PIC16F872 28-Pin, 8-Bit CMOS FLASH Microcontroller Devices Included in this Data Sheet: Pin Diagram • PIC16F872 Microcontroller Core Features: • High-performance RISC CPU • Only 35 single word instructions to learn • All single cycle instructions except for program branches which are two cycle • Operating speed: DC - 20 MHz clock input DC - 200 ns instruction cycle • 2K x 14 words of FLASH Program Memory 128 x 8 bytes of Data Memory (RAM) 64 x 8 bytes of EEPROM Data Memory • Pinout compatible to the PIC16C72A • Interrupt capability (up to 10 sources) • Eight level deep hardware stack • Direct, indirect and relative addressing modes • Power-on Reset (POR) • Power-up Timer (PWRT) and Oscillator Start-up Timer (OST) • Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation • Programmable code-protection • Power saving SLEEP mode • Selectable oscillator options • Low-power, high-speed CMOS FLASH/EEPROM technology • Fully static design • In-Circuit Serial Programming (ICSP) via two pins • Single 5V In-Circuit Serial Programming capability • In-Circuit Debugging via two pins • Processor read/write access to program memory • Wide operating voltage range: 2.0V to 5.5V • High Sink/Source Current: 25 mA • Commercial and Industrial temperature ranges • Low-power consumption: - < 2 mA typical @ 5V, 4 MHz - 20 µA typical @ 3V, 32 kHz - < 1 µA typical standby current 1999 Microchip Technology Inc. MCLR/VPP/THV RA0/AN0 RA1/AN1 RA2/AN2/VREFRA3/AN3/VREF+ RA4/T0CKI RA5/AN4/SS VSS OSC1/CLKIN OSC2/CLKOUT RC0/T1OSO/T1CKI RC1/T1OSI RC2/CCP1 RC3/SCK/SCL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 PIC16F872 DIP, SOIC, SSOP 28 27 26 25 24 23 22 21 20 19 18 17 16 15 RB7/PGD RB6/PGC RB5 RB4 RB3/PGM RB2 RB1 RB0/INT VDD VSS RC7 RC6 RC5/SDO RC4/SDI/SDA Peripheral Features: • Timer0: 8-bit timer/counter with 8-bit prescaler • Timer1: 16-bit timer/counter with prescaler, can be incremented during sleep via external crystal/clock • Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler • One Capture, Compare, PWM module - Capture is 16-bit, max. resolution is 12.5 ns - Compare is 16-bit, max. resolution is 200 ns - PWM max. resolution is 10-bit • 10-bit multi-channel Analog-to-Digital converter • Synchronous Serial Port (SSP) with SPI (Master Mode) and I2C (Master/Slave) • Brown-out detection circuitry for Brown-out Reset (BOR) Preliminary DS30221A-page 1 PIC16F872 Key Features PICmicro™ Mid-Range Reference Manual (DS33023) PIC16F872 Operating Frequency DC - 20 MHz Resets (and Delays) POR, BOR (PWRT, OST) FLASH Program Memory (14-bit words) 2K Data Memory (bytes) 128 EEPROM Data Memory 64 Interrupts 10 I/O Ports Ports A,B,C Timers 3 Capture/Compare/PWM module 1 Serial Communications MSSP 10-bit Analog-to-Digital Module 5 input channels Instruction Set DS30221A-page 2 35 Instructions Preliminary 1999 Microchip Technology Inc. PIC16F872 Table of Contents 1.0 Device Overview ........................................................................................................................................................................... 5 2.0 Memory Organization.................................................................................................................................................................... 7 3.0 I/O Ports...................................................................................................................................................................................... 23 4.0 Data EEPROM and FLASH Program Memory .......................................................................................................................... 29 5.0 Timer0 Module ............................................................................................................................................................................ 37 6.0 Timer1 Module ............................................................................................................................................................................ 41 7.0 Timer2 Module ........................................................................................................................................................................... 45 8.0 Capture/Compare/PWM (CCP) Module(s).................................................................................................................................. 47 9.0 Master Synchronous Serial Port (MSSP) Module....................................................................................................................... 53 10.0 Analog-to-Digital Converter (A/D) Module .................................................................................................................................. 85 11.0 Special Features of the CPU ...................................................................................................................................................... 95 12.0 Instruction Set Summary........................................................................................................................................................... 111 13.0 Development Support ............................................................................................................................................................... 119 14.0 Electrical Characteristics........................................................................................................................................................... 125 15.0 DC and AC Characteristics Graphs and Tables ....................................................................................................................... 143 16.0 Packaging Information .............................................................................................................................................................. 145 Appendix A: Revision History......................................................................................................................................................... 149 Appendix B: Conversion Considerations........................................................................................................................................ 149 Index ................................................................................................................................................................................... 151 On-Line Support................................................................................................................................................................................. 157 Product Identification System ............................................................................................................................................................ 159 To Our Valued Customers Most Current Data Sheet To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at: http://www.microchip.com You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page. The last character of the literature number is the version number. e.g., DS30000A is version A of document DS30000. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products. Errata An errata sheet may exist for current devices, describing minor operational differences (from the data sheet) and recommended workarounds. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision of silicon and revision of document to which it applies. To determine if an errata sheet exists for a particular device, please check with one of the following: • Microchip’s Worldwide Web site; http://www.microchip.com • Your local Microchip sales office (see last page) • The Microchip Corporate Literature Center; U.S. FAX: (480) 786-7277 When contacting a sales office or the literature center, please specify which device, revision of silicon and data sheet (include literature number) you are using. Corrections to this Data Sheet We constantly strive to improve the quality of all our products and documentation. We have spent a great deal of time to ensure that this document is correct. However, we realize that we may have missed a few things. If you find any information that is missing or appears in error, please: • Fill out and mail in the reader response form in the back of this data sheet. • E-mail us at [email protected]. We appreciate your assistance in making this a better document. 1999 Microchip Technology Inc. Preliminary DS30221A-page 3 PIC16F872 NOTES: DS30221A-page 4 Preliminary 1999 Microchip Technology Inc. PIC16F872 1.0 DEVICE OVERVIEW mentary document to this data sheet, and is highly recommended reading for a better understanding of the device architecture and operation of the peripheral modules. This document contains device-specific information. Additional information may be found in the PICmicro™ Mid-Range Reference Manual, (DS33023), which may be obtained from your local Microchip Sales Representative or downloaded from the Microchip website. The Reference Manual should be considered a comple- FIGURE 1-1: This data sheet covers the PIC16F872 device. The PIC16F872 is a 28-pin device and its block diagram is shown in Figure 1-1. PIC16F872 BLOCK DIAGRAM Device Program FLASH Data Memory Data EEPROM PIC16F872 2K 128 Bytes 64 Bytes 13 FLASH Program Memory PORTA RA0/AN0 RA1/AN1 RA2/AN2/VREFRA3/AN3/VREF+ RA4/T0CKI RA5/AN4/SS RAM File Registers 8 Level Stack (13-bit) Program Bus 8 Data Bus Program Counter 14 RAM Addr (1) PORTB 9 Addr MUX Instruction reg Direct Addr 7 8 Indirect Addr FSR reg STATUS reg 8 3 Power-up Timer Instruction Decode & Control Timing Generation OSC1/CLKIN OSC2/CLKOUT Oscillator Start-up Timer MUX ALU Power-on Reset PORTC RB0/INT RB1 RB2 RB3/PGM RB4 RB5 RB6/PGC RB7/PGD RC0/T1OSO/T1CKI RC1/T1OSI RC2/CCP1 RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6 RC7 8 Watchdog Timer Brown-out Reset In-Circuit Debugger W reg Low-Voltage Programming MCLR VDD, VSS Timer0 Timer1 Timer2 Data EEPROM CCP1 Synchronous Serial Port 10-bit A/D Note 1: Higher order bits are from the STATUS register. 1999 Microchip Technology Inc. Preliminary DS30221A-page 5 PIC16F872 TABLE 1-1: PIC16F872 PINOUT DESCRIPTION DIP Pin# SOIC Pin# I/O/P Type OSC1/CLKIN 9 9 I OSC2/CLKOUT 10 10 O — Oscillator crystal output. Connects to crystal or resonator in crystal oscillator mode. In RC mode, the OSC2 pin outputs CLKOUT, which has 1/4 the frequency of OSC1 and denotes the instruction cycle rate. MCLR/VPP/THV 1 1 I/P ST Master clear (reset) input or programming voltage input or high voltage test mode control. This pin is an active low reset to the device. RA0/AN0 2 2 I/O TTL RA1/AN1 3 3 I/O TTL RA1 can also be analog input1. RA2/AN2/VREF- 4 4 I/O TTL RA2 can also be analog input2 or negative analog reference voltage. RA3/AN3/VREF+ 5 5 I/O TTL RA3 can also be analog input3 or positive analog reference voltage. RA4/T0CKI 6 6 I/O ST RA4 can also be the clock input to the Timer0 module. Output is open drain type. RA5/SS/AN4 7 7 I/O TTL RA5 can also be analog input4 or the slave select for the synchronous serial port. Pin Name Buffer Type Description ST/CMOS(3) Oscillator crystal input/external clock source input. PORTA is a bi-directional I/O port. RA0 can also be analog input0. PORTB is a bi-directional I/O port. PORTB can be software programmed for internal weak pull-up on all inputs. RB0 can also be the external interrupt pin. RB0/INT 21 21 I/O TTL/ST(1) RB1 22 22 I/O TTL RB2 23 23 I/O TTL RB3/PGM 24 24 I/O TTL/ST(1) RB4 25 25 I/O TTL Interrupt on change pin. RB5 26 26 I/O TTL Interrupt on change pin. RB6/PGC 27 27 I/O TTL/ST(2) Interrupt on change pin or In-Circuit Debugger pin. Serial programming clock. RB7/PGD 28 28 I/O TTL/ST(2) Interrupt on change pin or In-Circuit Debugger pin. Serial programming data. RC0/T1OSO/T1CKI 11 11 I/O ST RC0 can also be the Timer1 oscillator output or Timer1 clock input. RC1/T1OSI 12 12 I/O ST RC1 can also be the Timer1 oscillator input. RC2/CCP1 13 13 I/O ST RC2 can also be the Capture1 input/Compare1 output/PWM1 output. RC3/SCK/SCL 14 14 I/O ST RC3 can also be the synchronous serial clock input/output for both SPI and I2C modes. RC4/SDI/SDA 15 15 I/O ST RC4 can also be the SPI Data In (SPI mode) or data I/O (I2C mode). RC5/SDO 16 16 I/O ST RC5 can also be the SPI Data Out (SPI mode). RC6 17 17 I/O ST ST RB3 can also be the low voltage programming input. PORTC is a bi-directional I/O port. RC7 18 18 I/O VSS 8, 19 8, 19 P — Ground reference for logic and I/O pins. VDD 20 20 P — Positive supply for logic and I/O pins. Legend: I = input O = output I/O = input/output P = power — = Not used TTL = TTL input ST = Schmitt Trigger input Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt or LVP. 2: This buffer is a Schmitt Trigger input when used in serial programming mode. 3: This buffer is a Schmitt Trigger input when configured in RC oscillator mode and a CMOS input otherwise. DS30221A-page 6 Preliminary 1999 Microchip Technology Inc. PIC16F872 2.0 MEMORY ORGANIZATION 2.2 There are three memory blocks in each of these PICmicro ® MCUs. The Program Memory and Data Memory have separate buses, so that concurrent access can occur, and is detailed in this section. The EEPROM data memory block is detailed in Section 4.0. Data Memory Organization The data memory is partitioned into multiple banks which contain the General Purpose Registers and the Special Function Registers. Bits RP1(STATUS<6>) and RP0 (STATUS<5>) are the bank select bits. RP<1:0> Bank Additional information on device memory may be found in the PICmicro Mid-Range Reference Manual, (DS33023). 00 0 01 1 10 2 2.1 11 3 Program Memory Organization The PIC16F872 devices have a 13-bit program counter capable of addressing an 8K x 14 program memory space. The PIC16F872 device has 2K x 14 words of FLASH program memory. Accessing a location above the physically implemented address will cause a wraparound. The reset vector is at 0000h and the interrupt vector is at 0004h. FIGURE 2-1: PIC16F872 PROGRAM MEMORY MAP AND STACK 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 General Purpose Registers, implemented as static RAM. All implemented banks contain Special Function Registers. Some “high use” Special Function Registers from one bank may be mirrored in another bank for code reduction and quicker access. Note: 2.2.1 EEPROM Data Memory description can be found in Section 4.0 of this Data Sheet GENERAL PURPOSE REGISTER FILE The register file can be accessed either directly, or indirectly through the File Select Register FSR. PC<12:0> 13 CALL, RETURN RETFIE, RETLW Stack Level 1 Stack Level 2 Stack Level 8 On-Chip Program Memory Reset Vector 0000h Interrupt Vector 0004h 0005h Page 0 07FFh 0800h 1FFFh 1999 Microchip Technology Inc. Preliminary DS30221A-page 7 PIC16F872 FIGURE 2-2: PIC16F872 REGISTER FILE MAP File Address Indirect addr.(*) TMR0 PCL STATUS FSR PORTA PORTB PORTC PCLATH INTCON PIR1 PIR2 TMR1L TMR1H T1CON TMR2 T2CON SSPBUF SSPCON CCPR1L CCPR1H CCP1CON ADRESH ADCON0 00h 01h 02h 03h 04h 05h 06h 07h 08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 19h 1Ah 1Bh 1Ch 1Dh 1Eh 1Fh 20h General Purpose Register Indirect addr.(*) 80h OPTION_REG 81h PCL 82h STATUS 83h FSR 84h TRISA 85h TRISB 86h TRISC 87h 88h 89h PCLATH 8Ah INTCON 8Bh PIE1 8Ch PIE2 8Dh PCON 8Eh 8Fh 90h SSPCON2 91h PR2 92h SSPADD 93h SSPSTAT 94h 95h 96h 97h 98h 99h 9Ah 9Bh 9Ch 9Dh ADRESL 9Eh 9Fh ADCON1 General Purpose Register A0h 32 Bytes BFh C0h 96 Bytes 7Fh Bank 0 accesses 70h-7Fh Bank 1 Indirect addr.(*) 100h 101h TMR0 102h PCL 103h STATUS 104h FSR 105h 106h PORTB 107h 108h 109h 10Ah PCLATH 10Bh INTCON 10Ch EEDATA EEADR 10Dh 10Eh EEDATH 10Fh EEADRH 110h TRISB PCLATH INTCON EECON1 EECON2 Reserved(1) Reserved(1) 180h 181h 182h 183h 184h 185h 186h 187h 188h 189h 18Ah 18Bh 18Ch 18Dh 18Eh 18Fh 190h 1A0h 120h accesses A0h - BFh accesses 20h-7Fh EFh F0h Indirect addr.(*) OPTION_REG PCL STATUS FSR 1BFh 1C0h accesses 70h-7Fh FFh Bank 2 16Fh 170h 17Fh accesses 70h-7Fh 1EFh 1F0h 1FFh Bank 3 Unimplemented data memory locations, read as ’0’. * Not a physical register. Note 1: These registers are reserved; maintain these registers clear. DS30221A-page 8 Preliminary 1999 Microchip Technology Inc. PIC16F872 2.2.2 SPECIAL FUNCTION REGISTERS The Special Function Registers can be classified into two sets: core (CPU) and peripheral. Those registers associated with the core functions are described in detail in this section. Those related to the operation of the peripheral features are described in detail in the peripheral feature section. The Special Function Registers are registers used by the CPU and peripheral modules for controlling the desired operation of the device. These registers are implemented as static RAM. A list of these registers is given in Table 2-1. TABLE 2-1: Address SPECIAL FUNCTION REGISTER SUMMARY 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 (2) Bank 0 00h(3) INDF Addressing this location uses contents of FSR to address data memory (not a physical register) 0000 0000 0000 0000 01h TMR0 Timer0 module’s register xxxx xxxx uuuu uuuu 02h(3) PCL Program Counter's (PC) Least Significant Byte 0000 0000 0000 0000 (3) 03h STATUS 04h(3) FSR 05h PORTA 06h PORTB PORTB Data Latch when written: PORTB pins when read xxxx xxxx uuuu uuuu 07h PORTC PORTC Data Latch when written: PORTC pins when read xxxx xxxx uuuu uuuu 08h — Unimplemented — — 09h — Unimplemented — — (1,3) IRP RP1 RP0 TO PD Z DC C Indirect data memory address pointer — — 0001 1xxx 000q quuu xxxx xxxx uuuu uuuu PORTA Data Latch when written: PORTA pins when read --0x 0000 --0u 0000 PCLATH — — — 0Bh(3) INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u 0Ch PIR1 (4) ADIF (4) (4) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 — (4) — EEIF BCLIF — — (4) -r-0 0--r -r-0 0--r 0Ah Write Buffer for the upper 5 bits of the Program Counter 0Dh PIR2 0Eh TMR1L Holding register for the Least Significant Byte of the 16-bit TMR1 register 0Fh TMR1H Holding register for the Most Significant Byte of the 16-bit TMR1 register 10h T1CON 11h TMR2 12h T2CON — — T1SYNC xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu T1CKPS1 T1CKPS0 T1OSCEN TMR1CS TMR1ON TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000 Timer2 module’s register — ---0 0000 ---0 0000 --00 0000 --uu uuuu 0000 0000 0000 0000 13h SSPBUF 14h SSPCON Synchronous Serial Port Receive Buffer/Transmit Register 15h CCPR1L Capture/Compare/PWM Register1 (LSB) 16h CCPR1H Capture/Compare/PWM Register1 (MSB) 17h CCP1CON 18h — Unimplemented — — 19h — Unimplemented — — 1Ah — Unimplemented — — 1Bh — Unimplemented — — 1Ch — Unimplemented — — 1Dh — Unimplemented — — 1Eh ADRESH A/D Result Register High Byte 1Fh ADCON0 WCOL SSPOV — ADCS1 — ADCS0 SSPEN CCP1X CHS2 CKP CCP1Y SSPM3 xxxx xxxx uuuu uuuu SSPM2 SSPM1 SSPM0 0000 0000 0000 0000 xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000 xxxx xxxx uuuu uuuu CHS1 CHS0 GO/ DONE — ADON 0000 00-0 0000 00-0 Legend: x = unknown, u = unchanged, q = value depends on condition, - = unimplemented read as ’0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. Note 1: The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8> whose contents are transferred to the upper byte of the program counter. 2: Other (non power-up) resets include external reset through MCLR and Watchdog Timer Reset. 3: These registers can be addressed from any bank. 4: These bits are reserved; always maintain these bits clear. 1999 Microchip Technology Inc. Preliminary DS30221A-page 9 PIC16F872 TABLE 2-1: Address SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED) 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 (2) Bank 1 80h(3) INDF 81h OPTION_REG 82h(3) PCL 83h(3) STATUS 84h(3) FSR 85h TRISA Addressing this location uses contents of FSR to address data memory (not a physical register) RBPU INTEDG T0CS T0SE PS2 PS1 PS0 1111 1111 1111 1111 PD Z DC C 0001 1xxx 000q quuu Program Counter’s (PC) Least Significant Byte IRP RP1 RP0 0000 0000 0000 0000 TO Indirect data memory address pointer — — 0000 0000 0000 0000 PSA xxxx xxxx uuuu uuuu PORTA Data Direction Register --11 1111 --11 1111 86h TRISB PORTB Data Direction Register 1111 1111 1111 1111 87h TRISC PORTC Data Direction Register 1111 1111 1111 1111 88h — Unimplemented — — 89h — Unimplemented — — (1,3) PCLATH — 8Bh(3) INTCON 8Ch PIE1 8Dh PIE2 8Eh PCON 8Fh — Unimplemented — — 90h — Unimplemented — — 91h SSPCON2 92h PR2 Timer2 Period Register 93h SSPADD Synchronous Serial Port (I2C mode) Address Register 94h SSPSTAT 95h — Unimplemented — — 96h — Unimplemented — — 97h — Unimplemented — — 98h — Unimplemented — — 99h — Unimplemented — — 9Ah — Unimplemented — — 9Bh — Unimplemented — — 9Ch — Unimplemented — — 9Dh — Unimplemented — — 9Eh ADRESL A/D Result Register Low Byte 9Fh ADCON1 8Ah — — GIE PEIE T0IE INTE RBIE T0IF INTF RBIF (4) ADIE (4) (4) SSPIE CCP1IE TMR2IE TMR1IE r0rr 0000 r0rr 0000 — (4) — EEIE BCLIE — — (4) -r-0 0--r -r-0 0--r — — — — — — POR BOR ---- --qq ---- --uu GCEN SMP ADFM ACKSTAT CKE — ACKDT Write Buffer for the upper 5 bits of the Program Counter ACKEN RCEN PEN RSEN SEN ---0 0000 ---0 0000 0000 000x 0000 000u 0000 0000 0000 0000 1111 1111 1111 1111 D/A — P 0000 0000 0000 0000 S R/W UA BF 0000 0000 0000 0000 xxxx xxxx uuuu uuuu — PCFG3 PCFG2 PCFG1 PCFG0 0--- 0000 0--- 0000 Legend: x = unknown, u = unchanged, q = value depends on condition, - = unimplemented read as ’0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. Note 1: The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8> whose contents are transferred to the upper byte of the program counter. 2: Other (non power-up) resets include external reset through MCLR and Watchdog Timer Reset. 3: These registers can be addressed from any bank. 4: These bits are reserved; always maintain these bits clear. DS30221A-page 10 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 2-1: Address SPECIAL FUNCTION REGISTER SUMMARY (CONTINUED) 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 (2) 0000 0000 0000 0000 Bank 2 100h(3) INDF Addressing this location uses contents of FSR to address data memory (not a physical register) 101h TMR0 Timer0 module’s register 102h(3) PCL Program Counter's (PC) Least Significant Byte 103h(3) STATUS (3) IRP xxxx xxxx uuuu uuuu RP1 RP0 TO 0000 0000 0000 0000 PD Z DC C 0001 1xxx 000q quuu 104h FSR Indirect data memory address pointer 105h — Unimplemented 106h PORTB PORTB Data Latch when written: PORTB pins when read 107h — Unimplemented — — 108h — Unimplemented — — 109h — Unimplemented — — 10Ah (1,3) PCLATH xxxx xxxx uuuu uuuu — — — — GIE PEIE T0IE 10Bh(3) INTCON 10Ch EEDATA EEPROM data register 10Dh EEADR EEPROM address register 10Eh EEDATH — — 10Fh EEADRH — — Write Buffer for the upper 5 bits of the Program Counter INTE RBIE — xxxx xxxx uuuu uuuu T0IF INTF RBIF ---0 0000 ---0 0000 0000 000x 0000 000u xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu EEPROM data register high byte — xxxx xxxx uuuu uuuu EEPROM address register high byte xxxx xxxx uuuu uuuu Bank 3 180h(3) INDF 181h OPTION_REG 182h(3) PCL 183h(3) STATUS (3) Addressing this location uses contents of FSR to address data memory (not a physical register) RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 PD Z DC C Program Counter's (PC) Least Significant Byte IRP RP1 RP0 TO 0000 0000 0000 0000 1111 1111 1111 1111 0000 0000 0000 0000 0001 1xxx 000q quuu 184h FSR Indirect data memory address pointer 185h — Unimplemented 186h TRISB PORTB Data Direction Register 187h — Unimplemented — — 188h — Unimplemented — — 189h — Unimplemented — — 18Ah (1,3) PCLATH xxxx xxxx uuuu uuuu — — — — — 1111 1111 1111 1111 Write Buffer for the upper 5 bits of the Program Counter ---0 0000 ---0 0000 18Bh(3) INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u 18Ch EECON1 EEPGD — — — WRERR WREN WR RD x--- x000 x--- u000 18Dh EECON2 EEPROM control register2 (not a physical register) ---- ---- ---- ---- 18Eh — Reserved maintain clear 0000 0000 0000 0000 18Fh — Reserved maintain clear 0000 0000 0000 0000 Legend: x = unknown, u = unchanged, q = value depends on condition, - = unimplemented read as ’0’, r = reserved. Shaded locations are unimplemented, read as ‘0’. Note 1: The upper byte of the program counter is not directly accessible. PCLATH is a holding register for the PC<12:8> whose contents are transferred to the upper byte of the program counter. 2: Other (non power-up) resets include external reset through MCLR and Watchdog Timer Reset. 3: These registers can be addressed from any bank. 4: These bits are reserved; always maintain these bits clear. 1999 Microchip Technology Inc. Preliminary DS30221A-page 11 PIC16F872 2.2.2.1 STATUS REGISTER For example, CLRF STATUS will clear the upper-three bits and set the Z bit. This leaves the STATUS register as 000u u1uu (where u = unchanged). The STATUS register contains the arithmetic status of the ALU, the RESET status and the bank select bits for data memory. It is recommended, therefore, that only BCF, BSF, SWAPF and MOVWF instructions are used to alter the STATUS register, because these instructions do not affect the Z, C or DC bits from the STATUS register. For other instructions not affecting any status bits, see the "Instruction Set Summary." The STATUS register can be the destination for any instruction, as with 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 disabled. These bits are set or cleared 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. Note: The C and DC bits operate as a borrow and digit borrow bit, respectively, in subtraction. See the SUBLW and SUBWF instructions for examples. REGISTER 2-1: STATUS REGISTER (ADDRESS 03h, 83h, 103h, 183h) 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 Z DC C bit7 bit 7: bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset IRP: Register Bank Select bit (used for indirect addressing) 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) 11 = Bank 3 (180h - 1FFh) 10 = Bank 2 (100h - 17Fh) 01 = Bank 1 (80h - FFh) 00 = Bank 0 (00h - 7Fh) Each bank is 128 bytes 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) (for borrow the polarity is reversed) 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 = 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: 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. DS30221A-page 12 Preliminary 1999 Microchip Technology Inc. PIC16F872 2.2.2.2 OPTION_REG REGISTER The OPTION_REG Register is a readable and writable register, which contains various control bits to configure the TMR0 prescaler/WDT postscaler (single assignable register known also as the prescaler), the External INT Interrupt, TMR0 and the weak pull-ups on PORTB. Note: To achieve a 1:1 prescaler assignment for the TMR0 register, assign the prescaler to the Watchdog Timer. REGISTER 2-2: OPTION_REG REGISTER (ADDRESS 81h, 181h) 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 bit7 bit0 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 pin 0 = Interrupt on falling edge of RB0/INT pin bit 5: T0CS: TMR0 Clock Source Select bit 1 = Transition on RA4/T0CKI pin 0 = Internal instruction cycle clock (CLKOUT) bit 4: T0SE: TMR0 Source Edge Select bit 1 = Increment on high-to-low transition on RA4/T0CKI pin 0 = Increment on low-to-high transition on RA4/T0CKI pin bit 3: PSA: Prescaler Assignment bit 1 = Prescaler is assigned to the WDT 0 = Prescaler is assigned to the Timer0 module R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 2-0: PS<2:0>: Prescaler Rate Select bits Bit Value 000 001 010 011 100 101 110 111 Note: TMR0 Rate 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 1 : 256 WDT Rate 1:1 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 When using Low Voltage ICSP Programming (LVP) and the pull-ups on PORTB are enabled, bit 3 in the TRISB register must be cleared to disable the pull-up on RB3 and ensure the proper operation of the device. 1999 Microchip Technology Inc. Preliminary DS30221A-page 13 PIC16F872 2.2.2.3 INTCON REGISTER Note: The INTCON Register is a readable and writable register, which contains various enable and flag bits for the TMR0 register overflow, RB Port change and External RB0/INT pin interrupts. Interrupt flag bits get 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 clear prior to enabling an interrupt. REGISTER 2-3: INTCON REGISTER (ADDRESS 0Bh, 8Bh, 10Bh, 18Bh) 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 bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 7: GIE: Global Interrupt Enable bit 1 = Enables all un-masked interrupts 0 = Disables all interrupts bit 6: PEIE: Peripheral Interrupt Enable bit 1 = Enables all un-masked 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 External Interrupt Enable bit 1 = Enables the RB0/INT external interrupt 0 = Disables the RB0/INT external interrupt bit 3: RBIE: RB Port Change Interrupt Enable bit 1 = Enables the RB port change interrupt 0 = Disables the RB port change interrupt bit 2: T0IF: TMR0 Overflow Interrupt Flag bit 1 = TMR0 register has overflowed (must be cleared in software) 0 = TMR0 register did not overflow bit 1: INTF: RB0/INT External Interrupt Flag bit 1 = The RB0/INT external interrupt occurred (must be cleared in software) 0 = The RB0/INT external interrupt did not occur bit 0: RBIF: RB Port Change Interrupt Flag bit 1 = At least one of the RB<7:4> pins changed state (must be cleared in software) 0 = None of the RB<7:4> pins have changed state DS30221A-page 14 Preliminary 1999 Microchip Technology Inc. PIC16F872 2.2.2.4 PIE1 REGISTER The PIE1 register contains the individual enable bits for the peripheral interrupts. Note: Bit PEIE (INTCON<6>) must be set to enable any peripheral interrupt. R/W-0 R/W-0 REGISTER 2-4: PIE1 REGISTER (ADDRESS 8Ch) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — ADIE — — SSPIE CCP1IE TMR2IE TMR1IE bit7 bit0 bit 7: Reserved: Always maintain this bit clear bit 6: ADIE: A/D Converter Interrupt Enable bit 1 = Enables the A/D converter interrupt 0 = Disables the A/D converter interrupt R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 5-4: Reserved: Always maintain this bit clear bit 3: SSPIE: Synchronous Serial Port Interrupt Enable bit 1 = Enables the SSP interrupt 0 = Disables the SSP interrupt bit 2: CCP1IE: CCP1 Interrupt Enable bit 1 = Enables the CCP1 interrupt 0 = Disables the CCP1 interrupt bit 1: TMR2IE: TMR2 to PR2 Match Interrupt Enable bit 1 = Enables the TMR2 to PR2 match interrupt 0 = Disables the TMR2 to PR2 match interrupt bit 0: TMR1IE: TMR1 Overflow Interrupt Enable bit 1 = Enables the TMR1 overflow interrupt 0 = Disables the TMR1 overflow interrupt 1999 Microchip Technology Inc. Preliminary DS30221A-page 15 PIC16F872 2.2.2.5 PIR1 REGISTER The PIR1 register contains the individual flag bits for the peripheral interrupts. Note: Interrupt flag bits get 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 bits are clear prior to enabling an interrupt. R/W-0 R/W-0 REGISTER 2-5: PIR1 REGISTER (ADDRESS 0Ch) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — ADIF — — SSPIF CCP1IF TMR2IF TMR1IF bit7 bit0 bit 7: Reserved: Always maintain this bit clear bit 6: ADIF: A/D Converter Interrupt Flag bit 1 = An A/D conversion completed 0 = The A/D conversion is not complete R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 5-4: Reserved: Always maintain this bit clear bit 3: SSPIF: Synchronous Serial Port (SSP) Interrupt Flag 1 = The SSP interrupt condition has occurred, and must be cleared in software before returning from the interrupt service routine. The conditions that will set this bit are: SPI A transmission/reception has taken place. I2C Slave A transmission/reception has taken place. I2C Master A transmission/reception has taken place. The initiated start condition was completed by the SSP module. The initiated stop condition was completed by the SSP module. The initiated restart condition was completed by the SSP module. The initiated acknowledge condition was completed by the SSP module. A start condition occurred while the SSP module was idle (Multimaster system). A stop condition occurred while the SSP module was idle (Multimaster system). 