high enough level for proper

operation. To take advantage of the POR, simply

connect the MCLR pin through a resistor to VDD. This

will eliminate external RC components usually needed

to create Power-on Reset. A maximum rise time for

VDD is required . See Section 19.0 “Electrica l Specifi-

cations” for details. If the BOR is enabled, the maxi-

mum rise time specification does not apply. The BOR

circuit ry will keep th e device in Reset u ntil VDD reache s

VBOR (see Section 16.3.3 “Brown-Out Reset

(BOR)”).

When the device starts normal operation (exits the

Reset condition), device operating parameters (i.e.,

voltage, frequency, temperature, etc.) must be met to

ensure operation. If these conditions are not met, the

device must be held in Reset until the operating

conditions are met.

For additional information, refer to Application Note

AN607, “Power-up Trouble Shooting” (DS00607).

16.3.1 MCLR

PIC16F946 has a noise filter in the MCLR Reset path.

The filter will de tect and ignore small pu lses .

It should be noted that a WDT Reset does not drive

MCLR pin low.

The behavior of the ESD protection on the MCLR pin

has been altered from early devices of this family.

Volta ges app lied to the pin th at exce ed it s spe cific ation

can resu lt in both MC L R Rese t s a nd e xc es sive c urrent

bey ond t h e de v ic e sp e ci fic at i on du ri ng th e ESD ev e nt .

For this rea son, Microc hip recomme nds that the MC LR

pin no long er be tied direc tly to VDD. The us e of an RC

network, as sh own in Figure 16-2, is suggested.

An internal MCLR option is enabled by clearing the

MCLRE bit in the Configuration Word register. When

clear e d, MC LR is internally tied to VDD and an internal

weak pull-up is enabled for the MCLR pin. In-Circuit

Serial Programming is not affected by selecting the

internal MCLR option.

FIGURE 16-2: RECOMMENDED MCLR

CIRCUIT

16.3.2 POWER-UP TIMER (PWRT)

The Power-up Timer provides a fixed 64 ms (nominal)

time-out on power-up only, from POR or Brown-out

Reset. The Power-up Timer operates from the 31 kHz

LFINTOSC oscillator. For more information, see

Section 4.4 “Inter nal Clock Mo des”. Th e chip is kept

in Reset as long as PWRT is active. The PWRT delay

allows the VDD to rise to an acceptable level. A config-

uration bit, PWRTE, can disable (if set) or enable (if

cleared or programmed) the Power-up Timer. The

Power-up Timer should be enabled when Brown-out

Reset is enabled, although it is not required.

The Power-up Timer delay will vary from chip-to-chip

and vary due to:

•V

DD variation

• Temperature variation

• Process variation

See DC parameters for details (Section 19.0

“Electrical Specifications”).

Note: The POR circuit does not produce an

internal Reset when VDD declines. To

re-enable the POR, VDD must reach Vss

for a minimum of 100 μs.

VDD PIC16F946

MCLR

1kΩ (or greater)

0.1 μF

(optional, not critical)

PIC16F946

16.3.3 BROWN-OUT RESET (BOR)

The BOREN0 and BOREN1 bits in the Configuration

Word register selects one of four BOR modes. Two

modes have been added to a llow softw are or hardwa re

control of the BOR enable. When BOREN<1:0> = 01,

the SBOREN bit (PCON<4>) enables/disables the

BOR allowing it to be controlled in software. By select-

ing BORE N<1:0>, the BO R is automa tically disabled in

Sleep to conserve power and enabled on wake-up. In

this mode, the SBOREN bit is disabled. See

If VDD falls below VBOR for greater than parameter

(TBOR) (see Section 19.0 “Electrical Specifica-

tions”), the Brown-out situation will reset the device.

This will occur regardless of VDD slew rate. A Reset is

not insured to occur if VDD falls below VBOR for less

than para me ter (T BOR).

On any Res et (Power-on , Brow n-out, Watchdog T i mer,

etc.), the chip will r emain in Re set until VDD rises ab ove

VBOR (see F igur e 16- 3). Th e Powe r-up Ti mer wi ll now

be invoked, if enabled and will keep the chip in Reset

an additional 64 ms.

If VDD drops below VBOR while the Power-up Timer is

running, the chip will go back into a Brown-out Reset

and the Power-u p Timer will be re-initialized. Onc e VDD

rises above VBOR, the Power-up Timer will execute a

64 ms Reset.

FIGURE 16-3: BROWN-OUT SITUATIONS

Note: The Power-up Timer is enabled by the

PWRTE bit in the Configuration Word.

64 ms(1)

VBOR

VDD

Internal

Reset

VBOR

VDD

Internal

Reset 64 ms(1)

< 64 ms

64 ms(1)

VBOR

VDD

Internal

Reset

Note 1: 64 ms delay only if PWRTE bit is programmed to ‘0’.

PIC16F946
DS41265A-page 196 Preliminary © 2005 Microchip Technology Inc.
16.3.4 TIME-OUT SEQUENCE
On power- up, the t ime-out sequ ence is a s follows:  first,
PWR T time- out is invo ked aft er POR has  expire d, then
OST is ac tiv ate d aft er the  PWRT time -out has exp ire d.
The tot a l time -ou t wil l vary bas ed on os ci llator config u-
ration and  PWRTE bit stat us. For exampl e, in EC mode
with PWRT E bit erased  (PWR T di sa ble d), there will  be
no time-out at all. Figure 16-4, Figure 16-5 and Figure
16-6 depict time-out sequences. The device can exe-
cute code from the INTOSC while OST is active, by
enablin g Two-Spee d Start-up o r Fail-Safe  Monit or (se e
Section 4.6.2 “Two-Speed Start-up Sequence” and
Section 4.7 “Fail-Safe Clock Monitor”).
Since the  time-outs oc cur from the POR  pulse, if MCLR
is kept low lon g enough, the time-out s will expire. Then,
bringing MCLR high will begin execution immediately
(see Figure 16-5). This is useful for testing purposes or
to synchronize more than one PIC16F946 device
operating in parallel.
Table 16-5 shows the Reset conditions for some
special registers, while Table 16-5 shows the Reset
conditions for all the registers. 
16.3.5 POWER CONTROL (PCON) 
REGISTER 
The Power C ontro l (PCON) re gister  (address  8Eh) ha s
two Status bits to indicate what type of Reset that last
occurred.
Bit 0 is BOR (Brown-out Reset). BOR is unknown on
Power-on Reset. It must then be set by the user and
checked on subsequent Resets to see if BOR = 0,
indicating that a Brown-out has occurred. The BOR
Status bit is a “don’t care” and is not necessarily
predictable if the brown-out circuit is disabled
(BOREN<1:0>  = 00 in the Configuration Word regis ter).
Bit 1 is POR (Power-on Reset). It is a ‘0’ on Power-on
Reset  and unaf fec ted oth erwise. T he user m ust write  a
‘1’ to this bit following a Power-on Reset. On a
subsequent Reset, if POR is ‘0’, it will indicate that a
Power-on Reset has occurred (i.e., VDD may have
gone too low).
For more inf ormation, see Section 16.3.3 “ Brown-Out
Reset (BOR)”.
TABLE 16-1: TIME-OUT IN VARIOUS SITUATIONS
TABLE 16-2: PCON BITS AND THEIR SIGNIFICANCE
TABLE 16-3: SUMMARY OF REGISTERS ASSOCIATED WITH BROWN-OUT
Oscillator Configuration Power-up Brown-out Reset Wake-up from 
Sleep
PWRTE = 0PWRTE = 1PWRTE = 0PWRTE = 1
XT, HS, LP(1) TPWRT + 1 024 • 
TOSC 1024 • TOSC TPWRT + 1024  • 
TOSC 1024 • TOSC 1024 • TOSC
RC, EC, INTOSC TPWRT —TPWRT ——
Note 1: LP mode with T1O SC  disa ble d.
POR BOR TO PD Condition
0u11Power-on Reset
1011Brown-out Reset
uu0uWDT Reset
uu00WDT Wake -up
uuuuMCLR Reset during normal operation
uu10MCLR Reset during Sleep
Legend: u = unchanged, x = unknown
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2  Bit 1 Bit 0 Valu e on 
POR, BOR
Value on 
all other 
Resets(1)
03h STATUS IRP RP1 RPO TO PD ZDC C0001 1xxx 000q quuu
8Eh PCON — — — SBOREN ——PORBOR --01 --qq --0u --uu
Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition. Shaded cells are 
not used by BOR.
Note 1: Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.

PIC16F946

FIGURE 16-4: TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 1

FIGURE 16-5: TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 2

FIGURE 16-6: TIME-OUT SEQUENCE ON POWER-UP (MCLR WITH VDD): CASE 3

TPWRT

TOST

VDD

MCLR

Internal POR

PWRT T ime-out

OST Time-out

Internal Reset

VDD

MCLR

Internal POR

PWRT Time-out

OST Time-out

Internal Reset

TPWRT

TOST

TPWRT

TOST

VDD

MCLR

Internal POR

PWRT Time-out

OST Time-out

Internal Reset

PIC16F946

TABLE 16-4: INITIALIZATION CONDITION FOR REGISTERS

Reset

•MCLR

Reset

• WDT Reset

• Brown-out Reset(1)

• Wake-up from Sleep

through interrupt

• Wake-up from Sleep

through WDT time-out

W—xxxx xxxx uuuu uuuu uuuu uuuu

INDF 00h/80h/

100h/180h xxxx xxxx xxxx xxxx uuuu uuuu

TMR0 01h/101h xxxx xxxx uuuu uuuu uuuu uuuu

PCL 02h/82h/

102h/182h 0000 0000 0000 0000 PC + 1(3)

STATUS 03h/83h/

103h/183h 0001 1xxx 000q quuu(4) uuuq quuu(4)

FSR 04h/84h/

104h/184h xxxx xxxx uuuu uuuu uuuu uuuu

PORTA 05h xxxx xxxx 0000 0000 uuuu uuuu

PORTB 06h/106h xxxx xxxx 0000 0000 uuuu uuuu

PORTC 07h xxxx xxxx 0000 0000 uuuu uuuu

PORTD 08h xxxx xxxx 0000 0000 uuuu uuuu

PORTE 09h xxxx xxxx 0000 0000 uuuu uuuu

PCLATH 0Ah/8Ah/

10Ah/18Ah ---0 0000 ---0 0000 ---u uuuu

INTCON 0Bh/8Bh/

10Bh/18Bh 0000 000x 0000 000x uuuu uuuu(2)

PIR1 0Ch 0000 0000 0000 0000 uuuu uuuu(2)

PIR2 0Dh 0000 -0-0 0000 -0-0 uuuu -u-u

TMR1L 0Eh xxxx xxxx uuuu uuuu uuuu uuuu

TMR1H 0Fh xxxx xxxx uuuu uuuu uuuu uuuu

T1CON 10h 0000 0000 uuuu uuuu uuuu uuuu

TMR2 11h 01-0 0-00 01-0 0-00 uu-u u-uu

T2CON 12h -000 0000 -000 0000 -uuu uuuu

SSPBUF 13h xxxx xxxx xxxx xxxx uuuu uuuu

SSPCON 14h 0000 0000 0000 0000 uuuu uuuu

CCPR1L 15h 0000 0000 0000 0000 uuuu uuuu

CCPR1H 16h 0000 0010 0000 0010 uuuu uuuu

CCP1CON 17h 000x 000x 000x 000x uuuu uuuu

RCSTA 18h ---0 1000 ---0 1000 ---u uuuu

TXREG 19h 0000 0000 0000 0000 uuuu uuuu

RCREG 1Ah 0000 0000 0000 0000 uuuu uuuu

CCP2CON 1Dh --00 0000 --00 0000 --uu uuuu

ADRESH 1Eh xxxx xxxx uuuu uuuu uuuu uuuu

Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition.

Note 1: If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.

2: One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).

3: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt

vector (0004h).

4: See Table 16-5 for Reset value for specific condition.

5: If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.

PIC16F946

ADCON0 1Fh 0000 0000 0000 0000 uuuu uuuu

OPTION_REG 81h/181h 1111 1111 1111 1111 uuuu uuuu

TRISA 85h 1111 1111 1111 1111 uuuu uuuu

TRISB 86h/186h 1111 1111 1111 1111 uuuu uuuu

TRISC 87h 1111 1111 1111 1111 uuuu uuuu

TRISD 88h 1111 1111 1111 1111 uuuu uuuu

TRISE 89h 1111 1111 1111 1111 uuuu uuuu

PIE1 8Ch 0000 0000 0000 0000 uuuu uuuu

PIE2 8Dh 0000 0000 0000 0000 uuuu uuuu

PCON 8Eh --01 --0x --0u --uu(1,5) --uu --uu

OSCCON 8Fh -110 q000 -110 x000 -uuu uuuu

OSCTUNE 90h ---0 0000 ---u uuuu ---u uuuu

ANSEL 91h 1111 1111 1111 1111 uuuu uuuu

PR2 92h 1111 1111 1111 1111 1111 1111

SSPADD 93h 0000 0000 0000 0000 uuuu uuuu

SSPSTAT 94h 0000 0000 0000 0000 uuuu uuuu

WPUB 95h 1111 1111 1111 1111 uuuu uuuu

IOCB 96h 0000 ---- 0000 ---- uuuu ----

CMCON1 97h ---- --10 ---- --10 ---- --uu

TXSTA 98h 0000 -010 0000 -010 uuuu -uuu

SPBRG 99h 0000 0000 0000 0000 uuuu uuuu

CMCON0 9Ch 0000 0000 0000 0000 uuuu uuuu

VRCON 9Dh 0-0- 0000 0-0- 0000 u-u- uuuu

ADRESL 9Eh xxxx xxxx uuuu uuuu uuuu uuuu

ADCON1 9Fh -000 ---- -000 ---- -uuu ----

WDTCON 105h ---0 1000 ---0 1000 ---u uuuu

LCDCON 107h 0001 0011 0001 0011 uuuu uuuu

LCDPS 108h 0000 0000 0000 0000 uuuu uuuu

LVDCON 109h --00 -100 --00 -100 --uu -uuu

EEDATL 10Ch 0000 0000 0000 0000 uuuu uuuu

EEADRL 10Dh 0000 0000 0000 0000 uuuu uuuu

EEDATH 10Eh --00 0000 0000 0000 uuuu uuuu

EEADRH 10Fh ---0 0000 0000 0000 uuuu uuuu

LCDDATA0 110h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA1 111h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA2 112h xxxx xxxx uuuu uuuu uuuu uuuu

TABLE 16-4: INITIALIZATION CONDITION FOR REGISTERS (CONTINUED)

Reset

•MCLR

Reset

• WDT Reset

• Brown-out Reset(1)

• Wake-up from Sleep

through interrupt

• Wake-up from Sleep

through WDT time-out

Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition.

Note 1: If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.

2: One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).

3: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt

vector (0004h).

4: See Table 16-5 for Reset value for specific condition.

5: If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.

PIC16F946

LCDDATA3 113h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA4 114h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA5 115h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA6 116h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA7 117h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA8 118h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA9 119h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA10 11Ah xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA11 11Bh xxxx xxxx uuuu uuuu uuuu uuuu

LCDSE0 11Ch 0000 0000 uuuu uuuu uuuu uuuu

LCDSE1 11Dh 0000 0000 uuuu uuuu uuuu uuuu

LCDSE2 11Eh 0000 0000 uuuu uuuu uuuu uuuu

TRISF 185h 1111 1111 1111 1111 uuuu uuuu

TRISG 187h --11 1111 --11 1111 --uu uuuu

PORTF 188h xxxx xxxx 0000 0000 uuuu uuuu

PORTG 189h --xx xxxx --00 0000 --uu uuuu

LCDDATA12 190h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA13 191h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA14 192h ---- --xx ---- --uu ---- --uu

LCDDATA15 193h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA16 194h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA17 195h ---- --xx ---- --uu ---- --uu

LCDDATA18 196h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA19 197h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA20 198h ---- --xx ---- --uu ---- --uu

LCDDATA21 199h xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA22 19Ah xxxx xxxx uuuu uuuu uuuu uuuu

LCDDATA23 19Bh ---- --xx ---- --uu ---- --uu

LCDSE3 19Ch 0000 0000 uuuu uuuu uuuu uuuu

LCDSE4 19Dh 0000 0000 uuuu uuuu uuuu uuuu

LCDSE5 19Eh ---- --00 ---- --uu ---- --uu

EECON1 18Ch x--- x000 u--- q000 u--- uuuu

TABLE 16-4: INITIALIZATION CONDITION FOR REGISTERS (CONTINUED)

Reset

•MCLR

Reset

• WDT Reset

• Brown-out Reset(1)

• Wake-up from Sleep

through interrupt

• Wake-up from Sleep

through WDT time-out

Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition.

Note 1: If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.

2: One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).

3: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt

vector (0004h).

4: See Table 16-5 for Reset value for specific condition.

5: If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u.

PIC16F946

TABLE 16-5: INITIALIZATION CONDITION FOR SPECIAL REGISTERS

Condition Program

Counter Status

Power-on Reset 000h 0001 1xxx --01 --0x

MCLR Reset during normal operation 000h 000u uuuu --0u --uu

MCLR Reset during Sleep 000h 0001 0uuu --0u --uu

WDT R eset 000h 0000 uuuu --0u --uu

WDT Wake-up PC + 1 uuu0 0uuu --uu --uu

Brown-out Reset 000h 0001 1uuu --01 --10

Interrupt Wake-up from Sleep PC + 1(1) uuu1 0uuu --uu --uu

Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’.

Note 1: When the w ake-up is due to an in terrupt an d Glob al Interru pt Enable bit, GIE, is se t, the PC is lo aded w ith

the interrupt vector (0004h) after execution of PC + 1.

PIC16F946

16.4 Interrupts

The PIC16F946 has multiple sources of interrupt:

• External Inte rrup t RB0/INT/SEG0

• TMR0 Overfl ow Interru pt

• PORTB Change Interrupts

• 2 Comparator Interrupts

• A/D Interrupt

• Timer1 Overflow Interrupt

• EEPROM Data Write Interrupt

• Fail-Safe Clock Monitor Interrupt

• LCD Interrupt

• PLVD Interrupt

• USART Receive and Transmit Interrupts

• CCP1 and CCP2 Interrupts

• TMR2 Interrupt

The Interrup t Control (INTCON) register and Peripheral

Interrupt Request 1 (PIR1) register record individual

interrupt requests in flag bits. The INTCON register

also has individual and global interrupt enable bits.

A Global Interrupt Enable bit, GIE (INTCON<7>),

enables (if set) all unmasked interrupts, or disables (if

cleared) all interrupts. Individual interrupts can be

disabled through their corresponding enable bits in the

INTCON register and PIE1 register. GIE is cleared on

Reset.

The Return from Interrupt instruction, RETFIE, exits

the interrupt routine, as well as sets the GIE bit, which

re-enabl es unm as ke d inte rrupts.

The following interrupt flags are contained in the

INTCON register:

• INT Pin Interrupt

• PORTB Change Interrupt

• TMR0 Overfl ow Interru pt

The peripheral interrupt flags are contained in the special

registers, PIR1 and PIR2. The corresponding interrupt

enable bit are contained in the special registers, PIE1

and PIE2.

The following interrupt flags are contained in the PIR1

• EEPROM Data Write Interrupt

• A/D Interrupt

• USART Receive and Transmit Interrupts

• Timer1 Overflow Interrupt

• CCP1 Interrupt

• SSP Interrupt

The following interrupt flags are contained in the PIR2

• Fail- Safe Clock Monitor Interru pt

• Comparator 1 and 2 Interrupts

• LCD Interrupt

• PLVD Interrupt

• CCP2 Interrupt

When an interrupt is serviced:

• The GIE is c lea red t o di sa ble any fu rthe r int errup t.

• The return address is pushed onto the stack.

• The PC is loaded with 0004h.

For external interrupt events, such as the INT pin or

PORTB change interrupt, the interrupt latency will be

three or four instruction cycles. The exact latency

depends upon when the interrupt event occurs (see

Figure 16-8). The latency is the same for one or

two-cycle instructions. Once in the Interrupt Service

Routine, the source(s) of the interrupt can be

determined by polling the interrupt flag bits. The

interrupt flag bit(s) must be cleared in software before

re-enabling interrupts to avoid multiple interrupt

requests.

For additional information on Timer1, A/D or data

EEPROM modules, refer to the respective peripheral

section.

Note 1: Individual interrupt flag bits are set,

regardless of the status of their

corresponding mask bit or the GIE bit.

2: When an instruction that clears the GIE

bit is executed, any interrupts that were

pending for execution in the next cycle

are ignored. The interrupts, which were

ignored, are still pending to be serviced

when the GIE bit is set again.

Note: The ANSEL (91h) and CMCON0 (9Ch)

registers must be initialized to configure

an analog channel as a digital input. Pins

configured as analog inputs will read ‘0’.