0 = No SSP interrupt condition has occurred. 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 Match Interrupt Flag bit 1 = 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 = TMR1 register overflowed (must be cleared in software) 0 = TMR1 register did not overflow DS30221A-page 16 Preliminary 1999 Microchip Technology Inc. PIC16F872 2.2.2.6 PIE2 REGISTER The PIE2 register contains the individual enable bits for the SSP bus collision interrupt and the EEPROM write operation interrupt. REGISTER 2-6: PIE2 REGISTER (ADDRESS 8Dh) U-0 R/W-0 U-0 R/W-0 R/W-0 U-0 U-0 R/W-0 — — — EEIE BCLIE — — — bit7 bit0 bit 7: Unimplemented: Read as '0' bit 6: Reserved: Always maintain this bit clear bit 5: Unimplemented: Read as '0' bit 4: EEIE: EEPROM Write Operation Interrupt Enable 1 = Enable EE Write Interrupt 0 = Disable EE Write Interrupt bit 3: BCLIE: Bus Collision Interrupt Enable 1 = Enable Bus Collision Interrupt 0 = Disable Bus Collision Interrupt R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 2-1: Unimplemented: Read as '0' bit 0: Reserved: Always maintain this bit clear 1999 Microchip Technology Inc. Preliminary DS30221A-page 17 PIC16F872 2.2.2.7 PIR2 REGISTER . The PIR2 register contains the flag bits for the SSP bus collision interrupt and the EEPROM write operation interrupt. Note: Interrupt flag bits get 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 clear prior to enabling an interrupt. REGISTER 2-7: PIR2 REGISTER (ADDRESS 0Dh) U-0 R/W-0 U-0 R/W-0 R/W-0 U-0 U-0 R/W-0 — — — EEIF BCLIF — — — bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 7: Unimplemented: Read as '0' bit 6: Reserved: Always maintain this bit clear bit 5: Unimplemented: Read as '0' bit 4: EEIF: EEPROM Write Operation Interrupt Flag bit 1 = The write operation completed (must be cleared in software) 0 = The write operation is not complete or has not been started bit 3: BCLIF: Bus Collision Interrupt Flag 1 = A bus collision has occurred in the SSP, when configured for I2C master mode 0 = No bus collision has occurred bit 2-1: Unimplemented: Read as '0' bit 0: Reserved: Always maintain this bit clear DS30221A-page 18 Preliminary 1999 Microchip Technology Inc. PIC16F872 2.2.2.8 PCON REGISTER Note: The Power Control (PCON) Register contains flag bits to allow differentiation between a Power-on Reset (POR), a Brown-out Reset (BOR), a Watch-dog Reset (WDT) and an external MCLR Reset. BOR is unknown on POR. It must be set by the user and checked on subsequent resets to see if BOR is clear, indicating a brown-out has occurred. The BOR status bit is a don’t care and is not predictable if the brown-out circuit is disabled (by clearing the BODEN bit in the configuration word). REGISTER 2-8: PCON REGISTER (ADDRESS 8Eh) U-0 U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-1 — — — — — — POR BOR bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 7-2: 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) 1999 Microchip Technology Inc. Preliminary DS30221A-page 19 PIC16F872 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 upper bits (PC<12:8>) are not readable, but are indirectly writable through the PCLATH register. On any reset, the upper bits of the PC will be cleared. Figure 2-3 shows the two situations for the loading of the PC. The upper example in the figure shows how the PC is loaded on a write to PCL (PCLATH<4:0> → PCH). The lower example in the figure 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 PCH PCL 12 8 7 0 PC 5 8 PCLATH<4:0> Instruction with PCL as Destination ALU PCLATH PCH 12 11 10 PCL 8 PC PCLATH<4:3> 11 Opcode <10:0> PCLATH COMPUTED GOTO A computed GOTO is accomplished by adding an offset to the program counter (ADDWF PCL). When doing a table read using a computed GOTO method, care should be exercised if the table location crosses a PCL memory boundary (each 256 byte block). Refer to the application note, “Implementing a Table Read" (AN556). 2.3.2 2.4 Program Memory Paging The PIC16CXXX architecture is capable of addressing a continuous 8K word block of program memory. The CALL and GOTO instructions provide 11 bits of the address, which allows branches within any 2K program memory page. Therefore, the 8K words of program memory are broken into four pages. Since the PIC16FC872 has only 2K words of program memory or one page, additional code is not required to ensure that the correct page is selected before a CALL or GOTO instruction is executed. The PCLATH<4:3> bits should always be maintained as zeros. If a return from a CALL instruction (or interrupt) is executed, the entire 13-bit PC is popped off the stack. Manipulation of the PCLATH is not required for the return instructions. GOTO,CALL 2 2.3.1 2: There are no instructions/mnemonics called PUSH or POP. These are actions that occur from the execution of the CALL, RETURN, RETLW and RETFIE instructions or the vectoring to an interrupt address. 2.5 0 7 Note 1: There are no status bits to indicate stack overflow or stack underflow conditions. Indirect Addressing, INDF and FSR Registers The INDF register is not a physical register. Addressing the INDF register will cause indirect addressing. Indirect addressing is possible by using the INDF register. Any instruction using the INDF register actually accesses the register pointed to by the File Select Register, FSR. Reading the INDF register itself indirectly (FSR = ’0’) will read 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 Figure 2-4. A simple program to clear RAM locations 20h-2Fh using indirect addressing is shown in Example 2-1. EXAMPLE 2-1: STACK The PIC16CXX family has an 8-level deep x 13-bit wide hardware stack. 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. NEXT movlw movwf clrf incf btfss goto INDIRECT ADDRESSING 0x20 FSR INDF FSR,F FSR,4 NEXT ;initialize pointer ;to RAM ;clear INDF register ;inc pointer ;all done? ;no clear next CONTINUE : ;yes continue The stack operates as a circular buffer. This means that after the stack has been PUSHed eight times, the ninth push overwrites the value that was stored from the first push. The tenth push overwrites the second push (and so on). DS30221A-page 20 Preliminary 1999 Microchip Technology Inc. PIC16F872 FIGURE 2-4: DIRECT/INDIRECT ADDRESSING Direct Addressing Indirect Addressing from opcode RP1:RP0 6 bank select location select 0 IRP 7 bank select 00 01 10 FSR register 0 location select 11 00h 80h 100h 180h 7Fh FFh 17Fh 1FFh Data Memory(1) Bank 0 Note 1: Bank 1 Bank 2 Bank 3 For register file map detail see Figure 2-2. 1999 Microchip Technology Inc. Preliminary DS30221A-page 21 PIC16F872 NOTES: DS30221A-page 22 Preliminary 1999 Microchip Technology Inc. PIC16F872 3.0 I/O PORTS FIGURE 3-1: Some pins for these I/O ports are multiplexed with an alternate function for the peripheral features on the device. In general, when a peripheral is enabled, that pin may not be used as a general purpose I/O pin. Additional information on I/O ports may be found in the PICmicro™ Mid-Range Reference Manual, (DS33023). Data Bus BLOCK DIAGRAM OF RA<3:0> AND RA5 PINS D Q VDD WR Port Q CK P Data Latch 3.1 PORTA and the TRISA Register D PORTA is a 6-bit wide, bi-directional port. The corresponding data direction register is TRISA. Setting a TRISA bit (=1) will make the corresponding PORTA pin an input (i.e., put the corresponding output driver in a hi-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). WR TRIS TRIS Latch Other PORTA pins are multiplexed with analog inputs and analog VREF input. The operation of each pin is selected by clearing/setting the control bits in the ADCON1 register (A/D Control Register1). Note: Q RD Port To A/D Converter Note 1: I/O pins have protection diodes to VDD and VSS. FIGURE 3-2: Data Bus The TRISA register controls the direction of the RA pins, even when they are being used as analog inputs. The user must ensure the bits in the TRISA register are maintained set when using them as analog inputs. WR Port STATUS, RP0 STATUS, RP1 PORTA BSF MOVLW MOVWF MOVLW STATUS, RP0 0x06 ADCON1 0xCF MOVWF TRISA ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; BLOCK DIAGRAM OF RA4/ T0CKI PIN D Q CK Q N I/O pin(1) Data Latch INITIALIZING PORTA BCF BCF CLRF D EN On a Power-on Reset, these pins are configured as analog inputs and read as '0'. EXAMPLE 3-1: TTL Input Buffer RD TRIS Reading the PORTA register 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 read, the value is modified and then written to the port data latch. Pin RA4 is multiplexed with the Timer0 module clock input to become the RA4/T0CKI pin. The RA4/T0CKI pin is a Schmitt Trigger input and an open drain output. All other PORTA pins have TTL input levels and full CMOS output drivers. VSS Analog Input Mode Q CK I/O pin(1) N Q WR TRIS Bank0 Initialize PORTA by clearing output data latches Select Bank 1 Configure all pins as digital inputs Value used to initialize data direction Set RA<3:0> as inputs RA<5:4> as outputs TRISA<7:6> are always read as ’0’. D Q CK Q VSS Schmitt Trigger Input Buffer TRIS Latch RD TRIS Q D ENEN RD Port TMR0 clock input Note 1: I/O pin has protection diodes to VSS only. 1999 Microchip Technology Inc. Preliminary DS30221A-page 23 PIC16F872 TABLE 3-1: PORTA FUNCTIONS Name Bit# Buffer Function RA0/AN0 bit0 TTL Input/output or analog input RA1/AN1 bit1 TTL Input/output or analog input RA2/AN2 bit2 TTL Input/output or analog input RA3/AN3/VREF bit3 TTL Input/output or analog input or VREF RA4/T0CKI bit4 ST Input/output or external clock input for Timer0 Output is open drain type RA5/SS/AN4 bit5 TTL Input/output or slave select input for synchronous serial port or analog input Legend: TTL = TTL input, ST = Schmitt Trigger input. TABLE 3-2: Address SUMMARY OF REGISTERS ASSOCIATED WITH PORTA Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RA5 RA4 RA3 RA2 RA1 RA0 05h PORTA — — 85h TRISA — — 9Fh ADCON1 ADFM — PORTA Data Direction Register — — Value on: Value on all POR, other BOR resets --0x 0000 --0u 0000 --11 1111 --11 1111 PCFG3 PCFG2 PCFG1 PCFG0 --0- 0000 --0- 0000 Legend: x = unknown, u = unchanged, - = unimplemented locations read as '0'. Shaded cells are not used by PORTA. Note: When using the SSP module in SPI slave mode and SS enabled, the A/D converter must be set to one of the following modes where PCFG<3:0> = 0100,0101, 011x, 1101, 1110, 1111. DS30221A-page 24 Preliminary 1999 Microchip Technology Inc. PIC16F872 3.2 PORTB and the TRISB Register PORTB is an 8-bit wide bi-directional port. The corresponding data direction register is TRISB. Setting a TRISB bit (=1) will make the corresponding PORTB pin an input (i.e., put the corresponding output driver in a hi-impedance mode). Clearing a TRISB bit (=0) will make the corresponding PORTB pin an output (i.e., put the contents of the output latch on the selected pin). Three pins of PORTB are multiplexed with the Low Voltage Programming function; RB3/PGM, RB6/PGC and RB7/PGD. The alternate functions of these pins are described in the Special Features Section. Each of the PORTB pins has a weak internal pull-up. A single control bit can turn on all the pull-ups. This is performed by clearing bit RBPU (OPTION_REG<7>). The 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. FIGURE 3-3: BLOCK DIAGRAM OF RB<3:0> PINS Data Bus WR Port weak P pull-up Data Latch D Q Any read or write of PORTB. This will end the mismatch condition. Clear flag bit RBIF. b) A mismatch condition will continue to set flag bit RBIF. Reading PORTB will end the mismatch condition and allow flag bit RBIF to be cleared. The interrupt on change feature is recommended for wake-up on key depression operation and operations where PORTB is only used for the interrupt on change feature. Polling of PORTB is not recommended while using the interrupt on change feature. This interrupt on mismatch feature, together with software configurable pull-ups on these four pins, allow easy interface to a keypad and make it possible for wake-up on key-depression. Refer to the Embedded Control Handbook, “Implementing Wake-Up on Key Stroke” (AN552). RB0/INT is discussed in detail in Section 11.10.1. FIGURE 3-4: I/O pin(1) CK VDD TTL Input Buffer CK weak P pull-up Data Latch D Q Data Bus WR Port TRIS Latch Q D D WR TRIS RD Port TTL Input Buffer RD TRIS Schmitt Trigger Buffer RD Port I/O pins have diode protection to VDD and VSS. To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit (OPTION_REG<7>). Four of PORTB’s pins, RB<7:4>, have an interrupt on change feature. Only pins configured as inputs can cause this interrupt to occur (i.e., any RB<7:4> pin configured as an output is excluded from the interrupt on change comparison). The input pins (of RB<7:4>) are compared with the old value latched on the last read of PORTB. The “mismatch” outputs of RB<7:4> are OR’ed together to generate the RB Port Change Interrupt with flag bit RBIF (INTCON<0>). Note: Q CK EN RB0/INT RB3/PGM 1: 2: I/O pin(1) CK RD TRIS Note BLOCK DIAGRAM OF RB<7:4> PINS RBPU(2) TRIS Latch D Q WR TRIS a) RB0/INT is an external interrupt input pin and is configured using the INTEDG bit (OPTION_REG<6>). VDD RBPU(2) This interrupt can wake the device from SLEEP. The user, in the interrupt service routine, can clear the interrupt in the following manner: Q Latch D EN RD Port ST Buffer Q1 Set RBIF From other RB<7:4> pins Q D RD Port EN Q3 RB<7:6> in serial programming mode Note 1: 2: I/O pins have diode protection to VDD and VSS. To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit (OPTION_REG<7>). When using Low Voltage ICSP Programming (LVP) and the pull-ups on PORTB are enabled, bit 3 in the TRISB register must be cleared to disable the pull-up on RB3 and ensure the proper operation of the device. 1999 Microchip Technology Inc. Preliminary DS30221A-page 25 PIC16F872 TABLE 3-3: Name PORTB FUNCTIONS Bit# Buffer (1) RB0/INT bit0 TTL/ST RB1 bit1 TTL RB2 bit2 TTL Function Input/output pin or external interrupt input. Internal software programmable weak pull-up. Input/output pin. Internal software programmable weak pull-up. Input/output pin. Internal software programmable weak pull-up. (1) RB3/PGM bit3 TTL/ST Input/output pin or programming pin in LVP mode. Internal software programmable weak pull-up. RB4 bit4 TTL Input/output pin (with interrupt on change). Internal software programmable weak pull-up. RB5 bit5 TTL Input/output pin (with interrupt on change). Internal software programmable weak pull-up. RB6/PGC bit6 TTL/ST(2) Input/output pin (with interrupt on change) or In-Circuit Debugger pin. Internal software programmable weak pull-up. Serial programming clock. RB7/PGD bit7 TTL/ST(2) Input/output pin (with interrupt on change) or In-Circuit Debugger pin. Internal software programmable weak pull-up. Serial programming data. Legend: TTL = TTL input, ST = Schmitt Trigger input. Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt or LVP mode. 2: This buffer is a Schmitt Trigger input when used in serial programming mode. TABLE 3-4: Address SUMMARY OF REGISTERS ASSOCIATED WITH PORTB Name 06h, 106h PORTB 86h, 186h TRISB 81h, 181h OPTION_REG Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 PORTB Data Direction Register RBPU INTEDG T0CS T0SE Value on: POR, BOR Value on all other resets xxxx xxxx uuuu uuuu 1111 1111 1111 1111 PSA PS2 PS1 PS0 1111 1111 1111 1111 Legend: x = unknown, u = unchanged. Shaded cells are not used by PORTB. DS30221A-page 26 Preliminary 1999 Microchip Technology Inc. PIC16F872 3.3 FIGURE 3-6: PORTC and the TRISC Register PORTC is an 8-bit wide, bi-directional port. The corresponding data direction register is TRISC. Setting a TRISC bit (=1) will make the corresponding PORTC pin an input (i.e., put the corresponding output driver in a hi-impedance mode). Clearing a TRISC bit (=0) will make the corresponding PORTC pin an output (i.e., put the contents of the output latch on the selected pin). PORTC is multiplexed with several peripheral functions (Table 3-5). PORTC pins have Schmitt Trigger input buffers. When the I2C module is enabled, the PORTC (3:4) pins can be configured with normal I2C levels or with SMBUS levels by using the CKE bit (SSPSTAT<6>). When enabling peripheral functions, care should be taken in defining TRIS bits for each PORTC pin. Some peripherals override the TRIS bit to make a pin an output, while other peripherals override the TRIS bit to make a pin an input. Since the TRIS bit override is in effect while the peripheral is enabled, read-modifywrite instructions (BSF, BCF, XORWF) with TRISC as destination should be avoided. The user should refer to the corresponding peripheral section for the correct TRIS bit settings. FIGURE 3-5: PORTC BLOCK DIAGRAM (PERIPHERAL OUTPUT OVERRIDE) RC<3:4> Port/Peripheral Select(2) Peripheral Data Out Data Bus WR Port D VDD 0 Q P 1 CK Q Data Latch WR TRIS D CK I/O pin(1) Q Q N TRIS Latch Vss Schmitt Trigger RD TRIS Peripheral OE(3) Q RD Port D EN 0 Schmitt Trigger with SMBus levels SSPl Input 1 CKE SSPSTAT<6> Note 1: I/O pins have diode protection to VDD and VSS. 2: Port/Peripheral select signal selects between port data and peripheral output. 3: Peripheral OE (output enable) is only activated if peripheral select is active. PORTC BLOCK DIAGRAM (PERIPHERAL OUTPUT OVERRIDE) RC<0:2> RC<5:7> Port/Peripheral Select(2) Peripheral Data Out Data Bus WR Port VDD 0 D Q P 1 CK Q Data Latch WR TRIS D CK I/O pin(1) Q Q N TRIS Latch VSS Schmitt Trigger RD TRIS Peripheral OE(3) Q RD Port Peripheral Input D EN Note 1: I/O pins have diode protection to VDD and VSS. 2: Port/Peripheral select signal selects between port data and peripheral output. 3: Peripheral OE (output enable) is only activated if peripheral select is active. 1999 Microchip Technology Inc. Preliminary DS30221A-page 27 PIC16F872 TABLE 3-5: PORTC FUNCTIONS Name Bit# Buffer Type Function RC0/T1OSO/T1CKI bit0 ST Input/output port pin or Timer1 oscillator output/Timer1 clock input. RC1/T1OSI bit1 ST Input/output port pin or Timer1 oscillator input. RC2/CCP1 bit2 ST Input/output port pin or Capture1 input/Compare1 output/PWM1 output. RC3/SCK/SCL bit3 ST RC3 can also be the synchronous serial clock for both SPI and I2C modes. RC4/SDI/SDA bit4 ST RC4 can also be the SPI Data In (SPI mode) or data I/O (I2C mode). RC5/SDO bit5 ST Input/output port pin or Synchronous Serial Port data output. RC6 bit6 ST Input/output port pin. RC7 bit7 ST Input/output port pin. Legend: ST = Schmitt Trigger input. TABLE 3-6: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR 07h PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 xxxx xxxx uuuu uuuu 87h TRISC 1111 1111 1111 1111 Address PORTC Data Direction Register Value on all other resets Legend: x = unknown, u = unchanged. DS30221A-page 28 Preliminary 1999 Microchip Technology Inc. PIC16F872 4.0 DATA EEPROM AND FLASH PROGRAM MEMORY The Data EEPROM and FLASH Program Memory are readable and writable during normal operation over the entire VDD range. A bulk erase operation may not be issued from user code (which includes removing code protection). The data memory is not directly mapped in the register file space. Instead, it is indirectly addressed through the Special Function Registers (SFR). There are six SFRs used to read and write the program and data EEPROM memory. These registers are: • • • • • • EECON1 EECON2 EEDATA EEDATH EEADR EEADRH 4.1 EEADR The address registers can address up to a maximum of 256 bytes of data EEPROM or up to a maximum of 8K words of program FLASH. However, the PIC16F872 has 64 bytes of data EEPROM and 2K words of program FLASH. When selecting a program address value, the MSByte of the address is written to the EEADRH register and the LSByte is written to the EEADR register. When selecting a data address value, only the LSByte of the address is written to the EEADR register. The EEPROM data memory allows byte read and write. When interfacing to the data memory block, EEDATA holds the 8-bit data for read/write and EEADR holds the address of the EEPROM location being accessed. The registers EEDATH and EEADRH are not used for data EEPROM access. The PIC16F872 device has 64 bytes of data EEPROM with an address range from 0h to 3Fh. The EEPROM data memory is rated for high erase/ write cycles. The write time is controlled by an on-chip timer. The write time will vary with voltage and temperature, as well as from chip-to-chip. Please refer to the specifications for exact limits. The program memory allows word reads and writes. Program memory access allows for checksum calculation and calibration table storage. A byte or word write automatically erases the location and writes the new data (erase before write). Writing to program memory will cease operation until the write is complete. The program memory cannot be accessed during the write, therefore code cannot execute. During the write operation, the oscillator continues to clock the peripherals, and therefore, they continue to operate. Interrupt events will be detected and essentially “queued” until the write is completed. When the write completes, the next instruction in the pipeline is executed and the branch to the interrupt vector address will occur. When interfacing to the program memory block, the EEDATH:EEDATA registers form a two byte word, which holds the 14-bit data for read/write. The EEADRH:EEADR registers form a two byte word, which holds the 13-bit address of the FLASH location being accessed. The PIC16F872 device has 2K words of program FLASH with an address range from 0h to 7FFh. The unused upper bits in both the EEDATH and EEDATA registers all read as “0’s”. 1999 Microchip Technology Inc. The value written to program memory does not need to be a valid instruction. Therefore, up to 14-bit numbers can be stored in memory for use as calibration parameters, serial numbers, packed 7-bit ASCII, etc. Executing a program memory location containing data that forms an invalid instruction results in a NOP. On the PIC16F872 device, the upper two bits of the EEADR must always be cleared to prevent inadvertent access to the wrong location in data EEPROM. This also applies to the program memory. The upper five MSbits of EEADRH must always be clear during program FLASH access. 4.2 EECON1 and EECON2 Registers EECON1 is the control register for memory accesses. EECON2 is not a physical register. Reading EECON2 will read all '0's. The EECON2 register is used exclusively in the memory write sequence. Control bit EEPGD determines if the access will be a program or a data memory access. When clear, any subsequent operations will operate on the data memory. When set, any subsequent operations will operate on the program memory. Control bits RD and WR initiate read and write operations, respectively. These bits cannot be cleared, only set, in software. They are cleared in hardware at the completion of the read or write operation. The inability to clear the WR bit in software prevents the accidental or premature termination of a write operation. The WREN bit, when set, will allow a write operation. On power-up, the WREN bit is clear. The WRERR bit is set when a write operation is interrupted by a MCLR reset 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 value of the data and address registers and the EEPGD bit remains unchanged. Interrupt flag bit EEIF, in the PIR2 register, is set when write is complete. It must be cleared in software. Preliminary DS30221A-page 29 PIC16F872 REGISTER 4-1: EECON1 REGISTER (ADDRESS 18Ch) R/W-x U-0 U-0 U-0 R/W-x R/W-0 R/S-0 R/S-0 EEPGD — — — WRERR WREN WR RD bit7 bit 7: bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset EEPGD: Program / Data EEPROM Select bit 1 = Accesses Program memory 0 = Accesses data memory (This bit cannot be changed while a read or write operation is in progress) bit 6-4: Unimplemented: Read as '0' bit 3: WRERR: EEPROM Error Flag bit 1 = A write operation is prematurely terminated (any MCLR reset or any WDT reset during normal operation) 0 = The write operation completed bit 2: WREN: EEPROM Write Enable bit 1 = Allows write cycles 0 = Inhibits write to the EEPROM bit 1: WR: Write Control bit 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 EEPROM is complete bit 0: RD: Read Control bit 1 = Initiates an EEPROM read RD is cleared in hardware. The RD bit can only be set (not cleared) in software. 0 = Does not initiate an EEPROM read DS30221A-page 30 Preliminary 1999 Microchip Technology Inc. PIC16F872 4.3 Reading the Data EEPROM Memory To read a data memory location, the user must write the address to the EEADR register, clear the EEPGD control bit (EECON1<7>) and then set control bit RD (EECON1<0>). The data is available in the very next instruction cycle of the EEDATA register, therefore it can be read by the next instruction. EEDATA will hold this value until another read operation or until it is written to by the user (during a write operation). 4.4 EXAMPLE 4-1: DATA EEPROM READ BSF STATUS, RP1 ; BCF STATUS, RP0 ;Bank 2 MOVLW DATA_EE_ADDR ; MOVWF EEADR ;Data Memory Address to read BSF STATUS, RP0 ;Bank 3 BCF EECON1, EEPGD ;Point to DATA memory BSF EECON1, RD ;EEPROM Read BCF STATUS, RP0 ;Bank 2 MOVF EEDATA, W ;W = EEDATA Writing to the Data EEPROM Memory To write an EEPROM data location, the address must first be written to the EEADR register and the data written to the EEDATA register. Then the sequence in Example 4-2 must be followed to initiate the write cycle. EXAMPLE 4-2: DATA EEPROM WRITE BSF STATUS, RP1 ; BCF STATUS, RP0 ; Bank 2 MOVLW DATA_EE_ADDR ; MOVWF EEADR ; Data Memory Address to write MOVLW DATA_EE_DATA ; MOVWF EEDATA ; Data Memory Value to write BSF STATUS, RP0 ; Bank 3 BCF EECON1, EEPGD ; Point to DATA memory BSF EECON1, WREN ; Enable writes BCF INTCON, GIE ; Disable Interrupts MOVLW 55h ; Required MOVWF EECON2 ; Write 55h Sequence MOVLW AAh ; MOVWF EECON2 ; Write AAh BSF EECON1, WR ; Set WR bit to begin write BSF INTCON, GIE ; Enable Interrupts SLEEP BCF ; Wait for interrupt to signal write complete EECON1, WREN ; Disable writes The write will not initiate if the above sequence is not exactly followed (write 55h to EECON2, write AAh to EECON2, then set WR bit) for each byte. It is strongly recommended that interrupts be disabled during this code segment. Additionally, the WREN bit in EECON1 must be set to enable writes. This mechanism prevents accidental writes to data EEPROM due to unexpected code execution (i.e., runaway programs). The WREN bit should be kept clear at all times, except when updating the EEPROM. The WREN bit is not cleared by hardware is set. The WREN bit must be set on a previous instruction. Both WR and WREN cannot be set with the same instruction. At the completion of the write cycle, the WR bit is cleared in hardware and the EEPROM Write Complete Interrupt Flag bit (EEIF) is set. EEIF must be cleared by software. After a write sequence has been initiated, clearing the WREN bit will not affect the current write cycle. The WR bit will be inhibited from being set unless the WREN bit 1999 Microchip Technology Inc. Preliminary DS30221A-page 31 PIC16F872 4.5 Reading the FLASH Program Memory A program memory location may be read by writing two bytes of the address to the EEADR and EEADRH registers, setting the EEPGD control bit (EECON1<7>) and then setting control bit RD (EECON1<0>). Once the read control bit is set, the microcontroller will use the next two instruction cycles to read the data. The EXAMPLE 4-3: Required data is available in the EEDATA and EEDATH registers after the second NOP instruction. Therefore, it can be read as two bytes in the following instructions. The EEDATA and EEDATH registers will hold this value until another read operation or until it is written to by the user (during a write operation). FLASH PROGRAM READ BSF STATUS, RP1 ; BCF STATUS, RP0 ; Bank 2 MOVLW ADDRH ; MOVWF EEADRH ; MSByte of Program Address to read MOVLW ADDRL ; MOVWF EEADR ; LSByte of Program Address to read BSF STATUS, RP0 ; Bank 3 BSF EECON1, EEPGD ; Point to PROGRAM memory BSF EECON1, RD ; EEPROM Read Sequence NOP ; memory is read in the next two cycles after BSF EECON1,RD NOP DS30221A-page 32 ; BCF STATUS, RP0 ; Bank 2 MOVF EEDATA, W ; W = LSByte of Program EEDATA MOVF EEDATH, W ; W = MSByte of Program EEDATA Preliminary 1999 Microchip Technology Inc. PIC16F872 4.6 and then set control bit WR (EECON1<1>). The sequence in Example 4-4 must be followed to initiate a write to program memory. Writing to the FLASH Program Memory When the PIC16F872 is fully code protected or not code protected, a word of the FLASH program memory may be written provided the WRT configuration bit is set. If the PIC16F872 is partially code protected, then a word of FLASH program memory may be written if the word is in a non-code protected segment of memory and the WRT configuration bit is set. To write a FLASH program location, the first two bytes of the address must be written to the EEADR and EEADRH registers and two bytes of the data to the EEDATA and EEDATH registers, set the EEPGD control bit (EECON1<7>), EXAMPLE 4-4: The microcontroller will then halt internal operations during the next two instruction cycles for the TPEW (parameter D133) in which the write takes place. This is not SLEEP mode, as the clocks and peripherals will continue to run. Therefore, the two instructions following the “BSF EECON, WR” should be NOP instructions. After the write cycle, the microcontroller will resume operation with the 3rd instruction after the EECON1 write instruction. FLASH PROGRAM WRITE BSF STATUS, RP1 ; BCF STATUS, RP0 ; Bank 2 MOVLW ADDRH ; MOVWF EEADRH ; MSByte of Program Address to read MOVLW ADDRL ; MOVWF EEADR ; LSByte of Program Address to read MOVLW DATAH ; MOVWF EEDATH ; MS Program Memory Value to write MOVLW DATAL ; MOVWF EEDATA ; LS Program Memory Value to write BSF STATUS, RP0 ; Bank 3 BSF EECON1, EEPGD ; Point to PROGRAM memory BSF EECON1, WREN ; Enable writes BCF INTCON, GIE ; Disable Interrupts MOVLW 55h ; Required MOVWF EECON2 ; Write 55h Sequence MOVLW AAh ; MOVWF EECON2 ; Write AAh BSF EECON1, WR ; Set WR bit to begin write NOP ; Instructions here are ignored by the microcontroller NOP ; Microcontroller will halt operation and wait for ; a write complete. After the write ; the microcontroller continues with 3rd instruction BSF INTCON, BCF EECON1, WREN 1999 Microchip Technology Inc. GIE ; Enable Interrupts ; Disable writes Preliminary DS30221A-page 33 PIC16F872 4.7 Write Verify 4.9 Depending on the application, good programming practice may dictate that the value written to the memory should be verified against the original value. This should be used in applications where excessive writes can stress bits near the specification limit. Generally a write failure will be a bit which was written as a ’1’, but reads back as a ’0’ (due to leakage off the bit). 4.8 Protection Against Spurious Write 4.8.1 EEPROM DATA MEMORY Each reprogrammable memory block has its own code protect mechanism. External Read and Write operations are disabled if either of these mechanisms are enabled. 4.9.1 DATA EEPROM MEMORY The microcontroller itself can both read and write to the internal Data EEPROM, regardless of the state of the code protect configuration bit. 4.9.2 There are conditions when the device may not want to write to the data EEPROM memory. To protect against spurious EEPROM writes, various mechanisms have been built-in. On power-up, the WREN bit is cleared. Also, the Power-up Timer (72 ms duration) prevents EEPROM write. The write initiate sequence and the WREN bit together help prevent an accidental write during brown-out, power glitch, or software malfunction. 4.8.2 Operation during Code Protect PROGRAM FLASH MEMORY PROGRAM FLASH MEMORY The microcontroller can read and execute instructions out of the internal FLASH program memory, regardless of the state of the code protect configuration bits. However, the WRT configuration bit and the code protect bits have different effects on writing to program memory. Table 4-1 shows the various configurations and status of reads and writes. To erase the WRT or code protection bits in the configuration word requires that the device be fully erased. Note: To protect against spurious writes to FLASH program memory, the WRT bit in the configuration word may be programmed to ‘0’ to prevent writes. The write initiate sequence must also be followed. WRT and the configuration word cannot be programmed by user code, only through the use of an external programmer. TABLE 4-1: The PIC16F872 devices can perform self writes to any location in program memory when not code protected or fully code protected. READ/WRITE STATE OF INTERNAL FLASH PROGRAM MEMORY Configuration Bits Memory Location CP1 CP0 WRT 0 0 0 0 0 0 1 1 1 1 1 1 0 0 1 1 1 1 0 0 0 0 1 1 1 0 0 0 1 1 0 0 1 1 0 1 DS30221A-page 34 Internal Read Internal Write Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes No No No Yes No No Yes All program memory All program memory Unprotected areas Protected areas Unprotected areas Protected areas Unprotected areas Protected areas Unprotected areas Protected areas All program memory All program memory Preliminary ICSP Read ICSP Write No No Yes No Yes No Yes No Yes No Yes Yes No No No No No No No No No No Yes Yes 1999 Microchip Technology Inc. PIC16F872 TABLE 4-2: Address REGISTERS ASSOCIATED WITH DATA EEPROM/PROGRAM FLASH Name 0Bh, 8Bh, INTCON 10Bh, 18Bh 10Dh EEADR 10Fh EEADRH 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 GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u xxxx xxxx uuuu uuuu — — xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu xxxx xxxx uuuu uuuu EEPROM address register — — — 10Ch EEDATA 10Eh EEDATH — — 18Ch EECON1 EEPGD — 18Dh EECON2 8Dh PIE2 — (1) — EEIE 0Dh PIR2 — (1) — EEIF EEPROM address high EEPROM data resister EEPROM data resister high — — WREN WR RD x--- x000 x--- u000 BCLIE — — (1) -r-0 0--r -r-0 0--r BCLIF — — (1) -r-0 0--r -r-0 0--r WRERR EEPROM control resister2 (not a physical resister) Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented read as ’0’. Shaded cells are not used by the Timer1 module. Note 1: These bits are reserved; always maintain these bits clear. 1999 Microchip Technology Inc. Preliminary DS30221A-page 35 PIC16F872 NOTES: DS30221A-page 36 Preliminary 1999 Microchip Technology Inc. PIC16F872 5.0 TIMER0 MODULE Counter mode is selected by setting bit T0CS (OPTION_REG<5>). In counter mode, Timer0 will increment either on every rising or falling edge of pin RA4/T0CKI. The incrementing edge is determined by the Timer0 Source Edge Select bit T0SE (OPTION_REG<4>). Clearing bit T0SE selects the rising edge. Restrictions on the external clock input are discussed in detail in Section 5.2. 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 The prescaler is mutually exclusively shared between the Timer0 module and the watchdog timer. The prescaler is not readable or writable. Section 5.3 details the operation of the prescaler. Figure 5-1 is a block diagram of the Timer0 module and the prescaler shared with the WDT. 5.1 Additional information on the Timer0 module is available in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023). The TMR0 interrupt is generated when the TMR0 register overflows from FFh to 00h. This overflow sets bit T0IF (INTCON<2>). The interrupt can be masked by clearing bit T0IE (INTCON<5>). Bit T0IF must be cleared in software by the Timer0 module interrupt service routine before re-enabling this interrupt. The TMR0 interrupt cannot awaken the processor from SLEEP since the timer is shut off during SLEEP. Timer mode is selected by clearing bit T0CS (OPTION_REG<5>). In timer mode, the Timer0 module will increment every instruction cycle (without prescaler). If the TMR0 register is written, the increment is inhibited for the following two instruction cycles. The user can work around this by writing an adjusted value to the TMR0 register. FIGURE 5-1: Timer0 Interrupt BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER Data Bus CLKOUT (= FOSC/4) 0 RA4/T0CKI Pin 8 M U X 1 M U X 0 1 SYNC 2 Cycles TMR0 reg T0SE T0CS Set Flag Bit T0IF on Overflow PSA PRESCALER 0 Watchdog Timer M U X 1 8-bit Prescaler 8 8 - to - 1MUX PS<2:0> PSA WDT Enable bit 1 0 MUX PSA WDT Time-out Note: T0CS, T0SE, PSA, PS<2:0> are (OPTION_REG<5:0>). 1999 Microchip Technology Inc. Preliminary DS30221A-page 37 PIC16F872 5.2 Using Timer0 with an External Clock module means that there is no prescaler for the watchdog timer, and vice-versa. This prescaler is not readable or writable (see Figure 5-1). 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 2TOSC (and a small RC delay of 20 ns) and low for at least 2TOSC (and a small RC delay of 20 ns). Refer to the electrical specification of the desired device. 5.3 The PSA and PS<2:0> bits (OPTION_REG<3:0>) determine the prescaler assignment and prescale ratio. When assigned to the Timer0 module, all instructions writing to the TMR0 register (i.e., 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. The prescaler is not readable or writable. Prescaler Note: There is only one prescaler available, which is mutually exclusively shared between the Timer0 module and the watchdog timer. A prescaler assignment for the Timer0 Writing to TMR0, when the prescaler is assigned to Timer0, will clear the prescaler count, but will not change the prescaler assignment. REGISTER 5-1: OPTION_REG REGISTER 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 bit 6: INTEDG bit 5: T0CS: TMR0 Clock Source Select bit 1 = Transition on T0CKI pin 0 = Internal instruction cycle clock (CLKOUT) bit 4: T0SE: TMR0 Source Edge Select bit 1 = Increment on high-to-low transition on T0CKI pin 0 = Increment on low-to-high transition on T0CKI pin bit 3: PSA: Prescaler Assignment bit 1 = Prescaler is assigned to the WDT 0 = Prescaler is assigned to the Timer0 module R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR reset bit 2-0: PS<2:0>: Prescaler Rate Select bits Note: Bit Value TMR0 Rate WDT Rate 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 To avoid an unintended device RESET, the instruction sequence shown in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023) must be executed when changing the prescaler assignment from Timer0 to the WDT. This sequence must be followed even if the WDT is disabled. DS30221A-page 38 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 5-1: Address REGISTERS ASSOCIATED WITH TIMER0 Name Bit 7 Bit 6 01h,101h TMR0 0Bh,8Bh, 10Bh,18Bh INTCON 81h,181h OPTION_REG RBPU INTEDG Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Timer0 module’s register GIE PEIE Value on: POR, BOR Value on all other resets xxxx xxxx uuuu uuuu T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111 Legend: x = unknown, u = unchanged, - = unimplemented locations read as '0'. Shaded cells are not used by Timer0. 1999 Microchip Technology Inc. Preliminary DS30221A-page 39 PIC16F872 NOTES: DS30221A-page 40 Preliminary 1999 Microchip Technology Inc. PIC16F872 6.0 TIMER1 MODULE In timer mode, Timer1 increments every instruction cycle. In counter mode, it increments on every rising edge of the external clock input. The Timer1 module is a 16-bit timer/counter consisting of two 8-bit registers (TMR1H and TMR1L), which are readable and writable. The TMR1 Register pair (TMR1H:TMR1L) increments from 0000h to FFFFh and rolls over to 0000h. The TMR1 Interrupt, if enabled, is generated on overflow, which is latched in interrupt flag bit TMR1IF (PIR1<0>). This interrupt can be enabled/disabled by setting/clearing TMR1 interrupt enable bit TMR1IE (PIE1<0>). Timer1 can be enabled/disabled by setting/clearing control bit TMR1ON (T1CON<0>). Timer1 also has an internal “reset input”. This reset can be generated by the CCP module (Section 8.0). Register 6-1 shows the Timer1 control register. When the Timer1 oscillator is enabled (T1OSCEN is set), the RC1/T1OSI and RC0/T1OSO/T1CKI pins become inputs. That is, the TRISC<1:0> value is ignored. Timer1 can operate in one of two modes: • As a timer • As a counter Additional information on timer modules is available in the PICmicro™ Mid-range MCU Family Reference Manual (DS33023). The operating mode is determined by the clock select bit, TMR1CS (T1CON<1>). REGISTER 6-1: T1CON: TIMER1 CONTROL REGISTER (ADDRESS 10h) U-0 — bit7 U-0 — R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR reset bit 7-6: Unimplemented: Read as '0' 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: bit 2: T1OSCEN: Timer1 Oscillator Enable Control bit 1 = Oscillator is enabled 0 = Oscillator is shut off (The oscillator inverter is turned off to eliminate power drain) 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 when TMR1CS = 0. bit 1: TMR1CS: Timer1 Clock Source Select bit 1 = External clock from pin RC0/T1OSO/T1CKI (on the rising edge) 0 = Internal clock (FOSC/4) bit 0: TMR1ON: Timer1 On bit 1 = Enables Timer1 0 = Stops Timer1 1999 Microchip Technology Inc. Preliminary DS30221A-page 41 PIC16F872 6.1 Timer1 Operation in Timer Mode 6.2 Timer mode is selected by clearing the TMR1CS (T1CON<1>) bit. In this mode, the input clock to the timer is FOSC/4. The synchronize control bit T1SYNC (T1CON<2>) has no effect since the internal clock is always in sync. FIGURE 6-1: Timer1 Counter Operation Timer1 may operate in asynchronous or usynchronous mode depending on the setting of the TMR1CS bit. When Timer1 is being incremented via an external source, increments occur on a rising edge. After Timer1 is enabled in counter mode, the module must first have a falling edge before the counter begins to increment. TIMER1 INCREMENTING EDGE T1CKI (Default high) T1CKI (Default low) Note: Arrows indicate counter increments. 6.3 Timer1 Operation in Synchronized Counter Mode If T1SYNC is cleared, then the external clock input is synchronized with internal phase clocks. The synchronization is done after the prescaler stage. The prescaler stage is an asynchronous ripple-counter. Counter mode is selected by setting bit TMR1CS. In this mode, the timer increments on every rising edge of clock input on pin RC1/T1OSI, when bit T1OSCEN is set, or on pin RC0/T1OSO/T1CKI, when bit T1OSCEN is cleared. FIGURE 6-2: In this configuration, during SLEEP mode, Timer1 will not increment even if the external clock is present, since the synchronization circuit is shut off. The prescaler however will continue to increment. TIMER1 BLOCK DIAGRAM Set flag bit TMR1IF on Overflow 0 TMR1 TMR1H Synchronized clock input TMR1L 1 TMR1ON on/off T1OSC RC0/T1OSO/T1CKI RC1/T1OSI (2) T1SYNC (2) 1 T1OSCEN FOSC/4 Enable Internal Oscillator(1) Clock Synchronize Prescaler 1, 2, 4, 8 det 0 2 T1CKPS<1:0> Q Clock TMR1CS Note 1: When the T1OSCEN bit is cleared, the inverter is turned off. This eliminates power drain. 2: For the PIC16F872, the Schmitt Trigger is not implemented in external clock mode. DS30221A-page 42 Preliminary 1999 Microchip Technology Inc. PIC16F872 6.4 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 (Section 6.4.1). In asynchronous counter mode, Timer1 can not be used as a time-base for capture or compare operations. 6.4.1 READING AND WRITING TIMER1 IN ASYNCHRONOUS COUNTER MODE Reading TMR1H or TMR1L while the timer is running from an external asynchronous clock will guarantee a valid read (taken care of in hardware). However, the user should keep in mind that reading the 16-bit timer in two 8-bit values itself poses certain problems, since the timer may overflow between the reads. For writes, it is recommended that the user 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 produce an unpredictable value in the timer register. Reading the 16-bit value requires some care. Examples 12-2 and 12-3 in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023) show how to read and write Timer1 when it is running in asynchronous mode. 6.5 Timer1 Oscillator A crystal oscillator circuit is built-in between pins T1OSI (input) and T1OSO (amplifier output). It is enabled by setting control bit T1OSCEN (T1CON<3>). The oscillator is a low power oscillator rated up to 200 kHz. It will continue to run during SLEEP. It is primarily intended for use with a 32 kHz crystal. Table 6-1 shows the capacitor selection for the Timer1 oscillator. The Timer1 oscillator is identical to the LP oscillator. The user must provide a software time delay to ensure proper oscillator start-up. TABLE 6-1: CAPACITOR SELECTION FOR THE TIMER1 OSCILLATOR Osc Type Freq C1 C2 LP 32 kHz 100 kHz 200 kHz 33 pF 15 pF 15 pF 33 pF 15 pF 15 pF These values are for design guidance only. Crystals Tested: 32.768 kHz 100 kHz 200 kHz Epson C-001R32.768K-A Epson C-2 100.00 KC-P STD XTL 200.000 kHz ± 20 PPM ± 20 PPM ± 20 PPM Note 1: Higher capacitance increases the stability of oscillator, but also increases the start-up time. 2: Since each resonator/crystal has its own characteristics, the user should consult the resonator/ crystal manufacturer for appropriate values of external components. 6.6 Resetting Timer1 using CCP1 Trigger Output If the CCP1 module is configured in compare mode to generate a “special event trigger” (CCP1M<3:0> = 1011), this signal will reset Timer1. Note: The special event trigger from the CCP1 module will not set interrupt flag bit TMR1IF (PIR1<0>). Timer1 must be configured for either timer or synchronized 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, the write will take precedence. In this mode of operation, the CCPR1H:CCPR1L register pair effectively becomes the period register for Timer1. 6.7 Resetting of Timer1 Register Pair (TMR1H, TMR1L) TMR1H and TMR1L registers are not reset to 00h on a POR or any other reset except by the CCP1 special event trigger. 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. 6.8 Timer1 Prescaler The prescaler counter is cleared on writes to the TMR1H or TMR1L registers. 1999 Microchip Technology Inc. Preliminary DS30221A-page 43 PIC16F872 TABLE 6-2: Address REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER 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 PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u 0Bh, 8Bh, 10Bh, 18Bh INTCON GIE 0Ch PIR1 (1) ADIF (1) (1) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 8Ch PIE1 (1) ADIE (1) (1) SSPIE CCP1IE TMR2IE TMR1IE r0rr 0000 r0rr 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 --00 0000 --uu uuuu — — T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented read as ’0’. Shaded cells are not used by the Timer1 module. Note 1: These bits are reserved; always maintain these bits clear. DS30221A-page 44 Preliminary 1999 Microchip Technology Inc. PIC16F872 7.0 TIMER2 MODULE 7.1 Timer2 is an 8-bit timer with a prescaler and a postscaler. It 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 input clock (FOSC/4) has a prescale option of 1:1, 1:4 or 1:16, selected by control bits T2CKPS<1:0> (T2CON<1:0>). 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. 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 (latched in flag bit TMR2IF, (PIR1<1>)). Timer2 Prescaler and Postscaler 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 (POR, MCLR reset, WDT reset or BOR) TMR2 is not cleared when T2CON is written. 7.2 Output of TMR2 The output of TMR2 (before the postscaler) is fed to the SSPort module, which optionally uses it to generate shift clock. FIGURE 7-1: Sets flag bit TMR2IF TIMER2 BLOCK DIAGRAM TMR2 output (1) Timer2 can be shut off by clearing control bit TMR2ON (T2CON<2>) to minimize power consumption. Reset TMR2 reg Register 7-1 shows the Timer2 control register. Postscaler 1:1 to 1:16 Additional information on timer modules is available in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023). EQ Comparator Prescaler 1:1, 1:4, 1:16 FOSC/4 2 T2CKPS<1:0> 4 PR2 reg T2OUTPS<3:0> Note 1: TMR2 register output can be software selected by the SSP module as a baud clock. REGISTER 7-1: T2CON: TIMER2 CONTROL REGISTER (ADDRESS 12h) U-0 — R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON R/W-0 R/W-0 T2CKPS1 T2CKPS0 bit7 bit0 bit 7: Unimplemented: Read as '0' bit 6-3: TOUTPS<3:0>: Timer2 Output Postscale Select bits 0000 = 1:1 Postscale 0001 = 1:2 Postscale 0010 = 1:3 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 1999 Microchip Technology Inc. Preliminary R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR reset DS30221A-page 45 PIC16F872 TABLE 7-1: REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR 0Bh,8Bh, INTCON 10Bh,18Bh GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u 0Ch PIR1 (1) ADIF (1) (1) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 8Ch PIE1 (1) ADIE (1) (1) SSPIE CCP1IE TMR2IE TMR1IE Address Name 11h TMR2 12h T2CON 92h PR2 r0rr 0000 r0rr 0000 0000 0000 0000 0000 Timer2 module’s register — Value on all other resets TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000 1111 1111 1111 1111 Timer2 Period Register Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented read as ’0’. Shaded cells are not used by the Timer2 module. Note 1: These bits are reserved; always maintain these bits clear. DS30221A-page 46 Preliminary 1999 Microchip Technology Inc. PIC16F872 8.0 CAPTURE/COMPARE/PWM MODULE generated by a compare match and will reset Timer1 and start an A/D conversion (if the A/D module is enabled). The 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 Additional information on CCP modules is available in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023) and in Application Note 594, “Using the CCP Modules” (DS00594). TABLE 8-1: Table 8-1 shows the resources used by the CCP module. In the following sections, the operation of a CCP module is described. CCP1 Module: Capture/Compare/PWM Register1 (CCPR1) is comprised 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 CCP MODE - TIMER RESOURCES REQUIRED CCP Mode Timer Resource Capture Compare PWM Timer1 Timer1 Timer2 REGISTER 8-1: CCP1CON REGISTER (ADDRESS: 17h) U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — — CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR reset bit 7-6: Unimplemented: Read as ’0’ bit 5-4: CCP1<X:Y>: 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 CCPR1L. bit 3-0: CCP1M<3:0>: CCPx Mode Select bits 0000 = Capture/Compare/PWM off (resets CCP 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 (CCP1IF bit is set) 1001 = Compare mode, clear output on match (CCP1IF bit is set) 1010 = Compare mode, generate software interrupt on match (CCP1IF bit is set, CCP pin is unaffected) 1011 = Compare mode, trigger special event (CCP1IF bit is set, CCP1 pin is unaffected); CCP1 resets TMR1 and starts an A/D conversion (if A/D module is enabled) 11xx = PWM mode 1999 Microchip Technology Inc. Preliminary DS30221A-page 47 PIC16F872 8.1 Capture Mode 8.1.2 In Capture mode, CCPR1H:CCPR1L captures the 16-bit value of the TMR1 register when an event occurs on pin RC2/CCP1. An event is defined as: • • • • Every falling edge Every rising edge Every 4th rising edge Every 16th rising edge 8.1.1 CCP PIN CONFIGURATION In Capture mode, the RC2/CCP1 pin should be configured as an input by setting the TRISC<2> bit. Note: If the RC2/CCP1 pin is configured as an output, a write to the port can cause a capture condition. FIGURE 8-1: CAPTURE MODE OPERATION BLOCK DIAGRAM Prescaler ÷ 1, 4, 16 Set flag bit CCP1IF (PIR1<2>) RC2/CCP1 Pin CCPR1H and edge detect Timer1 must be running in timer mode or synchronized counter mode for the CCP module to use the capture feature. In asynchronous counter mode, the capture operation may not work. 8.1.3 An event is selected by control bits CCP1M<3:0> (CCP1CON<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 value will be lost. 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. 8.1.4 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 cleared, therefore, the first capture may be from a non-zero prescaler. Example 8-1 shows the recommended method for switching between capture prescalers. This example also clears the prescaler counter and will not generate the “false” interrupt. EXAMPLE 8-1: CCPR1L Capture Enable TMR1H TIMER1 MODE SELECTION TMR1L CLRF MOVLW MOVWF CCP1CON<3:0> CHANGING BETWEEN CAPTURE PRESCALERS CCP1CON ;Turn CCP module off NEW_CAPT_PS ;Load the W reg with ; the new precscaler ; move value and CCP ON CCP1CON ;Load CCP1CON with this ; value Q’s DS30221A-page 48 Preliminary 1999 Microchip Technology Inc. PIC16F872 8.2 . Compare Mode In Compare mode, the 16-bit CCPR1 register value is constantly compared against the TMR1 register pair value. When a match occurs, the RC2/CCP1 pin is: • Driven high • Driven low • Remains unchanged 8.3 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 8-2: COMPARE MODE OPERATION BLOCK DIAGRAM Special event trigger will: reset Timer1, but not set interrupt flag bit TMR1IF (PIR1<0>), and set bit GO/DONE (ADCON0<2>). Special Event Trigger Set flag bit CCP1IF (PIR1<2>) CCPR1H CCPR1L Q S Output Logic match RC2/CCP1 R Pin TRISC<2> Output Enable CCP1CON<3:0> Mode Select 8.2.1 The special event trigger from the CCP1 module will not set interrupt flag bit TMR1IF (PIR1<0>). PWM Mode (PWM) In pulse width modulation mode, the CCP1 pin produces up to a 10-bit resolution PWM output. Since the CCP1 pin is multiplexed with the PORTC data latch, the TRISC<2> bit must be cleared to make the CCP1 pin an output. Note: Clearing the CCP1CON register will force the CCP1 PWM output latch to the default low level. This is not the PORTC I/O data latch. Figure 8-3 shows a simplified block diagram of the CCP module in PWM mode. For a step-by-step procedure on how to set up the CCP module for PWM operation, see Section 8.3.3. FIGURE 8-3: TMR1H Duty Cycle Registers TMR1L CCP PIN CONFIGURATION CCPR1H (Slave) Clearing the CCP1CON register will force the RC2/CCP1 compare output latch to the default low level. This is not the data latch. SOFTWARE INTERRUPT MODE Q RC2/CCP1 (Note 1) S TIMER1 MODE SELECTION When Generate Software Interrupt mode is chosen, the CCP1 pin is not affected. The CCPIF bit is set causing a CCP interrupt (if enabled). 8.2.4 R Comparator Timer1 must be running in Timer mode or Synchronized Counter mode if the CCP module is using the compare feature. In Asynchronous Counter mode, the compare operation may not work. 8.2.3 CCP1CON<5:4> CCPR1L TMR2 8.2.2 SIMPLIFIED PWM BLOCK DIAGRAM Comparator The user must configure the RC2/CCP1 pin as an output by clearing the TRISC<2> bit. Note: Note: TRISC<2> Comparator PR2 Clear Timer, CCP1 pin and latch D.C. Note 1: 8-bit timer is concatenated with 2-bit internal Q clock or 2 bits of the prescaler to create 10-bit time-base. SPECIAL EVENT TRIGGER In this mode, an internal hardware trigger is generated, which may be used to initiate an action. The special event trigger output of CCP1 resets the TMR1 register pair and starts an A/D conversion (if the A/D module is enabled). This allows the CCPR1 register to effectively be a 16-bit programmable period register for Timer1. 1999 Microchip Technology Inc. Preliminary DS30221A-page 49 PIC16F872 A PWM output (Figure 8-4) 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 8-4: PWM OUTPUT The CCPR1H register and a 2-bit internal latch are used to double buffer the PWM duty cycle. This double buffering is essential for glitchless PWM operation. When the CCPR1H and 2-bit latch match TMR2 concatenated with an internal 2-bit Q clock or 2 bits of the TMR2 prescaler, the CCP1 pin is cleared. Maximum PWM resolution (bits) for a given PWM frequency: Period Resolution Duty Cycle = FOSC log FPWM ( log(2) ) bits TMR2 = PR2 Note: TMR2 = Duty Cycle TMR2 = PR2 8.3.3 8.3.1 PWM period = [(PR2) + 1] • 4 • TOSC • (TMR2 prescale value) The following steps should be taken when configuring the CCP module for PWM operation: 1. 2. 3. PWM frequency is defined as 1 / [PWM period]. When TMR2 is equal to PR2, the following three events occur on the next increment cycle: 4. • TMR2 is cleared • The CCP1 pin is set (exception: if PWM duty cycle = 0%, the CCP1 pin will not be set) • The PWM duty cycle is latched from CCPR1L into CCPR1H 5. 8.3.2 SET-UP FOR PWM OPERATION PWM PERIOD The PWM period is specified by writing to the PR2 register. The PWM period can be calculated using the following formula: Note: If the PWM duty cycle value is longer than the PWM period, the CCP1 pin will not be cleared. Set the PWM period by writing to the PR2 register. Set the PWM duty cycle by writing to the CCPR1L register and CCP1CON<5:4> bits. Make the CCP1 pin an output by clearing the TRISC<2> bit. Set the TMR2 prescale value and enable Timer2 by writing to T2CON. Configure the CCP1 module for PWM operation. The Timer2 postscaler (see Section 8.1) 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. 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-bit resolution is available. The CCPR1L contains 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: PWM duty cycle = (CCPR1L:CCP1CON<5:4>) • Tosc • (TMR2 prescale value) 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. DS30221A-page 50 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 8-2: Address REGISTERS ASSOCIATED WITH CAPTURE, COMPARE AND TIMER1 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 000u 0Ch PIR1 (1) ADIF (1) (1) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 8Ch PIE1 (1) ADIE (1) (1) SSPIE CCP1IE TMR2IE TMR1IE r0rr 0000 r0rr 0000 87h TRISC PORTC Data Direction Register 1111 1111 1111 1111 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 --00 0000 --uu uuuu 15h CCPR1L Capture/Compare/PWM register1 (LSB) xxxx xxxx uuuu uuuu 16h CCPR1H Capture/Compare/PWM register1 (MSB) xxxx xxxx uuuu uuuu 17h CCP1CON --00 0000 --00 0000 — — — — T1CKPS1 CCP1X T1CKPS0 CCP1Y T1OSCEN CCP1M3 T1SYNC CCP1M2 TMR1CS CCP1M1 TMR1ON CCP1M0 Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented read as ’0’. Shaded cells are not used by Capture and Timer1. Note 1: These bits are reserved; always maintain these bits clear. TABLE 8-3: Address REGISTERS ASSOCIATED WITH PWM AND TIMER2 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 000u 0Ch PIR1 (1) ADIF (1) (1) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 8Ch PIE1 (1) ADIE (1) (1) SSPIE CCP1IE TMR2IE TMR1IE r0rr 0000 r0rr 0000 87h TRISC PORTC Data Direction Register 1111 1111 1111 1111 11h TMR2 Timer2 module’s register 0000 0000 0000 0000 92h PR2 Timer2 module’s period register 1111 1111 1111 1111 12h T2CON -000 0000 -000 0000 15h CCPR1L Capture/Compare/PWM register1 (LSB) xxxx xxxx uuuu uuuu 16h CCPR1H Capture/Compare/PWM register1 (MSB) xxxx xxxx uuuu uuuu 17h CCP1CON --00 0000 --00 0000 — TOUTPS3 — — TOUTPS2 CCP1X TOUTPS1 CCP1Y TOUTPS0 CCP1M3 TMR2ON CCP1M2 T2CKPS1 CCP1M1 T2CKPS0 CCP1M0 Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented read as ’0’. Shaded cells are not used by PWM and Timer2. Note 1: These bits are reserved; always maintain these bits clear. 1999 Microchip Technology Inc. Preliminary DS30221A-page 51 PIC16F872 NOTES: DS30221A-page 52 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.0 MASTER SYNCHRONOUS SERIAL PORT (MSSP) MODULE The Master Synchronous Serial Port (MSSP) module is a serial interface useful for communicating with other peripheral or microcontroller devices. These peripheral devices may be serial EEPROMs, shift registers, display drivers, A/D converters, etc. The MSSP module can operate in one of two modes: • Serial Peripheral Interface (SPI) • Inter-Integrated Circuit (I 2C) Figure 9-1 shows a block diagram for the SPI mode, while Figure 9-5 and Figure 9-9 show the block diagrams for the two different I2C modes of operation. 1999 Microchip Technology Inc. Preliminary DS30221A-page 53 PIC16F872 REGISTER 9-1: SSPSTAT: SYNC SERIAL PORT STATUS REGISTER (ADDRESS: 94h) R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0 SMP CKE D/A P S R/W UA BF bit7 bit 7: bit 6: bit 5: bit 4: bit 3: bit 2: bit 1: bit 0: bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset SMP: Sample bit SPI Master Mode 1 = Input data sampled at end of data output time 0 = Input data sampled at middle of data output time SPI Slave Mode SMP must be cleared when SPI is used in slave mode In I2C master or slave mode: 1= Slew rate control disabled for standard speed mode (100 kHz and 1 MHz) 0= Slew rate control enabled for high speed mode (400 kHz) CKE: SPI Clock Edge Select (Figure 9-4, Figure 9-5 and Figure 9-6) SPI Mode: CKP = 0 1 = Transmit happens on transition from active clock state to idle clock state 0 = Transmit happens on transition from idle clock state to active clock state CKP = 1 1 = Data transmitted on falling edge of SCK 0 = Data transmitted on rising edge of SCK In I2C Master or Slave Mode: 1 = Input levels conform to SMBUS spec 0 = Input levels conform to I2C specs 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 P: Stop bit (I2C mode only. This bit is cleared when the MSSP module is disabled, 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 S: Start bit (I2C mode only. This bit is cleared when the MSSP module is disabled, 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 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 not ACK bit. In I2C slave mode: 1 = Read 0 = Write In I2C master mode: 1 = Transmit is in progress 0 = Transmit is not in progress. Or’ing this bit with SEN, RSEN, PEN, RCEN or ACKEN will indicate if the MSSP is in IDLE mode. UA: Update Address (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 BF: Buffer Full Status bit Receive (SPI and I2C modes) 1 = Receive complete, SSPBUF is full 0 = Receive not complete, SSPBUF is empty Transmit (I2C mode only) 1 = Data Transmit in progress (does not include the ACK and stop bits), SSPBUF is full 0 = Data Transmit complete (does not include the ACK and stop bits), SSPBUF is empty DS30221A-page 54 Preliminary 1999 Microchip Technology Inc. PIC16F872 REGISTER 9-2: SSPCON: SYNC SERIAL PORT CONTROL REGISTER (ADDRESS 14h) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 7: WCOL: Write Collision Detect bit Master Mode: 1 = A write to SSPBUF was attempted while the I2C conditions were not valid 0 = No collision Slave Mode: 1 = SSPBUF register is written while 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 received while SSPBUF holds previous data. Data in SSPSR is lost on overflow. In slave mode, the user must read the SSPBUF, even if only transmitting data to avoid overflows. In master mode, the overflow bit is not set since each operation is initiated by writing to the SSPBUF register. (Must be cleared in software.) 