Also, if a LCD output function is active on

an external interrupt pin, that interrupt

function will be disabled.

PIC16F946

16.4.1 RB0/INT/SEG0 INTERRUPT

External interrupt on RB0/INT/SEG0 pin is edge-trig-

gere d; eith er rising if the I NTEDG b it (OPTIO N<6>) is

set, or falling, if the INTEDG bit is clear. When a valid

edge appears on the RB0/INT/SEG0 pin, the INTF bit

(INTCON<1>) is set. This interrupt can be disabled by

clear ing th e INTE control bit (IN TCON<4> ). The I NTF

bit must be cleared in software in the Interrupt Service

Routine before re-enabling this interrupt. The

RB0/INT/SEG0 interrupt can wake-up the processor

from Sleep if the INTE bit was set prior to going into

Sleep. The st atus of the GIE b it dec ides wh ether or n ot

the proces sor branches to the inter rupt vector follow ing

wake-up (0004h). See Section 16.7 “Power-Down

Mode (Sleep)” for details on Sleep and Figure 16-10

for timing of wake-up from Sleep through

RB0/INT/SEG0 inte rrupt.

16.4.2 TMR0 INTERRUPT

An overflow (FFh → 00h) in the TMR0 register will set

the T0IF (INTCON<2>) bit. The interrupt can be

enabled/disabled by setting/clearing T0IE

(INTCON<5>) bit. See Section 5.0 “Timer0 Module”

for operation of the T im er0 mo dul e.

16.4.3 PORTB INTERRUPT

An input change on PORTB sets the RBIF

(INTCON<0>) bit. The interrupt can be

enabled/disabled by setting/clearing the RBIE

(INTCON<3>) bit. Plus, individual pins can be

configured through the IOCB register.

FIGURE 16-7: INTERRUPT LOGIC

Note: If a change on the I/O pin should occur

when the read operation is being executed

(start of the Q2 cycle), then the RBIF

interrupt flag may not get set.

TMR1IF

TMR1IE

C1IF

C1IE

TMR0IF

TMR0IE

INTF

INTE

RBIF

RBIE

GIE

PEIE

Wake-up (If in Sleep mode)

Inte rr u p t to CPU

PEIF

EEIE

EEIF

ADIF

ADIE

IOC-RB4

IOCB4

IOC-RB5

IOCB5

IOC-RB6

IOCB6

IOC-RB7

IOCB7

CCP2IF

CCP2IE

OSFIF

OSFIE

C2IF

C2IE

CCP1IF

CCP1IE

SSPIE

SSPIF

RCIF

RCIE

TXIF

TXIE

LCDIF

LCDIE

LVDIF

LVDIE

TMR2IF

TMR2IE

PIC16F946

FIGURE 16-8: INT PIN INTERRUPT TIMING

TABLE 16-6: SUMMARY OF INTERRUPT REGISTERS

Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on

POR, BOR

Value on

all other

Resets

0Bh,

8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000x

0Ch PIR1 EEIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

0Dh PIR2 OSFIF C2IF C1IF LCDIF —LVDIF — CCP2IF 0000 -0-0 0000 -0-0

8Ch PIE1 EEIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

8Dh PIE2 OSFIE C2IE C1IE LCDIE —LVDIE — CCP2IE 0000 -0-0 0000 -0-0

Legend: x = unknown, u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition.

Shaded cell s are not us ed by the inte rrup t modu le.

Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4

OSC1

CLKO(3)

INT p i n

INTF Fl a g

(INTCON<1>)

GIE bit

(INTCON<7>)

Instruction Flow

Instruction

Fetched

Instruction

Executed

Interrupt Latency

PC PC + 1 PC + 1 0004h 0005h

Inst (0004h) Inst (0005h)

Dummy Cycl e

Inst (PC) Inst (PC + 1)

Inst (PC - 1) Inst (0004h)

Dummy Cycl e

Inst ( PC)

—

Note 1: INTF flag is sampled here (every Q1).

2: Asynchronous interru pt latency = 3-4 TCY. Synchronous latency = 3 TCY, where TCY = instruction cycle time.

Latency is the same whether Inst (PC) is a single cycle or a two-cycle instruction.

3: CLKO is available only in INTOSC and RC Oscillator modes.

4: For minimum width of INT pulse, refer to AC specifications in Section 19.0 “Electrical Specifications”.

5: INTF is enabled to be set any time during the Q4-Q1 cycles.

(1) (2)

(4)

(5)

(1)

PIC16F946

16.5 Context Saving During Interrupts

During an interrupt, only the return PC value is saved

on the stack. Typically, users may wish to save key

registers during an interrupt (e.g., W and Status

registers). This must be implemented in software.

Since the lower 16 bytes of all banks are common in the

PIC16F946 (see Figure 2-2), temporary holding

registers, W_TEMP and STATUS_TEMP, should be

placed in here. These 16 locations do not require

banking and therefore, make it easier to context save

and restore. The same code shown in Example 16-1

can be used to:

• Store the W register

• Store the Status register

• Execute the ISR code

• Restore the Status (and Bank Select Bit register)

• Restore the W register

EXAMPLE 16-1: SAVING STATUS AND W REGISTERS IN RAM

Note: The PIC1 6F946 n ormal ly doe s not re quire

saving the PCLATH. However, if

computed GOTO’s are used in the ISR an d

the main code, the PCLATH must be

saved and restored in the ISR.

MOVWF W_TEMP ;Copy W to TEMP register

SWAPF STATUS,W ;Swap status to be saved into W

CLRF STATUS ;bank 0, regardless of current bank, Clears IRP,RP1,RP0

MOVWF STATUS_TEMP ;Save status to bank zero STATUS_TEMP register

:(ISR) ;Insert user code here

SWAPF STATUS_TEMP,W ;Swap STATUS_TEMP register into W

;(sets bank to original state)

MOVWF STATUS ;Move W into Status register

SWAPF W_TEMP,F ;Swap W_TEMP

SWAPF W_TEMP,W ;Swap W_TEMP into W

PIC16F946

16.6 Watchdog Timer (WDT)

For PIC16F946, the WDT has been modified from

previous PIC16F devices. The new WDT is code and

functionally compatible with previous PIC16F WDT

modul es a n d ad ds a 1 6 - bi t p r es ca l er to t he W D T. T h is

allow s the user to have a scaled value for the WDT and

TMR0 at the same time. In addition, the WDT time-out

value c an be extend ed to 268 se conds. WDT is cleared

under certain conditions described in Table 16-7.

16.6.1 WDT OSCILLAT OR

The WDT derives its time base from the 31 kHz

LFINTOSC. The LTS bit does not reflect that the

LFINTOSC is enabled.

The va lue of WDTCON is ‘---0 1000’ on all Resets.

This gives a nominal time base of 16 ms, which is

compatible with the time base generated with previous

PIC16F mic roc on trol ler ve rsi ons .

A new prescaler has been added to the path between

the INTOSC and the multiplexers used to select the

path for the WDT. This prescaler is 16 bits and can be

programmed to divide the INTOSC by 32 to 65536,

giving the WDT a nominal range of 1 ms to 268s.

16.6.2 WDT CONTROL

The WDTE bit is located in the Configuration Word

When the WDTE bi t in the Configuratio n Word re gister

is set, the S WDTEN bit (WDTC ON<0>) ha s no effect.

If WDTE is c le ar, then th e SWDTEN bi t ca n be us ed to

enable a nd disabl e the WD T. Setting the bit will enable

it and clearing the bit will disable it.

The PSA and PS<2:0> bits (OPTION_REG) have the

same function as in previous versions of the PIC16F

family of microcontrollers. See Section 5.0 “Timer0

Module” for more information.

FIGURE 16-9: WATCHDOG TIMER BLOCK DIAGRAM

Note: When the Oscillator Start-up Timer (OST)

is invoked, the WDT is held in Reset,

bec ause the WD T Ri pple C ounte r i s us ed

by the OST to perform the oscillator delay

count. When the OST count has expired,

the WDT will begin counting (if enabled).

TABLE 16-7: WDT STATUS

Conditions WDT

WDTE = 0

Cleared

CLRWDT Command

Oscillator Fail Detected

Exit Sleep + System Clock = T1OSC, EXTRC, INTOSC, EXTCLK

Exit Sleep + System Clock = XT, HS, LP Cleared until the end of OST

31 kHz

PSA

16-bit WDT Prescaler

From TMR0 Clock Source

Prescaler(1)

PS<2:0>

PSA

WDT Time-out

To TMR0

WDTPS<3:0>

WDTE from Configuration Word register

SWDTEN from WDTCON

LFINTOSC Clock

Note 1: This is the shared Timer0/WDT prescaler . See Section 5.4 “Prescaler” for more information.

PIC16F946

TABLE 16-8: SUMMARY OF WATCHDOG TIMER REGISTERS

U-0 U-0 U-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0

— — — WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4-1 WDTPS<3:0>: Watchdog Timer Period Select bits

Bit Value = Prescale Rate

0000 = 1:32

0001 = 1:64

0010 = 1:128

0011 = 1:256

0100 = 1:5 12 (Reset value)

0101 = 1:1024

0110 = 1:2048

0111 = 1:4096

1000 = 1:8192

1001 = 1:16384

1010 = 1:32768

1011 = 1:65536

1100 = reserved

1101 = reserved

1110 = reserved

1111 = reserved

bit 0 SWDTEN: Software Enable or Disable the Watchdog Timer bit(1)

1 = WDT is turned on

0 = WDT is turned off (Reset value)

Note 1: If WDTE configuration bit = 1, then WDT is always enabled, irrespective of this

control bit. If WDTE co nfigura tion bit = 0, th en i t is p os sible to turn W D T on/o f f wi th

this control bit.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

105h WDTCON — — — WDTPS3 WDTPS2 WSTPS1 WDTPS0 SWDTEN

81h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0

2007h(1) CONFIG CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0

Legend: Shaded cells are not used by the Watchdog Timer.

Note 1: See Register 16-1 for operation of all Configuration Word register bits.

PIC16F946

16.7 Power-Down Mode (Sleep)

The Power-down mode is entered by executing a

SLEEP instruction.

If the Watchdog Timer is enabled:

• WDT will be cleared but keeps running.

•PD

bit in the Status register is cleared.

•TO

bit is set.

• Oscillator driver is turned off.

• I/O ports maintain the status they had before

SLEEP was executed (driving high, low or

high-impedance).

For lowest current consumption in this mode, all I/O

pins should be either at VDD or VSS, with no external

circuitry drawing current from the I/O pin, and the

comparators and CVREF should be disabled. I/O pins

that are high-impedance inputs should be pulled high

or low ex ternally to av oid swit ch ing current s ca us ed b y

floating inputs. The T0CKI input should also be at VDD

or VSS for lowest current consumption. The

contribution from on-chip pull-ups on PORTB should be

considered.

The MCLR pin must be at a logic high level.

16.7.1 WAKE-UP FROM SLEE P

The devi ce can wake -up from Sleep through one of th e

following events:

1. External Reset input on MCLR pin.

2. Watchdog Timer wake-up (if WDT was

enabled).

3. Interrupt from RB0/INT/SEG0 pin, PORTB

change or a peripheral interrupt.

The firs t event wi ll cause a devic e Reset. The two latter

events are considered a continuation of program

execution. The TO and PD bits in the Status register

can be us ed to determi ne the ca us e of a device R ese t.

The PD bit, whic h is se t on p ower -up, is cl eare d wh en

Sleep is invoked. TO bit is cleared if WDT wake-up

occurred.

The follo wing periphe ral interrupt s can wake the device

from Sleep:

1. TMR1 Interru pt. Timer1 must be operatin g as an

asynchronous counter.

2. EUSART Receive Interrupt

3. A/D conversion (when A/D clock source is RC)

4. EEPROM write operation completion

5. Comparator output changes state

6. Interrupt-on-change

7. External Interrupt from INT pin

8. PLVD Interrupt

9. LCD Interrupt (if running during Sleep)

Other peripherals cannot generate interrupts since

during Sleep, no on-chip clocks are present.

When the SLEEP instruction is being execut ed, the next

instruction (PC + 1) is pre-fetched. For the device to

wake-up thro ugh an interrupt eve nt, the co rres pon ding

interrupt enable bit must be set (enabled). Wa ke-up is

regardless of the state of the GIE bit. If the GIE bit is

clear (disabled), the device continues execution at the

instruction after the SLEEP instruction. If the GIE bit is

set (enabled), the device executes the instruction after

the SLEEP instruction, then branches to the interrupt

address (0004h). In cases where the execution of the

instruction following SLEEP is not desirable, the user

should hav e a NOP after the SLEEP instruction.

The WDT is cleared when the device wakes up from

Sleep, regardless of the source of wake-up.

16.7.2 WAKE-UP USING INTERRUPTS

When global interrupts are disabled (GIE cleared) and

any interrupt source has both its interrupt enable bit

and inte rrupt fla g bit s et, one of the fo llow ing wil l occur:

• If the interrupt occurs before the execution of a

SLEEP instruction, the SLEEP instruct ion will

comple te as a NOP. Therefor e, the WDT and WDT

prescaler and postscaler (if enabled) will not be

cleared, the TO bit will not be set and the PD bit

will not be cleared.

• If the interrupt occurs during or after the

execution of a SLEEP instructio n, the dev ic e will

immediately wake-up from Sleep. The SLEEP

instruction will be completely executed before the

wake-up. The refore, the WDT and WDT pres caler

and pos tsc aler (if enable d) wi ll be c leared , the T O

bit will be set and the PD bit will be cleared.

Note: It should be noted that a Reset generated

by a WDT time-out does not drive MCLR

pin low.

Note: If the g lobal interrup ts a re disa bled (G IE is

cleared ), but any interrup t source has bo th

it s interrupt enabl e bit and the corres pond-

ing interrupt flag bits set, the device will

immediately wake-up from Sleep. The

SLEEP instruction is comple tely executed.

PIC16F946

Even if the flag bits were checked before executing a

SLEEP instruction, it may be possible for flag bits to

become set before the SLEEP instruction completes. To

determine whether a SLEEP instruction executed, test

the PD bit. If the PD bit is set, the SLEEP instruction

was executed as a NOP.

To ensure that the WDT is clea red, a CLRWDT instruction

should be executed before a SLEEP instruction.

FIGURE 16-10: WAKE-UP FROM SLEEP THROUGH INTERRUPT

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

OSC1(1)

CLKO(4)

INT pin

INTF flag

(INTCON<1>)

GIE bit

(INTCON<7>)

Instruction Flow

Instruction

Fetched

Instruction

Executed

PC PC + 1 PC + 2

Inst(PC) = Sleep

Inst(PC - 1)

Inst(PC + 1)

Sleep

Processor in

Sleep

Interrupt Latency(3)

Inst(PC + 2)

Inst(PC + 1)

Inst(0004h) Inst(0005h)

Inst(0004h)

Dummy Cycle

PC + 2 0004h 0005h

Dummy Cycle

TOST(2)

PC + 2

Note 1: XT, HS or LP Oscilla tor mode assume d.

2: TOST = 1024 TOSC (drawing not to scale). This delay does not apply to EC and RC Oscillator modes.

3: GIE = 1 assumed. In this case after wake-up, the processor jumps to 0004h. If GIE = 0, execut i on will cont i nue in-lin e.

4: CLKO is not available in XT, HS, LP or EC Oscillator modes, but shown here for timing reference.

PIC16F946

16.8 Code Protection

If the code protection bit(s) have not been

programmed, the on-chip program memory can be

read out usin g ICSP for verific ation purposes.

16.9 ID Locations

Four memory locations (2000h-2003h) are designated

as ID locations where the user can store checksum or

other code identification numbers. These locations are

not accessible during normal execution, but are

readable and writable during Program/Verify mode.

Only the Least Significant 7 bits of the ID locations are

used.

16.10 In-Circuit Serial Programmin g

The PIC16F946 microcontrollers can be serially

progra mmed w hile in t he en d app licati on c ircuit. This i s

simply done with tw o lines for cl ock and data and thre e

other lines for:

• power

• ground

• programming voltage

This allows customers to manufacture boards with

unprogrammed devices and then program the micro-

controller just before shipping the product. This also

allows the most recent firmware or a custom firmware

to be programmed.

The device is placed into a Program/Verify mode by

holding the RB7/ICSPDAT/ICDDAT/SEG13 and

RB6/ICSPCLK/ICDCK/SEG14 pins low, while raising

the MCLR (VPP) pin from VIL to VIHH. See

“PIC16F91X/946 Memory Programming Specification”

(DS41244) for more information. RB7/ICSPDAT/ICD-

DAT/SEG13 becomes the programming data and

RB6/ICSPCLK/ICDCK/SEG14 becomes the program-

ming clock. Both RB7/ICSPDAT/ICDDAT/SEG13 and

RB6/ICSPCLK/ICDCK/SEG14 are Schmitt Trigger

inputs in this mode .

After Reset, to place the device into Program/Verify

mode, th e Pr ogram Cou nte r (P C) i s at l oca tio n 00h . A

6-bit command is then supplied to the device.

Depending on the command, 14 bits of program data

are then supplied to or from the device, depending on

whether the command was a load or a read. For

comple te d et a ils of s eri al p rog ram mi ng, p lea se refe r to

the “PIC16F91X/946 Memory Programming

Specification” (DS41244).

A typical In-Circuit Serial Programming connection is

shown in Figure 16-11.

FIGURE 16-11: TYPICAL IN-CIRCUIT

SERIAL PROGRAMMING

CONNECTION

Note: The entire data EEPROM and Flash

program memory will be erased when the

code protection is turned off. See the

“PIC16F91X/946 Memory Programming

Specification” (DS41244) for more infor-

mation. External

Connector

Signals

To Normal

Connections

To Normal

Connections

PIC16F946

VDD

VSS

RE3/MCLR/VPP

RB6/ICSPCLK/

RB7/ICSPDATA/

+5V

VPP

CLK

Data I/O

* * *

* Isola tion devices (as required)

ICDCK/SEG14

ICDDAT/SEG13

PIC16F946

16.11 In-Circuit Debugger

The PIC16F946-ICD can be used in any of the p ackage

types. The device will be mounted on the target appli-

cation b oard, which in turn has a 3 or 4 wire c onnectio n

to the ICD tool.

When the debug bit in the Configuration Word

(CONFIG<12>) is programmed to a ‘0’, the In-Circuit

Debug ger fun ct ion ali ty is enabled. Thi s fun ct ion allo w s

simple debugging functions when used with MPLAB®

ICD 2. When the microcontroller has this feature

enabled, some of the resources are not available for

general use. See Table 16-9 for more detail.

For more information, see “Using MPLAB® ICD 2”

(DS51265), available on Microchip’s web site

(www.microchip.com).

16.11.1 ICD PINOUT

The devices in the PIC16F946 device carries the

circuitry for the In-Circuit Debugger on-chip and on

existing device pins. This eliminates the need for a

sepa rate di e or p acka ge for th e ICD d evice . The pi nout

for the ICD device is the same as the devices (see

Section 1.0 “Device Overview” for complete pinout

and pin descriptions). Table 16-9 shows the location

and function of the ICD related pins on the 28 and 40

pin devices.

TABLE 16-9: PIC16F946-ICD PIN DESCRIPTIONS

Note: The user’s application must have the

circuitry required to support ICD

functionality. Once the ICD circuitry is

enabled, normal device pin functions on

RB6/ICSPCLK/ICDCK/SEG14 and

RB7/ICSPDAT/ICDDAT/SEG13 will not be

usable. The ICD circuitry uses these pins for

communication with the ICD2 external

debugger.

Pin Name Type Pull-up Description

24 ICDDATA TTL — In Circuit Debugger Bidirectional data

23 ICDCLK ST — In Circuit Debugger Bidirectional clock

36 MCLR/VPP HV — Programming voltage

10, 19, 38, 57 VDD P—

9, 20, 41, 56 VSS P—

26 AVDD P—

25 AVDD P—

Legend: TTL = TTL input buffer, ST = Schmitt Trigger input buffer, P = Power, HV = High Voltage

PIC16F946

NOTES:

PIC16F946

17.0 INSTRUCTION SET SUMMARY

The PIC 16F946 i nstructio n set i s highly orthogon al and

is comprised of three basic categories:

•Byte-oriented operations

•Bit-oriented operations

•Literal and cont rol operations

Each PIC16 instruction is a 14-bit word divided into an

opcode, which specifi es the instructi on type and one or

more operands, which further specify the operation of

the instruction. The formats for each of the categories

is presented in Figure 17-1, while the various opcode

fields are sum m ariz ed in Table 17-1.

Table 17-2 lists the instructions recognized by the

MPASMTM assembler. A complete description of each

instruction is also available in the “PICmicro®

Mid-Range MCU Family Reference Manual”

(DS33023).