0 = No overflow In I2 C mode 1 = A byte is received while the SSPBUF is holding the previous byte. SSPOV is a "don’t care" in transmit mode. (Must be cleared in software.) 0 = No overflow bit 5: SSPEN: Synchronous Serial Port Enable bit In SPI mode, when enabled, these pins must be properly configured as input or output. 1 = Enables serial port and configures SCK, SDO, SDI, and SS as the source of the serial port pins 0 = Disables serial port and configures these pins as I/O port pins In I2C mode, when enabled, these pins must be properly configured as input or output. 1 = Enables the serial port and configures the SDA and SCL pins as the source of the serial port pins 0 = Disables serial port and configures these pins as I/O port pins bit 4: CKP: Clock Polarity Select bit In SPI mode 1 = Idle state for clock is a high level 0 = Idle state for clock is a low level In I2 C slave mode, SCK release control 1 = Enable clock 0 = Holds clock low (clock stretch) (Used to ensure data setup time) In I2 C master mode Unused in this mode bit 3-0: SSPM<3:0>: Synchronous Serial Port 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, clock = TMR2 output/2 0100 = SPI slave mode, clock = SCK pin. SS pin control enabled. 0101 = SPI slave mode, clock = SCK pin. SS pin control disabled. SS can be used as I/O pin. 0110 = I2C slave mode, 7-bit address 0111 = I2C slave mode, 10-bit address 1000 = I2C master mode, clock = FOSC / (4 * (SSPADD+1) ) 1011 = I2C firmware controlled master mode (slave idle) 1110 = I2C firmware controlled master mode, 7-bit address with start and stop bit interrupts enabled. 1111 = I2C firmware controlled master mode, 10-bit address with start and stop bit interrupts enabled. 1001, 1010, 1100, 1101 = reserved 1999 Microchip Technology Inc. Preliminary DS30221A-page 55 PIC16F872 REGISTER 9-3: SSPCON2: SYNC SERIAL PORT CONTROL REGISTER2 (ADDRESS 91h) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 GCEN ACKSTAT ACKDT ACKEN RCEN PEN RSEN SEN bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n= Value at POR reset bit 7: GCEN: General Call Enable bit (In I2C slave mode only) 1 = Enable interrupt when a general call address (0000h) is received in the SSPSR. 0 = General call address disabled. bit 6: ACKSTAT: Acknowledge Status bit (In I2C master mode only) In master transmit mode: 1 = Acknowledge was not received from slave. 0 = Acknowledge was received from slave. bit 5: ACKDT: Acknowledge Data bit (In I2C master mode only) In master receive mode: Value that will be transmitted when the user initiates an Acknowledge sequence at the end of a receive. 1 = Not Acknowledge. 0 = Acknowledge. bit 4: ACKEN: Acknowledge Sequence Enable bit (In I2C master mode only). In master receive mode: 1 = Initiate Acknowledge sequence on SDA and SCL pins, and transmit ACKDT data bit. Automatically cleared by hardware. 0 = Acknowledge sequence idle. bit 3: RCEN: Receive Enable bit (In I2C master mode only). 1 = Enables Receive mode for I2C. 0 = Receive idle. bit 2: PEN: Stop Condition Enable bit (In I2C master mode only). SCK release control 1 = Initiate Stop condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Stop condition idle. bit 1: RSEN: Repeated Start Condition Enabled bit (In I2C master mode only) 1 = Initiate Repeated Start condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Repeated Start condition idle. bit 0: SEN: Start Condition Enabled bit (In I2C master mode only) 1 = Initiate Start condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Start condition idle. Note: For bits ACKEN, RCEN, PEN, RSEN, SEN: If the I2C module is not in the idle mode, this bit may not be set (no spooling), and the SSPBUF may not be written (or writes to the SSPBUF are disabled). DS30221A-page 56 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.1 SPI Mode FIGURE 9-1: The SPI mode allows 8 bits of data to be synchronously transmitted and received simultaneously. All four modes of SPI are supported. To accomplish communication, typically three pins are used: MSSP BLOCK DIAGRAM (SPI MODE) Internal Data Bus Read • Serial Data Out (SDO) • Serial Data In (SDI) • Serial Clock (SCK) Write SSPBUF reg Additionally, a fourth pin may be used when in a slave mode of operation: SSPSR reg SDI • Slave Select (SS) When initializing the SPI, several options need to be specified. This is done by programming the appropriate 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) Shift Clock bit0 SDO SS Control Enable SS Edge Select 2 Clock Select SSPM3:SSPM0 SMP:CKE 4 2 Figure 9-4 shows the block diagram of the MSSP module when in SPI mode. Edge Select SCK TMR2 output 2 Prescaler 4, 16, 64 TOSC Data to TX/RX in SSPSR Data direction bit To enable the serial port, MSSP Enable bit, SSPEN (SSPCON<5>) must be set. To reset or reconfigure SPI mode, clear bit SSPEN, re-initialize the SSPCON registers, and then set bit SSPEN. This configures the SDI, SDO, SCK and SS pins as serial port pins. For the pins to behave as the serial port function, some must have their data direction bits (in the TRIS register) appropriately programmed. That is: • SDI is automatically controlled by the SPI module • SDO must have TRISC<5> cleared • SCK (Master mode) must have TRISC<3> cleared • SCK (Slave mode) must have TRISC<3> set • SS must have TRISA<5> set Any serial port function that is not desired may be overridden by programming the corresponding data direction (TRIS) register to the opposite value. 1999 Microchip Technology Inc. Preliminary DS30221A-page 57 PIC16F872 9.1.1 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 9-5) is to broadcast data by the software protocol. In Master mode, the data is transmitted/received as soon as the SSPBUF register is written to. If the SPI module is only going to receive, the SDO output could be disabled (programmed as an input). The SSPSR register will continue to shift in the signal present on the 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”. Figure 9-6, Figure 9-8 and Figure 9-9 where the MSb is transmitted first. In Master mode, the SPI clock rate (bit rate) is user programmable to be one of the following: • • • • FOSC/4 (or TCY) FOSC/16 (or 4 • TCY) FOSC/64 (or 16 • TCY) Timer2 output/2 This allows a maximum bit clock frequency (at 20 MHz) of 5.0 MHz. Figure 9-6 shows the waveforms for Master mode. When CKE = 1, the SDO data is valid before there is a clock edge on SCK. The change of the input sample is shown based on the state of the SMP bit. The time when the SSPBUF is loaded with the received data is shown. The clock polarity is selected by appropriately programming bit CKP (SSPCON<4>). This then would give waveforms for SPI communication as shown in FIGURE 9-2: SPI MODE TIMING, MASTER MODE SCK (CKP = 0, CKE = 0) SCK (CKP = 0, CKE = 1) SCK (CKP = 1, CKE = 0) SCK (CKP = 1, CKE = 1) bit7 SDO bit6 bit5 bit4 bit3 bit2 bit1 bit0 SDI (SMP = 0) bit7 bit0 SDI (SMP = 1) bit7 bit0 SSPIF DS30221A-page 58 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.1.2 SLAVE MODE While in SLEEP mode, the slave can transmit/receive data. When a byte is received, the device will wake-up from sleep. In Slave mode, the data is transmitted and received as the external clock pulses appear on SCK. When the last bit is latched, the interrupt flag bit SSPIF (PIR1<3>) 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. FIGURE 9-3: Note: When the SPI module is in Slave mode with SS pin control enabled, (SSPCON<3:0> = 0100) the SPI module will reset if the SS pin is set to VDD. Note: If the SPI is used in Slave mode with CKE = ’1’, then SS pin control must be enabled. SPI MODE TIMING (SLAVE MODE WITH CKE = 0) SS (optional) SCK (CKP = 0) SCK (CKP = 1) bit6 bit7 SDO bit5 bit2 bit3 bit4 bit1 bit0 SDI (SMP = 0) bit7 bit0 SSPIF FIGURE 9-4: SPI MODE TIMING (SLAVE MODE WITH CKE = 1) SS SCK (CKP = 0) SCK (CKP = 1) SDO bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 SDI (SMP = 0) bit7 bit0 SSPIF 1999 Microchip Technology Inc. Preliminary DS30221A-page 59 PIC16F872 TABLE 9-1 REGISTERS ASSOCIATED WITH SPI OPERATION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 POR, BOR MCLR, WDT GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u Address Name 0Bh, 8Bh, 10Bh,18Bh INTCON 0Ch PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000 8Ch PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000 13h SSPBUF xxxx xxxx uuuu uuuu 14h SSPCON Synchronous Serial Port Receive Buffer/Transmit Register WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000 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 used by the SSP in SPI mode. Note 1: These bits are reserved on the 28-pin devices; always maintain these bits clear. DS30221A-page 60 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.2 MSSP I2 C Operation The MSSP module in I 2C mode fully implements all master and slave functions (including general call support) and provides interrupts-on-start and stop bits in hardware to determine a free bus (multi-master function). The MSSP module implements the standard mode specifications, as well as 7-bit and 10-bit addressing. Refer to Application Note AN578, "Use of the SSP Module in the I 2C Multi-Master Environment." A "glitch" filter is on the SCL and SDA pins when the pin is an input. This filter operates in both the 100 kHz and 400 kHz modes. In the 100 kHz mode, when these pins are an output, there is a slew rate control of the pin that is independent of device frequency. FIGURE 9-5: I2C SLAVE MODE BLOCK DIAGRAM Write Shift Clock SSPSR reg SDA MSb LSb Match detect • • • • • SSP Control Register (SSPCON) SSP Control Register2 (SSPCON2) 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 I 2C operation. Four mode selection bits (SSPCON<3:0>) allow one of the following I 2C modes to be selected: Before selecting any I 2C mode, the SCL and SDA pins must be programmed to inputs by setting the appropriate TRIS bits. Selecting an I 2C mode, by setting the SSPEN bit, enables the SCL and SDA pins to be used as the clock and data lines in I 2C mode. SSPBUF reg SCL The MSSP module has six registers for I2C operation. They are the: • I 2C Slave mode (7-bit address) • I 2C Slave mode (10-bit address) • I 2C Master mode, clock = OSC/4 (SSPADD +1) Internal Data Bus Read Two pins are used for data transfer. These are the SCL pin, which is the clock, and the SDA pin, which is the data. The SDA and SCL pins are automatically configured when the I2C mode is enabled. The SSP module functions are enabled by setting SSP Enable bit SSPEN (SSPCON<5>). Addr Match The CKE bit (SSPSTAT<6:7>) sets the levels of the SDA and SCL pins in either Master or Slave mode. When CKE = 1, the levels will conform to the SMBUS specification. When CKE = 0, the levels will conform to the I2C specification. SSPADD reg Start and Stop bit detect 1999 Microchip Technology Inc. Set, Reset S, P bits (SSPSTAT reg) Preliminary DS30221A-page 61 PIC16F872 The SSPSTAT register gives the status of the data transfer. This information includes detection of a START (S) or STOP (P) bit, specifies if the received byte was data or address, if the next byte is the completion of 10-bit address, and if this will be a read or write data transfer. SSPBUF is the register to which the transfer data is written to or read from. The SSPSR register shifts the data in or out of the device. In receive operations, the SSPBUF and SSPSR create a doubled buffered receiver. This allows reception of the next byte to begin before reading the last byte of received data. When the complete byte is received, it is transferred to the SSPBUF register and flag bit SSPIF is set. If another complete byte is received before the SSPBUF register is read, a receiver overflow has occurred and bit SSPOV (SSPCON<6>) is set and the byte in the SSPSR is lost. The SSPADD register holds the slave address. In 10-bit mode, the user needs to write the high byte of the address (1111 0 A9 A8 0). Following the high byte address match, the low byte of the address needs to be loaded (A7:A0). 9.2.1 SLAVE MODE In Slave mode, the SCL and SDA pins must be configured as inputs. The MSSP module will override the input state with the output data when required (slavetransmitter). When an address is matched or the data transfer after an address match is received, the hardware automatically will generate the acknowledge (ACK) pulse, and then load the SSPBUF register with the received value currently in the SSPSR register. 9.2.1.1 Once the MSSP 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) c) d) In 10-bit address mode, two address bytes need to be received by the slave. 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 would equal ‘1111 0 A9 A8 0’, where A9 and A8 are the two MSbs of the address. The sequence of events for a 10-bit address is as follows, with steps 7- 9 for slavetransmitter: 1. a) 4. If the BF bit is set, the SSPSR register value is not loaded into the SSPBUF, but bit SSPIF and SSPOV are set. Table 9-2 shows what happens when a data transfer byte is received, given the status of bits BF and SSPOV. The shaded cells show the condition where user software did not properly 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 time for proper operation. The high and low times of the I2C specification, as well as the requirement of the MSSP module, is shown in timing parameter #100 and parameter #101 of the electrical specifications. DS30221A-page 62 Receive first (high) byte of Address (bits SSPIF, BF and UA (SSPSTAT<1>) are set). Update the SSPADD register with the second (low) byte of Address (clears bit UA and releases the SCL line). Read the SSPBUF register (clears bit BF) and clear flag bit SSPIF. Receive second (low) byte of Address (bits SSPIF, BF and UA are set). Update the SSPADD register with the first (high) byte of Address. This will clear bit UA and release the SCL line. Read the SSPBUF register (clears bit BF) and clear flag bit SSPIF. Receive Repeated Start condition. Receive first (high) byte of Address (bits SSPIF and BF are set). Read the SSPBUF register (clears bit BF) and clear flag bit SSPIF. 2. 3. b) The SSPSR register value is loaded into the SSPBUF register on the falling edge of the 8th SCL pulse. The buffer full bit, BF, is set on the falling edge of the 8th SCL pulse. An ACK pulse is generated. SSP interrupt flag bit, SSPIF (PIR1<3>), is set (interrupt is generated if enabled) on the falling edge of the 9th SCL pulse. b) There are certain conditions that will cause the MSSP module not to give this ACK pulse. These are if either (or both): The buffer full bit BF (SSPSTAT<0>) was set before the transfer was received. The overflow bit SSPOV (SSPCON<6>) was set before the transfer was received. ADDRESSING 5. 6. 7. 8. 9. Note: Preliminary Following the Repeated Start condition (step 7) in 10-bit mode, the user only needs to match the first 7-bit address. The user does not update the SSPADD for the second half of the address. 1999 Microchip Technology Inc. PIC16F872 9.2.1.2 SLAVE RECEPTION 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 received byte. When the R/W bit of the address byte is clear and an address match occurs, the R/W bit of the SSPSTAT register is cleared. The received address is loaded into the SSPBUF register. Note: The SSPBUF will be loaded if the SSPOV bit is set and the BF flag is cleared. If a read of the SSPBUF was performed, but the user did not clear the state of the SSPOV bit before the next receive occurred, the ACK is not sent and the SSPBUF is updated. 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 bit SSPOV (SSPCON<6>) is set. TABLE 9-2 DATA TRANSFER RECEIVED BYTE ACTIONS Status Bits as Data Transfer is Received Set bit SSPIF (SSP Interrupt occurs if enabled) BF SSPOV SSPSR → SSPBUF Generate ACK Pulse 0 0 Yes Yes Yes 1 0 No No Yes 1 1 No No Yes 0 1 Yes No Yes Note 1: Shaded cells show the conditions where the user software did not properly clear the overflow condition. 9.2.1.3 SLAVE TRANSMISSION An SSP interrupt is generated for each data transfer byte. The SSPIF flag bit must be cleared in software and the SSPSTAT register is used to determine the status of the byte transfer. The SSPIF flag bit is set on the falling edge of the ninth clock pulse. 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 the SCL pin is held low. The transmit data must be loaded into the SSPBUF register, which also loads the SSPSR register. Then the SCL pin should be enabled by setting bit CKP (SSPCON<4>). The master must monitor 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 9-7). I 2C WAVEFORMS FOR RECEPTION (7-BIT ADDRESS) FIGURE 9-6: R/W=0 ACK Receiving Address A7 A6 A5 A4 A3 A2 A1 SDA SCL S 1 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 is high (not ACK), then the data transfer is complete. When the not ACK is latched by the slave, the slave logic is reset and the slave then monitors for another occurrence of the START bit. If the SDA line was low (ACK), the transmit data must be loaded into the SSPBUF register, which also loads the SSPSR register. Then the SCL pin should be enabled by setting the CKP bit. 2 3 4 5 6 7 Receiving Data ACK D7 D6 D5 D4 D3 D2 D1 D0 8 9 1 2 3 4 5 6 7 8 9 Not Receiving Data ACK D7 D6 D5 D4 D3 D2 D1 D0 1 2 3 4 5 6 7 8 SSPIF 9 P Bus Master terminates transfer BF (SSPSTAT<0>) Cleared in software SSPBUF register is read SSPOV (SSPCON<6>) Bit SSPOV is set because the SSPBUF register is still full. ACK is not sent. 1999 Microchip Technology Inc. Preliminary DS30221A-page 63 PIC16F872 I 2C WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS) FIGURE 9-7: R/W = 1 ACK Receiving Address SDA A7 SCL S A6 1 2 Data in sampled A5 A4 A3 A2 A1 3 4 5 6 7 D7 8 9 R/W = 0 Not ACK Transmitting Data 1 SCL held low while CPU responds to SSPIF D6 D5 D4 D3 D2 D1 D0 2 3 4 5 6 7 8 9 P SSPIF BF (SSPSTAT<0>) cleared in software SSPBUF is written in software From SSP interrupt service routine CKP (SSPCON<4>) Set bit after writing to SSPBUF (the SSPBUF must be written-to before the CKP bit can be set) 9.2.2 GENERAL CALL ADDRESS SUPPORT If the general call address matches, the SSPSR is transferred to the SSPBUF, the BF flag is set (eighth bit), and on the falling edge of the ninth bit (ACK bit), the SSPIF flag is set. I2C bus is such that The addressing procedure for the the first byte after the START condition usually determines which device will be the slave addressed by the master. The exception is the general call address, which can address all devices. When this address is used, all devices should, in theory, respond with an acknowledge. When the interrupt is serviced, the source for the interrupt can be checked by reading the contents of the SSPBUF to determine if the address was device specific or a general call address. In 10-bit mode, the SSPADD is required to be updated for the second half of the address to match, and the UA bit is set (SSPSTAT<1>). If the general call address is sampled when GCEN is set while the slave is configured in 10-bit address mode, then the second half of the address is not necessary, the UA bit will not be set, and the slave will begin receiving data after the acknowledge (Figure 9-8). The general call address is one of eight addresses reserved for specific purposes by the I2C protocol. It consists of all 0’s with R/W = 0 The general call address is recognized when the General Call Enable bit (GCEN) is enabled (SSPCON2<7> is set). Following a start-bit detect, 8 bits are shifted into SSPSR and the address is compared against SSPADD. It is also compared to the general call address and fixed in hardware. FIGURE 9-8: SLAVE MODE GENERAL CALL ADDRESS SEQUENCE (7 OR 10-BIT MODE) Address is compared to General Call Address after ACK, set interrupt flag R/W = 0 ACK D7 General Call Address SDA Receiving data ACK D6 D5 D4 D3 D2 D1 D0 2 3 4 5 6 7 8 SCL S 1 2 3 4 5 6 7 8 9 1 9 SSPIF BF (SSPSTAT<0>) Cleared in software SSPBUF is read SSPOV (SSPCON<6>) ’0’ GCEN (SSPCON2<7>) ’1’ DS30221A-page 64 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.2.3 SLEEP OPERATION 9.2.4 While in SLEEP mode, the I2C module can receive addresses or data. When an address match or complete byte transfer occurs, wake the processor from sleep (if the SSP interrupt is enabled). EFFECTS OF A RESET A RESET disables the SSP module and terminates the current transfer. REGISTERS ASSOCIATED WITH I2C OPERATION TABLE 9-3 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 POR, BOR MCLR, WDT INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u PIR1 (1) ADIF (1) (1) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 8Ch PIE1 (1) ADIE (1) (1) SSPIE CCP1IE TMR2IE TMR1IE r0rr 0000 r0rr 0000 0Dh PIR2 — (1) — EEIF BCLIF — — (1) -r-0 0--r -r-0 0--r — (1) — EEIE BCLIE — — (1) -r-0 0--r -r-0 0--r xxxx xxxx uuuu uuuu Address Name 0Bh, 8Bh, 10Bh,18Bh 0Ch 8Dh PIE2 13h SSPBUF Synchronous Serial Port Receive Buffer/Transmit Register 14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000 91h SSPCON2 GCEN ACKSTAT ACKDT ACKEN RCEN PEN RSEN SEN 0000 0000 0000 0000 94h SSPSTAT SMP CKE D/A P S R/W UA BF 0000 0000 0000 0000 Legend: x = unknown, u = unchanged, r= reserved, - = unimplemented read as ’0’. Shaded cells are not used by the SSP in I2C mode. Note 1: These bits are reserved; always maintain these bits clear. 1999 Microchip Technology Inc. Preliminary DS30221A-page 65 PIC16F872 MASTER MODE In Master mode, the SCL and SDA lines are manipulated by the MSSP hardware. Master mode of operation is supported by interrupt generation on the detection of the START and STOP conditions. The STOP (P) and START (S) bits are cleared from a RESET or when the MSSP module is disabled. Control of the I 2C bus may be TACKEN when the P bit is set, or the bus is idle with both the S and P bits clear. FIGURE 9-9: The following events will cause the SSP Interrupt Flag bit, SSPIF, to be set (SSP Interrupt if enabled): • • • • • START condition STOP condition Data transfer byte transmitted/received Acknowledge transmit Repeated Start SSP BLOCK DIAGRAM (I2C MASTER MODE) SSPM<3:0>, SSPADD<6:0> Internal Data Bus Read Write SSPBUF Baud Rate Generator Shift Clock SDA SDA in SSPSR SCL in Bus Collision DS30221A-page 66 LSb Start bit, Stop bit, Acknowledge Generate Start bit detect, Stop bit detect Write collision detect Clock Arbitration State counter for end of XMIT/RCV Preliminary clock cntl SCL Receive Enable MSb clock arbitrate/WCOL detect (hold off clock source) 9.2.5 Set/Reset, S, P, WCOL (SSPSTAT) Set SSPIF, BCLIF Reset ACKSTAT, PEN (SSPCON2) 1999 Microchip Technology Inc. PIC16F872 9.2.6 MULTI-MASTER MODE 9.2.7.4 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) bits are cleared from a RESET or when the MSSP module is disabled. Control of the I 2C bus may be TACKEN when bit P (SSPSTAT<4>) is set, or the bus is idle with both the S and P bits clear. When the bus is busy, enabling the SSP Interrupt will generate the interrupt when the STOP condition occurs. In multi-master operation, the SDA line must be monitored for arbitration to see if the signal level is the expected output level. This check is performed in hardware, with the result placed in the BCLIF bit. The states where arbitration can be lost are: • • • • • Address Transfer Data Transfer A Start Condition A Repeated Start Condition An Acknowledge Condition 9.2.7 I2C MASTER MODE SUPPORT Master mode is enabled by setting and clearing the appropriate SSPM bits in SSPCON and by setting the SSPEN bit. Once Master mode is enabled, the user has six options. - Assert a start condition on SDA and SCL. - Assert a Repeated Start condition on SDA and SCL. - Write to the SSPBUF register initiating transmission of data/address. - Generate a stop condition on SDA and SCL. - Configure the I2C port to receive data. - Generate an Acknowledge condition at the end of a received byte of data. I2C MASTER MODE OPERATION The master device generates all of the serial clock pulses and the START and STOP conditions. A transfer is ended with a STOP condition or with a Repeated Start condition. Since the Repeated Start condition is also the beginning of the next serial transfer, the I2C bus will not be released. In Master Transmitter mode, serial data is output through SDA, while SCL outputs the serial clock. The first byte transmitted contains the slave address of the receiving device (7 bits) and the Read/Write (R/W) bit. In this case, the R/W bit will be logic '0'. Serial data is transmitted 8 bits at a time. After each byte is transmitted, an acknowledge bit is received. START and STOP conditions are output to indicate the beginning and the end of a serial transfer. In Master Receive mode, the first byte transmitted contains the slave address of the transmitting device (7 bits) and the R/W bit. In this case, the R/W bit will be logic '1'. Thus, the first byte transmitted is a 7-bit slave address followed by a '1' to indicate receive bit. Serial data is received via SDA, while SCL outputs the serial clock. Serial data is received 8 bits at a time. After each byte is received, an acknowledge bit is transmitted. START and STOP conditions indicate the beginning and end of transmission. The baud rate generator used for SPI mode operation is now used to set the SCL clock frequency for either 100 kHz, 400 kHz or 1 MHz I2C operation. The baud rate generator reload value is contained in the lower 7 bits of the SSPADD register. The baud rate generator will automatically begin counting on a write to the SSPBUF. Once the given operation is complete (i.e., transmission of the last data bit is followed by ACK), the internal clock will automatically stop counting and the SCL pin will remain in its last state A typical transmit sequence would go as follows: Note: The MSSP Module, when configured in I2C Master mode, does not allow queueing of events. For instance, the user is not allowed to initiate a start condition and immediately write the SSPBUF register to initiate transmission before the START condition is complete. In this case, the SSPBUF will not be written to and the WCOL bit will be set, indicating that a write to the SSPBUF did not occur. a) b) c) d) e) f) g) h) 1999 Microchip Technology Inc. Preliminary The user generates a Start Condition by setting the START enable bit (SEN) in SSPCON2. SSPIF is set. The module will wait the required start time before any other operation takes place. The user loads the SSPBUF with address to transmit. Address is shifted out the SDA pin until all 8 bits are transmitted. The MSSP Module shifts in the ACK bit from the slave device and writes its value into the SSPCON2 register ( SSPCON2<6>). The module generates an interrupt at the end of the ninth clock cycle by setting SSPIF. The user loads the SSPBUF with eight bits of data. DATA is shifted out the SDA pin until all 8 bits are transmitted. DS30221A-page 67 PIC16F872 i) j) k) l) The MSSP module shifts in the ACK bit from the slave device, and writes its value into the SSPCON2 register ( SSPCON2<6>). The MSSP module generates an interrupt at the end of the ninth clock cycle by setting the SSPIF bit. The user generates a STOP condition by setting the STOP enable bit PEN in SSPCON2. Interrupt is generated once the STOP condition is complete. 9.2.8 In I2C Master mode, the BRG is reloaded automatically. If Clock Arbitration is taking place for instance, the BRG will be reloaded when the SCL pin is sampled high (Figure 9-11). FIGURE 9-10: BAUD RATE GENERATOR BLOCK DIAGRAM SSPM<3:0> BAUD RATE GENERATOR SSPADD<6:0> SSPM<3:0> Reload SCL Control In I2C Master mode, the reload value for the BRG is located in the lower 7 bits of the SSPADD register (Figure 9-10). When the BRG is loaded with this value, the BRG counts down to 0 and stops until another reload has TACKEN place. The BRG count is decremented twice per instruction cycle (TCY), on the Q2 and Q4 clock. CLKOUT Reload BRG Down Counter FOSC/4 FIGURE 9-11: BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION SDA DX DX-1 SCL deasserted but slave holds SCL low (clock arbitration) SCL allowed to transition high SCL BRG decrements (on Q2 and Q4 cycles) BRG value 03h 02h 01h 00h (hold off) 03h 02h SCL is sampled high, reload takes place, and BRG starts its count. BRG reload DS30221A-page 68 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.2.9 I2C MASTER MODE START CONDITION TIMING Note: To initiate a START condition, the user sets the start condition enable bit, SEN (SSPCON2<0>). If the SDA and SCL pins are sampled high, the baud rate generator is re-loaded with the contents of SSPADD<6:0> and starts its count. If SCL and SDA are both sampled high when the baud rate generator times out (TBRG), the SDA pin is driven low. The action of the SDA being driven low while SCL is high is the START condition, and causes the S bit (SSPSTAT<3>) to be set. Following this, the baud rate generator is reloaded with the contents of SSPADD<6:0> and resumes its count. When the baud rate generator times out (TBRG), the SEN bit (SSPCON2<0>) will be automatically cleared by hardware. The baud rate generator is suspended leaving the SDA line held low, and the START condition is complete. If at the beginning of START condition the SDA and SCL pins are already sampled low, or if during the START condition the SCL line is sampled low before the SDA line is driven low, a bus collision occurs, the Bus Collision Interrupt Flag (BCLIF) is set, the START condition is aborted, and the I2C module is reset into its IDLE state. 9.2.9.5 WCOL STATUS FLAG If the user writes the SSPBUF when an START sequence is in progress, then WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur). Note: Because queueing of events is not allowed, writing to the lower 5 bits of SSPCON2 is disabled until the START condition is complete. FIGURE 9-12: FIRST START BIT TIMING Set S bit (SSPSTAT<3>) Write to SEN bit occurs here. SDA = 1, SCL = 1 TBRG At completion of start bit, Hardware clears SEN bit and sets SSPIF bit TBRG Write to SSPBUF occurs here 1st Bit SDA 2nd Bit TBRG SCL TBRG S 1999 Microchip Technology Inc. Preliminary DS30221A-page 69 PIC16F872 9.2.10 I2C MASTER MODE REPEATED START CONDITION TIMING Immediately following the SSPIF bit getting set, the user may write the SSPBUF with the 7-bit address in 7-bit mode, or the default first address in 10-bit mode. After the first eight bits are transmitted and an ACK is received, the user may then transmit an additional eight bits of address (10-bit mode) or eight bits of data (7-bit mode). A Repeated Start condition occurs when the RSEN bit (SSPCON2<1>) is programmed high and the I2C module is in the idle state. When the RSEN bit is set, the SCL pin is asserted low. When the SCL pin is sampled low, the baud rate generator is loaded with the contents of SSPADD<6:0> and begins counting. The SDA pin is released (brought high) for one baud rate generator count (TBRG). When the baud rate generator times out if SDA is sampled high, the SCL pin will be deasserted (brought high). When SCL is sampled high the baud rate generator is reloaded with the contents of SSPADD<6:0> and begins counting. SDA and SCL must be sampled high for one TBRG. This action is then followed by assertion of the SDA pin (SDA is low) for one TBRG, while SCL is high. Following this, the RSEN bit in the SSPCON2 register will be automatically cleared and the baud rate generator will not be reloaded, leaving the SDA pin held low. As soon as a start condition is detected on the SDA and SCL pins, the S bit (SSPSTAT<3>) will be set. The SSPIF bit will not be set until the baud rate generator has timed-out. 9.2.10.6 WCOL STATUS FLAG If the user writes the SSPBUF when a Repeated Start sequence is in progress, then WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur). Note: Because queueing of events is not allowed, writing of the lower 5 bits of SSPCON2 is disabled until the Repeated Start condition is complete. Note 1: If RSEN is programmed while any other event is in progress, it will not take effect. Note 2: A bus collision during the Repeated Start condition occurs if: • SDA is sampled low when SCL goes from low to high. • SCL goes low before SDA is asserted low. This may indicate that another master is attempting to transmit a data "1". FIGURE 9-13: REPEAT START CONDITION WAVEFORM Write to SSPCON2 occurs here. SDA = 1, SCL(no change) Set S (SSPSTAT<3>) SDA = 1, SCL = 1 TBRG At completion of start bit, hardware clear RSEN bit and set SSPIF TBRG TBRG 1st Bit SDA Falling edge of ninth clock End of Xmit Write to SSPBUF occurs here. TBRG SCL TBRG Sr = Repeated Start DS30221A-page 70 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.2.11 I2C MASTER MODE TRANSMISSION 9.2.11.9 Transmission of a data byte, a 7-bit address or either half of a 10-bit address, is accomplished by simply writing a value to SSPBUF register. This action will set the buffer full flag (BF) and allow the baud rate generator to begin counting and start the next transmission. Each bit of address/data will be shifted out onto the SDA pin after the falling edge of SCL is asserted (see data hold time spec). SCL is held low for one baud rate generator rollover count (TBRG). Data should be valid before SCL is released high (see data setup time spec). When the SCL pin is released high, it is held that way for TBRG. The data on the SDA pin must remain stable for that duration and some hold time after the next falling edge of SCL. After the eighth bit is shifted out (the falling edge of the eighth clock), the BF flag is cleared and the master releases SDA allowing the slave device being addressed to respond with an ACK bit during the ninth bit time, if an address match occurs or if data was received properly. The status of ACK is read into the ACKDT on the falling edge of the ninth clock. If the master receives an acknowledge, the acknowledge status bit (ACKSTAT) is cleared. If not, the bit is set. After the ninth clock, the SSPIF is set and the master clock (baud rate generator) is suspended until the next data byte is loaded into the SSPBUF, leaving SCL low and SDA unchanged (Figure 9-14). ACKSTAT STATUS FLAG In Transmit mode, the ACKSTAT bit (SSPCON2<6>) is cleared when the slave has sent an acknowledge (ACK = 0) and is set when the slave does not acknowledge (ACK = 1). A slave sends an acknowledge when it has recognized its address (including a general call) or when the slave has properly received its data. After the write to the SSPBUF, each bit of address will be shifted out on the falling edge of SCL until all seven address bits and the R/W bit are completed. On the falling edge of the eighth clock, the master will de-assert the SDA pin allowing the slave to respond with an acknowledge. On the falling edge of the ninth clock, the master will sample the SDA pin to see if the address was recognized by a slave. The status of the ACK bit is loaded into the ACKSTAT status bit (SSPCON2<6>). Following the falling edge of the ninth clock transmission of the address, the SSPIF is set, the BF flag is cleared, and the baud rate generator is turned off until another write to the SSPBUF takes place, holding SCL low and allowing SDA to float. 9.2.11.7 BF STATUS FLAG In Transmit mode, the BF bit (SSPSTAT<0>) is set when the CPU writes to SSPBUF and is cleared when all 8 bits are shifted out. 9.2.11.8 WCOL STATUS FLAG If the user writes the SSPBUF when a transmit is already in progress (i.e., SSPSR is still shifting out a data byte), then WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur). WCOL must be cleared in software. 1999 Microchip Technology Inc. Preliminary DS30221A-page 71 DS30221A-page 72 S Preliminary R/W PEN SEN BF (SSPSTAT<0>) SSPIF SCL SDA A6 A5 A4 A3 A2 A1 3 4 5 Cleared in software 2 6 7 8 9 After start condition SEN cleared by hardware. SSPBUF written 1 D7 3 D5 4 D4 5 D3 6 D2 7 D1 8 D0 SSPBUF is written in software Cleared in software service routine From SSP interrupt 2 D6 Transmitting Data or Second Half of 10-bit address From slave clear ACKSTAT bit SSPCON2<6> 1 SCL held low while CPU responds to SSPIF ACK = 0 R/W = 0 SSPBUF written with 7-bit address and R/W start transmit A7 Transmit Address to Slave SEN = 0 Write SSPCON2<0> SEN = 1 START condition begins P Cleared in software 9 ACK ACKSTAT in SSPCON2 = 1 PIC16F872 FIGURE 9-14: I 2C MASTER MODE TIMING (TRANSMISSION, 7 OR 10-BIT ADDRESS) 1999 Microchip Technology Inc. PIC16F872 9.2.12 I2C MASTER MODE RECEPTION Master mode reception is enabled by programming the receive enable bit, RCEN (SSPCON2<3>). Note: The SSP module must be in an IDLE STATE before the RCEN bit is set or the RCEN bit will be disregarded. The baud rate generator begins counting, and on each rollover, the state of the SCL pin changes (high to low/low to high), and data is shifted into the SSPSR. After the falling edge of the eighth clock, the receive enable flag is automatically cleared, the contents of the SSPSR are loaded into the SSPBUF, the BF flag is set, the SSPIF is set, and the baud rate generator is suspended from counting, holding SCL low. The SSP is now in IDLE state, awaiting the next command. When the buffer is read by the CPU, the BF flag is automatically cleared. The user can then send an acknowledge bit at the end of reception, by setting the acknowledge sequence enable bit, ACKEN (SSPCON2<4>). 9.2.12.10 BF STATUS FLAG In receive operation, BF is set when an address or data byte is loaded into SSPBUF from SSPSR. It is cleared when SSPBUF is read. 9.2.12.11 SSPOV STATUS FLAG In receive operation, SSPOV is set when 8 bits are received into the SSPSR and the BF flag is already set from a previous reception. 9.2.12.12 WCOL STATUS FLAG If the user writes the SSPBUF when a receive is already in progress (i.e., SSPSR is still shifting in a data byte), then WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur). 1999 Microchip Technology Inc. Preliminary DS30221A-page 73 DS30221A-page 74 S Preliminary ACKEN SSPOV BF (SSPSTAT<0>) SDA = 0, SCL = 1 while CPU responds to SSPIF SSPIF SCL SDA 2 1 A4 4 A5 3 5 A3 Cleared in software A6 A7 6 A2 Transmit Address to Slave SEN = 0 Write to SSPBUF occurs here Start XMIT Write to SSPCON2<0> (SEN = 1) Begin Start Condition 7 A1 8 9 R/W = 1 ACK ACK from Slave 2 D6 3 D5 5 D3 6 D2 7 D1 8 D0 9 ACK 2 D6 3 D5 4 D4 5 D3 6 D2 Receiving Data from Slave 7 D1 Cleared in software Set SSPIF interrupt at end of acknowledge sequence Cleared in software Set SSPIF at end of receive 9 ACK is not sent ACK P Set SSPIF interrupt at end of acknowledge sequence Bus Master terminates transfer Set P bit (SSPSTAT<4>) and SSPIF PEN bit = 1 written here SSPOV is set because SSPBUF is still full 8 D0 RCEN cleared automatically Set ACKEN start acknowledge sequence SDA = ACKDT = 1 Data shifted in on falling edge of CLK 1 D7 RCEN = 1 start next receive ACK from Master SDA = ACKDT = 0 Last bit is shifted into SSPSR and contents are unloaded into SSPBUF Cleared in software Set SSPIF interrupt at end of receive 4 D4 Receiving Data from Slave Cleared in software 1 D7 RCEN cleared automatically Master configured as a receiver by programming SSPCON2<3>, (RCEN = 1) Write to SSPCON2<4> to start acknowledge sequence SDA = ACKDT (SSPCON2<5>) = 0 PIC16F872 FIGURE 9-15: I 2C MASTER MODE TIMING (RECEPTION 7-BIT ADDRESS) 1999 Microchip Technology Inc. PIC16F872 9.2.13 ACKNOWLEDGE SEQUENCE TIMING the baud rate generator counts for TBRG. The SCL pin is then pulled low. Following this, the ACKEN bit is automatically cleared, the baud rate generator is turned off, and the SSP module then goes into IDLE mode. (Figure 9-16) An acknowledge sequence is enabled by setting the acknowledge sequence enable bit, ACKEN (SSPCON2<4>). When this bit is set, the SCL pin is pulled low and the contents of the acknowledge data bit is presented on the SDA pin. If the user wishes to generate an acknowledge, the ACKDT bit should be cleared. If not, the user should set the ACKDT bit before starting an acknowledge sequence. The baud rate generator then counts for one rollover period (TBRG), and the SCL pin is deasserted (pulled high). When the SCL pin is sampled high (clock arbitration), 9.2.13.13 WCOL STATUS FLAG If the user writes the SSPBUF when an acknowledege sequence is in progress, the WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur). FIGURE 9-16: ACKNOWLEDGE SEQUENCE WAVEFORM Acknowledge sequence starts here, Write to SSPCON2 ACKEN = 1, ACKDT = 0 ACKEN automatically cleared TBRG TBRG SDA ACK D0 SCL 9 8 SSPIF Set SSPIF at the end of receive Cleared in software Cleared in software Set SSPIF at the end of acknowledge sequence Note: TBRG = one baud rate generator period. 1999 Microchip Technology Inc. Preliminary DS30221A-page 75 PIC16F872 9.2.14 STOP CONDITION TIMING while SCL is high, the P bit (SSPSTAT<4>) is set. A TBRG later, the PEN bit is cleared and the SSPIF bit is set (Figure 9-17). A stop bit is asserted on the SDA pin at the end of a receive/transmit by setting the Stop Sequence Enable bit PEN (SSPCON2<2>). At the end of a receive/transmit, the SCL line is held low after the falling edge of the ninth clock. When the PEN bit is set, the master will assert the SDA line low . When the SDA line is sampled low, the baud rate generator is reloaded and counts down to 0. When the baud rate generator times out, the SCL pin will be brought high, and one TBRG (baud rate generator rollover count) later, the SDA pin will be deasserted. When the SDA pin is sampled high Whenever the firmware decides to take control of the bus, it will first determine if the bus is busy by checking the S and P bits in the SSPSTAT register. If the bus is busy, then the CPU can be interrupted (notified) when a Stop bit is detected (i.e., bus is free). 9.2.14.14 WCOL STATUS FLAG If the user writes the SSPBUF when a STOP sequence is in progress, then WCOL is set and the contents of the buffer are unchanged (the write doesn’t occur). FIGURE 9-17: STOP CONDITION RECEIVE OR TRANSMIT MODE SCL = 1 for TBRG, followed by SDA = 1 for TBRG after SDA sampled high. P bit (SSPSTAT<4>) is set Write to SSPCON2 Set PEN PEN bit (SSPCON2<2>) is cleared by hardware and the SSPIF bit is set Falling edge of 9th clock TBRG SCL SDA ACK P TBRG TBRG TBRG SCL brought high after TBRG SDA asserted low before rising edge of clock to setup stop condition. Note: TBRG = one baud rate generator period. DS30221A-page 76 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.2.15 CLOCK ARBITRATION 9.2.16 Clock arbitration occurs when the master, during any receive, transmit, or repeated start/stop condition, deasserts the SCL pin (SCL allowed to float high). When the SCL pin is allowed to float high, the baud rate generator (BRG) is suspended from counting until the SCL pin is actually sampled high. When the SCL pin is sampled high, the baud rate generator is reloaded with the contents of SSPADD<6:0> and begins counting. This ensures that the SCL high time will always be at least one BRG rollover count in the event that the clock is held low by an external device (Figure 9-18). SLEEP OPERATION While in SLEEP mode, the I2C module can receive addresses or data, and when an address match or complete byte transfer occurs, wake the processor from sleep (if the SSP interrupt is enabled). 9.2.17 EFFECTS OF A RESET A RESET disables the SSP module and terminates the current transfer. FIGURE 9-18: CLOCK ARBITRATION TIMING IN MASTER TRANSMIT MODE BRG overflow, Release SCL, If SCL = 1 Load BRG with SSPADD<6:0>, and start count to measure high time interval BRG overflow occurs, Release SCL, Slave device holds SCL low. SCL = 1 BRG starts counting clock high interval. SCL SCL line sampled once every machine cycle (TOSC • 4). Hold off BRG until SCL is sampled high. SDA TBRG 1999 Microchip Technology Inc. TBRG TBRG Preliminary DS30221A-page 77 PIC16F872 9.2.18 MULTI -MASTER COMMUNICATION, BUS COLLISION, AND BUS ARBITRATION Multi-Master mode support is achieved by bus arbitration. When the master outputs address/data bits onto the SDA pin, arbitration takes place when the master outputs a ’1’ on SDA by letting SDA float high and another master asserts a ’0’. When the SCL pin floats high, data should be stable. If the expected data on SDA is a ’1’ and the data sampled on the SDA pin = ’0’, a bus collision has taken place. The master will set the Bus Collision Interrupt Flag, BCLIF, and reset the I2C port to its IDLE state. (Figure 9-19). If a transmit was in progress when the bus collision occurred, the transmission is halted, the BF flag is cleared, the SDA and SCL lines are deasserted, and the SSPBUF can be written to. When the user services the bus collision interrupt service routine, and if the I2C bus is free, the user can resume communication by asserting a START condition. If a START, Repeated Start, STOP or Acknowledge condition was in progress when the bus collision occurred, the condition is aborted, the SDA and SCL lines are deasserted, and the respective control bits in the SSPCON2 register are cleared. When the user services the bus collision interrupt service routine, and if the I2C bus is free, the user can resume communication by asserting a START condition. The master will continue to monitor the SDA and SCL pins, and if a STOP condition occurs, the SSPIF bit will be set. A write to the SSPBUF will start the transmission of data at the first data bit, regardless of where the transmitter left off when the bus collision occurred. In Multi-Master mode, the interrupt generation on the detection of start and stop conditions allows the determination of when the bus is free. Control of the I2C bus can be taken when the P bit is set in the SSPSTAT register, or the bus is idle and the S and P bits are cleared. FIGURE 9-19: BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE Data changes while SCL = 0 SDA line pulled low by another source SDA released by master Sample SDA. While SCL is high, data doesn’t match what is driven by the master. Bus collision has occurred. SDA SCL Set bus collision interrupt. BCLIF DS30221A-page 78 Preliminary 1999 Microchip Technology Inc. PIC16F872 9.2.18.15 BUS COLLISION DURING A START CONDITION During a START condition, a bus collision occurs if: a) SDA or SCL are sampled low at the beginning of the START condition (Figure 9-20). SCL is sampled low before SDA is asserted low. (Figure 9-21). b) During a START condition both the SDA and the SCL pins are monitored. If: while SDA is high, a bus collision occurs, because it is assumed that another master is attempting to drive a data ’1’ during the START condition. If the SDA pin is sampled low during this count, the BRG is reset and the SDA line is asserted early (Figure 9-22). If, however, a ’1’ is sampled on the SDA pin, the SDA pin is asserted low at the end of the BRG count. The baud rate generator is then reloaded and counts down to 0. During this time, if the SCL pins are sampled as ’0’, a bus collision does not occur. At the end of the BRG count, the SCL pin is asserted low. Note: the SDA pin is already low or the SCL pin is already low, then: the START condition is aborted, and the BCLIF flag is set, and the SSP module is reset to its IDLE state (Figure 9-20). The START condition begins with the SDA and SCL pins deasserted. When the SDA pin is sampled high, the baud rate generator is loaded from SSPADD<6:0> and counts down to 0. If the SCL pin is sampled low The reason that bus collision is not a factor during a START condition is that no two bus masters can assert a START condition at the exact same time. Therefore, one master will always assert SDA before the other. This condition does not cause a bus collision, because the two masters must be allowed to arbitrate the first address following the START condition. If the address is the same, arbitration must be allowed to continue into the data portion, REPEATED START or STOP conditions. FIGURE 9-20: BUS COLLISION DURING START CONDITION (SDA ONLY) SDA goes low before the SEN bit is set. Set BCLIF, S bit and SSPIF set because SDA = 0, SCL = 1 SDA SCL Set SEN, enable start condition if SDA = 1, SCL=1 SEN cleared automatically because of bus collision. SSP module reset into idle state. SEN BCLIF SDA sampled low before START condition. Set BCLIF. S bit and SSPIF set because SDA = 0, SCL = 1 SSPIF and BCLIF are cleared in software. S SSPIF SSPIF and BCLIF are cleared in software. 1999 Microchip Technology Inc. Preliminary DS30221A-page 79 PIC16F872 FIGURE 9-21: BUS COLLISION DURING START CONDITION (SCL = 0) SDA = 0, SCL = 1 TBRG TBRG SDA Set SEN, enable start sequence if SDA = 1, SCL = 1 SCL SCL = 0 before SDA = 0, Bus collision occurs, Set BCLIF SEN SCL = 0 before BRG time out, Bus collision occurs, Set BCLIF BCLIF Interrupts cleared in software S ’0’ ’0’ SSPIF ’0’ ’0’ FIGURE 9-22: BRG RESET DUE TO SDA COLLISION DURING START CONDITION SDA = 0, SCL = 1 Set S Less than TBRG SDA TBRG SDA pulled low by other master Reset BRG and assert SDA SCL s SCL pulled low after BRG Timeout SEN BCLIF Set SSPIF ’0’ Set SEN, enable start sequence if SDA = 1, SCL = 1 S SSPIF SDA = 0, SCL = 1 Set SSPIF DS30221A-page 80 Preliminary Interrupts cleared in software 1999 Microchip Technology Inc. PIC16F872 9.2.18.16 BUS COLLISION DURING A REPEATED START CONDITION sampled high, the BRG is reloaded and begins counting. If SDA goes from high to low before the BRG times out, no bus collision occurs, because no two masters can assert SDA at exactly the same time. During a Repeated Start condition, a bus collision occurs if: a) b) If, however, SCL goes from high to low before the BRG times out and SDA has not already been asserted, a bus collision occurs. In this case, another master is attempting to transmit a data ’1’ during the Repeated Start condition. A low level is sampled on SDA when SCL goes from low level to high level. SCL goes low before SDA is asserted low, indicating that another master is attempting to transmit a data ’1’. If, at the end of the BRG time out, both SCL and SDA are still high, the SDA pin is driven low, the BRG is reloaded and begins counting. At the end of the count, regardless of the status of the SCL pin, the SCL pin is driven low and the Repeated Start condition is complete (Figure 9-23). When the user deasserts SDA and the pin is allowed to float high, the BRG is loaded with SSPADD<6:0> and counts down to 0. The SCL pin is then deasserted, and when sampled high, the SDA pin is sampled. If SDA is low, a bus collision has occurred (i.e., another master is attempting to transmit a data ’0’). If, however, SDA is FIGURE 9-23: BUS COLLISION DURING A REPEATED START CONDITION (CASE 1) SDA SCL Sample SDA when SCL goes high. If SDA = 0, set BCLIF and release SDA and SCL RSEN BCLIF S ’0’ Cleared in software ’0’ SSPIF ’0’ ’0’ FIGURE 9-24: BUS COLLISION DURING REPEATED START CONDITION (CASE 2) TBRG TBRG SDA SCL SCL goes low before SDA, Set BCLIF. Release SDA and SCL BCLIF Interrupt cleared in software RSEN S ’0’ ’0’ SSPIF ’0’ ’0’ 1999 Microchip Technology Inc. Preliminary DS30221A-page 81 PIC16F872 9.2.18.17 BUS COLLISION DURING A STOP CONDITION The STOP condition begins with SDA asserted low. When SDA is sampled low, the SCL pin is allow to float. When the pin is sampled high (clock arbitration), the baud rate generator is loaded with SSPADD<6:0> and counts down to 0. After the BRG times out, SDA is sampled. If SDA is sampled low, a bus collision has occurred. This is due to another master attempting to drive a data ’0’. If the SCL pin is sampled low before SDA is allowed to float high, a bus collision occurs. This is a case of another master attempting to drive a data ’0’ (Figure 9-25). Bus collision occurs during a STOP condition if: a) b) After the SDA pin has been deasserted and allowed to float high, SDA is sampled low after the BRG has timed out. After the SCL pin is deasserted, SCL is sampled low before SDA goes high. FIGURE 9-25: BUS COLLISION DURING A STOP CONDITION (CASE 1) TBRG TBRG TBRG SDA sampled low after TBRG, Set BCLIF. SDA SDA asserted low SCL PEN BCLIF P ’0’ ’0’ SSPIF ’0’ ’0’ FIGURE 9-26: BUS COLLISION DURING A STOP CONDITION (CASE 2) TBRG TBRG TBRG SDA SCL goes low before SDA goes high Set BCLIF Assert SDA SCL PEN BCLIF P ’0’ SSPIF ’0’ DS30221A-page 82 Preliminary 1999 Microchip Technology Inc. PIC16F872 Connection Considerations for I2C Bus For standard-mode I2C bus devices, the values of resistors Rp and Rs in Figure 9-27 depend on the following parameters: example, with a supply voltage of VDD = 5V+10% and VOL max = 0.4V at 3 mA, Rp min = (5.5-0.4)/0.003 = 1.7 kΩ. VDD as a function of Rp is shown in Figure 9-27. The desired noise margin of 0.1VDD for the low level limits the maximum value of Rs. Series resistors are optional and used to improve ESD susceptibility. • Supply voltage • Bus capacitance • Number of connected devices (input current + leakage current). The bus capacitance is the total capacitance of wire, connections, and pins. This capacitance limits the maximum value of Rp due to the specified rise time (Figure 9-27). The supply voltage limits the minimum value of resistor Rp due to the specified minimum sink current of 3 mA at VOL max = 0.4V for the specified output stages. For The SMP bit is the slew rate control enabled bit. This bit is in the SSPSTAT register, and controls the slew rate of the I/O pins when in I2C mode (master or slave). 9.3 FIGURE 9-27: SAMPLE DEVICE CONFIGURATION FOR I2C BUS VDD + 10% Rp DEVICE Rp Rs Rs SDA SCL Cb=10 - 400 pF Note: I2C devices with input levels related to VDD must have one common supply line to which the pull-up resistor is also connected. 1999 Microchip Technology Inc. Preliminary DS30221A-page 83 PIC16F872 NOTES: DS30221A-page 84 Preliminary 1999 Microchip Technology Inc. PIC16F872 10.0 ANALOG-TO-DIGITAL CONVERTER (A/D) MODULE The A/D module has four registers. These registers are: • • • • The Analog-to-Digital (A/D) Converter module has five inputs. The analog input charges a sample and hold capacitor. The output of the sample and hold capacitor is the input into the converter. The converter then generates a digital result of this analog level via successive approximation. The A/D conversion of the analog input signal results in a corresponding 10-bit digital number. The A/D module has high and low voltage reference input that is software selectable to some combination of VDD, VSS, RA2 or RA3. A/D Result High Register (ADRESH) A/D Result Low Register (ADRESL) A/D Control Register0 (ADCON0) A/D Control Register1 (ADCON1) The ADCON0 register, shown in Register 10-1, controls the operation of the A/D module. The ADCON1 register, shown in Register 10-2, configures the functions of the port pins. The port pins can be configured as analog inputs (RA3 can also be the voltage reference) or as digital I/O. Additional information on using the A/D module can be found in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023). The A/D converter has a unique feature of being able to operate while the device is in SLEEP mode. To operate in SLEEP, the A/D clock must be derived from the A/D’s internal RC oscillator. REGISTER 10-1: ADCON0 REGISTER (ADDRESS: 1Fh) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 R/W-0 ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE — ADON bit7 bit0 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR reset bit 7-6: ADCS<1:0>: A/D Conversion Clock Select bits 00 = FOSC/2 01 = FOSC/8 10 = FOSC/32 11 = FRC (clock derived from an RC oscillation) bit 5-3: CHS<2:0>: Analog Channel Select bits 000 = channel 0, (RA0/AN0) 001 = channel 1, (RA1/AN1) 010 = channel 2, (RA2/AN2) 011 = channel 3, (RA3/AN3) 100 = channel 4, (RA5/AN4) bit 2: GO/DONE: A/D Conversion Status bit If ADON = 1 1 = A/D conversion in progress (setting this bit starts the A/D conversion) 0 = A/D conversion not in progress (this bit is automatically cleared by hardware when the A/D conversion is complete) bit 1: Unimplemented: Read as '0' bit 0: ADON: A/D On bit 1 = A/D converter module is operating 0 = A/D converter module is shutoff and consumes no operating current 1999 Microchip Technology Inc. Preliminary DS30221A-page 85 PIC16F872 REGISTER 10-2: ADCON1 REGISTER (ADDRESS 9Fh) U-0 U-0 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 ADFM — — — PCFG3 PCFG2 PCFG1 PCFG0 bit7 bit0 bit 7: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR reset ADFM: A/D Result format select 1 = Right Justified. 6 most significant bits of ADRESH are read as ‘0’. 0 = Left Justified. 6 least significant bits of ADRESL are read as ‘0’. bit 6-4: Unimplemented: Read as '0' bit 3-0: PCFG<3:0>: A/D Port Configuration Control bits PCFG<3:0> AN4 RA5 AN3 RA3 AN2 RA2 AN1 RA1 AN0 RA0 VREF+ VREF- CHAN / Refs(1) 0000 A A A A A VDD VSS 5/0 0001 A VREF+ A A A RA3 VSS 4/1 0010 A A A A A VDD VSS 5/0 0011 A VREF+ A A A RA3 VSS 4/1 0100 D A D A A VDD VSS 3/0 0101 D VREF+ D A A RA3 VSS 2/1 011x D D D D D VDD VSS 0/0 1000 A VREF+ VREF- A A RA3 RA2 3/2 1001 A A A A A VDD VSS 5/0 1010 A VREF+ A A A RA3 VSS 4/1 1011 A VREF+ VREF- A A RA3 RA2 3/2 1100 A VREF+ VREF- A A RA3 RA2 3/2 1101 D VREF+ VREF- A A RA3 RA2 2/2 1110 D D D D A VDD VSS 1/0 1111 D VREF+ VREF- D A RA3 RA2 1/2 A = Analog input D = Digital I/O Note 1: This column indicates the number of analog channels available as A/D inputs and the number of analog channels used as voltage reference inputs. DS30221A-page 86 Preliminary 1999 Microchip Technology Inc. PIC16F872 The ADRESH:ADRESL registers contain the 10-bit result of the A/D conversion. When the A/D conversion is complete, the result is loaded into this A/D result register pair, the GO/DONE bit (ADCON0<2>) is cleared and the A/D interrupt flag bit ADIF is set. The block diagram of the A/D module is shown in Figure 10-1. 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 10.1. After this acquisition time has elapsed, the A/D conversion can be started. The following steps should be followed for doing an A/D conversion: 1. 2. 3. 4. 5. Configure the A/D module: • Configure analog pins / voltage reference / and digital I/O (ADCON1) • Select A/D input channel (ADCON0) • Select A/D conversion clock (ADCON0) • Turn on A/D module (ADCON0) Configure A/D interrupt (if desired): • Clear ADIF bit • Set ADIE bit • Set GIE bit Wait the required acquisition time. Start conversion: • Set GO/DONE bit (ADCON0) Wait for A/D conversion to complete, by either: • Polling for the GO/DONE bit to be cleared OR 6. 7. • Waiting for the A/D interrupt Read A/D Result register pair (ADRESH:ADRESL), clear bit ADIF if required. 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 2TAD is required before next acquisition starts. 1999 Microchip Technology Inc. Preliminary DS30221A-page 87 PIC16F872 FIGURE 10-1: A/D BLOCK DIAGRAM CHS<2:0> 100 RA5/AN4 VAIN 011 (Input voltage) RA3/AN3/VREF+ 010 RA2/AN2/VREF- A/D Converter 001 RA1/AN1 000 VDD RA0/AN0 VREF+ (Reference voltage) PCFG<3:0> VREF(Reference voltage) VSS PCFG<3:0> 10.1 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 10-2. 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 varies over the device voltage (VDD), Figure 10-2. The maximum recommended 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, TACQ, see the PICmicro™ Mid-Range Reference Manual (DS33023). To calculate the minimum acquisition time, Equation 10-1 may be used. This equation assumes that 1/2 LSb error is used (1024 steps for the A/D). The 1/2 LSb error is the maximum error allowed for the A/D to meet its specified resolution. DS30221A-page 88 Preliminary 1999 Microchip Technology Inc. PIC16F872 EQUATION 10-1: TACQ TC TACQ ACQUISITION TIME = Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient = = = = = = = TAMP + TC + TCOFF 2µS + TC + [(Temperature -25°C)(0.05µS/°C)] CHOLD (RIC + RSS + RS) In(1/2047) - 120pF (1kΩ + 7kΩ + 10kΩ) In(0.0004885) 16.47µS 2µS + 16.47µS + [(50°C -25×C)(0.05µS/×C) 19.72µS 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. 4: After a conversion has completed, a 2.0TAD delay must complete before acquisition can begin again. During this time, the holding capacitor is not connected to the selected A/D input channel. FIGURE 10-2: ANALOG INPUT MODEL VDD RS VT = 0.6V ANx VA CPIN 5 pF VT = 0.6V RIC ≤ 1k Sampling Switch SS RSS CHOLD = DAC capacitance = 120 pF I LEAKAGE ± 500 nA VSS Legend CPIN = input capacitance VT = threshold voltage I LEAKAGE = leakage current at the pin due to various junctions RIC SS CHOLD 1999 Microchip Technology Inc. = interconnect resistance = sampling switch = sample/hold capacitance (from DAC) Preliminary 6V 5V VDD 4V 3V 2V 5 6 7 8 9 10 11 Sampling Switch ( kΩ ) DS30221A-page 89 PIC16F872 10.2 Selecting the A/D Conversion Clock For correct A/D conversions, the A/D conversion clock (TAD) must be selected to ensure a minimum TAD time of 1.6 µs. The A/D conversion time per bit is defined as TAD. The A/D conversion requires a minimum 12TAD per 10-bit conversion. The source of the A/D conversion clock is software selected. The four possible options for TAD are: • • • • Table 10-1shows the resultant TAD times derived from the device operating frequencies and the A/D clock source selected. 2TOSC 8TOSC 32TOSC Internal RC oscillator TABLE 10-1: TAD vs. MAXIMUM DEVICE OPERATING FREQUENCIES (STANDARD DEVICES (C)) AD Clock Source (TAD) Maximum Device Frequency Operation ADCS<1:0> Max. 2TOSC 00 1.25 MHz 8TOSC 01 5 MHz 32TOSC 10 20 MHz RC(1, 2, 3) 11 Note 1 Note 1: The RC source has a typical TAD time of 4 µs but can vary between 2-6 µs. 2: When the device frequencies are greater than 1 MHz, the RC A/D conversion clock source is only recommended for sleep operation. 