For byte-oriented instructions, ‘f’ represents a file

designator. The file register designator specifies which

file register is to be used by the instruction.

The desti nation designator specifies where the result of

the operation is to be placed. If ‘d’ is zero , th e r e su lt is

placed in the W re gister . If ‘ d’ is one, the result is placed

in the file register specified in the instruction.

For bit-oriented instructions, ‘b’ represents a bit field

designator, which selects the bit affected by the

operatio n, whi le ‘f’ re pre sen t s t he ad dres s o f the f ile in

which the bit is located.

For literal and control operations, ‘k’ represents an

8-bit or 11-bit constant, or literal value.

One instr uction cycle co nsists of four os cillator periods ;

for an oscillator frequency o f 4 MHz, t his gives a normal

instruction execution time of 1 μs. All instructions are

executed within a single instruction cycle, unless a

conditional test is true, or the program counter is

change d as a result of an instruction. When this occurs,

the execution takes two instruction cycles, with the

second cycle executed as a NOP.

All instruction examples use the format ‘0xhh’ to

represent a hexadecimal number, where ‘h’ signifies a

hexadecimal digit.

17.1 READ-MODIFY-WRITE

OPERATIONS

Any instruction that specifies a file register as part of

the instruction performs a Read-Modify-Write (RMW)

operation. The register is read, the data is modified,

and the result is stored according to either the instruc-

tion, or the destination designator ‘d’. A read oper ation

is performed on a register even if the instruction writes

to that register.

For exam pl e, a CLRF GPIO in st ruc tion w i ll read G P IO,

clear all the data bits, then write the result back to

GPIO. This example would have the unintended result

of clearing the condition that set the GPIF flag.

TABLE 17-1: OPCODE FIELD

DESCRIPTIONS

Note: To maintain upward compatibility with

future products, do not use the OPTION

and TRIS instructions.

Field Description

fRegister file address (0x00 to 0x7F)

WWorking register (accumulator)

bBit address within an 8-bit file register

kLiteral field, constant data or label

xDon’t care location (= 0 or 1).

The assembler will generate code with x = 0.

It is the recommended form of use for

compatibility with all Microchip software tools.

dDestination select; d = 0: store result in W,

d = 1: store result in file register f.

Default is d = 1.

PC Program Counter

TO Time-out bit

PD Power-down bit

PIC16F946

FIGURE 17-1: GENERAL FORMAT FOR

INSTRUCTIONS

Byte-oriented file register operations

13 8 7 6 0

d = 0 for destination W

OPCODE d f (FILE #)

d = 1 for destination f

f = 7-bit file register address

Bit-oriented file register operations

13 10 9 7 6 0

OPCODE b (BIT # ) f (FILE #)

b = 3-bit bit address

f = 7-bit file register address

Literal and control operations

13 8 7 0

OPCODE k (litera l )

k = 8-bit immediate value

13 11 10 0

OPCODE k (literal)

k = 11-bit immediate value

General

CALL and GOTO instructions only

PIC16F946

TABLE 17-2: PIC16F946 INSTRUCTION SET

Mnemonic,

Operands Description Cycles 14-Bit Opcode Status

Affected Notes

MSb LSb

BYTE-ORIENTED FILE REGISTER OPERATIONS

ADDWF

ANDWF

CLRF

CLRW

COMF

DECF

DECFSZ

INCF

INCFSZ

IORWF

MOVF

MOVWF

NOP

RLF

RRF

SUBWF

SWAPF

XORWF

f, d

Add W and f

AND W with f

Clear f

Clear W

Complement f

Decrement f

Decrement f, Skip if 0

Increment f

Increment f, Skip if 0

Inclusive OR W with f

Move f

Move W to f

No Operation

Rotate Left f through Carry

Rotate Right f through Carry

Subtract W from f

Swap nibbles in f

Exclusive OR W with f

1(2)

0111

0101

0001

1001

0011

1011

1010

1111

0100

1000

0000

1101

1100

0010

1110

0110

dfff

lfff

0xxx

dfff

lfff

0xx0

dfff

ffff

xxxx

ffff

0000

ffff

C,DC,Z

1, 2

1, 2, 3

1, 2

1, 2, 3

1, 2

BIT-ORIENTED FILE REGISTER OPERATIONS

BCF

BSF

BTFSC

BTFSS

f, b

Bit Clear f

Bit Set f

Bit Test f, Skip if Clear

Bit Test f, Skip if Set

1 (2)

00bb

01bb

10bb

11bb

bfff

ffff

1, 2

LITERAL AND CONTROL OPERATIONS

ADDLW

ANDLW

CALL

CLRWDT

GOTO

IORLW

MOVLW

RETFIE

RETLW

RETURN

SLEEP

SUBLW

XORLW

Add literal and W

AND literal with W

Call subroutine

Clear Watchdog Timer

Go to address

Inclusive OR literal with W

Move literal to W

Return from interrupt

Return with literal in W

Return from Subroutine

Go into Standby mode

Subtract W from literal

Exclusive OR literal with W

111x

1001

0kkk

0000

1kkk

1000

00xx

0000

01xx

0000

110x

1010

kkkk

0110

kkkk

0000

kkkk

0000

0110

kkkk

0100

kkkk

1001

kkkk

1000

0011

kkkk

C,DC,Z

TO,PD

C,DC,Z

Note 1: When an I/O register is modified as a function of itself (e.g., MOVF GPIO, 1), the value used will be that value present

on the pins themselves. For example, if the data latch is ‘1’ for a pin confi gured as input and is driven low by an external

device, the data will be written back with a ‘0’.

2: If this instruction is executed on the TMR0 register (and where applicable, d = 1), the prescaler will be cleared if

assigned to the Timer0 module.

3: If Program Counter (PC) is modified, or a conditional test is true, the instruction requires two cycles. The second cycle

is executed as a NOP.

PIC16F946

17.2 Instruction Descriptions

ADDLW Add Literal and W

Syntax: [ label ] ADDLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) + k → (W)

Status Affected: C, DC, Z

Description: The contents of the W register

are added to the eight-bit literal ‘k’

and the result is placed in the W

ADDWF Add W and f

Syntax: [ label ] ADDWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) + (f) → (destination)

Status Affected: C, DC, Z

Desc ription: Add the conten ts of the W regis ter

with register ‘f’. If ‘d’ is ‘0’, the

result is stored in the W registe r . I f

‘d’ is ‘1’, the result is stored back

in register ‘f’.

ANDLW AND Literal with W

Syntax: [ label ] ANDLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .AND. (k) → (W)

Status Affected: Z

Description: The contents of W register are

AND’ed with the eight-bit literal

‘k’. The result is place d in the W

ANDWF AND W with f

Syntax: [ label ] ANDWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) .AND. (f) → (destination)

Status Affected: Z

Description: AND the W register with register

‘f’. If ‘d’ is ‘0’, the resu lt is stored in

the W register. If ‘d’ is ‘1’, the

result is sto r ed bac k in regi ste r ‘f’.

BCF Bit Clear f

Syntax: [ label ] BCF f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b ≤ 7

Operation: 0 → (f<b>)

Status Af fe cte d: None

Description: Bit ‘b’ in register ‘f’ is cleared.

BSF Bit Set f

Syntax: [ label ] BSF f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b ≤ 7

Operation: 1 → (f<b>)

Status Af fe cte d: None

Description: Bit ‘b’ in register ‘f’ is set.

BTFSC Bit Test, Skip if Clear

Syntax: [ label ] BTFSC f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b ≤ 7

Operation: skip if (f<b>) = 0

Status Af fe cte d: None

Descr iption: If bit ‘b’ in regi ster ‘f’ is ‘1’, the next

instructi on is ex ecuted.

If bit ‘b’ in registe r ‘f’ is ‘0’, the nex t

instructi on is discarded, and a NOP

is exec ute d in stead, m ak ing thi s a

two-cycle instruction.

PIC16F946

BTFSS Bit Test f, Skip if Set

Syntax: [ label ] BTFSS f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b < 7

Operation: skip if (f<b>) = 1

Status Affected: None

Desc ription: If bit ‘b’ in regist er ‘f’ is ‘0’, the next

instruction is executed.

If bit ‘b’ is ‘1’, then the next

inst ruc tion is di sc arde d and a NOP

is exec ute d ins te ad, m ak in g thi s a

two-cycle instruction.

CALL Call Subroutine

Syntax: [ label ] CALL k

Operands: 0 ≤ k ≤ 2047

Operation: (PC)+ 1→ TOS,

k → PC<10:0>,

(PCLATH<4:3>) → PC<12:11>

Status Affected: None

Description: Call Subroutine. First, return

address (PC + 1) is PUSHed onto

the stack. The eleven-bit

immediate address is loaded into

PC bits <10:0>. The upper bits of

the PC are loa ded from PC LATH.

CALL is a two-cycle instruction.

CLRF Clear f

Syntax: [ label ] CLRF f

Operands: 0 ≤ f ≤ 127

Operation: 00h → (f)

1 → Z

Status Affected: Z

Desc ript ion : The conten t s of regi ste r ‘f’ are

cleared and the Z bit is set.

CLRW Clear W

Syntax: [ label ] CLRW

Operands: None

Operation: 00h → (W)

1 → Z

Status Affected: Z

Description: W register is cleared. Zero bit (Z)

is set.

CLRWDT Clear Watchdog Timer

Syntax: [ label ] CLRWDT

Operands: None

Operation: 00h → WDT

0 → WDT prescaler,

1 → TO

1 → PD

Status Af fe cte d: TO, PD

Description: CLRWDT instruction resets the

W atchdog T imer . It also resets the

prescaler of the WDT.

Status bits TO and PD are set.

COMF Complement f

Syntax: [ label ] COMF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) → (destination)

Status Af fe cte d: Z

Description: The contents of register ‘f’ are

complemented. If ‘d’ is ‘0’, the

result is stored in W. If ‘d’ is ‘1’,

the result is stored back in

DECF Decrement f

Syntax: [ label ] DECF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) - 1 → (destination)

Status Af fe cte d: Z

Description: Decrement register ‘f’. If ‘d’ is ‘0’,

the result is stored in the W

stored back in register ‘f’.

PIC16F946

DECFSZ Decrement f, Skip if 0

Syntax: [ label ] DECFSZ f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) - 1 → (destination);

skip if result = 0

Status Affected: None

Description: The contents of register ‘f’ are

decrem ented. If ‘d’ is ‘0’, th e result

is placed in the W register. If ‘d’ is

‘1’, the result is placed back in

If the result is ‘1’, the next

instruction is executed. If the

resu lt is ‘0’, then a NOP is

executed instead, making it a

two-cycle instruction.

GOTO Go to Address

Syntax: [ label ] GOTO k

Operands: 0 ≤ k ≤ 2047

Operation: k → PC<10:0>

PCLATH<4:3> → PC<12:11>

Status Affected: None

Description: GOTO is an unconditional branch.

The e le ven -bi t im me dia t e v al ue i s

loaded into PC bits <10:0>. The

upper bits of PC are loaded from

PCLATH<4:3>. GOTO is a

two-cycle instruction.

INCF Increment f

Syntax: [ label ] INCF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) + 1 → (destination)

Status Affected: Z

Description: The contents of register ‘f’ are

incremen ted. I f ‘ d’ is ‘0’, the res ult

is place d in the W register. If ‘d’ is

‘1’, the result is placed back in

INCFSZ Increment f, Skip if 0

Syntax: [ label ] INCFSZ f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) + 1 → (destination),

skip if result = 0

Status Af fe cte d: None

Description: The contents of register ‘f’ are

incremented. If ‘d’ is ‘0’, the result

is placed in the W register. If ‘d’ is

‘1’, the result is placed back in

If the result is ‘1’, the next

instruction is executed. If the

result is ‘0’, a NOP is executed

instead, making it a two-cycle

instruction.

IORLW Inclusive OR Literal with W

Syntax: [ label ] IORLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .OR. k → (W)

Status Af fe cte d: Z

Descr iption: The con tents of t he W register a re

OR’ed with the eight-bit literal ‘k’.

The result is placed in the W

IORWF Inclusive OR W with f

Syntax: [ label ] IORWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) .OR. (f) → (destination)

Status Af fe cte d: Z

Description: Inclusive OR the W register with

placed in the W register. If ‘d’ is

‘1’, the result is placed back in

PIC16F946

MOVF Move f

Syntax: [ label ] MOVF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) → (dest)

Status Affected: Z

Encoding: 00 1000 dfff ffff

Desc ript ion : The conten t s of regi ste r ‘f’ is

moved to a destination dependent

upon the status of ‘d’. If ‘d’ = 0,

destination is W register. If ‘d’ = 1,

the destination is file register ‘f’

itself. ‘d’ = 1 is useful to test a file

affected.

Words: 1

Cycles: 1

Example:MOVF FSR, 0

After Instruction

W= value in FSR

Z= 1

MOVLW Move Literal to W

Syntax: [ label ] MOVLW k

Operands: 0 ≤ k ≤ 255

Operation: k → (W)

Status Affected: None

Encoding: 11 00xx kkkk kkkk

Description: The eight bit literal ‘k’ is loaded

into W register. The “don’t cares”

will assemble as ‘0’s.

Words: 1

Cycles: 1

Example:MOVLW 0x5A

After Instruction

W = 0x5A

MOVWF Move W to f

Syntax: [ label ] MOVWF f

Operands: 0 ≤ f ≤ 127

Operation: (W) → (f)

Status Af fe cte d: None

Encoding: 00 0000 1fff ffff

Description: Move data from W register to

Words: 1

Cycles: 1

Example:MOVWF OPTION

Before Instruction

OPTION= 0xFF

W = 0x4F

After Instruction

OPTION= 0x4F

W = 0x4F

NOP No Operation

Syntax: [ label ] NOP

Operands: None

Operation: No operation

Status Af fe cte d: None

Encoding: 00 0000 0xx0 0000

Description: No operation.

Words: 1

Cycles: 1

Example:NOP

PIC16F946

RETFIE Return from Interrupt

Syntax: [ label ] RETFIE

Operands: None

Operation: TOS → PC,

1 → GIE

Status Affected: None

Encoding: 00 0000 0000 1001

Description: Return from Interrupt. Stack is

POPed and Top-of-Stack (TOS) is

loaded in the PC. Interrupts are

enable d by setting Glob al Interrupt

Enable bit, GIE (INTCON<7>).

This is a two-cycle instruction.

Words: 1

Cycles: 2

Example:RETFIE

After Interrupt

PC = TOS

GIE = 1

RETLW Return with Literal in W

Syntax: [ label ] RETLW k

Operands: 0 ≤ k ≤ 255

Operation: k → (W);

TOS → PC

Status Af fe cte d: None

Encoding: 11 01xx kkkk kkkk

Description: The W register is loaded with the

eight-bit literal ‘k’. The program

counter is loaded from the top of

the stack (the return address).

This is a two-cycle instruction.

Words: 1

Cycles: 2

Example:

TABLE

CALL TABLE ;W contains table

;offset value

• ;W now has table

value

•

ADDWF PC ;W = offset

RETLW k1 ;Begin table

RETLW k2 ;

•

RETLW kn ; End of table

Before Instruction

W = 0x07

After Instruction

W = value of k8

RETURN Return from Subroutine

Syntax: [ label ] RETURN

Operands: None

Operation: TOS → PC

Status Af fe cte d: None

Description: Return from subroutine. The stack

is POPed an d the top of the s t a ck

(TOS) is loaded into the program

counter. This is a two-cycle

instruction.

PIC16F946

RLF Rotate Left f through Carry

Syntax: [ label ] RLF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: See description below

Status Affected: C

Encoding: 00 1101 dfff ffff

Description: The contents of register ‘f’ are

rotated one bit to the left through

the Carry Flag. If ‘d’ is ‘0’, the

result i s pla ced in the W regist er. If

‘d’ is ‘1’ , the result is sto red back in

Words: 1

Cycles: 1

Example:RLF REG1,0

Before Instruction

REG1 = 1110 0110

C=0

After Instruction

REG1 = 1110 0110

W = 1100 1100

C=1

RRF Rotate Right f through Carry

Syntax: [ label ] RRF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: See description below

Status Affected: C

Desc ript ion : The contents of regis te r ‘f’ are

rotat ed one bit to the r ight throug h

the Carry Flag. If ‘d’ is ‘0’, the

result is placed in the W register.

If ‘d’ is ‘1’, the resu lt is place d

back in register ‘f’.

SLEEP Go into Standby mode

Syntax: [ label ] SLEEP

Operands: None

Operation: 00h → WDT,

0 → WDT prescaler,

1 → TO,

0 → PD

Status Af fe cte d: TO, PD

Descripti on: The power-down S tatus bit, PD is

cleared. Time-out Status bit, TO

is set. Watchdog Timer and its

prescaler are cleare d.

The processor is put into Sleep

mode with the oscillator stopped.

SUBLW Subtract W from Literal

Syntax: [ label ] SUBLW k

Operands: 0 ≤ k ≤ 255

Operation: k - (W) → (W)

Status Affected: C, DC, Z

Description: The W register is subtracted (2’s

complement method) from the

eight-bit literal ‘k’. The result is

placed in the W register.

SUBWF Subtract W from f

Syntax: [ label ] SUBWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) - (W) → (destination)

Status Affected: C, DC, Z

Description: Subtract (2’s complement method)

W register from register ‘f’. If ‘d’ is

‘0’, the result is stored in the W

stored back in register ‘f’.

PIC16F946

SWAPF Swap Nibbles in f

Syntax: [ label ] SWAPF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f<3:0>) → (destination<7:4>),

(f<7:4>) → (destination<3:0>)

Status Affected: None

Description: The upper and lower nibbles of

‘0’, the result is placed in the W

placed in register ‘f’.

XORLW Exclusive OR Literal with W

Syntax: [ label ] XORLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .XOR. k → (W)

Status Affected: Z

Description: The contents of the W register

are XOR’ed with the eight-bit

literal ‘k’. The result is placed in

the W register.

XORWF Exclusive OR W with f

Syntax: [ label ] XORWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) .XOR. (f) → (destination)

Status Affected: Z

Descrip tion: Exclusive OR the contents of the

W register with register ‘f’. If ‘d’ is

‘0’, the result is stored in the W

stored back in register ‘f’.

PIC16F946

18.0 DEVELOPMENT SUPPORT

The PICmicro® microcontrollers are supported with a

full ran ge of hardware a nd softwa re develo pment to ols:

• Integrated Development Environment

- MPLAB® IDE Software

• Assemblers/Compilers/Linkers

- MPASMTM Assembler

- MPLAB C17 and MPLAB C18 C Compilers

-MPLINK

TM Object Linker/

MPLIBTM Object Librarian

- MPLAB C30 C Compiler

- MPLAB ASM30 Assembler/Linker/Library

• Simulators

- MPLAB SIM Software Simulator

- MPLAB dsPIC30 Software Simulator

•Emulators

- MPLAB ICE 2000 In-Circuit Emulator

- MPLAB ICE 4000 In-Circuit Emulator

• In-Circuit Debugger

- MPLAB ICD 2

• Device Progra mmers

-PRO MATE

® II Univer sa l D evi ce Pro gr a mm er

- PICSTART® Plus Development Programmer

- MPLAB PM3 Device Programmer

• Low-Cost Demonstration Boards

- PICDEMTM 1 Demonstration Board

- PICDEM.netTM De monstration Board

- PICDEM 2 Plus Demonstration Board

- PICDEM 3 Demonstration Board

- PICDEM 4 Demonstration Board

- PICDEM 17 Demonstration Board

- PICDEM 18R Demonstration Board

- PICDEM LIN Demonstration Board

- PICDEM USB Demonstration Board

• Evaluation Kits

-K

EELOQ® Security ICs

- P ICDEM MSC

-microID

® RFID

-CAN

- PowerSmart® Battery Management

-Analog

18.1 MPLAB Integrated Development

Environment Software

The MPLAB IDE software brings an ease of software

development previously unseen in the 8/16-bit micro-

controller market. The MPLAB IDE is a Windows®

based application that contains:

• An interface to deb ugging tools

- simulator

- programmer (sold separately)

- emulator (sold separately)

- in-circuit debugger (sold separately)

• A full-featured editor with color coded context

• A multiple project manager

• Customizable data windows with direct edit of

contents

• High-level source code debugging

• Mouse over variable inspection

• Exten si ve on-l in e help

The MPLAB IDE allows you to:

• Edit your sour ce fil es (either assembly or C)

• One touch assemble (or compile) and download

to PICmicro emulator and simulator tools

(automatically updates all project information)

• Debug us ing :

- source files (as sembl y or C)

- mixed assembly and C

- machine code

MPLAB IDE supports multiple debugging tools in a

single development paradigm, from the cost effective

simulators, through low-cost in-circuit debuggers, to

full-featured emulators. This eliminates the learning

curve whe n upgrading to tools with increasin g flexibi lity

and power.