3: For extended voltage devices (LC), please refer to the Electrical Specifications section. 10.3 Configuring Analog Port Pins The ADCON1, and TRIS registers control the operation of the A/D port pins. The port pins that are desired as analog inputs must have their corresponding TRIS bits set (input). If the TRIS bit is cleared (output), the digital output level (VOH or VOL) will be converted. The A/D operation is independent of the state of the CHS<2:0> bits and the TRIS bits. Note 1: When reading the port register, any pin configured as an analog input channel will read as cleared (a low level). Pins configured as digital inputs will convert an analog input. Analog levels on a digitally configured input will not affect the conversion accuracy. 2: Analog levels on any pin that is defined as a digital input (including the AN<4:0> pins), may cause the input buffer to consume current that is out of the device specifications. DS30221A-page 90 Preliminary 1999 Microchip Technology Inc. PIC16F872 10.4 required before the next acquisition is started. After this 2TAD wait, acquisition on the selected channel is automatically started. A/D Conversions Clearing the GO/DONE bit during a conversion will abort the current conversion. The A/D result register pair will NOT be updated with the partially completed A/D conversion sample. That is, the ADRESH:ADRESL registers will continue to contain the value of the last completed conversion (or the last value written to the ADRESH:ADRESL registers). After the A/D conversion is aborted, a 2TAD wait is In Figure 10-3, after the GO bit is set, the first time segment has a minimum of TCY and a maximum of TAD. Note: The GO/DONE bit should NOT be set in the same instruction that turns on the A/D. FIGURE 10-3: A/D CONVERSION TAD CYCLES TCY to TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 b9 b8 b7 b6 b5 b4 b3 TAD9 TAD10 TAD11 b2 b1 b0 Conversion Starts Holding capacitor is disconnected from analog input (typically 100 ns) Set GO bit 1999 Microchip Technology Inc. ADRES is loaded, GO bit is cleared, ADIF bit is set, holding capacitor is connected to analog input. Preliminary DS30221A-page 91 PIC16F872 10.4.1 A/D RESULT REGISTERS The ADRESH:ADRESL register pair is the location where the 10-bit A/D result is loaded at the completion of the A/D conversion. This register pair is 16-bits wide. The A/D module gives the flexibility to left or right justify the 10-bit result in the 16-bit result register. The A/D Format Select bit (ADFM) controls this justification. Figure 10-4 shows the operation of the A/D result justification. The extra bits are loaded with ’0’s’. When an A/D result will not overwrite these locations (A/D disable), these registers may be used as two general purpose 8-bit registers. 10.5 SLEEP. If the A/D interrupt is not enabled, the A/D module will then be turned off, although the ADON bit will remain set. When the A/D clock source is another clock option (not RC), a SLEEP instruction will cause the present conversion to be aborted and the A/D module to be turned off, though the ADON bit will remain set. Turning off the A/D places the A/D module in its lowest current consumption state. Note: A/D Operation During Sleep The A/D module can operate during SLEEP mode. This requires that the A/D clock source be set to RC (ADCS<1:0> = 11). When the RC clock source is selected, the A/D module waits one instruction cycle before starting the conversion. This allows the SLEEP instruction to be executed, which eliminates all digital switching noise from the conversion. When the conversion is completed, the GO/DONE bit will be cleared and the result loaded into the ADRES register. If the A/D interrupt is enabled, the device will wake-up from 10.6 For the A/D module to operate in SLEEP, the A/D clock source must be set to RC (ADCS<1:0> = 11). To allow the conversion to occur during SLEEP, ensure the SLEEP instruction immediately follows the instruction that sets the GO/DONE bit. Effects of a Reset A device RESET forces all registers to their RESET state. This forces the A/D module to be turned off, and any conversion is aborted. The value that is in the ADRESH:ADRESL registers is not modified for a Power-on Reset. The ADRESH:ADRESL registers will contain unknown data after a Power-on Reset. FIGURE 10-4: A/D RESULT JUSTIFICATION 10-Bit Result ADFM = 0 ADFM = 1 7 0 2107 7 0765 0000 00 0000 00 ADRESH ADRESL ADRESH ADRESL 10-bit Result 10-bit Result Left Justified Right Justified DS30221A-page 92 0 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 10-2: Addr Name REGISTERS/BITS ASSOCIATED WITH A/D Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 POR, BOR MCLR, WDT 0Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u 0Ch PIR1 (1) ADIF (1) (1) SSPIF CCP1IF TMR2IF TMR1IF r0rr 0000 r0rr 0000 8Ch PIE1 (1) ADIE (1) (1) SSPIE CCP1IE TMR2IE TMR1IE r0rr 0000 r0rr 0000 1Eh ADRESH A/D Result Register High Byte xxxx xxxx uuuu uuuu 9Eh ADRESL A/D Result Register Low Byte xxxx xxxx uuuu uuuu 1Fh ADCON0 ADCS1 ADCS0 CHS2 CHS1 CHS0 GO/DONE — ADON 0000 00-0 0000 00-0 9Fh ADCON1 ADFM — — — PCFG3 PCFG2 PCFG1 PCFG0 --0- 0000 --0- 0000 85h TRISA — — PORTA Data Direction Register --11 1111 --11 1111 05h PORTA — — PORTA Data Latch when written: PORTA pins when read --0x 0000 --0u 0000 Legend: x = unknown, u = unchanged, - = unimplemented read as ’0’. Shaded cells are not used for A/D conversion. Note 1: These bits are reserved; always maintain these bits clear. 1999 Microchip Technology Inc. Preliminary DS30221A-page 93 PIC16F872 NOTES: DS30221A-page 94 Preliminary 1999 Microchip Technology Inc. PIC16F872 11.0 SPECIAL FEATURES OF THE CPU These devices have a host of features intended to maximize system reliability, minimize cost through elimination of external components, provide power saving operating modes and offer code protection. These are: • OSC Selection • Reset - Power-on Reset (POR) - Power-up Timer (PWRT) - Oscillator Start-up Timer (OST) - Brown-out Reset (BOR) • Interrupts • Watchdog Timer (WDT) • SLEEP • Code protection • ID locations • In-Circuit Serial Programming • Low Voltage In-Circuit Serial Programming • In-Circuit Debugger 11.1 Configuration Bits The configuration bits can be programmed (read as '0') or left unprogrammed (read as '1') to select various device configurations. These bits are mapped in program memory location 2007h. The user will note that address 2007h is beyond the user program memory space. In fact, it belongs to the special test/configuration memory space (2000h through 3FFFh), which can be accessed only during programming. These devices have a Watchdog Timer, which can be shut off only through configuration bits. It runs off its own RC oscillator for added reliability. There are two timers that offer necessary delays on power-up. One is the Oscillator Start-up Timer (OST), intended to keep the chip in RESET until the crystal oscillator is stable. The other is the Power-up Timer (PWRT), which provides a fixed delay of 72 ms (nominal) on power-up only. It is designed to keep the part in RESET while the power supply stabilizes. With these two timers on-chip, most applications need no external reset circuitry. SLEEP mode is designed to offer a very low current power-down mode. The user can wake-up from SLEEP through external reset, Watchdog Timer Wake-up, or through an interrupt. Several oscillator options are also made available to allow the part to fit the application. The RC oscillator option saves system cost while the LP crystal option saves power. A set of configuration bits are used to select various options. Additional information on special features is available in the PICmicro™ Mid-Range Reference Manual, (DS33023). 1999 Microchip Technology Inc. Preliminary DS30221A-page 95 PIC16F872 REGISTER 11-1: CONFIGURATION WORD CP1 CP0 DEBUG — WRT CPD LVP BODEN CP1 CP0 PWRTE WDTE bit13 F0SC1 F0SC0 bit0 Register: CONFIG Address 2007h bit 13-12: bit 5-4: CP<1:0>: Flash Program Memory Code Protection bits (2) 11 = Code protection off 10 = 0000h to 06FFh code protected 01 = 0000h to 03FFh code protected 00 = 0000h to 07FFh code protected bit 11: DEBUG: In-Circuit Debugger Mode 1 = In-Circuit Debugger disabled, RB6 and RB7 are general purpose I/O pins. 0 = In-Circuit Debugger enabled, RB6 and RB7 are dedicated to the debugger. bit 10: Unimplemented: Read as ‘1’ bit 9: WRT: Flash Program Memory Write Enable 1 = Unprotected program memory may be written to by EECON control 0 = Unprotected program memory may not be written to by EECON control bit 8: CPD: Data EE Memory Code Protection 1 = Code protection off 0 = Data EEPROM memory code protected bit 7: LVP: Low Voltage In-Circuit Serial Programming Enable bit 1 = RB3/PGM pin has PGM function, low voltage programming enabled 0 = RB3 is digital I/O, HV on MCLR must be used for programming bit 6: BODEN: Brown-out Reset Enable bit (1) 1 = BOR enabled 0 = BOR disabled bit 3: PWRTE: Power-up Timer Enable bit (1) 1 = PWRT disabled 0 = PWRT enabled bit 2: WDTE: Watchdog Timer Enable bit 1 = WDT enabled 0 = WDT disabled bit 1-0: FOSC1:FOSC0: Oscillator Selection bits 11 = RC oscillator 10 = HS oscillator 01 = XT oscillator 00 = LP oscillator Note 1: Enabling Brown-out Reset automatically enables Power-up Timer (PWRT), regardless of the value of bit PWRTE. Ensure the Power-up Timer is enabled anytime Brown-out Reset is enabled. 2: All of the CP<1:0> pairs have to be given the same value to enable the code protection scheme listed. DS30221A-page 96 Preliminary 1999 Microchip Technology Inc. PIC16F872 11.2 Oscillator Configurations 11.2.1 OSCILLATOR TYPES TABLE 11-1: Ranges Tested: The PIC16F872 can be operated in four different oscillator modes. The user can program two configuration bits (FOSC1 and FOSC0) to select one of these four modes: • • • • LP XT HS RC 11.2.2 CERAMIC RESONATORS Mode Freq OSC1 OSC2 XT 455 kHz 2.0 MHz 4.0 MHz 68 - 100 pF 15 - 68 pF 15 - 68 pF 68 - 100 pF 15 - 68 pF 15 - 68 pF HS 8.0 MHz 16.0 MHz 10 - 68 pF 10 - 22 pF 10 - 68 pF 10 - 22 pF Low Power Crystal Crystal/Resonator High Speed Crystal/Resonator Resistor/Capacitor These values are for design guidance only. See notes at bottom of page. Resonators Used: CRYSTAL OSCILLATOR/CERAMIC RESONATORS In XT, LP or HS modes, a crystal or ceramic resonator is connected to the OSC1/CLKIN and OSC2/CLKOUT pins to establish oscillation (Figure 11-1). The PIC16F872 oscillator design requires the use of a parallel cut crystal. Use of a series cut crystal may give a frequency out of the crystal manufacturers specifications. When in XT, LP or HS modes, the device can have an external clock source to drive the OSC1/ CLKIN pin (Figure 11-2). 455 kHz Panasonic EFO-A455K04B ± 0.3% 2.0 MHz Murata Erie CSA2.00MG ± 0.5% 4.0 MHz Murata Erie CSA4.00MG ± 0.5% 8.0 MHz Murata Erie CSA8.00MT ± 0.5% 16.0 MHz Murata Erie CSA16.00MX ± 0.5% All resonators used did not have built-in capacitors. FIGURE 11-1: CRYSTAL/CERAMIC RESONATOR OPERATION (HS, XT OR LP OSC CONFIGURATION) C1(1) OSC1 XTAL To internal logic RF(3) OSC2 SLEEP RS(2) PIC16F872 C2(1) Note 1: See Table 11-1 and Table 11-2 for recommended values of C1 and C2. 2: A series resistor (RS) may be required for AT strip cut crystals. 3: RF varies with the crystal chosen. FIGURE 11-2: EXTERNAL CLOCK INPUT OPERATION (HS, XT OR LP OSC CONFIGURATION) OSC1 Clock from ext. system PIC16F872 Open OSC2 1999 Microchip Technology Inc. Preliminary DS30221A-page 97 PIC16F872 TABLE 11-2: Osc Type LP XT HS CAPACITOR SELECTION FOR CRYSTAL OSCILLATOR Crystal Freq Cap. Range C1 Cap. Range C2 32 kHz 33 pF 33 pF 200 kHz 15 pF 15 pF 200 kHz 47-68 pF 47-68 pF 1 MHz 15 pF 15 pF 4 MHz 15 pF 15 pF 4 MHz 15 pF 15 pF 8 MHz 15-33 pF 15-33 pF 20 MHz 15-33 pF 15-33 pF 11.2.3 RC OSCILLATOR For timing insensitive applications, the “RC” device option offers additional cost savings. 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 process parameter variation. Furthermore, the difference in lead frame capacitance between package types will also affect the oscillation frequency, especially for low CEXT values. The user also needs to take into account variation due to tolerance of external R and C components used. Figure 11-3 shows how the R/C combination is connected to the PIC16F872. FIGURE 11-3: RC OSCILLATOR MODE These values are for design guidance only. See notes at bottom of page. VDD Crystals Used 32 kHz Epson C-001R32.768K-A ± 20 PPM 200 kHz STD XTL 200.000KHz ± 20 PPM 1 MHz ECS ECS-10-13-1 ± 50 PPM 4 MHz ECS ECS-40-20-1 ± 50 PPM CEXT VSS 8 MHz EPSON CA-301 8.000M-C ± 30 PPM 20 MHz EPSON CA-301 20.000M-C ± 30 PPM REXT OSC1 PIC16F872 FOSC/4 Recommended values: Note 1: Higher capacitance increases the stability of oscillator but also increases the start-up time. Internal Clock OSC2/CLKOUT 3 kΩ ≤ REXT ≤ 100 kΩ CEXT > 20pF 2: Since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. 3: Rs may be required in HS mode, as well as XT mode, to avoid overdriving crystals with low drive level specification. 4: When migrating from other PICmicro devices, oscillator performance should be verified. DS30221A-page 98 Preliminary 1999 Microchip Technology Inc. PIC16F872 11.3 Reset The PIC16F872 differentiates between various kinds of reset: • • • • • • Power-on Reset (POR) MCLR Reset during normal operation MCLR Reset during SLEEP WDT Reset (during normal operation) WDT Wake-up (during SLEEP) Brown-out Reset (BOR) Brown-out Reset (BOR). They are not affected by a WDT Wake-up, which is viewed as the resumption of normal operation. The TO and PD bits are set or cleared differently in different reset situations as indicated in Table 11-4. These bits are used in software to determine the nature of the reset. See Table 11-6 for a full description of reset states of all registers. A simplified block diagram of the on-chip reset circuit is shown in Figure 11-4. Some registers are not affected in any RESET condition. Their status is unknown on POR and unchanged in any other RESET. Most other registers are reset to a “reset state” on Power-on Reset (POR), on the MCLR and WDT Reset, on MCLR Reset during SLEEP, and These devices have a MCLR noise filter in the MCLR Reset path. The filter will detect and ignore small pulses. It should be noted that a WDT Reset does not drive MCLR pin low. FIGURE 11-4: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT External Reset MCLR WDT Module WDT SLEEP Time-out Reset VDD rise detect Power-on Reset VDD Brown-out Reset S BODEN OST/PWRT OST Chip_Reset R 10-bit Ripple counter Q OSC1 (1) On-chip RC OSC PWRT 10-bit Ripple counter Enable PWRT Enable OST Note 1: This is a separate oscillator from the RC oscillator of the CLKIN pin. 1999 Microchip Technology Inc. Preliminary DS30221A-page 99 PIC16F872 11.4 Power-On Reset (POR) 11.8 A Power-on Reset pulse is generated on-chip when VDD rise is detected (in the range of 1.2V - 1.7V). To take advantage of the POR, tie the MCLR pin directly (or through a resistor) to VDD. This will eliminate external RC components usually needed to create a Poweron Reset. A maximum rise time for VDD is specified. See Electrical Specifications for details. When the device starts normal operation (exits the RESET condition), device operating parameters (voltage, frequency, temperature,...) 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. Brown-out Reset may be used to meet the start-up conditions. For additional information, refer to Application Note, AN007, “Power-up Trouble Shooting”, (DS00007). 11.5 Power-up Timer (PWRT) The Power-up Timer provides a fixed 72 ms nominal time-out on power-up only from the POR. The Powerup Timer operates on an internal RC oscillator. The chip is kept in RESET as long as the PWRT is active. The PWRT’s time delay allows VDD to rise to an acceptable level. A configuration bit is provided to enable/disable the PWRT. The power-up time delay will vary from chip to chip due to VDD, temperature and process variation. See DC parameters for details (TPWRT, parameter #33). 11.6 Time-out Sequence On power-up, the Time-out Sequence is as follows: The PWRT delay starts (if enabled) when a POR reset occurs. Then OST starts counting 1024 oscillator cycles when PWRT ends (LP, XT, HS). When the OST ends, the device comes out of RESET. If MCLR is kept low long enough, the time-outs will expire. Bringing MCLR high will begin execution immediately. This is useful for testing purposes or to synchronize more than one PIC16CXX device operating in parallel. Table 11-5 shows the reset conditions for the STATUS, PCON and PC registers, while Table 11-6 shows the reset conditions for all the registers. 11.9 Power Control/Status Register (PCON) The Power Control/Status Register, PCON, has up to two bits depending upon the device. Bit0 is Brown-out Reset Status bit, BOR. Bit BOR is unknown on a Power-on Reset. It must then be set by the user and checked on subsequent resets to see if bit BOR cleared, indicating a BOR occurred. The BOR bit is a "don’t care" bit and is not necessarily predictable if the Brown-out Reset circuitry is disabled (by clearing bit BODEN in the Configuration Word). Bit1 is POR (Power-on Reset Status bit). It is cleared on a Power-on Reset and unaffected otherwise. The user must set this bit following a Power-on Reset. Oscillator Start-up Timer (OST) The Oscillator Start-up Timer (OST) provides 1024 oscillator cycle (from OSC1 input) delay after the PWRT delay is over. This ensures that the crystal oscillator or resonator has started and stabilized. The OST time-out is invoked only for XT, LP and HS modes and only on Power-on Reset or wake-up from SLEEP. 11.7 Brown-Out Reset (BOR) The configuration bit, BODEN, can enable or disable the Brown-out Reset circuit. If VDD falls below VBOR (parameter D005, about 4V) for longer than TBOR (parameter #35, about 100µS), the brown-out situation will reset the device. If VDD falls below VBOR for less than TBOR, a RESET may not occur. Once the brown-out occurs, the device will remain in Brown-out Reset until VDD rises above VBOR. The Power-up Timer then keeps the device in RESET for TPWRT (parameter #33, about 72mS). If VDD should fall below VBOR during TPWRT, the Brown-out Reset process will restart when VDD rises above VBOR with the Power-up Timer reset. The Power-up Timer is always enabled when the Brown-out Reset circuit is enabled regardless of the state of the PWRT configuration bit. DS30221A-page 100 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 11-3: TIME-OUT IN VARIOUS SITUATIONS Oscillator Configuration Brown-out Wake-up from SLEEP PWRTE = 0 PWRTE = 1 XT, HS, LP 72 ms + 1024TOSC 1024TOSC 72 ms + 1024TOSC 1024TOSC RC 72 ms — 72 ms — TABLE 11-4: POR Power-up BOR STATUS BITS AND THEIR SIGNIFICANCE TO PD 0 x 1 1 Power-on Reset 0 x 0 x Illegal, TO is set on POR 0 x x 0 Illegal, PD is set on POR 1 0 1 1 Brown-out Reset 1 1 0 1 WDT Reset 1 1 0 0 WDT Wake-up 1 1 u u MCLR Reset during normal operation 1 1 1 0 MCLR Reset during SLEEP or interrupt wake-up from SLEEP TABLE 11-5: RESET CONDITION FOR SPECIAL REGISTERS Program Counter STATUS Register PCON Register Power-on Reset 000h 0001 1xxx ---- --0x MCLR Reset during normal operation 000h 000u uuuu ---- --uu MCLR Reset during SLEEP 000h 0001 0uuu ---- --uu 000h 0000 1uuu ---- --uu PC + 1 uuu0 0uuu ---- --uu Condition WDT Reset WDT Wake-up Brown-out Reset Interrupt wake-up from SLEEP 000h 0001 1uuu ---- --u0 PC + 1(1) uuu1 0uuu ---- --uu Legend: u = unchanged, x = unknown, - = unimplemented bit read as '0'. Note 1: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector (0004h). 1999 Microchip Technology Inc. Preliminary DS30221A-page 101 PIC16F872 TABLE 11-6: INITIALIZATION CONDITIONS FOR ALL REGISTERS Register Power-on Reset, MCLR Resets Wake-up via WDT or Brown-out Reset WDT Reset Interrupt W xxxx xxxx uuuu uuuu uuuu uuuu INDF N/A N/A N/A TMR0 xxxx xxxx uuuu uuuu uuuu uuuu PCL 0000h 0000h PC + 1(2) (3) STATUS 0001 1xxx 000q quuu uuuq quuu(3) FSR xxxx xxxx uuuu uuuu uuuu uuuu PORTA --0x 0000 --0u 0000 --uu uuuu PORTB xxxx xxxx uuuu uuuu uuuu uuuu PORTC xxxx xxxx uuuu uuuu uuuu uuuu PCLATH ---0 0000 ---0 0000 ---u uuuu INTCON 0000 000x 0000 000u uuuu uuuu(1) PIR1 r0rr 0000 r0rr 0000 rurr uuuu(1) PIR2 -r-0 0--r -r-0 0--r -r-u u--r(1) TMR1L xxxx xxxx uuuu uuuu uuuu uuuu TMR1H xxxx xxxx uuuu uuuu uuuu uuuu T1CON --00 0000 --uu uuuu --uu uuuu TMR2 0000 0000 0000 0000 uuuu uuuu T2CON -000 0000 -000 0000 -uuu uuuu SSPBUF xxxx xxxx uuuu uuuu uuuu uuuu SSPCON 0000 0000 0000 0000 uuuu uuuu CCPR1L xxxx xxxx uuuu uuuu uuuu uuuu CCPR1H xxxx xxxx uuuu uuuu uuuu uuuu CCP1CON --00 0000 --00 0000 --uu uuuu ADRESH xxxx xxxx uuuu uuuu uuuu uuuu ADCON0 0000 00-0 0000 00-0 uuuu uu-u OPTION_REG 1111 1111 1111 1111 uuuu uuuu TRISA --11 1111 --11 1111 --uu uuuu TRISB 1111 1111 1111 1111 uuuu uuuu TRISC 1111 1111 1111 1111 uuuu uuuu PIE1 r0rr 0000 r0rr 0000 rurr uuuu PIE2 -r-0 0--r -r-0 0--r -r-u u--r PCON ---- --qq ---- --uu ---- --uu PR2 1111 1111 1111 1111 1111 1111 SSPADD 0000 0000 0000 0000 uuuu uuuu SSPSTAT --00 0000 --00 0000 --uu uuuu ADRESL xxxx xxxx uuuu uuuu uuuu uuuu ADCON1 0--- 0000 0--- 0000 u--- uuuu EEDATA 0--- 0000 0--- 0000 u--- uuuu EEADR xxxx xxxx uuuu uuuu uuuu uuuu EEDATH xxxx xxxx uuuu uuuu uuuu uuuu EEADRH xxxx xxxx uuuu uuuu uuuu uuuu EECON1 x--- x000 u--- u000 u--- uuuu EECON2 ---- ------- ------- ---Legend: u = unchanged, x = unknown, r = reserved, - = unimplemented bit, read as ’0’, q = value depends on condition, r = reserved maintain clear. Note 1: One or more bits in INTCON, PIR1 and/or PIR2 will be affected (to cause wake-up). 2: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector (0004h). 3: See Table 11-5 for reset value for specific condition. DS30221A-page 102 Preliminary 1999 Microchip Technology Inc. PIC16F872 FIGURE 11-5: TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD) VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET FIGURE 11-6: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1 VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET FIGURE 11-7: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2 VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET 1999 Microchip Technology Inc. Preliminary DS30221A-page 103 PIC16F872 FIGURE 11-8: SLOW RISE TIME (MCLR TIED TO VDD) 5V VDD 1V 0V MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET DS30221A-page 104 Preliminary 1999 Microchip Technology Inc. PIC16F872 11.10 Interrupts The PIC16F872 has 10 sources of interrupt. The interrupt control register (INTCON) records individual interrupt requests in flag bits. It also has individual and global interrupt enable bits. Note: Individual interrupt flag bits are set, regardless of the status of their corresponding mask bit or the GIE bit. A global interrupt enable bit, GIE (INTCON<7>) enables (if set) all un-masked interrupts or disables (if cleared) all interrupts. When bit GIE is enabled, and an interrupt’s flag bit and mask bit are set, the interrupt will vector immediately. Individual interrupts can be disabled through their corresponding enable bits in various registers. Individual interrupt bits are set regardless of the status of the GIE bit. The GIE bit is cleared on reset. The “return from interrupt” instruction, RETFIE, exits the interrupt routine, as well as sets the GIE bit, which re-enables interrupts. The RB0/INT pin interrupt, the RB port change interrupt and the TMR0 overflow interrupt flags are contained in the INTCON register. The peripheral interrupt flags are contained in the Special Function Registers, PIR1 and PIR2. The corresponding interrupt enable bits are contained in Special Function Registers, PIE1 and PIE2, and the peripheral interrupt enable bit is contained in Special Function Register INTCON. When an interrupt is responded to, the GIE bit is cleared to disable any further interrupt, the return address is pushed onto the stack and the PC is loaded with 0004h. 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 recursive interrupts. 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 when the interrupt event occurs. The latency is the same for one or two cycle instructions. Individual interrupt flag bits are set regardless of the status of their corresponding mask bit or the GIE bit FIGURE 11-9: INTERRUPT LOGIC T0IF T0IE EEIF EEIE INTF INTE ADIF ADIE Wake-up (If in SLEEP mode) Interrupt to CPU RBIF RBIE SSPIF SSPIE CCP1IF CCP1IE PEIE GIE TMR2IF TMR2IE TMR1IF TMR1IE BCLIF BCLIE 1999 Microchip Technology Inc. Preliminary DS30221A-page 105 PIC16F872 11.10.1 INT INTERRUPT 11.11 Context Saving During Interrupts External interrupt on the RB0/INT pin is edge triggered, either rising, if bit INTEDG (OPTION_REG<6>) is set, or falling, if the INTEDG bit is clear. When a valid edge appears on the RB0/INT pin, flag bit INTF (INTCON<1>) is set. This interrupt can be disabled by clearing enable bit INTE (INTCON<4>). Flag bit INTF must be cleared in software in the interrupt service routine before re-enabling this interrupt. The INT interrupt can wake-up the processor from SLEEP, if bit INTE was set prior to going into SLEEP. The status of global interrupt enable bit GIE decides whether or not the processor branches to the interrupt vector following wake-up. See Section 11.13 for details on SLEEP mode. During an interrupt, only the return PC value is saved on the stack. Typically, users may wish to save key registers during an interrupt (i.e., W register and STATUS register). This will have to be implemented in software. Since the upper 16 bytes of each bank are common in the PIC16F872 devices, temporary holding registers W_TEMP, STATUS_TEMP and PCLATH_TEMP should be placed in here. These 16 locations don’t require banking and therefore, make it easier for context save and restore. Example 11-1 can be used to save and restore context for interrupts. 11.10.2 TMR0 INTERRUPT An overflow (FFh → 00h) in the TMR0 register will set flag bit T0IF (INTCON<2>). The interrupt can be enabled/disabled by setting/clearing enable bit T0IE (INTCON<5>) (Section 5.0). 11.10.3 PORTB INTCON CHANGE An input change on PORTB<7:4> sets flag bit RBIF (INTCON<0>). The interrupt can be enabled/disabled by setting/clearing enable bit RBIE (INTCON<4>) (Section 3.2). EXAMPLE 11-1: SAVING STATUS, W, AND PCLATH REGISTERS IN RAM MOVWF SWAPF CLRF MOVWF MOVF MOVWF CLRF : :(ISR) : MOVF MOVWF SWAPF W_TEMP STATUS,W STATUS STATUS_TEMP PCLATH, W PCLATH_TEMP PCLATH ;Copy ;Swap ;bank ;Save ;Only ;Save ;Page PCLATH_TEMP, W PCLATH STATUS_TEMP,W MOVWF SWAPF SWAPF STATUS W_TEMP,F W_TEMP,W ;Restore PCLATH ;Move W into PCLATH ;Swap STATUS_TEMP register into W ;(sets bank to original state) ;Move W into STATUS register ;Swap W_TEMP ;Swap W_TEMP into W DS30221A-page 106 W to TEMP register status to be saved into W 0, regardless of current bank, Clears IRP,RP1,RP0 status to bank zero STATUS_TEMP register required if using pages 1, 2 and/or 3 PCLATH into W zero, regardless of current page Preliminary 1999 Microchip Technology Inc. PIC16F872 11.12 WDT time-out period values may be found in the Electrical Specifications section under parameter #31. Values for the WDT prescaler (actually a postscaler, but shared with the Timer0 prescaler) may be assigned using the OPTION_REG register. Watchdog Timer (WDT) The Watchdog Timer is as a free running on-chip RC oscillator which does not require any external components. This RC oscillator is separate from the RC oscillator of the OSC1/CLKIN pin. That means that the WDT will run, even if the clock on the OSC1/CLKIN and OSC2/CLKOUT pins of the device has been stopped, for example, by execution of a SLEEP instruction. During normal operation, a WDT time-out generates a device RESET (Watchdog Timer Reset). If the device is in SLEEP mode, a WDT time-out causes the device to wake-up and continue with normal operation (Watchdog Timer Wake-up). The TO bit in the STATUS register will be cleared upon a Watchdog Timer time-out. Note: The CLRWDT and SLEEP instructions clear the WDT and the postscaler, if assigned to the WDT, and prevent it from timing out and generating a device RESET condition. Note: When a CLRWDT instruction is executed and the prescaler is assigned to the WDT, the prescaler count will be cleared, but the prescaler assignment is not changed. . The WDT can be permanently disabled by clearing configuration bit WDTE (Section 11.1). FIGURE 11-10: WATCHDOG TIMER BLOCK DIAGRAM From TMR0 Clock Source (Figure 5-1) 0 WDT Timer Postscaler M U X 1 8 8 - to - 1 MUX PS<2:0> PSA WDT Enable Bit To TMR0 (Figure 5-1) 0 1 MUX PSA WDT Time-out Note: PSA and PS<2:0> are bits in the OPTION_REG register. FIGURE 11-11: SUMMARY OF WATCHDOG TIMER REGISTERS Address Name 2007h Config. bits 81h,181h OPTION_REG Bit 7 Bit 6 (1) BODEN(1) RBPU INTEDG Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 CP1 CP0 PWRTE(1) WDTE FOSC1 FOSC0 T0CS T0SE PSA PS2 PS1 PS0 Legend: Shaded cells are not used by the Watchdog Timer. Note 1: See Register 11-1 for operation of these bits. 1999 Microchip Technology Inc. Preliminary DS30221A-page 107 PIC16F872 11.13 Power-down Mode (SLEEP) Power-down mode is entered by executing a SLEEP instruction. If enabled, the Watchdog Timer will be cleared but keeps running, the PD bit (STATUS<3>) is cleared, the TO (STATUS<4>) bit is set, and the oscillator driver is turned off. The I/O ports maintain the status they had before the SLEEP instruction was executed (driving high, low, or hi-impedance). For lowest current consumption in this mode, place all I/O pins at either VDD or VSS, ensure no external circuitry is drawing current from the I/O pin, power-down the A/D and disable external clocks. Pull all I/O pins that are hi-impedance inputs, high or low externally, to avoid switching currents caused by 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 (VIHMC). 11.13.1 WAKE-UP FROM SLEEP The device can wake up from SLEEP through one of the following events: 1. 2. 3. External reset input on MCLR pin. Watchdog Timer wake-up (if WDT was enabled). Interrupt from INT pin, RB port change or some Peripheral Interrupts. External MCLR Reset will cause a device RESET. All other events are considered a continuation of program execution and cause a "wake-up". The TO and PD bits in the STATUS register can be used to determine the cause of device RESET. The PD bit, which is set on power-up, is cleared when SLEEP is invoked. The TO bit is cleared if a WDT time-out occurred and caused wake-up. 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 and then branches to the interrupt address (0004h). In cases where the execution of the instruction following SLEEP is not desirable, the user should have a NOP after the SLEEP instruction. 11.13.2 WAKE-UP USING INTERRUPTS When global interrupts are disabled (GIE cleared) and any interrupt source has both its interrupt enable bit and interrupt flag bit set, one of the following will occur: • If the interrupt occurs before the execution of a SLEEP instruction, the SLEEP instruction will complete as a NOP. Therefore, the WDT and WDT postscaler will not be cleared, the TO bit will not be set and PD bits will not be cleared. • If the interrupt occurs during or after the execution of a SLEEP instruction, the device will immediately wake up from sleep. The SLEEP instruction will be completely executed before the wake-up. Therefore, the WDT and WDT postscaler will be cleared, the TO bit will be set and the PD bit will be cleared. 