18.2 MPASM Assembler

The MPASM assembler is a full-featured, universal

macro assembler for all PICmicro MCUs.

The MPASM assembler generates relocatable object

files for the MPLINK object linker, Intel® standard hex

files, M AP files to detail memory u sage and symbol re f-

erence, a bsolute LST files that contain source lines and

generated machine code and COFF files for

debugging.

The MPASM assembler features include:

• Integration into MPLAB IDE projects

• User de fined m acros to strea mline asse mbly cod e

• Condit ion al as sem bl y for multi-purpose sourc e

files

• Directives that allow complete control over the

assembly p rocess

PIC16F946

18.3 MPLAB C17 and MPLAB C18

C Compilers

The MPLAB C17 and MPLAB C18 Code Development

Systems are complete ANSI C compilers for

Microchip’s PIC17CXXX and PIC18CXXX family of

microcontrollers. These compilers provide powerful

integration capabilities, superior code optimization and

ease of use not found with other compilers.

For easy source level debugging, the compilers provide

symbol info rmation tha t is optimized to the MPLAB IDE

debugger.

18.4 MPLINK Object Linker/

MPLIB Object Librari an

The MPLINK object linker combines relocatable

objects created by the MPASM assembler and the

MPLAB C17 and MPLAB C18 C compilers. It can link

relocatable objects from precompiled libraries, using

directives from a linker script.

The MPLIB object librarian manages the creation and

modification of library files of precompiled code. When

a routine from a library is called from a source file , only

the modules that contain that routine will be linked in

with the application. This allows large libraries to be

used efficiently in many different applications.

The object linker/library features include:

• Efficient linking of single libraries instead of many

smaller files

• Enhanced code maintainability by grouping

related modules together

• Flexible creation of libraries with easy module

listing, replacement , deletion and extr action

18.5 MPLAB C30 C Compiler

The MPLAB C30 C compiler is a full-featured, ANSI

compliant, optimizing compiler that translates standard

ANSI C programs into dsPIC30F assembly language

source. The compiler also supports many command

line options and language extensions to take full

adv antage of the dsPIC 30F dev ice ha rdwar e capab ili-

ties and afford fine control of the compiler code

generator.

MPLAB C30 is distributed with a complete ANSI C

standard library. All library functions have been vali-

dated an d c on form to the ANSI C li brary standard . Th e

library includes functions for string manipulation,

dynamic memory allocation, data conversion, time-

keepin g and math func tions (trigonome tric, expone ntial

and hyperbolic). The compiler provides symbolic

information for high-level source debugging with the

MPLAB IDE.

18.6 MPLAB ASM30 Assembler, Linker

and Librarian

MPLAB ASM30 assembler produces relocatable

machine code from symbolic assembly language for

dsPIC30F devices. MPLAB C30 compiler uses the

assembler to produce it’s object file. The assembler

generates relocatable object files that can then be

archived or lin ked with other relocatable ob ject files and

arch ives to c rea te an e xecu tabl e fil e. N otabl e fe atu res

of the assembler include:

• Support for the entire dsPIC30F instruction set

• Support for fixed-point and floating-point data

• Command line interface

• Rich dire cti ve set

• Flexible macro language

• MPLAB IDE compatibility

18.7 MPLAB SIM Software Simulator

The MPLAB SIM sof tware simulat or allows code deve l-

opment in a PC hosted environment by simulating the

PICmicro series microcontrollers on an instruction

level. On any given instruction, the data areas can be

examined or modified and stimuli can be applied from

a file, or use r de fined key p ress, to any pin. The exec u-

tion can be performed in Single-Step, Execute Until

Break or Trace mode.

The MPLAB SIM simulator fully supports symbolic

debugging using the MPLAB C17 and MPLAB C18

C Compilers, as well as the MPASM assembler. The

software simulator offers the flexibility to develop and

debug code outside of the laboratory environment,

making it an excellent, economical software

development tool .

18.8 MPLAB SIM30 Software Simulator

The MPLAB SIM30 software simulator allows code

develop ment in a PC hosted en vironment by simulating

the dsPIC30F series microcontrollers on an instruction

level. On any given instruction, the data areas can be

examined or modified and stimuli can be applied from

a file, or user defined key press, to any of the pins.

The MPLAB SIM30 simulator fully supports symbolic

debugging using the MPLAB C30 C Compiler and

MPLAB ASM30 assembler . The simulator runs in either

a Command Line mode for automated tasks, or from

MPLAB IDE. This high-speed simulator is designed to

debug, analyze and optimize time intensive DSP

routines.

PIC16F946

18.9 MPLAB ICE 2000

High-Performance Universal

In-Circui t Emu lator

The MPLAB ICE 2000 universal in-circuit emulator is

intended to provide the product development engineer

with a complete microcontroller design tool set for

PICmicro microcontrollers. Software control of the

MPLAB ICE 2000 in-circuit emulator is advanced by

the MPLAB Integrated Development Environment,

which all ows ed iting, b uildin g, do wnlo ading and sourc e

debuggi ng from a singl e envi ronm en t.

The MPLAB ICE 2000 is a full-featured emulator

system with enhanced trace, trigger and data monitor-

ing feat ures. Interc hangeabl e proces sor modul es allow

the system to be easily reconfigured for emulation of

different processors. The universal architec ture of the

MPLAB ICE in-circuit emulator allows expansion to

support new PICmicro microcontrollers.

The MPLAB ICE 2000 in-circuit emulator system has

been designed as a real-time emulation system with

advanced features that are typically found on more

expensive development tools. The PC platform and

Microsoft® Windows 32-bit operating system were

chosen to best make these features available in a

simple, unified application.

18.10 MPLAB ICE 4000

High-Performance Universal

In-Circui t Emu lator

The MPLAB ICE 4000 universal in-circuit emulator is

intended to provide the product development engineer

with a complete microcontroller design tool set for

high-end PICmicro microcontrollers. Software control

of the M PLAB ICE in- circui t emulato r is provi ded by th e

MPLAB Integrated Development Environment, which

allows editing, building, downloading and source

debuggi ng from a singl e envi ronm en t.

The MPLAB ICD 4000 is a premium emulator system,

providing the features of MPLAB ICE 2000, but with

increased emulation memory and high-speed perfor-

mance for dsPIC30F and PIC18XXXX devices. Its

advanc ed emulator fe atures inc lude complex t riggering

and timing, up to 2 Mb of emulation memory and the

ability to view variables in real-time.

The MPLAB ICE 4000 in-circuit emulator system has

been designed as a real-time emulation system with

advanced features that are typically found on more

expensive development tools. The PC platform and

Microsoft Windows 32-bit operating system were

chosen to best make these features available in a

simple, unified application.

18.11 MPLAB ICD 2 In-Circuit Debugger

Microchip’s In-Circuit Debugger, MPLAB ICD 2, is a

powerful, low-cost, run-time development tool,

connecting to the host PC via an RS-232 or high-speed

USB interface. This tool is based on the Flash

PICmicro MCUs and can be used to develop for these

and other PICmicro microcontrollers. The MPLAB

ICD 2 utilizes the in-circuit debugging capability built

into the Flash devices. This feature, along with

Microchip’s In-Circuit Serial ProgrammingTM (ICSPTM)

protocol , offe rs cost ef fective i n-circuit Flash debug ging

from the graphical user interface of the MPLAB

Integrated Development Environment. This enables a

designer to develop and debug source code by setting

breakpoints, single-stepping and watching variables,

CPU status and peripheral registers. Running at full

speed enables testing hardware and applications in

real-tim e. MPLAB ICD 2 also serv es as a devel opme nt

programmer for selected PICmicro devices.

18.12 PRO MATE II Universal Device

Programmer

The PRO MATE II is a universal, CE compliant device

programmer with programmable voltage verification at

VDDMIN and VDDMAX for maxi mum reli abili ty. It fea tures

an LCD display for instructions and error messages

and a modular detachable socket assembly to support

various package types. In Stand-Alone mode, the

PRO MATE II device programmer can read, verify and

program PICmicro devices without a PC connection. It

can also set code protection in this mode.

18.13 MPLAB PM3 Device Programmer

The MPLAB PM3 is a universal, CE compliant device

programmer with programmable voltage verification at

VDDMIN and VDDMAX for maxi mum reli abili ty. It fea tures

a large LCD display (128 x 64) for menus and error

messages and a modular detachable socket assembly

to support various package types. The ICSP™ cable

assembly is included as a standard item. In

Stand-Alone mode, the MPLAB PM3 device program-

mer can read, verify and program PICmicro devices

without a PC connec tion. It can also set code protection

in this mo de. MPLAB PM 3 c onn ects to the host PC via

an RS-23 2 or USB cable . MPLAB PM3 h as high-spee d

communications and optimized algorithms for quick

programming of large memory devices and incorpo-

rates an SD/M MC ca rd for file st orage an d secu re dat a

applications.

PIC16F946

18.14 PICSTART Plus Development

Programmer

The PICSTART Plus development programmer is an

easy-to-use, low-cost, prototype programmer. It con-

nects to the PC via a COM (RS-232) port. MPLAB

Inte grated Dev elopmen t En vironme nt so ftware makes

using the programmer simple and efficient. The

PICSTART Plus development programmer supports

most PICmicro devices up to 40 pins. Larger pin count

devices, such as the PIC16C92X and PIC17C76X,

may be supported with an adapter socket. The

PICSTART Plus development programmer is CE

compliant.

18.15 PICDEM 1 PICmicro

Demonstration Board

The PICDEM 1 demo nstrat ion boa rd demo nstrate s the

capabilities of the PIC16C5X (PIC16C54 to

PIC16C58A), PIC16C61, PIC16C62X, PIC16C71,

PIC16C8X, PIC17C42, PIC17C43 and PIC17C44. All

necessary hardware and software is included to run

basic demo programs. The sample microcontrollers

provi d ed wi t h the P IC DE M 1 de mo ns t rat i on b oar d c an

be pro gramme d with a PRO MATE I I devi ce prog ram-

mer or a PICSTART Plus development programmer.

The PICDE M 1 demonstrati on board can be conne cted

to the MPLAB ICE in-circuit emulator for testing. A

proto type area extends the ci rcuitry for a dditio nal appli-

cation components. Features include an RS-232

interface, a potentiometer for simulated analog input,

push button switches and eight LEDs.

18.16 PICDEM.net Internet/E thernet

Demonstration Board

The PICDEM.net demonstration board is an Inter-

net/Ethernet demonstration board using the

PIC18F452 microcontroller and TCP/IP firmware. The

board s upp orts a ny 40 -pin DI P de vic e tha t c onf orm s to

the standard pinout used by the PIC16F877 or

PIC18C452. This kit features a user friendly TCP/IP

stack, web server with HTML, a 24L256 Serial

EEPROM for Xmodem download to web pages into

Serial EEPROM, ICSP/MPLAB ICD 2 interface con-

nector, an Ethernet interface, RS-232 interface and a

16 x 2 LCD display. Also included is the book and

CD-ROM “TCP/IP Lean, Web Servers for Embedded

Systems,” by Jeremy Bentham

18.17 PICDEM 2 Plus

Demonstration Board

The PICDEM 2 Plus demonstration board supports

many 18, 28 and 40-pin microcontrollers, including

PIC16F87X and PIC18FXX2 devices. All the neces-

sary ha rdware and s oftware is included to run the dem-

onstration programs. The sample microcontrollers

provided with the PICDEM 2 demonstration board can

be programmed with a PRO MATE II device program-

mer, PICSTART Plus development programmer, or

MPLAB ICD 2 with a Universal Programmer Adapter.

The MPLAB I CD 2 and MPLAB ICE in-circuit emul ators

may also be used with the PICDEM 2 demonstration

board to test firmware. A prototype area extends the

circuitry for additional application components. Some

of the features include an RS-232 interface, a 2 x 16

LCD display, a piezo speaker , an o n-board temperatu re

sensor, four LEDs and sample PIC18F452 and

PIC16F877 Flash microcontrollers.

18.18 PICDEM 3 PIC16C92X

Demonstration Board

The PICDEM 3 demonstration board supports the

PIC16C923 and PIC16C924 in the PLCC package. All

the necessary hardware and software is included to run

the demonstration programs.

18.19 PICDEM 4 8/14/18-Pin

Demonstration Board

The PICDEM 4 can be used to demonstrate the capa-

bilities of the 8, 14 and 18-pin PIC16XXXX and

PIC18XXXX MCUs, including the PIC16F818/819,

PIC16F87/88, PIC16F62XA and the PIC18F1320

family of microcontrollers. PICDEM 4 is intended to

showcase the many features of these low pin count

parts, including LIN and Motor Control using ECCP.

Special provisions are made for low-power operation

with the supercapacitor circuit and jumpers allow

on-board hardware to be disabled to eliminate current

draw in this mode. Included on the demo board are pro-

visions for Crystal, RC or Canned Oscillator modes, a

five volt regulator for use with a nine volt wall adapter

or battery, DB-9 RS-232 interface, ICD connector for

programming via ICSP and development with MPLAB

ICD 2, 2 x 16 liquid crystal display, PCB footprints for

H-Bridge motor driver, LIN transceiver and EEPROM.

Also included are: header for expansion, eight LEDs,

four potentiometers, three push buttons and a proto-

typing are a. Inc lud ed with the kit is a PIC16F627A and

a PIC18F1 320. Tutorial fir mware is included alo ng with

the User’s Guide.

PIC16F946

18.20 PICDEM 17 Demonstration Board

The PICDEM 17 demonstration board is an evaluation

board that demonstrates the capabilities of several

Microchip microcontrollers, including PIC17C752,

PIC17C756A, PIC17C762 and PIC17C766. A pro-

gramme d sample i s included. The PR O MA TE I I device

programmer, or the PICSTART Plus development pro-

gramme r , can be used to reprogram the device for user

tailored application development. The PICDEM 17

demonstration board supports program download and

execution from external on-board Flash memory. A

generous proto typ e area is av ailab le for user hardw are

expansion.

18.21 PICDEM 18R PIC18C601/801

Demonstration Board

The PICDEM 18R demonstration board serves to assist

development of the PIC18C601/801 family of Microchip

microcontrollers. It provides hardware implementation

of both 8-bit Multiplexed/Demultiplexed and 16-bit

Memory modes. The board includes 2 Mb external

Flash memory and 128 Kb SRAM memory, as well as

serial EEPROM, allowing access to the wide range of

memory types supported by the PIC18C601/801.

18.22 PICDEM LIN PIC16C43X

Demonstration Board

The pow erfu l LI N hard w are a nd s of tw are kit inclu des a

series of boards and three PICmicro microcontrollers.

The small footprint PIC16C432 and PIC16C433 are

used as slaves in the LIN communication and feature

on-board LIN transceivers. A PIC16F874 Flash

microcontroller serves as the master. All three micro-

controllers are programmed with firmware to provide

LIN b us communication.

18.23 PICkitTM 1 Flash Starter Kit

A complete “development system in a box”, the PICkit

Flash Starter Kit includes a convenient multi-section

board for p rogramming, evaluation a nd development of

8/14-pin Flash PIC® microcontrollers. Powered via

USB, the board operates un der a simple Windows GUI.

The PICkit 1 Starter Kit includes the User ’s Guide (on

CD ROM), PICkit 1 tutorial software and code for

various applications. Also included are MPLAB® IDE

(Integrated Development Environment) software,

software and hardware “Tips ‘n Tricks for 8-pin Flash

PIC® Microcontrollers” Handbook and a USB interface

cable. Supports all current 8/14-pin Flash PIC

microcontrollers, as well as many future planned

devices.

18.24 PICDEM USB PIC16C7X5

Demonstration Board

The PICDEM U SB Demo ns trati on Board sho w s o f f th e

capabilities of the PIC16C745 and PIC16C765 USB

microcontrollers. This board provides the basis for

future USB products.

18.25 Evaluation and

Programming Tools

In additio n to the PICDEM seri es of circuits, Microchip

has a line of evaluation kits and demonstration software

for the se products.

•K

EELOQ evaluation and prog ram mi ng too ls for

Microchip’s HCS Secure Data Products

• CAN developers kit for automotive network

applications

• Analog design boards and filter design software

• PowerSmart bat tery charging evaluation/

calibration kits

•IrDA

® development kit

• microID development and rfLabTM development

software

• SEEVAL® desi gn er k it f or m emory ev al uat ion and

endurance calculations

• PICDEM MSC demo boards for Switching mode

power supply, high-power IR driver, delta sigma

ADC and flow rate sensor

Check the Microchip web page and the latest Product

Selector Guide for the complete list of demonstration

and evaluation kits.

PIC16F946

NOTES:

PIC16F946

19.0 ELECTRICAL SPECIFICATIONS

Absolute Maximum Ratings(†)

Ambient temperature under bias..........................................................................................................-40° to +125°C

Storage temperature........................................................................................................................ -65°C to +150°C

Volta ge on VDD with respect to VSS ................................................................................................... -0.3V to +6.5V

Volta ge on MCLR with respect to Vss(2) ........................................................................................... -0.3V to +13.5V

Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V)

Total powe r dissipation(1) ...................................................................................................................................1.0 W

Maximum curr ent out of VSS pin .....................................................................................................................300 mA

Maximum curr ent into VDD pin........................................................................................................................250 mA

Input clamp current, IIK (VI < 0 or VI > VDD)................................................................................................................±20 mA

Output clamp cur rent, IOK (Vo < 0 or Vo >VDD)..........................................................................................................±20 mA

Maximum output current sunk by any I/O pin....................................................................................................25 mA

Maximum output current sourced by any I/O pin ..............................................................................................25 mA

Maximum current sunk by all ports (combined) ..............................................................................................200 mA

Maximum current sourced by all ports (combined).........................................................................................200 mA

Note 1: Po wer dissi pa tion is c alcul ated as follows: PDIS = VDD x {IDD – ∑ IOH} + ∑ {(VDD – VOH) x IOH} + ∑(VOL x IOL).

2: V olt age spike s below VSS at the MCLR pin, ind ucing curren ts gre ater than 8 0 mA, may ca use latch-up . Thus,

a series resistor of 50-100 Ω should be used when applying a “low” level to the MCLR pin, rather tha n

pulling this pin direct ly to VSS.

† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the

device . This is a s tress rating on ly and func tional ope ration of the d evice at th ose or any ot her conditi ons abov e those

indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for

extended periods may affect device reliability.

PIC16F946

FIGURE 19-1: PIC16F946 VOLT AGE-FREQUENCY GRAPH, -40°C ≤ TA ≤ +125°C

5.5

2.0

3.5

2.5

3.0

4.0

4.5

5.0

FREQUENCY (MHZ)

VDD

(VOLTS)

Note 1: The shaded region indicates the permissible combinations of voltage and frequency.

81612 2010

PIC16F946

19.1 DC Characteris tics: PIC16F946-I (Industrial), PIC16F946-E (Extended)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Sym Characteristic Min Typ† Max Units Conditions

D001

D001C

D001D

VDD Supply Voltage 2.0

3.0

4.5

—

5.5

FOSC < = 4 MHz:

FOSC < = 10 MHz

FOSC < = 20 MHz

D002 VDR RAM Data Retention

Voltage(1) 1.5* — — V Device in Sleep mode

D003 VPOR VDD Start Voltage to

ensure internal Power-on

Reset signal

—VSS —VSee Section 16.3 “Power-on Reset” for

details.

D004 SVDD VDD Rise Rate to ensure

internal Power-on Reset

signal

0.05

*— — V/ms See Section 16.3 “Power-on Reset” for

details.

D005 VBOR Brown-out Reset —2.1— V

* These parameters are characterized but not tested.

† Data in “Typ” c ol umn is at 5.0V, 25°C u nle ss ot herw i se st a t ed . The se p ar am eters are for des ig n gu idance

only and are not tested.

Note 1: This is the limit to which VDD can be lowered in Sleep mode without losing RAM data.

PIC16F946

19.2 DC Characteri stics: PIC16F946-I (Industria l)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Device Char ac teri s tics Min Typ† Ma x Units Conditions

VDD Note

D010 Supply Current (IDD)(1, 2 ) —8TBDμA2.0FOSC = 32 kHz

LP Oscillator mode

—11TBDμA3.0

—33TBDμA5.0

D011 — 110 TBD μA2.0F

OSC = 1 MHz

XT Oscill ator mode

—190TBDμA3.0

—330TBDμA5.0

D012 — 220 TBD μA2.0F

OSC = 4 MHz

XT Oscill ator mode

—370TBDμA3.0

— 0.6 TBD mA 5.0

D013 — 70 TBD μA2.0F

OSC = 1 MHz

EC Oscillator mode

—140TBDμA3.0

—260TBDμA5.0

D014 — 180 TBD μA2.0F

OSC = 4 MHz

EC Oscillator mode

—320TBDμA3.0

—500TBDμA5.0

D015 — 5 TBD μA2.0F

OSC = 31 kHz

INTOSC mode

—14TBDμA3.0

—30TBDmA5.0

D016 — 340 TBD μA2.0F

OSC = 4 MHz

INTOSC mode

—500TBDμA3.0

— 0.8 TBD mA 5.0

D017 — 180 TBD μA2.0F

OSC = 4 MHz

EXTRC mode

—320TBDμA3.0

—580TBDμA5.0

D018 — 2.1 TBD mA 4.5 FOSC = 20 MHz

HS Oscillator mode

— 3.0 TBD mA 5.0

Legend: TBD = To Be Determined

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested.

Note 1: The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square

wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD; M CLR = VDD; WDT disabled.

2: The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O

pin loa din g an d s w itc hi ng ra te, os cil la tor ty pe , in tern al code e xe cut ion p attern an d te mp erature, als o h av e

an impact on the current consumption.

3: The peri pheral cu rren t is the sum of the base IDD or IPD and the additional current consumed when this

peripheral is enabled. The peri pheral Δ current can be determined by subtracting the base IDD or IPD

current from this limit. Max values should be used when calculating total current consumption.

4: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is

measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD.

PIC16F946

D020 Power-down Base

Current (IPD)(4) —0.1TBDμA 2.0 WDT , BOR, Comparators, VREF and

T1OSC disabled

—0.5TBDμA3.0

—0.75TBDμA5.0

D021 — 0.6 TBD μA 2.0 WDT Current

—1.8TBDμA3.0

—8.4TBDμA5.0

D022 — 58 TBD μA 3.0 BOR Current

—75TBDμA5.0

D023 — 35 TBD μA 2.0 Comparator Current(3)

—65TBDμA3.0

—130TBDμA5.0

D024 — 40 TBD μA2.0CV

REF Current

— 50.5 TBD μA3.0

—80TBDμA5.0

D025 — 2.1 TBD μA 2.0 T1OSC Current

—2.5TBDμA3.0

—3.4TBDμA5.0

D026 — 1.2 TBD nA 3.0 A/D Current

—0.0022TBD μA5.0

19.2 DC Characteris tics: PIC16F946-I (Industrial) (Continued)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Device Char ac teri s tics Min Typ† Ma x Units Conditions

VDD Note

Legend: TBD = To Be Determined

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested.

Note 1: The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square

wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD; M CLR = VDD; WDT disabled.

2: The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O

pin load in g an d s w itc hi ng ra te, os cil la tor ty pe , in ternal cod e e xe cut ion p attern an d te mperature, also h av e

an impact on the current consumption.

3: The peri pheral cu rren t is the sum of the base IDD or IPD and the additional current consumed when this

peripheral is enabled. The peri pheral Δ current can be determined by subtracting the base IDD or IPD

current from this limit. Max values should be used when calculating total current consumption.

4: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is

measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD.

PIC16F946

19.3 DC Characteristics: PIC16F946-E (Extended)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +125°C for extended

Param

No. Device Characteristics Min Typ† Max Units Conditions

VDD Note

D010E Supply Current (IDD)(1, 2) —8TBDμA2.0FOSC = 32 kHz

LP Oscillator mode

—11 TBD μA3.0

—33TBDμA5.0

D011E — 110 TBD μA2.0F

OSC = 1 MHz

XT Oscillator mode

— 190 TBD μA3.0

— 330 TBD μA5.0

D012E — 220 TBD μA2.0F

OSC = 4 MHz

XT Oscillator mode

— 370 TBD μA3.0

— 0.6 TBD mA 5.0

D013E — 70 TBD μA2.0F

OSC = 1 MHz

EC Oscillator mode

— 140 TBD μA3.0

— 260 TBD μA5.0

D014E — 180 TBD μA2.0F

OSC = 4 MHz

EC Oscillator mode

— 320 TBD μA3.0

— 500 TBD μA5.0

D015E — 5 TBD μA2.0F

OSC = 31 kHz

INTOSC mode

—14TBDμA3.0

—30TBDmA5.0

D016E — 340 TBD μA2.0F

OSC = 4 MHz

INTOSC mode

— 500 TBD μA3.0

— 0.8 TBD mA 5.0

D017E — 180 TBD μA2.0F

OSC = 4 MHz

EXTRC mode

— 320 TBD μA3.0

— 580 TBD μA5.0

D018E — 2.1 TBD mA 4.5 FOSC = 20 MHz

HS Oscillator mode

— 3.0 TBD mA 5.0

Legend: TBD = To Be Determined

† Data in ‘Typ’ colum n is at 5.0 V, 25°C unles s othe rw is e st a ted. These p ara meters are for de sig n guidance

only and are not tested.

Note 1: The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square

wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD; M CLR = VDD; WDT disabled.

2: The suppl y c urrent is main ly a func tio n of the oper atin g vo lt a ge and frequen cy. Other fac tors , suc h as I/O

pin load ing and swi tching rate, os cilla tor type , interna l code execu tion p attern and tem peratu re, al so hav e

an impact on the current consumption.

3: The peri pheral cu rren t is the sum of the base IDD or IPD and the additional current consumed when this

peripheral is enabled. The peri pheral Δ current can be determined by subtracting the base IDD or IPD

current from this limit. Max values should be used when calculating total current consumption.

4: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is

measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD.

PIC16F946

D020E Power-dow n Base

Current (IPD)(4) —0.1TBDμA 2.0 WDT, BOR, Comparator s, VREF

and T1OSC disabled

—0.5TBDμA3.0

—0.75TBDμA5.0

D021E — 0.6 TBD μA 2.0 WDT Current

—1.8TBDμA3.0

—8.4TBDμA5.0

D022E — 58 TBD μA 3.0 BOR Current

—75TBDμA5.0

D023E — 35 TBD μA 2.0 Comparator Current(3)

—65TBDμA3.0

— 130 TBD μA5.0

D024E — 40 TBD μA2.0CV

REF Current

—50.5TBDμA3.0

—80TBDμA5.0

D025E — 2.1 TBD μA 2.0 T1OSC Current

—2.5TBDμA3.0

—3.4TBDμA5.0

D026E — 1.2 TBD μA 3.0 A/D Current(3)

— 0.0022 TBD μA5.0

19.3 DC Characteristics: PIC16F946-E (Extended) (Continued)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +125°C for extended

Param

No. Device Characteristics Min Typ† Max Units Conditions

VDD Note

Legend: TBD = To Be Determined

† Data in ‘Typ’ colum n is at 5.0 V, 25°C unles s othe rw is e st a ted. These p ara meters are for de sig n guidance

only and are not tested.

Note 1: The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square

wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD; M CLR = VDD; WDT disabled.

2: The suppl y c urrent is main ly a func tio n of the operating voltage an d frequency. Other fac tors , suc h as I/O

pin load ing and swi tching rate, os cilla tor type , interna l code execu tion p attern and tem peratu re, al so hav e

an impact on the current consumption.

3: The peri pheral cu rren t is the sum of the base IDD or IPD and the additional current consumed when this

peripheral is enabled. The peri pheral Δ current can be determined by subtracting the base IDD or IPD

current from this limit. Max values should be used when calculating total current consumption.

4: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is

measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD.

PIC16F946

19.4 DC Characteristics: PIC16F946-I (Industrial), PIC16F946-E (Extended)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for indu strial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Sym Characteristic Min Typ† Max Units Conditions

VIL Input Low Voltage

I/O port:

D030 with TTL buffer VSS —0.8V4.5V ≤ VDD ≤ 5.5V

D030A VSS —0.15 VDD V Otherwise

D031 with Schmitt Trigger buffer V SS — 0.2 VDD V Entire range

D032 MCLR, OSC1 (RC mode) VSS — 0.2 VDD V

D033 OSC1 (XT and LP modes)(1) VSS —0.3V

D033A OSC1 (HS mode)(1) VSS — 0.3 VDD V

D034 I2C ™ m ode VSS —0.3VDD VEntire VDD Range

VIH Input High Voltage

I/O port: —

D040

D040A with TTL buffer 2.0

(0.25 VDD +

0.8)

—

—VDD

VDD V

V4.5V ≤ VDD ≤ 5.5V

Otherwise

D041 with Schm itt Trigger buffer 0.8 VDD —VDD V En tir e ra nge

D042 MCLR 0.8 V DD —VDD V

D043 OSC1 (XT and LP modes) 1.6 — VDD V(Note 1 )

D043A OSC1 (HS mode) 0.7 VDD —VDD V(No te 1)

D043B OSC1 (RC mo de) 0.9 VDD —VDD V

D044 I2C mode 0.7VDD —VDD VEntire VDD Range

D070 IPUR PORTB Weak Pull-u p C ur r ent 50* 250 400 * μAVDD = 5.0V, VPIN = VSS

IIL Input Leakag e Cur re nt (2)

D060 I/O port — ± 0.1± 1μAVSS ≤ VPIN ≤ VDD,

Pin at high -im pe dance

D061 MCLR(3) —± 0.1± 5μAVSS ≤ VPIN ≤ VDD

D063 OSC1 — ± 0.1± 5μAVSS ≤ VPIN ≤ VDD, XT, HS and

LP OSC confi gur ation

VOL Output Low Voltage

D080 I/O port — — 0 .6 V IOL = 8.5 mA, VDD = 4.5V (Ind . )

D083 OSC2/C LKO ( R C m ode) — — 0 .6 V IOL = 1.6 mA, VDD = 4.5V (Ind . )

IOL = 1.2 mA, VDD = 4.5V (Ext.)

VOH Output High Voltage

D090 I/O port VDD – 0.7 — — V IOH = -3.0 mA, VDD = 4.5V (In d .)

D092 OSC2/C LKO ( R C m ode) VDD – 0.7 — — V IOH = -1.3 mA, VDD = 4.5V (In d .)

IOH = - 1. 0 mA , V DD = 4.5V (Ext.)

* These para m et er s ar e characterized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C un le ss otherwi se sta te d. T hes e pa ra m et er s ar e f or d esi gn guidance only

and ar e not teste d.

Note 1: In RC oscillator config ur at io n, the OSC1/CLKI pin is a Schmitt Trig ger input. It is not recommended to use an

external clock in RC mode.

2: Nega tive current is def i ned as curren t s our ced by the pin.

3: The lea kage current on the MCLR pi n i s str ongly dependent on th e app l ie d voltage level. The specifie d le vels

repre sent norm al operating con d itions. Higher leakag e current may be measured at different in put vol tag es.

PIC16F946

Capacitive Loading Specs

on Output Pins

D100 COS

C2 OSC2 pin — — 15* pF In XT, HS and LP modes

when ex ternal clock i s used to

drive OSC1

D101 CIO All I/O pins — — 50* pF

Data EEPROM Memory

D120 EDByte Endurance 100K 1M — E/W -40°C ≤ TA ≤ +85°C

D120A EDByte Endurance 10K 100K — E/W +85°C ≤ TA ≤ +125°C

D121 VDRW VDD for Read/Write VMIN — 5.5 V Using EECON1 to read/write

VMIN = Minimum operating

voltage

D122 TDEW Erase/Write Cycle Time — 5 6 ms

D123 TRETD Characteristic Retention 40 — — Year Provided no other specifica-

tions are violated

D124 TREF Number of Total Erase/Write

Cycl es bef ore Refres h (2) 1M 10M — E/W -40°C ≤ TA ≤ +85°C

Program Flash Memory

D130 EPCell Endurance 10K 100K — E/W -40°C ≤ TA ≤ +85°C

D130A EDCell Endurance 1K 10K — E/W +85°C ≤ TA ≤ +125°C

D131 VPR VDD for Read VMIN —5.5VVMIN = Minimum operating

voltage

D132 VPEW VDD for Erase/Write 4.5 — 5.5 V

D133 TPEW Erase/Write cycle time — 2 2.5 ms

D134 TRETD Characteristic Retention 40 — — Year Provided no other specifica-

tions are violated

19.4 DC Characteristics: PIC16F946-I (Industrial), PIC16F946-E (Ext ended) (Continued)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Sym Characteristic Min Typ† Max Units Conditions

* These para m et er s ar e characterized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C un le ss otherwi se sta te d. T hes e pa ra m et er s ar e f or d esi gn guidance only

and ar e not teste d.

Note 1: In RC oscillator config ur at io n, the OSC1/CLKI pin is a Schmitt Trig ger input. It is not recommended to use an

external clock in RC mode.

2: Nega tive current is def i ned as curren t s our ced by the pin.

3: The lea kage current on the MCLR pi n i s str ongly dependent on th e app l ie d voltage level. The specif ied le vels

repre sent norm al operating con d itions. Higher leakag e current may be measured at different in put vol tag es.

PIC16F946

19.5 Timing Parameter Symbology

The timing parameter symbols have been created with

one of the following formats:

FIGURE 19-2: LOAD CONDITIONS

1. TppS2ppS

2. TppS

TF Frequency T Time

Lowercase letters (pp) and their meanings:

cc CCP1 osc OSC1

ck CLKO rd RD

cs CS rw RD or WR

di SDI sc SCK

do SDO ss SS

dt Data in t0 T0CKI

io I/O port t1 T1CKI

mc MCLR wr WR

Uppe rcase letters and their meanings :

SFFall PPeriod

HHigh RRise

I Invalid (High-impedance) V Valid

L Low Z High-impedance

PIN PIN

RL= 464Ω

CL= 50 pF for all pins

15 pF for OSC2 output

Load Cond ition 1 Load Condition 2

Legend:

PIC16F946

19.6 AC Characteristics: PIC16F946 (Industrial, Extended)

FIGURE 19-3: EXTERNAL CLOCK TIMING

TABLE 19-1: EXTERNAL CLOCK T IMING REQUIREMENTS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

FOSC External CLKI Frequency(1) DC — 37 kHz LP Oscillator mode

DC — 4 MHz XT Oscillator mode

DC — 20 MHz HS Oscillator mode

DC — 20 MHz EC Oscillator mode

Oscillator Frequency(1) 5 — 37 kHz LP Oscillator mode

— 4 — MHz INTOSC mode

DC — 4 MHz RC Oscill ator mode

0.1 — 4 MHz XT Oscillator mode

1 — 20 MHz HS Oscillator mode

1TOSC External CLKI Period(1) 27 — ∞μs LP Oscillator mode

50 — ∞Ns HS Oscillator mode

50 — ∞ns EC Oscillato r mode

250 — ∞ns XT Oscillator mode

Oscillator Period(1) 27 200 μs LP Oscillator mode

— 250 — ns INTOSC mode

250 — — ns RC Oscillator mode

250 — 10,000 ns XT Oscillat or mode

50 — 1,000 ns HS Oscillato r mode

CY Instructi on C ycle Time(1) 200 TCY DC ns TCY = 4/FOSC

3TosL,

TosH External CLKI (OSC1) High

External CLKI Low 2* — — μs LP oscillator, TOSC L/H duty cycle

20* — — ns HS oscillator, TOSC L/H duty cycle

100 * — — ns XT oscillator, TOSC L/H duty cycle

4TosR,

TosF External CLKI Rise

External CLKI Fall — — 50* ns LP oscillator

— — 25* ns XT oscillator

— — 15* ns HS oscillator

* These parameters are characterized but not tested.

† D ata in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values

are based on charac teri za tion data for that p articula r osci lla tor type under st andard operati ng con di tions

with the device executing code. Exceeding these specified limits may result in an unstable oscillator

operation and/or higher than expected current consumption. All devices are tested to operate at ‘min’

values with an external clock applied to OSC1 pin. When an external clock input is used, the ‘max’ cycle

time limit is ‘DC’ (no clock) for all devices.

OSC1

CLKO

Q4 Q1 Q2 Q3 Q4 Q1

3344

PIC16F946

TABLE 19-2: PRECISION INTERNAL OSCILLATOR PARAMETERS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Freq.

Tolerance Min Typ† Max Units Conditions

F10 FOSC Internal Calibrated

INTOSC Frequency(1) ±1% — 8.00 TBD MHz VDD and Temperature TBD

±2% — 8.00 TBD MHz 2.5V ≤ VDD ≤ 5.5V

0°C ≤ TA ≤ +85°C

±5% — 8.00 TBD MHz 2.0V ≤ VDD ≤ 5.5V

-40°C ≤ TA ≤ +85°C (Ind.)

-40°C ≤ TA ≤ +125°C (Ext.)

F14 TIOSC

ST Oscillator Wake-up from

Sleep Start-up Time* ——TBDTBDμsVDD = 2.0V, -40°C to +85°C

——TBDTBDμsVDD = 3.0V, -40°C to +85°C

——TBDTBDμsVDD = 5.0V, -40°C to +85°C

Legend: TBD = To Be Determined

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

Note 1: To ensure these oscillator frequency tolerances, VDD and VSS must be capacitively decoupled as close to

the device as possible. 0.1 uF and 0.01 uF values in parallel are recommended.

PIC16F946

FIGURE 19-4: CLKO AND I/O TIMING

TABLE 19-3: CLKO AND I/O TIMING REQUIREMENTS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

10* TOSH2CKLOSC1↑ to CLOUT↓ — 75 200 ns (Note 1)

11* TOSH2CKHOSC1↑ to CLOUT↑ — 75 200 ns (Note 1)

12* TCKR CLKO Rise Time — 35 100 ns (Note 1)

13* TCKF CLKO Fall Time — 35 100 ns (Note 1)

14* TCKL2IOVCLKO↓ to Port Out Valid — — 0.5 TCY + 20 ns (Note 1)

15* TIOV2CKH Port In Valid before CL KO↑ TOSC + 200 ns — — n s (Note 1)

16* TCKH2IOI Port In Hold after CLKO↑ 0 — — ns (Note 1)

17* TOSH2IOVOSC1↑ (Q1 cycle) to Port Out Valid — 50 150* ns

——300ns

18* TOSH2IOIOSC1↑ (Q2 cycle) to Port

Input Invalid (I/O in hold time) 3.0-5.5V 100 — — ns

2.0-5.5V 200 — — ns

19* TIOV2OSH Port Input Valid to OSC1↑

(I/O in setup time) 0——ns

20* TIOR Port Output Rise Time 3.0-5.5V — 10 40 ns

2.0-5.5V — — 145

21* TIOF Port Output Fall Time 3.0-5.5V — 10 40 ns

2.0-5.5V — — 145

22* TINP INT Pin High or Low Time 25 — — ns

23* TRBP PORTA change INT High or Low Time TCY ——ns

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated.

Note 1: Measurements are taken in RC mode where CLKO output is 4 x TOSC.

OSC1

CLKO

I/O PI N

(Input)

I/O PI N

(Output)

Q4 Q1 Q2 Q3

20, 21

19 18

Old Value New Value

PIC16F946

FIGURE 19-5: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND

POWER-UP TIMER TIMING

FIGURE 19-6: BROWN-OUT RESET TIMING AND CHARACTERISTICS

VDD

MCLR

Internal

POR

PWRT

Time-out

OSC

Time-out

Internal

Reset

Watchdog

Timer

Reset

I/O Pins

BVDD

Reset (due to BOR)

VDD

(Device in Brown-out Reset)

(Device not in Brown-out Reset)

64 MS Time-out(1)

Note 1: 64 ms delay only if PWRTE bit in the Configuration Word is programmed to ‘0’.

PIC16F946

TABLE 19-4: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER

AND BROWN-OUT RESET REQUIREMENTS

FIGURE 19-7: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

30 TMCLMCLR Pulse Width (low) 2

11 —

18 —

24 μs

ms VDD = 5V, -40°C to +85°C

Extended temperature

31 TWDT Watchdog T im er Time-out

Period (No Prescaler) 10

10 17

17 25

30 ms

ms VDD = 5V, -40°C to +85°C

Extended temperature

32 TOST Oscill ati on Start-up Timer

Period — 1024 TOSC ——TOSC = OSC1 period

33* TPWRT Powe r-up Timer Period 28*

TBD 64

TBD 132*

TBD ms

ms VDD = 5V, -40°C to +85°C

Extended Temperature

34 TIOZ I/O High-impedance from

MCLR Low or Watchdog Timer

Reset

——2.0μs

BVDD Brown-out Reset Voltage 2.025 — 2.175 V

35 TBOR Brown-out Reset Pulse Width 100* — — μsVDD ≤ BVDD (D005)

Legend: TBD = To Be Determined

* These parameters are characterized but not tested.