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 cleared, a CLRWDT instruction should be executed before a SLEEP instruction. The following peripheral interrupts can wake the device from SLEEP: 1. 2. 3. 4. 5. 6. 7. TMR1 interrupt. Timer1 must be operating as an asynchronous counter. CCP capture mode interrupt. Special event trigger (Timer1 in asynchronous mode using an external clock). SSP (Start/Stop) bit detect interrupt. SSP transmit or receive in slave mode (SPI/I2C). A/D conversion (when A/D clock source is RC). EEPROM write operation completion. Other peripherals cannot generate interrupts since during SLEEP, no on-chip clocks are present. When the SLEEP instruction is being executed, the next instruction (PC + 1) is pre-fetched. For the device to wake-up through an interrupt event, the corresponding interrupt enable bit must be set (enabled). Wake-up is regardless of the state of the GIE bit. If the GIE bit is DS30221A-page 108 Preliminary 1999 Microchip Technology Inc. PIC16F872 FIGURE 11-12: 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 TOST(2) CLKOUT(4) INT pin INTF flag (INTCON<1>) Interrupt Latency (Note 2) GIE bit (INTCON<7>) Processor in SLEEP INSTRUCTION FLOW PC Instruction fetched Instruction executed PC PC+1 Inst(PC) = SLEEP Inst(PC - 1) PC+2 PC+2 Inst(PC + 1) Inst(PC + 2) SLEEP Inst(PC + 1) PC + 2 Dummy cycle 0004h 0005h Inst(0004h) Inst(0005h) Dummy cycle Inst(0004h) Note 1: XT, HS or LP oscillator mode assumed. 2: TOST = 1024TOSC (drawing not to scale) This delay will not be there for RC osc mode. 3: GIE = ’1’ assumed. In this case after wake- up, the processor jumps to the interrupt routine. If GIE = ’0’, execution will continue in-line. 4: CLKOUT is not available in these osc modes, but shown here for timing reference. 11.14 11.16 In-Circuit Debugger When the DEBUG bit in the configuration word is programmed to a ’0’, the In-Circuit Debugger functionality is enabled. This function allows simple debugging functions when used with MPLAB®. When the microcontroller has this feature enabled, some of the resources are not available for general use. Table 11-7 shows which features are consumed by the background debugger. TABLE 11-7: 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. It is recommended that only the 4 least significant bits of the ID location are used. DEBUGGER RESOURCES I/O pins RB6, RB7 Stack 1 level Program Memory Address 0000h must be NOP Last 100h words Data Memory 0x070(0x0F0, 0x170, 0x1F0) 0x1EB - 0x1EF To use the In-Circuit Debugger function of the microcontroller, the design must implement In-Circuit Serial Programming connections to MCLR/VPP, VDD, GND, RB7 and RB6. This will interface to the In-Circuit Debugger module available from Microchip or one of the third party development tool companies. 11.15 Program Verification/Code Protection If the code protection bit(s) have not been programmed, the on-chip program memory can be read out for verification purposes. 1999 Microchip Technology Inc. Preliminary DS30221A-page 109 PIC16F872 11.17 In-Circuit Serial Programming 11.18 The PIC16F872 microcontroller can be serially programmed while in the end application circuit. This is simply done with two lines for clock and data and three other lines for power, ground, and the programming voltage. This allows customers to manufacture boards with unprogrammed devices, and then program the microcontroller just before shipping the product. This also allows the most recent firmware or a custom firmware to be programmed. When using ICSP, the part must be supplied 4.5V to 5.5V if a bulk erase will be executed. This includes reprogramming of the code protect both from an onstate to off-state. For all other cases of ICSP, the part may be programmed at the normal operating voltages. This means calibration values, unique user IDs or user code can be reprogrammed or added. Low Voltage ICSP Programming The LVP bit of the configuration word enables low voltage ICSP programming. This mode allows the microcontroller to be programmed via ICSP using a VDD source in the operating voltage range. This only means that VPP does not have to be brought to VIHH, but can instead be left at the normal operating voltage. In this mode, the RB3/PGM pin is dedicated to the programming function and ceases to be a general purpose I/O pin. During programming, VDD is applied to the MCLR pin. To enter programming mode, VDD must be applied to the RB3/PGM provided the LVP bit is set. The LVP bit defaults to on (‘1’) from the factory. Note 1: The high voltage programming mode is always available, regardless of the state of the LVP bit, by applying VIHH to the MCLR pin. For complete details of serial programming, please refer to the In-Circuit Serial Programming (ICSP™) Guide, (DS30277). 2: While in low voltage ICSP mode, the RB3 pin can no longer be used as a general purpose I/O pin. 3: When using low voltage ICSP programming (LVP) and the pull-ups on PORTB are enabled, bit 3 in the TRISB register must be cleared to disable the pull-up on RB3 and ensure the proper operation of the device. If low-voltage programming mode is not used, the LVP bit can be programmed to a '0' and RB3/PGM becomes a digital I/O pin. However, the LVP bit may only be programmed when programming is entered with VIHH on MCLR. The LVP bit can only be charged when using high voltage on MCLR. It should be noted, that once the LVP bit is programmed to 0, only the high voltage programming mode is available and only high voltage programming mode can be used to program the device. When using low voltage ICSP, the part must be supplied 4.5V to 5.5V if a bulk erase will be executed. This includes reprogramming of the code protect bits from an on-state to off-state. For all other cases of low voltage ICSP, the part may be programmed at the normal operating voltage. This means calibration values, unique user IDs or user code can be reprogrammed or added. DS30221A-page 110 Preliminary 1999 Microchip Technology Inc. PIC16F872 12.0 INSTRUCTION SET SUMMARY Each PIC16CXX instruction is a 14-bit word divided into an OPCODE which specifies the instruction type and one or more operands which further specify the operation of the instruction. The PIC16CXX instruction set summary in Table 12-2 lists byte-oriented, bitoriented, and literal and control operations. Table 12-1 shows the opcode field descriptions. For byte-oriented instructions, ’f’ represents a file register designator and ’d’ represents a destination designator. The file register designator specifies which file register is to be used by the instruction. The destination designator specifies where the result of the operation is to be placed. If ’d’ is zero, the result is placed in the W register. 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 number of the bit affected by the operation, while ’f’ represents the number of the file in which the bit is located. execution time is 1 µs. If a conditional test is true or the program counter is changed as a result of an instruction, the instruction execution time is 2 µs. Table 12-2 lists the instructions recognized by the MPASM assembler. Figure 12-1 shows the general formats that the instructions can have. Note: All examples use the following format to represent a hexadecimal number: 0xhh where h signifies a hexadecimal digit. FIGURE 12-1: GENERAL FORMAT FOR INSTRUCTIONS Byte-oriented file register operations 13 8 7 6 OPCODE d f (FILE #) For literal and control operations, ’k’ represents an eight or eleven bit constant or literal value. TABLE 12-1: Bit-oriented file register operations 13 10 9 7 6 OPCODE b (BIT #) Description f Register file address (0x00 to 0x7F) W Working register (accumulator) b Bit address within an 8-bit file register k Literal field, constant data or label x Don'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. d Program Counter TO Time-out bit PD 0 f (FILE #) b = 3-bit bit address f = 7-bit file register address Literal and control operations General 13 8 7 OPCODE Destination select; d = 0: store result in W, d = 1: store result in file register f. Default is d = 1 PC 0 d = 0 for destination W d = 1 for destination f f = 7-bit file register address OPCODE FIELD DESCRIPTIONS Field To maintain upward compatibility with future PIC16CXX products, do not use the OPTION and TRIS instructions. 0 k (literal) k = 8-bit immediate value CALL and GOTO instructions only 13 11 OPCODE Power-down bit 10 0 k (literal) k = 11-bit immediate value The instruction set is highly orthogonal and is grouped into three basic categories: A description of each instruction is available in the PICmicro™ Mid-Range Reference Manual, (DS33023). • Byte-oriented operations • Bit-oriented operations • Literal and control operations All instructions are executed within one single instruction cycle, unless a conditional test is true or the program counter is changed as a result of an instruction. In this case, the execution takes two instruction cycles with the second cycle executed as a NOP. One instruction cycle consists of four oscillator periods. Thus, for an oscillator frequency of 4 MHz, the normal instruction 1999 Microchip Technology Inc. Preliminary DS30221A-page 111 PIC16F872 TABLE 12-2: PIC16CXXX INSTRUCTION SET Mnemonic, Operands Description Cycles 14-Bit Opcode MSb LSb Status Affected Notes C,DC,Z Z Z Z Z Z 1,2 1,2 2 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 f, d f f, d f, d f, d f, d f, d f, d f, d f f, d f, d f, d f, d 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 1 1 1 1 1 1(2) 1 1(2) 1 1 1 1 1 1 1 1 1 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0111 0101 0001 0001 1001 0011 1011 1010 1111 0100 1000 0000 0000 1101 1100 0010 1110 0110 dfff dfff lfff 0xxx dfff dfff dfff dfff dfff dfff dfff lfff 0xx0 dfff dfff dfff dfff dfff ffff ffff ffff xxxx ffff ffff ffff ffff ffff ffff ffff ffff 0000 ffff ffff ffff ffff ffff 00bb 01bb 10bb 11bb bfff bfff bfff bfff ffff ffff ffff ffff 111x 1001 0kkk 0000 1kkk 1000 00xx 0000 01xx 0000 0000 110x 1010 kkkk kkkk kkkk 0110 kkkk kkkk kkkk 0000 kkkk 0000 0110 kkkk kkkk kkkk kkkk kkkk 0100 kkkk kkkk kkkk 1001 kkkk 1000 0011 kkkk kkkk Z Z Z C C C,DC,Z Z 1,2 1,2 1,2,3 1,2 1,2,3 1,2 1,2 1,2 1,2 1,2 1,2 1,2 BIT-ORIENTED FILE REGISTER OPERATIONS BCF BSF BTFSC BTFSS f, b f, b f, b f, b Bit Clear f Bit Set f Bit Test f, Skip if Clear Bit Test f, Skip if Set ADDLW ANDLW CALL CLRWDT GOTO IORLW MOVLW RETFIE RETLW RETURN SLEEP SUBLW XORLW k k k k k k k k k 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 1 1 1 (2) 1 (2) 01 01 01 01 1,2 1,2 3 3 LITERAL AND CONTROL OPERATIONS 1 1 2 1 2 1 1 2 2 2 1 1 1 11 11 10 00 10 11 11 00 11 00 00 11 11 C,DC,Z Z TO,PD Z TO,PD C,DC,Z Z Note 1: When an I/O register is modified as a function of itself ( e.g., MOVF PORTB, 1), the value used will be that value present on the pins themselves. For example, if the data latch is ’1’ for a pin configured 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. Note: Additional information on the mid-range instruction set is available in the PICmicro™ Mid-Range MCU Family Reference Manual (DS33023). DS30221A-page 112 Preliminary 1999 Microchip Technology Inc. PIC16F872 12.1 Instruction Descriptions ADDLW Add Literal and W ANDWF AND W with f Syntax: [label] ADDLW Syntax: [label] ANDWF Operands: 0 ≤ k ≤ 255 Operands: 0 ≤ f ≤ 127 d ∈ [0,1] k f,d Operation: (W) + k → (W) Status Affected: C, DC, Z Operation: (W) .AND. (f) → (destination) Description: The contents of the W register are added to the eight bit literal ’k’ and the result is placed in the W register. Status Affected: Z Description: AND the W register with register 'f'. If 'd' is 0, the result is stored in the W register. If 'd' is 1, the result is stored back in register 'f'. BCF Bit Clear f Syntax: [label] BCF Operands: 0 ≤ f ≤ 127 0≤b≤7 Operation: 0 → (f<b>) Status Affected: None Description: Bit 'b' in register 'f' is cleared. BSF Bit Set f ADDWF Add W and f Syntax: [label] ADDWF Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (W) + (f) → (destination) Status Affected: C, DC, Z Description: Add the contents of the W register with register ’f’. If ’d’ is 0, the result is stored in the W register. If ’d’ is 1, the result is stored back in register ’f’. f,d ANDLW AND Literal with W Syntax: [label] BSF Operands: 0 ≤ f ≤ 127 0≤b≤7 1 → (f<b>) f,b f,b Syntax: [label] ANDLW Operands: 0 ≤ k ≤ 255 Operation: Operation: (W) .AND. (k) → (W) Status Affected: None Status Affected: Z Description: Bit 'b' in register 'f' is set. Description: The contents of W register are AND’ed with the eight bit literal 'k'. The result is placed in the W register. 1999 Microchip Technology Inc. k Preliminary DS30221A-page 113 PIC16F872 BTFSS Bit Test f, Skip if Set CLRF Clear f Syntax: [label] BTFSS f,b Syntax: [label] CLRF Operands: 0 ≤ f ≤ 127 0≤b<7 Operands: 0 ≤ f ≤ 127 Operation: Operation: skip if (f<b>) = 1 00h → (f) 1→Z Status Affected: None Status Affected: Z Description: If bit ’b’ in register ’f’ is ’0’, the next instruction is executed. If bit ’b’ is ’1’, then the next instruction is discarded and a NOP is executed instead making this a 2TCY instruction. Description: The contents of register ’f’ are cleared and the Z bit is set. CLRW Clear W 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 Affected: None Description: If bit ’b’ in register ’f’ is ’1’, the next instruction is executed. If bit ’b’, in register ’f’, is ’0’, the next instruction is discarded, and a NOP is executed instead, making this a 2TCY instruction. Syntax: [ label ] CLRW Operands: None Operation: 00h → (W) 1→Z f 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 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: TO, PD Status Affected: None Description: 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 loaded from PCLATH. CALL is a two cycle instruction. CLRWDT instruction resets the Watchdog Timer. It also resets the prescaler of the WDT. Status bits TO and PD are set. DS30221A-page 114 Preliminary 1999 Microchip Technology Inc. PIC16F872 COMF Complement f GOTO Unconditional Branch Syntax: [ label ] COMF Syntax: [ label ] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ k ≤ 2047 Operation: (f) → (destination) Operation: k → PC<10:0> PCLATH<4:3> → PC<12:11> Status Affected: Z Status Affected: None 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 register ’f’. Description: GOTO is an unconditional branch. The eleven bit immediate value is loaded into PC bits <10:0>. The upper bits of PC are loaded from PCLATH<4:3>. GOTO is a two cycle instruction. DECF Decrement f Syntax: [label] DECF f,d INCF Increment f Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Syntax: [ label ] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] (f) + 1 → (destination) f,d GOTO k INCF f,d Operation: (f) - 1 → (destination) Status Affected: Z Operation: Description: Decrement register ’f’. If ’d’ is 0, the result is stored in the W register. If ’d’ is 1, the result is stored back in register ’f’. Status Affected: Z 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 register ’f’. INCFSZ Increment f, Skip if 0 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 decremented. If ’d’ is 0, the result is placed in the W register. If ’d’ is 1, the result is placed back in register ’f’. If the result is 1, the next instruction is executed. If the result is 0, then a NOP is executed instead making it a 2TCY instruction. 1999 Microchip Technology Inc. Syntax: [ label ] 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 incremented. If ’d’ is 0, the result is placed in the W register. If ’d’ is 1, the result is placed back in register ’f’. If the result is 1, the next instruction is executed. If the result is 0, a NOP is executed instead making it a 2TCY instruction. Preliminary INCFSZ f,d DS30221A-page 115 PIC16F872 IORLW Inclusive OR Literal with W MOVLW Move Literal to W Syntax: [ label ] Syntax: [ label ] Operands: 0 ≤ k ≤ 255 Operands: 0 ≤ k ≤ 255 Operation: (W) .OR. k → (W) Operation: k → (W) Status Affected: Z Status Affected: None Description: The contents of the W register are OR’ed with the eight bit literal 'k'. The result is placed in the W register. Description: The eight bit literal 'k' is loaded into W register. The don’t cares will assemble as 0’s. MOVWF Move W to f IORWF Inclusive OR W with f Syntax: [ label ] Syntax: [ label ] Operands: Operands: 0 ≤ f ≤ 127 d ∈ [0,1] 0 ≤ f ≤ 127 Operation: (W) → (f) Operation: (W) .OR. (f) → (destination) Status Affected: None Status Affected: Z Description: Move data from W register to register 'f'. Description: Inclusive OR the W register with register 'f'. If 'd' is 0 the result is placed in the W register. If 'd' is 1 the result is placed back in register 'f'. NOP No Operation Syntax: [ label ] Operands: None Operation: No operation Status Affected: None Description: No operation. IORLW k IORWF f,d MOVF Move f Syntax: [ label ] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) → (destination) Status Affected: Z Description: The contents of register f are moved to a destination dependant 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 register since status flag Z is affected. DS30221A-page 116 MOVF f,d Preliminary MOVLW k MOVWF f NOP 1999 Microchip Technology Inc. PIC16F872 RETFIE Return from Interrupt RLF Rotate Left f through Carry Syntax: [ label ] Syntax: [ label ] Operands: None Operands: Operation: TOS → PC, 1 → GIE 0 ≤ f ≤ 127 d ∈ [0,1] Operation: See description below None Status Affected: C Description: The contents of register ’f’ are rotated one bit to the left through the Carry Flag. If ’d’ is 0, the result is placed in the W register. If ’d’ is 1, the result is stored back in register ’f’. Status Affected: RETFIE RLF C RETLW Return with Literal in W Syntax: [ label ] Operands: Operation: RETLW k f,d Register f RRF Rotate Right f through Carry 0 ≤ k ≤ 255 Syntax: [ label ] k → (W); TOS → PC Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Status Affected: None Operation: See description below 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. Status Affected: C Description: The contents of register ’f’ are rotated one bit to the right through the Carry Flag. If ’d’ is 0, the result is placed in the W register. If ’d’ is 1, the result is placed back in register ’f’. RRF f,d C Register f RETURN Return from Subroutine Syntax: [ label ] Operands: None SLEEP Operation: TOS → PC Syntax: [ label ] Status Affected: None Operands: None Description: Return from subroutine. The stack is POPed and the top of the stack (TOS) is loaded into the program counter. This is a two cycle instruction. Operation: 00h → WDT, 0 → WDT prescaler, 1 → TO, 0 → PD Status Affected: TO, PD Description: The power-down status bit, PD is cleared. Time-out status bit, TO is set. Watchdog Timer and its prescaler are cleared. The processor is put into SLEEP mode with the oscillator stopped. RETURN 1999 Microchip Technology Inc. Preliminary SLEEP DS30221A-page 117 PIC16F872 SUBLW Syntax: Subtract W from Literal [ label ] SUBLW k Operands: 0 ≤ k ≤ 255 Operands: 0 ≤ k ≤ 255 Operation: k - (W) → (W) Operation: (W) .XOR. k → (W) Status Affected: C, DC, Z Status Affected: 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. Description: The contents of the W register are XOR’ed with the eight bit literal 'k'. The result is placed in the W register. SUBWF Syntax: Subtract W from f [ label ] SUBWF f,d XORWF Exclusive OR W with f Syntax: [label] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) - (W) → (destination) Operation: (W) .XOR. (f) → (destination) Status Affected: C, DC, Z Status Affected: Z Description: Description: Exclusive OR the contents of the W register with register 'f'. If 'd' is 0, the result is stored in the W register. If 'd' is 1, the result is stored back in register 'f'. Subtract (2’s complement method) W register from register 'f'. If 'd' is 0, the result is stored in the W register. If 'd' is 1, the result is stored back in register 'f'. 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 register 'f' are exchanged. If 'd' is 0, the result is placed in W register. If 'd' is 1, the result is placed in register 'f'. DS30221A-page 118 XORLW Exclusive OR Literal with W Syntax: [label] Preliminary XORLW k XORWF f,d 1999 Microchip Technology Inc. PIC16F872 13.0 DEVELOPMENT SUPPORT MPLAB allows you to: PICmicro® The microcontrollers are supported with a full range of hardware and software development tools: • Integrated Development Environment - MPLAB® IDE Software • Assemblers/Compilers/Linkers - MPASM Assembler - MPLAB-C17 and MPLAB-C18 C Compilers - MPLINK/MPLIB Linker/Librarian • Simulators - MPLAB-SIM Software Simulator • Emulators - MPLAB-ICE Real-Time In-Circuit Emulator - PICMASTER®/PICMASTER-CE In-Circuit Emulator - ICEPIC™ • In-Circuit Debugger - MPLAB-ICD for PIC16F877 • Device Programmers - PRO MATE II Universal Programmer - PICSTART Plus Entry-Level Prototype Programmer • Low-Cost Demonstration Boards - SIMICE - PICDEM-1 - PICDEM-2 - PICDEM-3 - PICDEM-17 - SEEVAL - KEELOQ 13.1 The ability to use MPLAB with Microchip’s simulator, MPLAB-SIM, allows a consistent platform and the ability to easily switch from the cost-effective simulator to the full featured emulator with minimal retraining. 13.2 MPASM has a command line interface and a Windows shell and can be used as a standalone application on a Windows 3.x or greater system. MPASM generates relocatable object files, Intel standard HEX files, MAP files to detail memory usage and symbol reference, an absolute LST file which contains source lines and generated machine code, and a COD file for MPLAB debugging. MPASM features include: The MPLAB IDE software brings an ease of software development previously unseen in the 8-bit microcontroller market. MPLAB is a Windows-based application which contains: 1999 Microchip Technology Inc. MPASM Assembler MPASM is a full featured universal macro assembler for all PICmicro MCU’s. It can produce absolute code directly in the form of HEX files for device programmers, or it can generate relocatable objects for MPLINK. MPLAB Integrated Development Environment Software • Multiple functionality - editor - simulator - programmer (sold separately) - emulator (sold separately) • A full featured editor • A project manager • Customizable tool bar and key mapping • A status bar • On-line help • Edit your source files (either assembly or ‘C’) • One touch assemble (or compile) and download to PICmicro tools (automatically updates all project information) • Debug using: - source files - absolute listing file - object code • MPASM and MPLINK are integrated into MPLAB projects. • MPASM allows user defined macros to be created for streamlined assembly. • MPASM allows conditional assembly for multi purpose source files. • MPASM directives allow complete control over the assembly process. 13.3 MPLAB-C17 and MPLAB-C18 C Compilers The MPLAB-C17 and MPLAB-C18 Code Development Systems are complete ANSI ‘C’ compilers and integrated development environments for Microchip’s PIC17CXXX and PIC18CXXX family of microcontrollers, respectively. These compilers provide powerful integration capabilities and ease of use not found with other compilers. For easier source level debugging, the compilers provide symbol information that is compatible with the MPLAB IDE memory display. Preliminary DS30221A-page 119 PIC16F872 13.4 MPLINK/MPLIB Linker/Librarian MPLINK is a relocatable linker for MPASM and MPLAB-C17 and MPLAB-C18. It can link relocatable objects from assembly or C source files along with precompiled libraries using directives from a linker script. MPLIB is a librarian for pre-compiled code to be used with MPLINK. When a routine from a library is called from another source file, only the modules that contains that routine will be linked in with the application. This allows large libraries to be used efficiently in many different applications. MPLIB manages the creation and modification of library files. MPLINK features include: • MPLINK works with MPASM and MPLAB-C17 and MPLAB-C18. • MPLINK allows all memory areas to be defined as sections to provide link-time flexibility. MPLIB features include: • MPLIB makes linking easier because single libraries can be included instead of many smaller files. • MPLIB helps keep code maintainable by grouping related modules together. • MPLIB commands allow libraries to be created and modules to be added, listed, replaced, deleted, or extracted. 13.5 MPLAB-SIM Software Simulator The MPLAB-SIM Software Simulator allows code development in a PC host 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 user-defined key press to any of the pins. The execution can be performed in single step, execute until break, or trace mode. MPLAB-SIM fully supports symbolic debugging using MPLAB-C17 and MPLAB-C18 and MPASM. The Software Simulator offers the flexibility to develop and debug code outside of the laboratory environment making it an excellent multi-project software development tool. 13.6 MPLAB-ICE High Performance Universal In-Circuit Emulator with MPLAB IDE The MPLAB-ICE Universal In-Circuit Emulator is intended to provide the product development engineer with a complete microcontroller design tool set for PICmicro microcontrollers (MCUs). Software control of MPLAB-ICE is provided by the MPLAB Integrated Development Environment (IDE), which allows editing, “make” and download, and source debugging from a single environment. DS30221A-page 120 Interchangeable processor modules allow the system to be easily reconfigured for emulation of different processors. The universal architecture of the MPLAB-ICE allows expansion to support new PICmicro microcontrollers. The MPLAB-ICE Emulator System has been designed as a real-time emulation system with advanced features that are generally found on more expensive development tools. The PC platform and Microsoft® Windows 3.x/95/98 environment were chosen to best make these features available to you, the end user. MPLAB-ICE 2000 is a full-featured emulator system with enhanced trace, trigger, and data monitoring features. Both systems use the same processor modules and will operate across the full operating speed range of the PICmicro MCU. 13.7 PICMASTER/PICMASTER CE The PICMASTER system from Microchip Technology is a full-featured, professional quality emulator system. This flexible in-circuit emulator provides a high-quality, universal platform for emulating Microchip 8-bit PICmicro microcontrollers (MCUs). PICMASTER systems are sold worldwide, with a CE compliant model available for European Union (EU) countries. 13.8 ICEPIC ICEPIC is a low-cost in-circuit emulation solution for the Microchip Technology PIC16C5X, PIC16C6X, PIC16C7X, and PIC16CXXX families of 8-bit one-timeprogrammable (OTP) microcontrollers. The modular system can support different subsets of PIC16C5X or PIC16CXXX products through the use of interchangeable personality modules or daughter boards. The emulator is capable of emulating without target application circuitry being present. 13.9 MPLAB-ICD In-Circuit Debugger Microchip’s In-Circuit Debugger, MPLAB-ICD, is a powerful, low-cost run-time development tool. This tool is based on the flash PIC16F877 and can be used to develop for this and other PICmicro microcontrollers from the PIC16CXXX family. MPLAB-ICD utilizes the In-Circuit Debugging capability built into the PIC16F87X. This feature, along with Microchip’s In-Circuit Serial Programming protocol, offers cost-effective in-circuit flash programming and debugging from the graphical user interface of the MPLAB Integrated Development Environment. This enables a designer to develop and debug source code by watching variables, single-stepping and setting break points. Running at full speed enables testing hardware in real-time. The MPLAB-ICD is also a programmer for the flash PIC16F87X family. Preliminary 1999 Microchip Technology Inc. PIC16F872 13.10 PRO MATE II Universal Programmer The PRO MATE II Universal Programmer is a full-featured programmer capable of operating in stand-alone mode as well as PC-hosted mode. PRO MATE II is CE compliant. The PRO MATE II has programmable VDD and VPP supplies which allows it to verify programmed memory at VDD min and VDD max for maximum reliability. It has an LCD display for instructions and error messages, keys to enter commands and a modular detachable socket assembly to support various package types. In stand-alone mode the PRO MATE II can read, verify or program PICmicro devices. It can also set code-protect bits in this mode. 13.11 PICSTART Plus Entry Level Development System The PICSTART programmer is an easy-to-use, lowcost prototype programmer. It connects to the PC via one of the COM (RS-232) ports. MPLAB Integrated Development Environment software makes using the programmer simple and efficient. PICSTART Plus supports all PICmicro devices with up to 40 pins. Larger pin count devices such as the PIC16C92X, and PIC17C76X may be supported with an adapter socket. PICSTART Plus is CE compliant. 13.12 SIMICE Entry-Level Hardware Simulator SIMICE is an entry-level hardware development system designed to operate in a PC-based environment with Microchip’s simulator MPLAB-SIM. Both SIMICE and MPLAB-SIM run under Microchip Technology’s MPLAB Integrated Development Environment (IDE) software. Specifically, SIMICE provides hardware simulation for Microchip’s PIC12C5XX, PIC12CE5XX, and PIC16C5X families of PICmicro 8-bit microcontrollers. SIMICE works in conjunction with MPLAB-SIM to provide non-real-time I/O port emulation. SIMICE enables a developer to run simulator code for driving the target system. In addition, the target system can provide input to the simulator code. This capability allows for simple and interactive debugging without having to manually generate MPLAB-SIM stimulus files. SIMICE is a valuable debugging tool for entry-level system development. 13.13 PICDEM-1 Low-Cost PICmicro Demonstration Board The PICDEM-1 is a simple board which demonstrates the capabilities of several of Microchip’s microcontrollers. The microcontrollers supported are: 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 users can program the sample microcontrollers provided with 1999 Microchip Technology Inc. the PICDEM-1 board, on a PRO MATE II or PICSTART-Plus programmer, and easily test firmware. The user can also connect the PICDEM-1 board to the MPLAB-ICE emulator and download the firmware to the emulator for testing. Additional prototype area is available for the user to build some additional hardware and connect it to the microcontroller socket(s). Some of the features include an RS-232 interface, a potentiometer for simulated analog input, push-button switches and eight LEDs connected to PORTB. 