† D ata in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

T0CKI

T1CKI

40 41

45 46

47 48

TMR0 o r

TMR1

PIC16F946

TABLE 19-5: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS

FIGURE 19-8: USART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING

Param

No. Sym Characteristic Min Typ† Max Units Conditions

40* TT0H T0CKI High Pulse Width No Prescaler 0.5 TCY + 20 — — ns

With Prescaler 10 — — ns

41* TT0L T0CKI Low Pulse Width No Prescaler 0.5 TCY + 20 — — ns

With Prescaler 10 — — ns

42* TT0P T0CKI Period Greater of:

20 or TCY + 40

— — ns N = prescale

valu e (2 , 4 , ...,

256)

45* TT1H T1CKI High

Time Synchronous, No Prescaler 0.5 TCY + 20 — — ns

Synchronous,

with Prescaler 3.0-5.5V 15 — — ns

2.0-5.5V 25 — — ns

Asynchronous 3.0-5.5V 30 — — ns

2.0-5.5V 50 — — ns

46* TT1L T1CKI Low

Time Synchronous, No Prescaler 0.5 TCY + 20 — — ns

Synchronous,

with Prescaler 3.0-5.5V 15 — — ns

2.0-5.5V 25 — — ns

Asynchronous 3.0-5.5V 30 — — ns

2.0-5.5V 50 — — ns

47* TT1P T1CKI Input

Period Synchronous 3.0-5.5V GREATER OF:

30 OR TCY + 40

— — ns N = prescale

value (1, 2, 4, 8)

2.0-5.5V 50 OR TCY + 40

N ——ns

Asynchronous 3.0-5.5V 60 — — ns

2.0-5.5V 100 — — ns

FT1 Timer1 oscillator input frequency range

(oscillator enabled by setting bit T1OSCEN) DC — 37* kHz

48 TCKEZTMR1 Delay from external clock edge to timer

increment 2 TOSC*—7 TOSC*—

* Thes e parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are not

tested.

Note: Refer to Figu re 19- 2 for l oad condi tions.

121 121

120 122

RC6/TX/CK

RC7/RX/DT/

SCK/SCL/SEG9

SDI/SDA/SEG8

PIC16F946

TABLE 19-6: USART SYNCHRONOUS TRANSMISSION REQUIREMENTS

FIGURE 19-9: USART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING

TABLE 19-7: USART SYNCHRONOUS RECEIVE REQUIREMENTS

FIGURE 19-10: CAPTURE/COMPARE/PWM TIMINGS

Standard Operating Conditions (unless otherwise stated)

Operati ng Temperatu re -40°C ≤ TA ≤ +125°C

Param.

No. Symbol Characteristic Min Max Units Conditions

120 TCKH2DT

VSYNC XMIT (Master and Slave)

Clock high to data-out valid 3.0-5.5V — 80 ns

2.0-5.5V — 100 ns

121 TCKRF Clock out rise time and fall time

(Master mode) 3.0-5.5V — 45 ns

2.0-5.5V — 50 ns

122 TDTRF D ata-out rise time and fall time 3.0-5.5V — 45 ns

2.0-5.5V — 50 ns

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param.

No. Symbol Characteristic Min Max Units Conditions

125 TDTV2CKL SYNC RCV (Master and Slave)

Data-hold before CK ↓ (DT hold time) 10 — ns

126 TCKL2DTL Data-hold after CK ↓ (DT hold time) 15 — ns

Note: Refer to Figure 19-2 for load conditions.

125

126

RC6/TX/CK

SCK/SCL/SEG9

RC7/RX/DT/

SDI/SDA/SEG8

Note: Refer to Figure 19-2 for load conditions.

(Capture mode)

50 51

53 54

CCP1/CCP2

(Compare mode)

CCP1/CCP2

PIC16F946

TABLE 19-8: CAPTURE/COMPARE/PWM REQUIREMENTS

TABLE 19-9: COMPARATOR SPECIFICATIONS

TABLE 19-10: COMPARATOR VOLTAGE REFERENCE SPECIFICATIONS

Param.

No. Sym Characteristic Min Typ† Max Units Conditions

50* TCCL CCP1

input low tim e No Prescaler 0.5TCY + 5 — — ns

With Presca ler 3.0-5.5V 10 — — ns

2.0-5.5V 20 — — ns

51* TCCHCCP1

input high time No Prescaler 0.5TCY + 5 — — ns

With Presca ler 3.0-5.5V 10 — — ns

2.0-5.5V 20 — — ns

52* TCCPCCP1 input period 3TCY + 40

N— — ns N = prescale

value (1,4 or 16)

53* TCCR CCP1 ou tput fall time 3.0-5.5V — 1 0 25 ns

2.0-5.5V — 25 50 ns

54* TCCF CCP1 output f all time 3.0-5.5V — 10 25 ns

2.0-5.5V — 25 45 ns

* These parameters are characterized but not tested.

† Data in “Typ” col umn i s at 5V, 25°C unless oth erwis e st ated. Paramet ers are for desi gn gui dance only and

are not tested.

Comparator Specifications Standard Operating Conditi ons (unle ss otherwis e stated)

Operating temperature -40°C ≤ TA ≤ +125°C

Sym Characteristics Min Typ Max Units Comments

VOS Input Offset Voltage — ±5.0 ±10 mV

VCM Input Common Mode Voltage 0 — VDD – 1.5 V

CMRR Common Mode Rejection Ratio +55* — — db

TRT Response Time(1) — 150 400* ns

TMC2COV Comparator Mode Change to

Output Valid —— 10* μs

* These parameters are characterized but not tested.

Note 1: Respons e time mea sured w ith on e comp arator i nput at (VDD – 1. 5)/2 wh ile the other in put trans itions from

VSS to VDD – 1.5V.

Voltage Referen ce Spec ifica tions Standard Operating Conditions (unless otherwise stated)

Operating temperature -40° C ≤ TA ≤ +125°C

Sym. Characteristics Min Typ Max Units Comments

Resolution —

—VDD/24*

VDD/32 —

—LSb

LSb Low Range (VRR = 1)

High Range (VRR = 0)

Absolute Accuracy —

——

—±1/4*

±1/2* LSb

LSb Low Range (VRR = 1)

High Range (VRR = 0)

Unit Resistor Value (R) — 2K* — Ω

Settling Time(1) ——10*μs

* These parameters are characterized but not tested.

Note 1: Settling time measured while VRR = 1 and VR<3:0> transitions from ‘0000’ to ‘1111’.

PIC16F946

TABLE 19-11: PIC16F946 PLVD CHARACTERISTICS:

DC CHARACTERISTICS Standard Operating Conditions (unle ss otherw is e stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Operating Voltage VDD Range 2.0V-5.5V

Sym. Characteristic Min Typ† Max Units Conditions

VPLVD PLVD

Voltage LVDL<2:0> = 000 TBD 1.9 TBD V

TBD TBD 2.0 TBD V

TBD TBD 2.1 TBD V

TBD TBD 2.2 TBD V

TBD TBD 2.3 TBD V

TBD TBD 4.0 TBD V

TBD TBD 4.2 TBD V

TBD TBD 4.5 TBD V

Legend: TBD = To Be Determined

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested.

PIC16F946

FIGURE 19-11: SPI™ MASTER MODE TIMING (CKE = 0, SMP = 0)

FIGURE 19-12: SPI™ MASTER MODE TIMING (CKE = 1, SMP = 1)

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

73 74

75, 76

MSb LSb

bit 6 - - - - - -1

MSb In LSb In

bit 6 - - - -1

Note: Refer to Figure 19-2 for load conditions.

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

75, 76

MSb

MSb In

bit 6 - - - - - -1

LSb In

bit 6 - - - -1

LSb

Note: Refer to Figure 19-2 for load conditions.

PIC16F946

FIGURE 19-13: SPI™ SLAV E MODE TIMING (CKE = 0)

FIGURE 19-14: SPI™ SLAV E MODE TIMING (CKE = 1)

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

73 74

75, 76 77

MSb LSb

bit 6 - - - - - -1

MSb In bit 6 - - - -1 LS b In

Note: Refer to Figure 19-2 for load conditions.

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

75, 76

MSb bit 6 - - - - - -1 LSb

MSb In bit 6 - - - -1 LSb In

Note: Refer to Figure 19-2 for load conditions.

PIC16F946

TA BLE 19-12: SPI™ MODE REQUIREMENTS

FIGURE 19-15 : I2C™ BUS START/STOP BITS TIMING

Param

No. Symbol Characteristic Min Typ† Max Units Conditions

70* TSSL2SCH,

TSSL2SCLSS↓ to SCK↓ or SCK↑ input TCY ——ns

71* TSCH SCK input high time (Slave mode) TCY + 20 — — ns

72* TSCL SCK input low time (Slave mode) TCY + 20 — — ns

73* TDIV2SCH,

TDIV2SCLSetup time of SDI data input to SCK edge 100 — — ns

74* TSCH2DIL,

TSCL2DILHold time of SDI data input to SCK edge 100 — — ns

75* TDOR SDO data output rise time 3.0-5.5V — 10 25 ns

2.0-5.5V — 25 50 ns

76* TDOF SDO data output fall time — 10 25 ns

77* TSSH2DOZSS↑ to SDO output high-impedance 10 — 50 ns

78* TSCR SCK output rise time

(Master mode) 3.0-5.5V — 10 25 ns

2.0-5.5V — 25 50 ns

79* TSCF SCK output fall time (Master mode) — 10 25 ns

80* TSCH2DOV,

TSCL2DOVSDO data output valid after

SCK edge 3.0-5.5V — — 50 ns

2.0-5.5V — — 145 ns

81* TDOV2SCH,

TDOV2SCLSDO data output setup to SCK edge TCY ——ns

82* TSSL2DOV SDO data output valid after SS↓ edge — — 50 ns

83* TSCH2SSH,

TSCL2SSHSS ↑ after SCK edge 1.5TCY + 40 — — ns

* These parameters are characterized but not tested.

† Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

Note: Refer to Figure 19-2 for load conditions.

SCL

SDA

Start

Condition Stop

Condition

PIC16F946

TABLE 19-13: I2C™ BUS STAR T/STOP BITS REQUIREMENTS

FIGURE 19-16 : I2C™ BUS DATA TIMING

Param

No. Symbol Characteristic Min Typ Max Units Conditions

90* TSU:STA Start condition 100 kHz mode 4700 — — ns Only relevant for Repeated

Star t condition

Setup time 400 kHz mode 600 — —

91* THD:STA Start condition 100 kHz mode 4000 — — ns After this period, the first

clo ck pulse is generated

Hold time 400 kHz mode 600 — —

92* TSU:STO Stop condition 100 kHz mode 4700 — — ns

Setup time 400 kHz mode 600 — —

93 THD:STO Stop condition 100 kHz mode 4000 — — ns

Hold time 400 kHz mode 600 — —

* These parameters are characterized but not tested.

Note: Refer to Figure 19-2 for load conditions.

91 92

100 101

103

106 107

109 109 110

102

SCL

SDA

Out

PIC16F946

TABLE 19-14: I2C™ BUS DATA REQUIREMENTS

Param.

No. Symbol Characteristic Min Max Units Conditions

100* THIGH Clock high time 100 kHz mode 4.0 — μs Device must operate at a

minimum of 1.5 MHz

400 kHz mode 0.6 — μs Device must operate at a

minimum of 10 MHz

SSP Module 1.5TCY —

101* TLOW Clock low time 100 kHz mode 4.7 — μs Device must operate at a

minimum of 1.5 MHz

400 kHz mode 1.3 — μs Device must operate at a

minimum of 10 MHz

SSP Module 1.5TCY —

102* TRSDA and SCL rise

time 100 kHz mode — 1000 ns

400 kHz mode 20 + 0.1CB300 ns CB is specified to be from

10-400 pF

103* TFSDA and SCL fall

time 100 kHz mode — 300 ns

400 kHz mode 20 + 0.1CB300 ns CB is specified to be from

10-400 pF

90* TSU:STA Start condition

setup time 100 kHz mode 4.7 — μs Only relevant for

Repeated Start condition

400 kHz mode 0.6 — μs

91* THD:STA Start condition hold

time 100 kHz mode 4.0 — μs After this period the first

clock pulse is generated

400 kHz mode 0.6 — μs

106* THD:DAT Data input hold time 100 kHz mode 0 — ns

400 kHz mode 0 0.9 μs

107* TSU:DAT Data input setup

time 100 kHz mode 250 — ns (Note 2)

400 kHz mode 100 — ns

92* TSU:STO Stop condition

setup time 100 kHz mode 4.7 — μs

400 kHz mode 0.6 — μs

109* TAA Output valid from

clock 100 kHz mode — 3500 ns (Note 1)

400 kHz mode — — ns

110* TBUF Bus free time 100 kHz mode 4.7 — μs T im e the bu s must be free

before a new transmission

can start

400 kHz mode 1.3 — μs

CBBus capacitive loading — 400 pF

* These parameters are characterized but not tested.

Note 1: As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region

(min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions.

2: A Fast mode (400 kHz) I2C bus de vice can be used in a Standard mode (10 0 kHz) I 2C bus system, but the

requiremen t TSU:DAT ≥ 25 0 ns mus t the n be m et. Th is will auto maticall y be the c as e if the dev ic e do es n ot

stretch the low period of the SCL signal. If such a device does stretch the low period of the SCL signal, it

must outpu t the nex t da ta bit to the SDA l ine TR max. + TSU:DAT = 1000 + 250 = 12 50 ns (a cc ord ing to th e

Standard mode I2C bus specification), b efore the SCL li ne is released.

PIC16F946

TABLE 19-15: PIC16F946 A/D CONVERTER CHARACTERISTICS:

FIGURE 19-17: PIC16F946 A/D CONVERSION TIMING (NORMAL MODE)

Standard O perating Co ndi tions (unless o th erwise stated)

Operat i ng Tempera tu re -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

A01 NRResolution — — 10 bits bi ts

A03 EIL Integral Error — — <±1LSbVREF = 5.0V

A04 EDL Dif ferential Error — — <±1 LSb No missing codes to 10 bits

VREF = 5.0V

A06 EOFF Offset Error — — <±1LSbVREF = 5.0V

A07 EGN Gain Error — — <±1LSbVREF = 5.0 V

A10 — Monotonicity — assured(1) ——VSS ≤ VAIN ≤ VREF+

A20 VREF Referenc e Voltage

(VREF+ – VREF-) 2.5 — VDD V Ful l 1 0- bi t ac curacy

A21 VREF+ Refer ence Voltage High VDD – 2. 5V — VDD + 0. 3V V

A22 VREF- Referenc e Voltage Low VSS – 0.3V — VREF+ -2V V

A25 VAIN Analog Input Voltage VSS – 0.3V — VREF+ +0. 3V V

A30 ZAIN Recommended Imped-

ance of Ana lo g Voltage

Source

—— 10kΩ

A50 IREF VREF Inp ut Current (2) —— ±5

±150 μA

μADuring VAIN acquisition.

During A/D conversion cycle.

* These para m et er s ar e characterized but not tested.

† Data in ‘T yp’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and

are no t tested.

Note 1: The A/ D conversi on r esult neve r de cr eases with an increas e in th e input voltage and has no m i ssing codes.

2: VREF+ current is from RA3/AN3/C1+/VREF+/SEG 15 pi n or VDD, whiche ver is sele ct ed as the VREF+ source.

VREF- current is from R A 2 /AN2/C2+/VREF-/COM2 pin or VSS, whichever is sel ected as the VREF- source.

131

130

132

BSF ADCON0, GO

A/D CLK

A/D DATA

ADRES

ADIF

SAMPLE

OLD_DATA

SAMPLING STOPPED

DONE

NEW_DATA

987 3210

Note 1: If the A /D clock sourc e is selected as RC, a time of TCY is added before the A/D clock starts. This allows the

SLEEP instruction to be executed.

1 TCY

134 (TOSC/2)(1)

1 TCY

PIC16F946

TABLE 19-16: PIC16F946 A/D CONVERSION REQUIREMENTS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

130 TAD A/D Clock Period(2) 1.6 — — μsTOSC-bas ed, VREF ≥ 3.0V

3.0* — — μsT

OSC-bas ed, VREF full range

130 TAD A/D Internal RC

Oscillator Period 3.0* 6.0 9.0* μsADCS<1:0> = 11 (RC mode)

At V DD = 2.5V

2.0* 4.0 6.0* μsAt V

DD = 5.0V

131 TCNV Conve r si on Time

(not including

Acquisition Time)(1)

—11—TAD Set GO/DONE bit to new dat a in A/D

Result register

132 TACQ Acquisition Time

11.5

—

μs

μs The minimum time is the amplifier

settling time. This may be used if the

“new” in put volt age has not ch anged

by more than 1 LSb (i.e., 4.1 mV @

4.096V) from the last sampled

voltage (as stored on CHOLD).

134 TGO Q4 to A/D Clock

Start —TOSC/2 — — If the A/D clock source is selected as

RC, a time of TCY is added before

the A/D clock starts. This allows the

SLEEP inst ruction to be executed .

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

Note 1: ADRESH and ADRESL registers may be read on the following TCY cycle.

2: See Table 12-1 for minimum conditions.

PIC16F946

20.0 DC AND AC

CHARACTERISTICS GRAPHS

AND TABLES

Graphs are not available at this time.

PIC16F946

NOTES:

PIC16F946

21.0 PACKAGING INFORMATION

21.1 Package Marking Information

*Standard PICmicro® device marking consists of Microchip part number, year code, week code and

traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check

with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP

price.

Legend: XX...X Customer-specifi c info rma tio n

Y Year code (last digit of calendar year)

YY Year code (last 2 digits of calen dar ye ar)

WW Week code (week of January 1 is week ‘01’)

NNN Alphanumeric traceability code

Pb-free JEDEC designator for Matte Tin (Sn)

*This package is Pb-free. The Pb-free JEDEC designator ( )

can be found on the outer packaging for this package.

Note: In the event the f ull Microc hip p art num ber cann ot be mar ked on on e line, it will

be carried over to the next line, thus limiting the number of available

characters for customer-specific information.

64-Lead TQFP (10x10x1mm)

XXXXXXXXXX

YYWWNNN

Example

PICXXFXXXX

-I/PT0410017

PIC16F946

21.2 Package Details

The following sections give the technical details of the packages.

64-Lead Plastic Thin Quad Flatp ack (PT) 10x10x1 mm Body, 1.0/0.10 mm Lead Form (TQFP)

1510515105

Mold Draft Angle Bottom

1510515105

Mold Draft Angle Top

0.270.220.17.011.009.007BLead Width

0.230.180.13.009.007.005

Lead Thickness

1616n1Pins per Side

10.1010.009.90.398.394.390D1Molded Package Length

10.1010.009.90.398.394.390E1Molded Package Width

12.2512.0011.75.482.472.463DOverall Length

12.2512.0011.75.482.472.463EOverall Width

73.5073.50

Foot Angle

0.750.600.45.030.024.018LFoot Length

0.250.150.05.010.006.002A1Standoff

1.051.000.95.041.039.037A2Molded Package Thickness

1.20

1.101.00.047.043.039AOverall Height

0.50.020

Pitch

6464

Number of Pins

MAXNOMMINMAXNOMMINDimension Limits

MILLIMETERS*INCHESUnits

#leads=n1

CH x 45°

βφ

(F)

Footprint (Reference) (F) .039 1.00

Pin 1 Corner Chamfer CH .025 .035 .045 0.64 0.89 1.14

shall not exceed .010" (0.254mm) per side.

Dimensions D1 and E1 do not include mold flash or protrusions. Mold flash or protrusions

Notes:

JEDEC Equivalent: MS-026

Drawing No. C04-085

*Controlling Parameter

PIC16F946

APPENDIX A: DATA SHEET

REVISION HISTORY

Revision A

This is a new data sheet.

APPENDIX B: MIGRATING FROM

OTHER PICmicro®

DEVICES

This discusses some of the issues in migrating from

other PICmicro devices to the PIC16F946 family of

devices.

This device has been designed to perform to the

parameters of its data sheet. It has been tested to an

electrical specification designed to determine its con-

formanc e with these pa rameters. Due to proces s differ-

ences in the manufacture of this device, this device

may hav e diff erent performan ce charac teristics tha n its

earlier version. These differences may cause this

device to perform differently in your application than the

earlier version of this device.

B.1 PIC16F917 to PIC16F946

TABLE B-1: FEATURE COMPARISON

Feature PIC16F917 PIC16F946

Max Operating Speed 20 MHz 20 MHz

Max Program Memory

(Words) 8K 8K

I/O 35 53

LCD Segmen t Drivers 24 42

Max SRAM (Bytes) 352 336

A/D Resolution 10-bit 10-bit

Data EEPROM (bytes) 256 256

Timers (8/16-b it) 2/1 2/1

Oscillator Modes 8 8

Brown-out Reset Y Y

Internal Pull -up s RB<7:0> RB<7:0>

Interrupt-on-change RB<7:4> RB<7:4>

Comparator 2 2

USART Y Y

Extended WDT Y Y

Software Control

Option of WDT/BOR YY

INTOSC Frequencies 32 kHz -

8MHz 32 kHz -

8MHz

Clock Switch in g Y Y

PIC16F946

APPENDIX C: CONVERSION

CONSIDERATIONS

Considerations for converting from previous versions

of de vices to the one s listed in this dat a sheet are liste d

in Table C-1.

TABLE C-1: CONVERSION CONSIDERATIONS

Characteristic PIC16F946 PIC16F926 PIC18F6490

Pins 64 64 64

Timers 3 3 4

Interrupts 20 9 22

Communicatio n USAR T, SSP

(SPI™, I2C™ Slave) SSP

(SPI, I2C Maste r /Sla ve) USART, SSP

(SPI, I2C Master/Slave)

Frequency 20 MHz 20 MHz 20 MHz

Voltage 2.0V-5.5V 2.5V-5.5V 2.0V-5.5V

A/D 10-bit,

7 conve rsi on cl ock selects 10-bit,

4 conversion clock selects 10-bit,

8 conversion clock selects

CCP 2 1 2

Comparator 2 — 2

Comparator Voltage

Reference Yes — Yes

Prog ram Memory 8K Flash 8K OTP 8K Flash

RAM 332 bytes 336 bytes 768 bytes

EEPROM Data 256 bytes — —

Code Protection On/Off Segmented, starting at end

of program memory On/Off

Program Memory

Write Protection ———

LCD Module 4 2 s e gm e n t dri v er s ,

4 commons 32 segment drivers,

4 commons 32 segment driver s,

4 commons

Other In-Ci rcuit Debugg er — In-Circuit Debugger

© 2005 Microchip Technology Inc. Preliminary   DS41265A-page 261
PIC16F946
INDEX
A
A/D Acquisition Requirements............................ ......... ....155
Analog Port Pins.......................................................150
Associ a te d  Re g i sters..................... ................... ........157
Block Diag ram......... .............. ................... .................149
Calculating Acquisition Time.....................................155
Channel Selection.......................... .. .... .. .... .. ....... .... ..150
Configuration and Operation.....................................150
Configuring................................................................154
Configuring Interrupt.................................................154
Conversion (TAD) Cycles ..........................................151
Conversi o n  Clo ck...... ................... .............. ...............150
Effects of Reset.........................................................157
Internal Sampling Switch (RSS) Impedance..............155
Operation During Sleep ............................................156
Output Fo rmat..................... ................... ...................151
Reference Voltage (VREF).........................................150
Source Impedance................ ......... .... .... .... ......... .... ..155
Specifications............................................................254
Starting a Conversion ...............................................151
TAD vs. Operating Frequencies. ................................150
Absolute Maximum Ratings..............................................229
AC Characteristics
Industrial and Extended............................................239
Load Conditions........................... .. .... .. .. .. .. .. ....... .. .. ..238
ACK pulse.......... ....................... ....................... .................175
ADCON0 Register.............................................................152
ADCON1 Register.............................................................153
Addressable Universal Synchronous  Asynchronous  Rece iver
Transmitter. See USART
Analog Input Connections...................................................96
Analog-to-Digital Converter Module. See A/D
ANSEL Register................................................................152
Assembler
MPASM Assembler...................................................223
Asynchronous Reception
Associated Registers ......................... .... .... .......141, 143
Asynchronous Transmission
Associ a te d  Re g i sters..................... ................... ........139
B
Baud Rate Generator
Associ a te d  Re g i sters..................... ................... ........135
BF bit........ .................. ........................ .................. .............166
Block Diag ram of RF..... .......... ................... ............... ..........67
Block Diagrams
A/D............................................................................149
Analog Input Model.............................................96, 156
Capture Mod e....... .............. ................... ...................185
Comparator 1.......... ................... .................. ...............98
Comparator 2.......... ................... .................. ...............98
Comparator Modes . .... .. .. .... .. .. ....... .. .... .. .. .... ..... .... .. .. ..97
Comparator Voltage Reference (CVREF)..................100
Compare Mode....... .......... ................... ................... ..186
Fail-Safe Clock Monitor (FSCM).................................81
In-Circuit Serial Programming Connections..............210
Inter rupt Logic................. ....................... ...................203
LCD Clock Generation..............................................110
LCD Driver Module ...................................................104
LCD Resistor Ladder Connection.............................108
MCLR Circuit................... ............... ................... ........194
On-Chip Rese t Circuit......... ........... .............. ........... ..193
PIC16F946....................................................................6
PWM Mode..... ................... ....................... ................ 187
RA0 Pin ...................................................................... 29
RA1 Pin ...................................................................... 30
RA2 Pin ...................................................................... 31
RA3 Pin ...................................................................... 32
RA4 Pin ...................................................................... 33
RA5 Pin ...................................................................... 34
RA6 Pin ...................................................................... 35
RA7 Pin ...................................................................... 36
RB Pins....................................................................... 41
RB4 Pin ...................................................................... 42
RB5 Pin ...................................................................... 43
RB6 Pin ...................................................................... 44
RB7 Pin ...................................................................... 45
RC0 Pin...................................................................... 48
RC1 Pin...................................................................... 49
RC2 Pin...................................................................... 49
RC3 Pin...................................................................... 50
RC4 Pin...................................................................... 51
RC5 Pin...................................................................... 52
RC6 Pin...................................................................... 53
RC7 Pin...................................................................... 54
RD Pins ...................................................................... 59
RD0 Pin...................................................................... 58
RD1 Pin...................................................................... 58
RD2 Pin...................................................................... 59
RE Pins....................................................................... 63
Resonator Operation.................................................. 76
RF Pins..................... ....................... ....................... .... 67
RG Pins...................... ....................... ................... ...... 70
SSP (I2C Mode)........................................................ 175
SSP (SPI Mode) ....................................................... 168
System Clock.............................................................. 71
Timer1 ........................................................................ 87
Timer2 ........................................................................ 94
TMR0/WDT Prescaler ................................................ 83
USART Receive ........... ....... .... .. .... .... .. ....... .... .. 141, 142
USART Transm i t ...... ................... ................... .......... 138
Watchdog Timer (WDT)........................................ .... 206
BRGH bit .......................................................................... 135
Brown-o u t Re set (BOR)............... .............. ................... .... 195
Associ a te d  Re g i sters......... .................. ................... .. 196
Specifications ........................................................... 243
Timing and Characteristics................................... .... 242
C
C Compilers
MPLAB C17........ ....................... ....................... ........ 224
MPLAB C18........ ....................... ....................... ........ 224
MPLAB C30........ ....................... ....................... ........ 224
Capture/Compar e /PWM (CCP) ............... ............... .......... 183
Associated Registers
Capture, Compare and Timer1................... ...... 188
PWM and Timer2.............................................. 189
Capture Mod e............... ................... ................... ...... 185
Block Diag ram...... ............... ............... .............. 185
CCP1CON Regis te r... .................. ............... ...... 184
CCP1IF............................................................. 185
Prescaler .......................................................... 185
CCP Timer Resou rce s........... .............. ............... ...... 183
Compare
Special Trigger Output of CCP1. ...................... 186
Special Trigger Output of CCP2. ...................... 186
Compare Mode........... ............... ................... ............ 186

PIC16F946
DS41265A-page 262 Preliminary © 2005 Microchip Technology Inc.
Block Diag ram......... .............. ................... .........186
Softwa re In terrupt Mode ... ........... .............. .......186
Special Event Trigger........................................186
Interaction of Two CCP Modules (table)...................183
PWM Mode............................. ................... ...............186
Block Diag ram......... .............. ................... .........187
Duty Cycle........ ................... ............... ...............187
Example Frequencies/Resolutions (Table).......188
PWM Period...................... ........................... .....187
Special Event Trigger and A/D Conversions.............186
CCP. See Capture/Compare/PWM
CCP1CON Registe r..... ............... ............... .................60, 184
CCPR1H Registe r................. .............. ............... ...............183
CCPR1L Regis ter....... ............... .............. ............... ...........183
CCPxM0 bit.......................................................................184
CCPxM1 bit.......................................................................184
CCPxM2 bit.......................................................................184
CCPxM3 bit.......................................................................184
CCPxX bit..........................................................................184
CCPxY bit..........................................................................184
CKE bit..................... ................... ....................... ...............166
CKP bit..................... ................... ....................... ...............167
CMCON0 Register..............................................................95
CMCON1 Register..............................................................99
Code Examples
A/D Conversion............... .............. ............... .............154
Assigni n g  Presc aler to Timer 0............................. .......85
Assigni n g  Presc aler to WDT.............. ....................... ..85
Call of a Subroutine in Page 1 from Page 0....... .. .......25
Indirect Addressing .....................................................26
Initializing PORTA.......................................................27
Initializing PORTB.......................................................37
Initializing PORTC.......................................................47
Initializing PORTD.......................................................56
Initializing PORTE.......................................................61
Initializing PORTF.......................................................65
Initializing PORTG ......................................................68
Loading the SSPBUF (SSPSR) R egister..................169
Saving Status and W Registers in RAM ...................205
Code Protection ................................................................210
Comparator Module .............................. ....... .... .. .. .... .. .. .......95
Comparator Voltage Reference (CVREF)
Associ a te d  Re g i sters......................... .................. .....102
Effects of a Reset......................................................101
Response Time.......................................... .... .... .......101
Comparator Voltage Reference (CVREF)..........................100
Accuracy/Error ..........................................................100
Configuring................................................................100
Specifications............................................................246
Comparators
Associ a te d  Re g i sters......................... .................. .....102
C2OUT as T1 Gate............................ .............. .....88, 99
Configurations.............................................................97
Effects of a Reset......................................................101
Interrupts.....................................................................99
Operation ....................................................................96
Operation During Sleep ............................................101
Outputs .......................................................................99
Response Time.......................................... .... .... .......101
Specifications............................................................246
Synchro n i zing C2OUT w/ Timer1 .................... ...........99
CONFIG Regi ster........... ............... ................... .................192
Configuration Bits..............................................................192
Conversi on  Co n side ration s........................ .............. .........260
CPU Features ...................................................................191
Customer Change Notification Service........................... .. 269
Custome r Notification  Se rvice ........ ........... ............... ........ 269
Customer Support........................................................... .. 269
D
D/A bit...................... ................... ....................... ............... 166
Data EEPRO M Mem ory........ ................... ................... ...... 15 9
Associ a te d  Re g i sters...... ............... ....................... .... 164
Reading .................................................................... 162
Writing ...................................................................... 162
Data Memor y....... ................... ............... ................... .......... 11
Data/Address bit (D/A)...................................................... 166
DC Characteristics
Extended and Industrial............................................ 236
Industrial and Extended............................................ 231
Demonstration Boards
PICDEM 1................................................................. 226
PICDEM 17............................................................... 227
PICDEM 18R............................................................ 227
PICDEM 2 Plus ......................................................... 226
PICDEM 3................................................................. 226
PICDEM 4................................................................. 226
PICDEM LIN............................................................. 227
PICDEM USB........................................................... 227
PICDEM.net Internet/Ethernet..................................226
Development Support....................................................... 223
Device Overview ................................................................... 5
E
EEADRH Registers................................................... 159, 160
EEADRL Registers ................................................... 159, 160
EECON1 Register......................... .. ....... .. .... .. .. .... ..... 159, 161
EECON2 Regist e r.... ................... ............... ................... .... 159
EEDATH Register............................................................. 160
EEDATL Register ............................................................. 160
Electrical Specifications.................................................... 229
Enhanced Capture/Compare/PWM (ECCP)
Enhanced PWM Mode
TMR2 to PR2 Match........................................... 93
Errata.................................................................................... 3
Evaluation and Progra mmi n g  To ols......... ......................... 227
F
Fail-Safe Clock Monitor ...................................................... 81
Fail-Safe Condition Clearing....................................... 82
Reset and Wak e -up  fr o m Sleep... .............. ............... .. 82
Firmware Instructions ....................................................... 213
Flash Pr o g ram Memory......................... ........................... 159
Fuses. See Configuration Bits
G
General Purpose Register File ........................................... 11
I
I/O Ports............. ........................... ....................... ...............27
I2C Mode
Addressing................................................................ 176
Associ a te d  Re g i sters...... ................... ................... .... 182
Master Mode............................................................. 181
Mode Sele ction......... ................... ................... ..........175
Multi-Master Mode.................................................... 181
Operation.................................................................. 175
Reception ................................................................. 177
Slave Mode
SCL and SDA pins............................................ 175
Transmission ............................................................ 179

© 2005 Microchip Technology Inc. Preliminary   DS41265A-page 263
PIC16F946
ID Locations......................................................................210
In-Circuit Debugger...........................................................211
In-Circuit Serial Programming (ICSP)...............................210
Indirect Addressing, INDF and FSR Registers ...................26
Instruction Format.............................................................214
Instruction Set...................................................................213
ADDLW.....................................................................216
ADDWF.....................................................................216
ANDLW.....................................................................216
ANDWF.....................................................................216
BCF...........................................................................216
BSF...........................................................................216
BTFSC......................................................................217
BTFSS ......................................................................216
CALL.........................................................................217
CLRF.........................................................................217
CLRW .......................................................................217
CLRWDT...................................................................217
COMF .......................................................................217
DECF........................................................................217
DECFSZ....................................................................218
GOTO .......................................................................218
INCF..........................................................................218
INCFSZ.....................................................................218
IORLW......................................................................218
IORWF......................................................................218
MOVF........................................................................219
MOVLW ....................................................................219
MOVWF....................................................................219
NOP..........................................................................219
RETFIE.....................................................................220
RETLW .....................................................................220
RETURN...................................................................220
RLF...........................................................................221
RRF...........................................................................221
SLEEP ......................................................................221
SUBLW.....................................................................221
SUBWF.....................................................................221
SWAPF.....................................................................222
XORLW.....................................................................222
XORWF.....................................................................222
Summary Ta b l e..... .................. ................... ...............215
INTCON Register................................................................19
Inter-Integrated Circuit (I2C). See I2C Mode
Internal Oscillator Block
INTOSC
Specifications....................................................240
Internal Sampling Switch (Rss) Impedance......................155
Inter n e t Ad d ress....... ................... ....................... ...............269
Interrupt Sources
USART Receive/Transmit Complete ........................133
Interrupts...........................................................................202
A/D............................................................................154
Associ a te d  Re g i sters..................... ................... ........204
Comparators...............................................................99
Context Saving..........................................................205
Interrupt-on-change ....................................................37
PORTB Interrupt-on-C hange ....................................203
RB0/INT/SEG0..........................................................203
TMR0........................................................................203
TMR1..........................................................................88
TMR2 to PR2 Match ...................................................94
TMR2 to PR2 Match (PWM).......................................93
INTOSC Specification s......... .......... ........... ............... ........240
IOCB Register................... ................... ................... ............38
L
LCD Associ a te d  Re g i sters......... .................. ................... .. 128
Bias Types................................................................ 108
Clock Source Selection ............................................ 108
Configuring the Module ......... .. .. .. .... .. .. ..... .. .. .. .. .. .... .. 127
Frame Frequency ..................................................... 109
Interrupts .................................................................. 124
LCDCON Register.................................................... 103
LCDDATA Register .... ........... .......... ........... .......... .... 103
LCDPS Register....................................................... 103
LCDSE Register....................................................... 103
Multiplex Types..... .......... ................... ............... ........ 109
Operation During Sleep............................................ 125
Pixel Control............................................................. 109
Prescaler .................................................................. 108
Segment Enables ... .... .. .. ....... .. .... .. .. .... ..... .... .. .. .... .. .. 109
Waveform Generation .............................................. 113
LCDCON Register............................................................ 103
LCDDATA Register... ..................... ...... ........... .......... ........ 103
LCDPS Register............................................................... 103
LP Bits...................................................................... 108
LCDSE Register............................................................... 103
Liquid Crystal Display (LCD) Driver.................................. 103
Load Conditions................................................................ 238
M
MCLR ............................................................................... 194
Internal...................................................................... 194
Memory Organization ......................................................... 11
Data............................................................................ 11
Program...................................................................... 11
Microc h i p  In te r n e t Web Site..................... ....................... .. 269
Migratin g  fr o m oth e r  PICm ic ro Devices............ .............. .. 259
MPLAB ASM30 Assemble r, Link e r, Librar ia n......... .......... 224
MPLAB ICD 2 In-Circuit Debugger................................... 225
MPLAB ICE 2000 High-Perf orm ance Univers a l 
In-Circuit Emulator.................................................... 225
MPLAB ICE 4000 High-Perf orm ance Univers a l 
In-Circuit Emulator.................................................... 225
MPLAB Integrated Development Environment Software.. 223
MPLAB PM3 Device Programmer.................................... 225
MPL IN K Obje ct Link e r / M PLIB Ob j e ct Libra ri a n... ...... .. ..... 22 4
O
OPCODE Field Desc r i p tions................ ............... .............. 213
OPTION_R EG Re gister........................... ................... .. 18, 84
OSCCON Register.............................................................. 72
Oscillator
Associ a te d  Re g i sters......... .................. ................... .... 82
Oscillator Configurations. .. ......... ......................................... 71
Oscillato r Delay Examples......... ................... .............. 74
Special Cases............................................................. 73
Oscillato r S pecifications...... ........... ...... ........... .......... ........ 239
Oscillator Start-up Timer (OST)
Specifications ........................................................... 243
Oscillator Switching
Fail-Safe Clock Monitor.............................................. 81
Two-Spe ed Clock Start-up ....................... .............. .... 80
OSCTUNE Regis te r............ ............... ................... .............. 78
P
P (Stop) bit........................................................................ 166
Packaging......................................................................... 257
Marking..................................................................... 257
PDIP Details............................................................. 258

PIC16F946
DS41265A-page 264 Preliminary © 2005 Microchip Technology Inc.
Pagin g , Pr o gram Memory....... ....................... .....................25
PCL and PCLATH...............................................................25
Computed GOTO........................................................25
Stack...........................................................................25
PCON Register .................................................................196
PICkit 1 Flash Starter Kit...................................................227
PICSTART Plus Developm ent Programm er .....................226
PIE1 Register......................................................................20
PIE2 Register......................................................................21
Pin Diagram
PIC16F946, 64-Pin .......................................................2
Pinout Description.............. ....... .... .. .... .. ......... .. .... .. .... ....... ....7
PIR1 Regi ster................. ................... ................... ...............22
PIR2 Regi ster................. ................... ................... ...............23
PORTA
Associ a te d  Re g i sters......................... .................. .......36
Pin Descriptions and Diagrams...................................29
RA0.............................................................................29
RA1.............................................................................30
RA2.............................................................................31
RA3.............................................................................32
RA4.............................................................................33
RA5.............................................................................34
RA6.............................................................................35
RA7.............................................................................36
Registers.....................................................................27
Specifications............................................................241
PORTA Register .................................................................28
PORTB
Additional Pin Functions .............................................37
Weak Pull-up.......................................................37
Associ a te d  Re g i st e rs........ .............. ................... .........46
Interrupt-on-change ....................................................37
Pin Descriptions and Diagrams...................................40
RB0.............................................................................40
RB1.............................................................................40
RB2.............................................................................40
RB3.............................................................................40
RB4.............................................................................42
RB5.............................................................................43
RB6.............................................................................44
RB7.............................................................................45
Registers.....................................................................37
PORTB Register .................................................................38
PORTC
Associ a te d  Re g i sters......................... .................. .......55
Pin Descriptions and Diagrams...................................48
RC0.............................................................................48
RC1.............................................................................48
RC2.............................................................................48
RC3.............................................................................50
RC4.............................................................................51
RC5.............................................................................52
RC6.............................................................................53
RC6/TX/ CK/SCK/SCL/SEG9 Pin................... ...........134
RC7.............................................................................54
RC7/RX/DT Pin.........................................................135
RC7/RX/DT/SDI/SDA/ SEG8  Pin........ .............. .........134
Registers.....................................................................47
Specifications............................................................241
TRISC Register............... ................... .............. .........133
PORTC Register.................................................................47
PORTD
Associ a te d  Re g i sters......................... .................. .......60
Pin Descriptions and Diagrams...................................57
RD0 ............................................................................ 57
RD1 ............................................................................ 57
RD2 ............................................................................ 57
RD3 ............................................................................ 57
RD4 ............................................................................ 57
RD5 ............................................................................ 57
RD6 ............................................................................ 57
RD7 ............................................................................ 57
Registers .................................................................... 56
PORTD Register.................................................................56
PORTE
Associ a te d  Re g i sters...... ............... ....................... ...... 64
Pin Descriptions and Diagrams .................................. 62
RE0............................................................................. 62
RE1............................................................................. 62
RE2............................................................................. 62
RE3............................................................................. 62
RE4............................................................................. 62
RE5............................................................................. 62
RE6............................................................................. 62
RE7............................................................................. 62
Registers .................................................................... 61
PORTE Register................................................................. 61
PORTF
Associ a te d  Re g i sters...... ............... ....................... ...... 67
Pin Descriptions and Diagrams .................................. 66
Registers .................................................................... 65
RF0............................................................................. 66
RF1............................................................................. 66
RF2............................................................................. 66
RF3............................................................................. 66
RF4............................................................................. 66
RF5............................................................................. 66
RF6............................................................................. 66
RF7............................................................................. 66
PORTF Regist e r........... .................. ................... ................. 65
PORTG
Associ a te d  Re g i sters...... ............... ....................... ...... 70
Pin Descriptions and Diagrams .................................. 69
Registers .................................................................... 68
RG0 ............................................................................ 69
RG1 ............................................................................ 69
RG2 ............................................................................ 69
RG3 ............................................................................ 69
RG4 ............................................................................ 69
RG5 ............................................................................ 69
PORTG Regist e r........ ................... ............... ................... .... 68
Power-Down Mode (Sleep)............................................... 208
Power-on Reset................................................................ 194
Power-up Timer (PWRT).................................................. 194
Specifications ........................................................... 243
Precision  In ternal Os cillator Parameters ....... ........... ........ 240
Prescaler
Shared WDT/Timer0............. ............... ................... .... 85
Swit ch i n g  Pr escal e r  As si g n ment ...... .. ...... ..... .. ...... .. ... 8 5
PRO MATE II Univer sal Device Progr a mme r............... .... 225
Product Identification System........................................... 271
Program Memory................................................................ 11
Map and Stack (PIC16F946)...................................... 11
Paging ........................................................................ 25
Programmable Low-Voltage Detect (PLVD) Module ........ 131
Programming, Device Instructions.................................... 213
Pulse-Width Modulation.See Capture/Compare/PWM, PWM
Mode.

© 2005 Microchip Technology Inc. Preliminary   DS41265A-page 265
PIC16F946
R
R/W bit..............................................................................166
RCSTA Register
ADDEN Bit................................................................134
CREN Bit.... ............... ................... ................... ..........134
FERR Bit...................................................................134
OERR Bit ..................................................................134
RX9 Bit......................................................................134
RX9D Bit...................................................................134
SPEN Bit...........................................................133, 134
SREN Bit...... ....................... ................... ...................134
Reader Response.............................................................270
Read-Modify-Write Operations .........................................213
Receive  Over flo w  In d icator bi t (S SPOV) .................. ........167
Registers
ADCON0 (A/D Control 0)..........................................152
ADCON1 (A/D Control 1)..........................................153
ANSEL (Analog Select).............................................152
CCP1CON (CCP Control 2)............... ............... ........184
CCP2CON (CCP Control 1)............... ............... ........184
CMCON0 (Comparator Control 0) ..............................95
CMCON1 (Comparator Control 1) ..............................99
CONFIG (Configuratio n  Wo rd)..... .............. ...............192
EEADRH (EEPROM Address)..................................160
EEADRL (EEPROM Address) ..................................160
EECON1 (EEPROM Control 1 ).... .............. ........... ....161
EEDATH (EEPROM Data) ........................................160
EEDATL (EEPROM Data) ........................................160
INTCON (Interrupt Control).........................................19
IOCB (PORTB Interrupt-on-change)...........................38
LCDCON (LCD Control)............................................105
LCDDATAx (LCD Datax) ..........................................107
LCDPS (LCD Prescaler Select)................. ...............106
LCDSEn (LCD Segment)..........................................107
LVDCON (Low-Voltage Detect Control) ....................131
OPTION_REG ......................................................18, 84
OSCCON (Oscillator Control).....................................72
OSCTUNE ..................................................................78
PCON (Power Control) .............................................196
PIE1 (Peripheral Interrupt Enable 1)...........................20
PIE2 (Peripheral Interrupt Enable 2)...........................21
PIR1 (Peripheral Interrupt Register 1) ........................22
PIR2 (Peripheral Interrupt Register 2) ........................23
PORTA........................................................................28
PORTB........................................................................38
PORTC .......................................................................47
PORTD .......................................................................56
PORTE........................................................................61
PORTF........................................................................65
PORTG.......................................................................68
RCSTA (Receive Status and Control). ......................134
Reset Value s........... ................... .................. .............198
Reset Values (Special Registers).............................201
Special Function Register Map
PIC16F946..........................................................12
Special Register Summary
Bank 0........ ........................ .................. ...............13
Bank 1........ ........................ .................. ...............14
Bank 2........ ........................ .................. ...............15
Bank 3........ ........................ .................. ...............16
SSPCON (Sy nc Serial Port  Control) Register...........167
SSPSTAT (S ync Serial Port  Status) Register...........166
Status..........................................................................17
T1CON (Timer1 Con trol).................... .......... ...............89
T2CON (Timer2 Con trol).................... .......... ...............93
TRISA (PORTA Tri- state) ...........................................28
TRISB (PORTB Tri-state)........................................... 38
TRISC (PORTC Tri-state).......... ............... .......... ........ 47
TRISD (PORTD Tri-state).......... ............... .......... ........ 56
TRISE (PORTE Tri-state)........................................... 61
TRISF (PORTF Tri-state) ........................................... 65
TRISG (P ORTG  Tri-s ta t e ) .... ...... ...... ..... ...... ...... ......... 68
TXSTA (Transmit Status and Con trol)............ .......... 133
VRCON (Voltage Reference Control). ...................... 102
WDTCON (Watchdog Timer Contr ol).... ................... 207
WPUB (Wea k Pull-up PORTB).......... ......................... 39
Reset ................................................................................ 193
Revision History................................................................ 259
S
S (Start) bit ....................................................................... 166
SCI. See USART
Serial Communication Interface. See USART.
Slave Select Synchroniz a tio n.................... ................... .... 172
SMP bit............................................................................. 166
Softwar e  Simulat or ( MP L AB SIM) . ................... ................ 224
Softwar e  Simulat or ( MP L AB SIM30)....... ................... ...... 224
Special Function Registers................................................. 11
SPI Mode.................................................................. 165, 172
Associ a te d  Re g i sters......... .................. ................... .. 174
Bus Mode Compatibility..... .......... ...... ........... .......... .. 174
Effects of a Reset...................... ................... ............ 174
Enabling SPI I/O....................................................... 170
Master Mode............................................................. 171
Master/Slave Connection ...... .... .. .... .. .. ....... .... .. .... .. .. 170
Serial Clock (SCK pin).............................................. 165
Serial Data In (SDI pin)............................................. 165
Serial Data Out (SDO pin)........................................ 165
Slave Select.......... ....................... ................... .......... 165
Slave Select Synchroniz a tio n............ ................... .... 172
Sleep Operation. ....................................................... 174
SPI Clock.................................................................. 171
Typical Connection........................ .. .... ..... .... .. .... .. .. .. 170
SSP Overview
SPI Master/Slave Connection . .................................. 170
SSP I2C Operation ....... ............... ................... .............. .... 175
Slave Mode............................ ................... ................ 175
SSP Module
Clock Synchronization and the CKP Bit ................... 181
SPI Master Mode...................................................... 171
SPI Slave Mode........................................................ 172
SSPBUF................................................................... 171
SSPSR ..................................................................... 171
SSPEN bit........ ................... ................... ................... ........ 167
SSPM bits.... ....................... ................... ....................... .... 167
SSPOV bit ........................................................................ 167
Statu s Reg i ster....... ................... .................. ................... .... 17
Synchronous Master Reception
Associ a te d  Re g i sters......... .................. ................... .. 146
Synchronous Master Transmission
Associ a te d  Re g i sters......... .................. ................... .. 145
Synchronous Serial Port Enable bit (SSPEN) .................. 167
Synchronous Serial Port Mode Select bits (SSPM).......... 167
Synchronous Serial Port. See SSP
Synchronous Slave Reception
Associ a te d  Re g i sters......... .................. ................... .. 148
Synchronous Slave Transmission
Associ a te d  Re g i sters......... .................. ................... .. 148

PIC16F946
DS41265A-page 266 Preliminary © 2005 Microchip Technology Inc.
T
T1CON Regis te r... .............. ............... ............... ...................89
Time-out Sequence........................................ .... .... .. .... .....196
Timer0
Associ a te d  Re g i sters......................... .................. .......85
External Clock.............................................................84
External Clock Requirements ...................................244
Interrupt.......................................................................83
Operation ....................................................................83
T0CKI..........................................................................84
Timer0 Module....................................................................83
Timer1
Associ a te d  Re g i sters......................... .................. .......91
Asynchronous Counter Mode .....................................90
Reading and Writing ........................ .. .. .. .. .. .. ..... ..90
External Clock Requirements ...................................244
Interrupt.......................................................................88
Modes of Operations.................................. .... .. .... .......88
Operation During Sleep ..............................................91
Prescaler.....................................................................88
Resetting of Timer1 Registers ....................................91
Resetting Timer1 Using a CCP Trigger Output...........90
Timer1 Gate
Inverting Gate .....................................................88
Selectin g  So u rce............. ................... ...........88, 99
Synchro n i zing C2OUT w/ Timer1 ................ .......99
TMR1H Register.........................................................87
TMR1L Register..........................................................87
Timer1 Module with Gate Control .......................................87
Timer2.................................................................................93
Associ a te d  registe rs.............. ................... ...................94
Operation ....................................................................93
Postscaler...................................................................93
PR2 Register...............................................................93
Prescaler.....................................................................93
TMR2 Output ..............................................................94
TMR2 Register............................................................93
TMR2 to PR2 Match Interrupt...............................93, 94
Timing Diagrams
A/D Conversion............... .............. ............... .............253
Asynchronous Master Transmission.........................138
Asynchronous Master Transmission (Back-to-Back) 138
Asynchronous Reception..........................................141
Asynchronous R eception with Address By te First ....143
Asynchronous Re ception with Address Dete ct.........143
Brown-out Reset (BOR)............................................242
Brown-out Reset Situations ......................................195
Capture/Compare/PWM............................................245
CLKO and I/O . ..........................................................241
Clock Synchronization ..............................................182
Comparator Output....... .................. ................... .........96
External Clock...........................................................239
Fail-Safe Clock Monitor (FSCM).................................82
I2C Bus Data.............................................................251
I2C Bus Start/Stop Bits..............................................250
I2C Recepti o n (7-bit Addr e ss)......... ............... ...........177
I2C Slave Mode (Transmission, 10-bit Address).... ...180
I2C Slave Mode with SEN = 0 (Reception, 
10-bit Address)..................................................178
I2C Transmission (7-bit Address)..............................179
INT Pin Interrupt........................................................204
LCD Interrupt Timing in Quarter-Duty Cycle Drive....124
LCD Sleep Entry/Exit when SLPEN = 1 or CS = 00 .126
Reset, WDT, OST and Power-up Timer ...................242
Slave Synchronization ..............................................172
SPI Mast e r Mode (CKE = 1, SMP = 1)..................... 24 8
SPI Mode (Master Mode).......... ................................ 171
SPI Mode (Slave Mode with CKE = 0) ...................... 173
SPI Mode (Slave Mode with CKE = 1) ...................... 173
SPI Slave Mode (CKE = 0)....................................... 249
SPI Slave Mode (CKE = 1)....................................... 249
Synchronous Reception (Master Mode, SREN)....... 147
Synchronous Transmission ...................................... 145
Synchronous Transmission (Through TX EN)........... 145
Time-out Sequence
Case 1.............................................................. 197
Case 2.............................................................. 197
Case 3.............................................................. 197
Timer0 and Timer1 External Clock........................... 243
Timer1 Incrementing Edge......................................... 88
Two Speed Start-up............ .. .. ..... .. .... .. .. .. .. .. ....... .. .. .. .. 81
Type-A in 1/2 MUX, 1/2 Bias Drive........................... 114
Type-A in 1/2 MUX, 1/3 Bias Drive........................... 116
Type-A in 1/3 MUX, 1/2 Bias Drive........................... 118
Type-A in 1/3 MUX, 1/3 Bias Drive........................... 120
Type-A in 1/4 MUX, 1/3 Bias Drive........................... 122
Type-A/Type-B in Static Drive ..................................113
Type-B in 1/2 MUX, 1/2 Bias Drive........................... 115
Type-B in 1/2 MUX, 1/3 Bias Drive........................... 117
Type-B in 1/3 MUX, 1/2 Bias Drive........................... 119
Type-B in 1/3 MUX, 1/3 Bias Drive........................... 121
Type-B in 1/4 MUX, 1/3 Bias Drive........................... 123
USART Synchronous Receive (Master/Slave)......... 245
USART Synchronous Transmission (Master/Slave). 244
Wake-up from Interrupt .............................................209
Timing Pa ramete r Symbolog y .. ....................... ................. 238
Timing Requirements
I2C Bus Data ............................................................. 252
I2C Bus Sta rt/Stop  Bits... .......................................... 251
SPI Mode.................................................................. 250
TMR1H Register................................................................. 87
TMR1L Register.................................................................. 87
TRISA
Registers .................................................................... 27
TRISA Register................................................................... 28
TRISB
Registers .................................................................... 37
TRISB Register................................................................... 38
TRISC
Registers .................................................................... 47
TRISC Regist e r.... ................... ............... ................... .......... 47
TRISD
Registers .................................................................... 56
TRISD Regist e r.... ................... ............... ................... .......... 56
TRISE
Registers .................................................................... 61
TRISE Register................................................................... 61
TRISF
Registers .................................................................... 65
TRISF Register................................................................... 65
TRISG
Registers .................................................................... 68
TRISG Register .................................................................. 68
Two-Spe ed Clock Start-up Mode................. ................... .... 80
TXSTA Register
BRGH Bit.................................................................. 133
CSRC Bit................ ....................... ................... ........ 133
SYNC Bit ....... ........... ................... ................... .......... 13 3
TRMT Bit...... ................... ....................... ................... 133
TX9 Bit...................................................................... 133

© 2005 Microchip Technology Inc. Preliminary   DS41265A-page 267
PIC16F946
TX9D Bit....................................................................133
TXEN Bit...................................................................133
U
UA.....................................................................................166
Update Address bit, UA ...... .. .... .. .. ....... .... .. .. .... .. ....... .. .... ..166
USART..............................................................................133
Address Detect Enable (ADDEN Bit)........................134
Asynchronous Mode.................................................137
Asynchronous Re ceive (9-bit Mode).........................142
Asynchronous Re ceive with Address Detec t. 
See Asynchronous Receive (9-bit  Mode).
Asynchronous Receiver............................................140
Asynchronous Reception..........................................140
Asynchronous Transmitter........................................137
Baud Rate Generator (BRG) .....................................135
Baud Rate Formula...........................................135
Baud Rates, Asynchronous Mode (B RGH  = 0) 136
Baud Rates, Asynchronous Mode (B RGH  = 1) 136
High Baud Rate Select (BRGH Bit) ..................133
Sampling...........................................................135
Clock Source Select (CSRC Bit)...............................133
Continuous Receive Enable (CREN Bit)...................134
Framing  Er r or (FERR Bit) ............ .............. ...............134
Mode Select (SYNC Bit) ...........................................133
Overrun Error (OERR Bit).........................................134
Rece i ve  D a t a , 9 th  Bi t  (RX9D  Bi t)...... .. ...... ..... .. ...... .. .1 3 4
Rece i ve  En able ,  9 - b i t (R X9  Bi t ) ...... ...... .. ...... ..... .. .. ...134
Serial Port Enable (SPEN Bit)...........................133, 134
Single Receive Enable (SREN Bit)...........................134
Synchronous Master Mode.......................................144
Requirements, Synchronous Receive ..............245
Requirements, Synchronous Transm ission......245
Timing Diagram, Synchronous Receive ...........245
Timing Diagram, Synchronous Transmission...244
Synchronous Master Reception................................146
Synchronous Master Transmission...........................144
Synchronous Slave Mode.........................................147
Synchronous Slave Reception..................................148
Synchronous Slave Transmit....................................147
Transmit Data, 9th  Bit (TX9D).................. .................133
Transmit Enable (TXEN Bit)..................... .. ....... .... .. ..133
Transmit Enable, Nine-bit (TX9 Bit)..........................133
Transmit Shift Re gister Status (TRMT Bi t)........ ........133
V
Voltage Reference. See Comparator Voltage Reference
(CVREF)
VRCON Register...............................................................102
W
Wake-up Using Interrupts................................................. 208
Watchdog Timer (WDT)..................... .... .... .. ......... .... .... .... 206
Associ a te d  Re g i sters......... .................. ................... .. 207
Clock Source............................................................ 206
Modes....................................................................... 206
Period....................................................................... 206
Specifications ........................................................... 243
WCOL bit.................. ....................... ................... .............. 167
WDTCON Register................. ................... ............... ........ 207
WPUB Regist e r........... ................... ....................... .............. 39
Write Colli sion Detect bit ( WCOL)............................ ........ 167
WWW Addres s..................... ............................ ................ 269
WWW, On-Line Support....................................................... 3

PIC16F946

NOTES:

PIC16F946

THE MICROCHIP WEB SITE

Microc hip pro vides onl ine s upport v ia our W WW site at

www.microc hi p.c om. Thi s w eb si te i s us ed as a m ean s

to make files and information easily available to

customers. Accessible by using your favorite Internet

browser, the web site contains the following informa-

tion:

•Product Support – Da ta she et s an d e rrata, a ppl i-

cation note s and samp le prog ram s, des ig n

resources, user’s guides and hardware support

docume nts , latest softw are releas es and archived

software

•General Technical Support – Frequently Asked

Questions (FAQ), technical support requests,

online dis cu ss io n gr oups, Microchip consul t an t

program member listing

•Business of Microchip – Product selector and

ordering guides, latest Microchip press releases,

listing of seminars and events, listings of Micro-

chip sales offices, distributors and factory repre-

sentatives

CUSTOMER CHANGE NOTIFICATION

SERVICE

Microchip’s customer notification service helps keep

customers current on Microchip products. Subscribers

will receive e-mail notification whenever there are

change s, updates, rev isions or errat a related to a s pec-

ified product family or development tool of interest.

To register, access the Microchip web site at

www.microchip.com, click on Customer Change Notifi-

cation and follow the regi stration ins truc tio ns .

CUSTOMER SUPPORT

Users of Microchip products can receive assistance

through several channels:

• Distributor or Representative

• Local Sales Office

• Field Application Engineer (FAE)

• Technical Support

• Development Systems Information Line

Customers should contact their distributor, representa-

tive or field application engineer (FAE) for support.

Local sales offices are also available to help custom-

ers. A l isting of sal es offic es and locat ions is inc luded in

the back of this document.

Technic al support is avail able throug h the web si te

at: http://support.microchip.com

In addition, there is a Development Systems Informa-

tion Line which lists the latest versions of Microchip’s

development systems software products. This line also

provides information on how customers can receive

currently available upgrade kits.

The Development Systems Information Line num-

bers are:

1-800-755-2345 – United States and most of Canada

1-480-792-7302 – Other International Locations

PIC16F946

READER RESPONSE

It is ou r intention to pro vi de you wit h th e b es t docume ntation poss ib le to ens ure suc c es sfu l u se of y ou r Mic r oc hip pro d-

uct. If you wi sh to prov ide you r comment s on org anizatio n, clar ity, subj ect matte r , a nd ways i n whic h our doc umenta tion

can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150.

Please list the following information, and use this outline to provide us with your comments about this document.

To: Technical Publications Manager

RE: Reader Response Total Pages Sent ________

From: Name

Company

Address

City / State / ZIP / Country

Telephone: (_______) _________ - _________

Application (optional):

Would you like a reply? Y N

Device: Literature Number:

Questions:

FAX: (______) _________ - _________

DS41265APIC16F946

1. What are the best features of this docu ment?

2. How does this document meet your hardware and software development needs?

3. Do you find the organization of this document easy to follow? If not, why?

4. What additions to the document do you think would enhance the structure and subject?

5. What deletions from the document could be made without affecting the overall usefulness?

6. Is there any incorrect or misleading information (what and where)?

7. How would you improve this document?

PIC16F946

PRODUCT IDENTIFICATION SYSTEM

To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.

* JW Devices are UV er asable and can be programm ed to any device configuration . JW Devices meet the electrical requirem ent of

each oscillator type.

PART NO. X/XX XXX

PatternPackageTemperature

Range

Device

Device: PIC16F946(1), PIC16F946T (2)

Temperature

Range: I= -40°C to +85°C

E= -40°C to +125°C

Package: PT = TQFP (Thin Qua d Flatpack)

Pattern: 3-Digit Pattern Code for QTP (blank otherwise)

Examples:

a) PIC16F946-E/SP 301 = Extended Temp.,

skinny PDIP package, 20 MHz, QTP pattern

#301

b) PIC16F946-I/SO = Industrial Temp., SOIC

package, 20 MHz

Note 1: F = Standard Voltage Range

LF = Wide Voltage Range

2: T = In tape and reel.

AMERICAS

Corporate Office

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Tel: 480-792-7200

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Web Address:

www.microchip.com

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WORLDWIDE SALES AND SERVICE

04/20/05