13.14 PICDEM-2 Low-Cost PIC16CXX Demonstration Board The PICDEM-2 is a simple demonstration board that supports the PIC16C62, PIC16C64, PIC16C65, PIC16C73 and PIC16C74 microcontrollers. All the necessary hardware and software is included to run the basic demonstration programs. The user can program the sample microcontrollers provided with the PICDEM-2 board, on a PRO MATE II programmer or PICSTART-Plus, and easily test firmware. The MPLAB-ICE emulator may also be used with the PICDEM-2 board to test firmware. Additional prototype area has been provided to the user for adding additional hardware and connecting it to the microcontroller socket(s). Some of the features include a RS-232 interface, push-button switches, a potentiometer for simulated analog input, a Serial EEPROM to demonstrate usage of the I2C bus and separate headers for connection to an LCD module and a keypad. 13.15 PICDEM-3 Low-Cost PIC16CXXX Demonstration Board The PICDEM-3 is a simple demonstration board that supports the PIC16C923 and PIC16C924 in the PLCC package. It will also support future 44-pin PLCC microcontrollers with a LCD Module. All the necessary hardware and software is included to run the basic demonstration programs. The user can program the sample microcontrollers provided with the PICDEM-3 board, on a PRO MATE II programmer or PICSTART Plus with an adapter socket, and easily test firmware. The MPLAB-ICE emulator may also be used with the PICDEM-3 board to test firmware. Additional prototype area has been provided to the user for adding hardware and connecting it to the microcontroller socket(s). Some of the features include an RS-232 interface, push-button switches, a potentiometer for simulated analog input, a thermistor and separate headers for connection to an external LCD module and a keypad. Also provided on the PICDEM-3 board is an LCD panel, with 4 commons and 12 segments, that is capable of displaying time, temperature and day of the week. The PICDEM-3 provides an additional RS-232 interface and Windows 3.1 software for showing the demultiplexed LCD signals on a PC. A simple serial interface allows the user to construct a hardware demultiplexer for the LCD signals. Preliminary DS30221A-page 121 PIC16F872 13.16 PICDEM-17 The PICDEM-17 is an evaluation board that demonstrates the capabilities of several Microchip microcontrollers, including PIC17C752, PIC17C756, PIC17C762, and PIC17C766. All necessary hardware is included to run basic demo programs, which are supplied on a 3.5-inch disk. A programmed sample is included, and the user may erase it and program it with the other sample programs using the PRO MATE II or PICSTART Plus device programmers and easily debug and test the sample code. In addition, PICDEM-17 supports down-loading of programs to and executing out of external FLASH memory on board. The PICDEM-17 is also usable with the MPLAB-ICE or PICMASTER emulator, and all of the sample programs can be run and modified using either emulator. Additionally, a generous prototype area is available for user hardware. 13.17 SEEVAL Evaluation and Programming System The SEEVAL SEEPROM Designer’s Kit supports all Microchip 2-wire and 3-wire Serial EEPROMs. The kit includes everything necessary to read, write, erase or program special features of any Microchip SEEPROM product including Smart Serials and secure serials. The Total Endurance Disk is included to aid in tradeoff analysis and reliability calculations. The total kit can significantly reduce time-to-market and result in an optimized system. 13.18 KEELOQ Evaluation and Programming Tools KEELOQ evaluation and programming tools support Microchips HCS Secure Data Products. The HCS evaluation kit includes an LCD display to show changing codes, a decoder to decode transmissions, and a programming interface to program test transmitters. DS30221A-page 122 Preliminary 1999 Microchip Technology Inc. Software Tools Emulators 1999 Microchip Technology Inc. Programmers Debugger á PIC17C4X á á á á á á á PIC16C9XX á á á á á á á PIC16F8XX á á á á á PIC16C8X á á á á á á á PIC16C7XX á á á á á á á PIC16C7X á á á á á á á PIC16F62X á á á PIC16CXXX á á á á á PIC16C6X á á á á á á á PIC16C5X á á á á á á á PIC14000 á á á á á á PIC12CXXX á á á á á á á Preliminary MCP2510 á á á á á á á á á á á á á á á á á á ® * Contact the Microchip Technology Inc. web site at www.microchip.com for information on how to use the MPLAB -ICD In-Circuit Debugger (DV164001) with PIC16C62, 63, 64, 65, 72, 73, 74, 76, 77 ** Contact Microchip Technology Inc. for availability date. † Development tool is available on select devices. MCP2510 CAN Developer’s Kit MCRFXXX á á á 13.56 MHz Anticollision microID Developer’s Kit 125 kHz Anticollision microID Developer’s Kit 125 kHz microID Developer’s Kit microID™ Programmer’s Kit KEELOQ Transponder Kit KEELOQ® Evaluation Kit PICDEM-17 á PICDEM-14A á PICDEM-3 á á † á á PICDEM-2 á † 24CXX/ 25CXX/ 93CXX á † á PICDEM-1 á á á ** ** HCSXXX á SIMICE ® MPLAB -ICD In-Circuit Debugger ICEPIC Low-Cost In-Circuit Emulator PICMASTER/PICMASTER-CE * á PRO MATE II Universal Programmer á PICSTARTPlus Low-Cost Universal Dev. Kit á á á * PIC17C7XX á á ** PIC18CXX2 á á MPASM/MPLINK ® MPLAB -ICE TABLE 13-1: Demo Boards and Eval Kits ® MPLAB Integrated Development Environment ® MPLAB C17 Compiler ® MPLAB C18 Compiler PIC16F872 DEVELOPMENT TOOLS FROM MICROCHIP DS30221A-page 123 PIC16F872 NOTES: DS30221A-page 124 Preliminary 1999 Microchip Technology Inc. PIC16F872 14.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings † Ambient temperature under bias................................................................................................................ .-55 to +125°C Storage temperature .............................................................................................................................. -65°C to +150°C Voltage on any pin with respect to VSS (except VDD, MCLR. and RA4).......................................... -0.3V to (VDD + 0.3V) Voltage on VDD with respect to VSS ............................................................................................................ -0.3 to +7.5V Voltage on MCLR with respect to VSS (Note 2).............................................................................................0 to +13.25V Voltage on RA4 with respect to Vss ..................................................................................................................0 to +8.5V Total power dissipation (Note 1)................................................................................................................................1.0W Maximum current out of VSS pin ...........................................................................................................................300 mA Maximum current into VDD pin ..............................................................................................................................250 mA Input clamp current, IIK (VI < 0 or VI > VDD)..................................................................................................................... ± 20 mA Output clamp current, 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 PORTA and PORTB (combined) ................................................................................200 mA Maximum current sourced by PORTA and PORTB (combined) ...........................................................................200 mA Maximum current sunk by PORTC........................................................................................................................200 mA Maximum current sourced by PORTC ..................................................................................................................200 mA Note 1: Power dissipation is calculated as follows: Pdis = VDD x {IDD - ∑ IOH} + ∑ {(VDD - VOH) x IOH} + ∑(VOl x IOL) 2: Voltage spikes below VSS at the MCLR pin, inducing currents greater than 80 mA, may cause latch-up. Thus, a series resistor of 50-100Ω should be used when applying a “low” level to the MCLR pin, rather than pulling this pin directly to VSS.. † NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. 1999 Microchip Technology Inc. Preliminary DS30221A-page 125 PIC16F872 FIGURE 14-1: PIC16FXXX VOLTAGE-FREQUENCY GRAPH 6.0 V 5.5 V Voltage 5.0 V 4.5 V 4.0 V 3.5 V 3.0 V 2.5 V 2.0 V 20 MHz Frequency FIGURE 14-2: PIC16LFXXX VOLTAGE-FREQUENCY GRAPH 6.0 V 5.5 V Voltage 5.0 V 4.5 V 4.0 V 3.5 V 3.0 V Eq 2.5 V 2.0 V Eq 4 MHz tio ua ti ua on 2 n1 10 MHz 20 MHz Frequency Equation 1: FMAX = (6.0 MHz/V) (VDDAPPMIN - 2.0 V) + 4 MHz; VDDAPPMIN = 2.0V - 3.0V Equation 2: FMAX = (10.0 MHz/V) (VDDAPPMIN - 3.0 V) + 10 MHz; VDDAPPMIN = 3.0V - 4.0V Note 1: VDDAPPMIN is the minimum voltage of the PICmicro® device in the application. Note 2: FMAX has a maximum frequency of 10MHz. DS30221A-page 126 Preliminary 1999 Microchip Technology Inc. PIC16F872 14.1 DC Characteristics: PIC16F872 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial DC CHARACTERISTICS Param No. Characteristic D001 Supply Voltage D001A Sym VDD VDR Min Typ† Max Units 4.0 4.5 VBOR* - 5.5 5.5 5.5 V V V - 1.5 - V - VSS - V Conditions XT, RC and LP osc configuration HS osc configuration BOR enabled, Fmax = 14MHz (Note 7) D002* RAM Data Retention Voltage (Note 1) D003 VDD start voltage to VPOR ensure internal Power-on Reset signal D004* VDD rise rate to ensure internal Power-on Reset signal SVDD 0.05 - - D005 Brown-out Reset Voltage VBOR 3.7 4.0 4.35 V D010 Supply Current (Note 2,5) IDD - 1.6 4 mA XT, RC osc configuration FOSC = 4 MHz, VDD = 5.5V (Note 4) - 7 15 mA HS osc configuration FOSC = 20 MHz, VDD = 5.5V ∆IBOR - 85 200 µA BOR enabled VDD = 5.0V D020 Power-down Current D021 (Note 3,5) D021A IPD - 10.5 1.5 1.5 42 16 19 µA µA µA VDD = 4.0V, WDT enabled, -40°C to +85°C VDD = 4.0V, WDT disabled, -0°C to +70°C VDD = 4.0V, WDT disabled, -40°C to +85°C D023* ∆IBOR - 85 200 µA BOR enabled VDD = 5.0V D013 D015* Brown-out Reset Current (Note 6) Brown-out Reset Current (Note 6) See section on Power-on Reset for details V/ms See section on Power-on Reset for details BODEN bit in configuration word enabled Legend: * 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: This is the limit to which VDD can be lowered without losing RAM data. 2: The supply current is mainly a function of the operating voltage and frequency. Other factors such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail to rail; all I/O pins tristated, pulled to VDD MCLR = VDD; WDT enabled/disabled as specified. 3: 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 hi-impedance state and tied to VDD and VSS. 4: For RC osc configuration, current through REXT is not included. The current through the resistor can be estimated by the formula Ir = VDD/2REXT (mA) with REXT in kOhm. 5: Timer1 oscillator (when enabled) adds approximately 20 µA to the specification. This value is from characterization and is for design guidance only. This is not tested. 6: The ∆ current is the additional current consumed when this peripheral is enabled. This current should be added to the base IDD or IPD measurement. 7: When BOR is enabled, the device will operate correctly until the VBOR voltage trip point is reached. 1999 Microchip Technology Inc. Preliminary DS30221A-page 127 PIC16F872 14.2 DC Characteristics: PIC16LF872 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial DC CHARACTERISTICS Param No. Characteristic Sym Min Typ† Max Units Conditions D001 Supply Voltage VDD 2.0 - 5.5 V D002* RAM Data Retention Voltage (Note 1) VDR - 1.5 - V D003 VPOR VDD start voltage to ensure internal Power-on Reset signal - VSS - V D004* VDD rise rate to ensure internal Power-on Reset signal SVDD 0.05 - - D005 Brown-out Reset Voltage VBOR 3.7 4.0 4.35 V D010 Supply Current (Note 2,5) IDD - 0.6 2.0 mA XT, RC osc configuration FOSC = 4 MHz, VDD = 3.0V (Note 4) - 20 35 µA LP osc configuration FOSC = 32 kHz, VDD = 3.0V, WDT disabled D010A LP, XT, RC osc configuration (DC - 4 MHz) See section on Power-on Reset for details V/ms See section on Power-on Reset for details BODEN bit in configuration word enabled D015* Brown-out Reset Current ∆IBOR (Note 6) - 85 200 µA BOR enabled VDD = 5.0V D020 D021 D021A Power-down Current (Note 3,5) - 7.5 0.9 0.9 30 5 5 µA µA µA VDD = 3.0V, WDT enabled, -40°C to +85°C VDD = 3.0V, WDT disabled, 0°C to +70°C VDD = 3.0V, WDT disabled, -40°C to +85°C D023* Brown-out Reset Current ∆IBOR (Note 6) - 85 200 µA BOR enabled VDD = 5.0V IPD Legend: * 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: This is the limit to which VDD can be lowered without losing RAM data. 2: The supply current is mainly a function of the operating voltage and frequency. Other factors such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail to rail; all I/O pins tristated, pulled to VDD MCLR = VDD; WDT enabled/disabled as specified. 3: 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 hi-impedance state and tied to VDD and VSS. 4: For RC osc configuration, current through REXT is not included. The current through the resistor can be estimated by the formula Ir = VDD/2REXT (mA) with REXT in kOhm. 5: Timer1 oscillator (when enabled) adds approximately 20 µA to the specification. This value is from characterization and is for design guidance only. This is not tested. 6: The ∆ current is the additional current consumed when this peripheral is enabled. This current should be added to the base IDD or IPD measurement. DS30221A-page 128 Preliminary 1999 Microchip Technology Inc. PIC16F872 14.3 DC Characteristics: PIC16F872 and PIC16LF872 (Industrial) DC CHARACTERISTICS Param No. Characteristic Input Low Voltage I/O ports with TTL buffer D030 D030A D031 with Schmitt Trigger buffer D032 MCLR, OSC1 (in RC mode) D033 OSC1 (in XT, HS and LP) Ports RC3 and RC4 D034 with Schmitt Trigger buffer D034A with SMBus Input High Voltage I/O ports D040 with TTL buffer D040A D041 with Schmitt Trigger buffer D042 MCLR D042A OSC1 (XT, HS and LP) D043 OSC1 (in RC mode) Ports RC3 and RC4 D044 with Schmitt Trigger buffer D044A with SMBus D070 PORTB weak pull-up current Input Leakage Current (Notes 2, 3) D060 I/O ports D061 D063 MCLR, RA4/T0CKI OSC1 D080 Output Low Voltage I/O ports D083 OSC2/CLKOUT (RC osc config) D090 Output High Voltage I/O ports (Note 3) D092 OSC2/CLKOUT (RC osc config) Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial Operating voltage VDD range as described in DC spec Section 14.1 and Section 14.2. Sym Min Typ† Max Units Conditions VIL VSS VSS VSS VSS VSS - 0.15VDD 0.8V 0.2VDD 0.2VDD 0.3VDD V V V V V For entire VDD range 4.5V ≤ VDD ≤ 5.5V VSS -0.5 - 0.3VDD 0.6 V V For entire VDD range for VDD = 4.5 to 5.5V - VDD VDD V V 4.5V ≤ VDD ≤ 5.5V For entire VDD range - VDD VDD VDD VDD V V V V For entire VDD range VDD 5.5 400 V For entire VDD range V for VDD = 4.5 to 5.5V µA VDD = 5V, VPIN = VSS VIH 2.0 0.25VDD + 0.8V 0.8VDD 0.8VDD 0.7VDD 0.9VDD 0.7VDD 1.4 IPURB 50 250 - - ±1 - - ±5 ±5 - - 0.6 V - - 0.6 V VOH VDD - 0.7 - - V VDD - 0.7 - - V IIL VOL Note1 Note1 µA Vss ≤ VPIN ≤ VDD, Pin at hi-impedance µA Vss ≤ VPIN ≤ VDD µA Vss ≤ VPIN ≤ VDD, XT, HS and LP osc configuration IOL = 8.5 mA, VDD = 4.5V, -40°C to +85°C IOL = 1.6 mA, VDD = 4.5V, -40°C to +85°C IOH = -3.0 mA, VDD = 4.5V, -40°C to +85°C IOH = -1.3 mA, VDD = 4.5V, -40°C to +85°C Legend: * 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: In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended that the PIC16F87X be driven with external clock in RC mode. 2: The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified levels represent normal operating conditions. Higher leakage current may be measured at different input voltages. 3: Negative current is defined as current sourced by the pin. 1999 Microchip Technology Inc. Preliminary DS30221A-page 129 PIC16F872 DC CHARACTERISTICS Param Characteristic No. D150* Open-Drain High Voltage D100 D101 D102 D120 D121 D122 D130 D131 D132a Capacitive Loading Specs on Output Pins OSC2 pin All I/O pins and OSC2 (in RC mode) SCL, SDA in I2C mode Data EEPROM Memory Endurance VDD for read/write Erase/write cycle time Program FLASH Memory Endurance VDD for read VDD for erase/write Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial Operating voltage VDD range as described in DC spec Section 14.1 and Section 14.2. Sym Min Typ† Max Units Conditions VOD - - 8.5 V RA4 pin COSC2 - - 15 pF In XT, HS and LP modes when external clock is used to drive OSC1. CIO CB - - 50 400 pF pF ED VDRW 100K Vmin - 5.5 TDEW - 4 8 EP VPR 1000 Vmin Vmin - 5.5 5.5 E/W 25°C at 5V V Using EECON to read/write Vmin = min operating voltage ms E/W 25°C at 5V V Vmin = min operating voltage V using EECON to read/write, Vmin = min operating voltage ms D133 Erase/Write cycle time TPEW 4 8 Legend: * 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: In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended that the PIC16F87X be driven with external clock in RC mode. 2: The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified levels represent normal operating conditions. Higher leakage current may be measured at different input voltages. 3: Negative current is defined as current sourced by the pin. DS30221A-page 130 Preliminary 1999 Microchip Technology Inc. PIC16F872 14.4 Timing Parameter Symbology The timing parameter symbols have been created following one of the following formats: 1. TppS2ppS 3. TCC:ST (I2C specifications only) 2. TppS 4. Ts (I2C specifications only) T F Frequency Lowercase letters (pp) and their meanings: pp cc CCP1 ck CLKOUT cs CS di SDI do SDO dt Data in io I/O port mc MCLR Uppercase letters and their meanings: S F Fall H High I Invalid (Hi-impedance) L Low I2C only AA BUF output access Bus free TCC:ST (I2C specifications only) CC HD Hold ST DAT DATA input hold STA START condition T Time osc rd rw sc ss t0 t1 wr OSC1 RD RD or WR SCK SS T0CKI T1CKI WR P R V Z Period Rise Valid Hi-impedance High Low High Low SU Setup STO STOP condition FIGURE 14-3: LOAD CONDITIONS Load condition 1 Load condition 2 VDD/2 RL CL Pin CL Pin VSS VSS RL = 464Ω CL = 50 pF 15 pF for all pins except OSC2, but including PORTD and PORTE outputs as ports for OSC2 output Note: PORTD and PORTE are not implemented on the 28-pin devices. 1999 Microchip Technology Inc. Preliminary DS30221A-page 131 PIC16F872 FIGURE 14-4: EXTERNAL CLOCK TIMING Q4 Q1 Q2 Q3 Q4 Q1 OSC1 1 3 3 4 4 2 CLKOUT TABLE 14-1: Parameter No. EXTERNAL CLOCK TIMING REQUIREMENTS Sym Characteristic FOSC External CLKIN Frequency (Note 1) Oscillator Frequency (Note 1) 1 TOSC External CLKIN Period (Note 1) Oscillator Period (Note 1) 2 TCY Instruction Cycle Time (Note 1) TosL, External Clock in (OSC1) High TosH or Low Time Min Typ† Max DC DC DC DC DC 0.1 4 5 250 250 50 5 250 250 250 50 5 200 — — — — — — — — — — — — — — — — — TCY 4 4 20 200 4 4 20 200 — — — — — 10,000 250 250 — DC Units Conditions MHz MHz MHz kHz MHz MHz MHz kHz ns ns ns µs ns ns ns ns µs ns XT and RC osc mode HS osc mode (-04) HS osc mode (-20) LP osc mode RC osc mode XT osc mode HS osc mode LP osc mode XT and RC osc mode HS osc mode (-04) HS osc mode (-20) LP osc mode RC osc mode XT osc mode HS osc mode (-04) HS osc mode (-20) LP osc mode TCY = 4/FOSC 100 — — ns XT oscillator 2.5 — — µs LP oscillator 15 — — ns HS oscillator 4 TosR, External Clock in (OSC1) Rise — — 25 ns XT oscillator TosF or Fall Time — — 50 ns LP oscillator — — 15 ns HS oscillator Legend: † 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: Instruction cycle period (TCY) equals four times the input oscillator time-base period. All specified values are based on characterization data for that particular oscillator type under standard operating conditions 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 the OSC1/CLKIN pin. When an external clock input is used, the "Max." cycle time limit is "DC" (no clock) for all devices. 3 DS30221A-page 132 Preliminary 1999 Microchip Technology Inc. PIC16F872 FIGURE 14-5: CLKOUT AND I/O TIMING Q1 Q4 Q2 Q3 OSC1 11 10 CLKOUT 13 19 14 12 18 16 I/O Pin (input) 15 17 I/O Pin (output) new value old value 20, 21 Note: Refer to Figure 14-3 for load conditions. TABLE 14-2: Param Sym No. CLKOUT AND I/O TIMING REQUIREMENTS Characteristic Min Typ† Max Units Conditions 10* TosH2ckL OSC1↑ to CLKOUT↓ — 75 200 ns Note 1 11* TosH2ckH OSC1↑ to CLKOUT↑ — 75 200 ns Note 1 12* TckR CLKOUT rise time — 35 100 ns Note 1 13* TckF CLKOUT fall time — 35 100 ns Note 1 14* TckL2ioV CLKOUT ↓ to Port out valid — — 0.5TCY + 20 ns Note 1 15* TioV2ckH Port in valid before CLKOUT ↑ TOSC + 200 — — ns Note 1 16* TckH2ioI 0 — — ns Note 1 17* TosH2ioV OSC1↑ (Q1 cycle) to Port out valid — 100 255 ns 18* TosH2ioI Standard (F) 100 — — ns Extended (LF) 200 — — ns Port in hold after CLKOUT ↑ OSC1↑ (Q2 cycle) to Port input invalid (I/O in hold time) 19* TioV2osH Port input valid to OSC1↑ (I/O in setup time) 0 — — ns 20* TioR Port output rise time Standard (F) — 10 40 ns Extended (LF) — — 145 ns 21* TioF Port output fall time Standard (F) — 10 40 ns — — 145 ns 22††* Tinp INT pin high or low time TCY — — ns 23††* Trbp RB7:RB4 change INT high or low time TCY — — ns Extended (LF) Legend: * † 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. †† These parameters are asynchronous events not related to any internal clock edges. Note 1: Measurements are taken in RC Mode where CLKOUT output is 4 x TOSC. 1999 Microchip Technology Inc. Preliminary DS30221A-page 133 PIC16F872 FIGURE 14-6: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP TIMER TIMING VDD MCLR 30 Internal POR 33 PWRT Time-out 32 OSC Time-out Internal Reset Watchdog Timer Reset 31 34 34 I/O Pins Note: Refer to Figure 14-3 for load conditions. FIGURE 14-7: BROWN-OUT RESET TIMING VBOR VDD 35 TABLE 14-3: Parameter No. RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER, AND BROWN-OUT RESET REQUIREMENTS Sym Characteristic Min Typ† Max Units Conditions 30 TmcL MCLR Pulse Width (low) 2 — — µs VDD = 5V, -40°C to +85°C 31* Twdt Watchdog Timer Time-out Period (No Prescaler) 7 18 33 ms VDD = 5V, -40°C to +85°C 32 Tost Oscillation Start-up Timer Period — 1024 TOSC — — TOSC = OSC1 period 33* Tpwrt Power up Timer Period 28 72 132 ms VDD = 5V, -40°C to +85°C 34 TIOZ I/O Hi-impedance from MCLR Low or Watchdog Timer Reset — — 2.1 µs 35 TBOR Brown-out Reset pulse width 100 — — µs Legend: * † VDD ≤ VBOR (D005) 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. DS30221A-page 134 Preliminary 1999 Microchip Technology Inc. PIC16F872 FIGURE 14-8: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS RA4/T0CKI 41 40 42 RC0/T1OSO/T1CKI 46 45 47 48 TMR0 or TMR1 Note: Refer to Figure 14-3 for load conditions. TABLE 14-4: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS Param No. Sym Characteristic 40* Tt0H T0CKI High Pulse Width 41* Tt0L T0CKI Low Pulse Width 42* Tt0P T0CKI Period 45* 46* 47* Tt1H Tt1L Tt1P No Prescaler With Prescaler No Prescaler With Prescaler No Prescaler With Prescaler T1CKI High Time Synchronous, Prescaler = 1 Synchronous, Standard(F) Prescaler = Extended(LF) 2,4,8 Asynchronous Standard(F) Extended(LF) T1CKI Low Time Synchronous, Prescaler = 1 Synchronous, Standard(F) Prescaler = Extended(LF) 2,4,8 Asynchronous Standard(F) Extended(LF) T1CKI input period Synchronous Standard(F) Extended(LF) Asynchronous 48 * † Standard(F) Extended(LF) Ft1 Timer1 oscillator input frequency range (oscillator enabled by setting bit T1OSCEN) TCKEZtmr1 Delay from external clock edge to timer increment Min Typ† Max 0.5TCY + 20 — — ns 10 — — — — — — — — — — ns ns ns ns ns — — — — — — ns ns ns — — — — — — — — — — ns ns ns ns ns — — — — — — ns ns ns 0.5TCY + 20 10 TCY + 40 Greater of: 20 or TCY + 40 N 0.5TCY + 20 15 25 30 50 0.5TCY + 20 15 25 30 50 Greater of: 30 OR TCY + 40 N Greater of: 50 OR TCY + 40 N 60 100 DC 2Tosc Units Conditions Must also meet parameter 42 Must also meet parameter 42 N = prescale value (2, 4, ..., 256) Must also meet parameter 47 Must also meet parameter 47 N = prescale value (1, 2, 4, 8) N = prescale value (1, 2, 4, 8) — — — — — 200 ns ns kHz — 7Tosc — 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. 1999 Microchip Technology Inc. Preliminary DS30221A-page 135 PIC16F872 FIGURE 14-9: CAPTURE/COMPARE/PWM TIMINGS (CCP1) RC2/CCP1 (Capture Mode) 50 51 52 RC2/CCP1 (Compare or PWM Mode) 53 54 Note: Refer to Figure 14-3 for load conditions. TABLE 14-5: Param No. 50* CAPTURE/COMPARE/PWM REQUIREMENTS (CCP1) Sym Characteristic TccL CCP1 input low time Min No Prescaler Standard(F) With Prescaler 51* TccH CCP1 input high time With Prescaler 52* TccP CCP1 input period 53* TccR CCP1 output rise time 54* * † Extended(LF) No Prescaler TccF CCP1 output fall time Typ† Max Units Conditions 0.5TCY + 20 — — ns 10 — — ns 20 — — ns 0.5TCY + 20 — — ns Standard(F) 10 — — ns Extended(LF) 20 — — ns 3TCY + 40 N — — ns Standard(F) — 10 25 ns Extended(LF) — 25 50 ns Standard(F) — 10 25 ns Extended(LF) — 25 45 ns N = prescale value (1,4 or 16) 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. DS30221A-page 136 Preliminary 1999 Microchip Technology Inc. PIC16F872 FIGURE 14-10: SPI MASTER MODE TIMING (CKE = 0, SMP = 0) SS 70 SCK (CKP = 0) 71 72 78 79 79 78 SCK (CKP = 1) 80 BIT6 - - - - - -1 MSb SDO LSb 75, 76 SDI MSb IN BIT6 - - - -1 LSb IN 74 73 Note: Refer to Figure 14-3 for load conditions. FIGURE 14-11: SPI MASTER MODE TIMING (CKE = 1, SMP = 1) SS 81 SCK (CKP = 0) 71 72 79 73 SCK (CKP = 1) 80 78 SDO MSb BIT6 - - - - - -1 LSb 75, 76 SDI MSb IN BIT6 - - - -1 LSb IN 74 Note: Refer to Figure 14-3 for load conditions. 1999 Microchip Technology Inc. Preliminary DS30221A-page 137 PIC16F872 FIGURE 14-12: SPI SLAVE MODE TIMING (CKE = 0) SS 70 SCK (CKP = 0) 83 71 72 78 79 79 78 SCK (CKP = 1) 80 MSb SDO LSb BIT6 - - - - - -1 77 75, 76 SDI MSb IN BIT6 - - - -1 LSb IN 74 73 Note: Refer to Figure 14-3 for load conditions. FIGURE 14-13: SPI SLAVE MODE TIMING (CKE = 1) 82 SS SCK (CKP = 0) 70 83 71 72 SCK (CKP = 1) 80 SDO MSb BIT6 - - - - - -1 LSb 75, 76 SDI MSb IN 77 BIT6 - - - -1 LSb IN 74 Note: Refer to Figure 14-3 for load conditions. DS30221A-page 138 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 14-6: Param No. SPI MODE REQUIREMENTS Sym Characteristic Min Typ† Max Units TCY — — ns ns 70* TssL2scH, TssL2scL SS↓ to SCK↓ or SCK↑ input 71* TscH SCK input high time (slave mode) TCY + 20 — — 72* TscL SCK input low time (slave mode) TCY + 20 — — ns 73* TdiV2scH, TdiV2scL Setup time of SDI data input to SCK edge 100 — — ns 74* TscH2diL, TscL2diL Hold time of SDI data input to SCK edge 100 — — ns 75* TdoR SDO data output rise time — — 10 25 25 50 ns ns 76* TdoF SDO data output fall time — 10 25 ns 77* TssH2doZ SS↑ to SDO output hi-impedance 10 — 50 ns 78* TscR SCK output rise time (master mode) Standard(F) Extended(LF) — — 10 25 25 50 ns ns 79* TscF SCK output fall time (master mode) 80* TscH2doV, TscL2doV SDO data output valid after SCK edge 81* TdoV2scH, TdoV2scL SDO data output setup to SCK edge 82* TssL2doV SDO data output valid after SS↓ edge 83* TscH2ssH, TscL2ssH SS ↑ after SCK edge * † Standard(F) Extended(LF) Standard(F) Extended(LF) — 10 25 ns — — — — 50 145 ns TCY — — ns — — 50 ns 1.5TCY + 40 — — ns Conditions 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. FIGURE 14-14: I2C BUS START/STOP BITS TIMING SCL 93 91 90 92 SDA STOP Condition START Condition Note: Refer to Figure 14-3 for load conditions. TABLE 14-7: I2C BUS START/STOP BITS REQUIREMENTS Parameter No. Sym Characteristic 90 TSU:STA START condition 100 kHz mode 4700 — — Setup time 400 kHz mode 600 — — START condition 100 kHz mode 4000 — — Hold time 400 kHz mode 600 — — STOP condition 100 kHz mode 4700 — — Setup time 400 kHz mode 600 — — STOP condition 100 kHz mode 4000 — — Hold time 400 kHz mode 600 — — 91 92 93 THD:STA TSU:STO THD:STO 1999 Microchip Technology Inc. Min Typ Max Units Preliminary Conditions ns Only relevant for repeated START condition ns After this period the first clock pulse is generated ns ns DS30221A-page 139 PIC16F872 FIGURE 14-15: I2C BUS DATA TIMING 103 102 100 101 SCL 90 106 107 91 92 SDA In 110 109 109 SDA Out Note: Refer to Figure 14-3 for load conditions. I2C BUS DATA REQUIREMENTS TABLE 14-8: Param No. Sym Characteristic 100 THIGH Clock high time Min Max Units Conditions 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 1.5TCY — 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 101 TLOW Clock low time 1.5TCY — SDA and SCL rise time 100 kHz mode — 1000 ns 400 kHz mode 20 + 0.1Cb 300 ns SDA and SCL fall time 100 kHz mode — 300 ns 400 kHz mode 20 + 0.1Cb 300 ns Cb is specified to be from 10 to 400 pF START condition setup time 100 kHz mode 4.7 — µs 400 kHz mode 0.6 — µs Only relevant for repeated START condition START condition hold time 100 kHz mode 4.0 — µs 400 kHz mode 0.6 — µs Data input hold time 100 kHz mode 0 — ns 400 kHz mode 0 0.9 µs 100 kHz mode 250 — ns 400 kHz mode 100 — ns STOP condition setup time 100 kHz mode 4.7 — µs 400 kHz mode 0.6 — µs Output valid from clock 100 kHz mode — 3500 ns 400 kHz mode — — ns 100 kHz mode 4.7 — µs 400 kHz mode 1.3 — µs — 400 pF SSP Module 102 103 90 91 106 107 92 109 110 TR TF TSU:STA THD:STA THD:DAT TSU:DAT TSU:STO TAA TBUF Cb Data input setup time Bus free time Bus capacitive loading Cb is specified to be from 10 to 400 pF After this period the first clock pulse is generated Note 2 Note 1 Time the bus must be free before a new transmission can start 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 device can be used in a standard-mode (100 kHz) I2C-bus system, but the requirement tsu; DAT ≥ 250 ns must then be met. This will automatically be the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line TR max.+tsu; DAT = 1000 + 250 = 1250 ns (according to the standard-mode I2C bus specification) before the SCL line is released. DS30221A-page 140 Preliminary 1999 Microchip Technology Inc. PIC16F872 TABLE 14-9: Param No. PIC16F872 AND PIC16LF872 (INDUSTRIAL) Sym Characteristic Min Typ† Max Units Conditions A01 NR Resolution — — 10-bits bit VREF = VDD = 5.12V, VSS ≤ VAIN ≤ VREF A03 EIL Integral linearity error — — <±1 LSb VREF = VDD = 5.12V, VSS ≤ VAIN ≤ VREF A04 EDL Differential linearity error — — <±1 LSb VREF = VDD = 5.12V, VSS ≤ VAIN ≤ VREF A06 EOFF Offset error — — <±1 LSb VREF = VDD = 5.12V, VSS ≤ VAIN ≤ VREF A07 EGN Gain error — — <±1 LSb VREF = VDD = 5.12V, VSS ≤ VAIN ≤ VREF A10 — Monotonicity(3) — guaranteed — — VSS ≤ VAIN ≤ VREF 2.0V — VDD + 0.3 V Absolute minimum electrical spec. To ensure 10-bit accuracy. AVDD + 0.3V V A20 VREF Reference voltage (VREF+ - VREF-) A21 VREF Reference voltage High + AVDD - 2.5V A22 VREF- Reference voltage low AVSS - 0.3V VREF+ - 2.0V V A25 VAIN Analog input voltage VSS - 0.3 — VREF + 0.3 V A30 ZAIN Recommended impedance of analog voltage source — — 10.0 kΩ A40 IAD Standard — 220 — µA Extended — 90 — µA 10 — 1000 µA During VAIN acquisition. Based on differential of VHOLD to VAIN to charge CHOLD, see Section 10.1. — — 10 µA During A/D Conversion cycle A50 IREF A/D conversion current (VDD) VREF input current (Note 2) Average current consumption when A/D is on. (Note 1) * † 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: When A/D is off, it will not consume any current other than minor leakage current. The power-down current spec includes any such leakage from the A/D module. 2: VREF current is from RA3 pin or VDD pin, whichever is selected as reference input. 3: The A/D conversion result never decreases with an increase in the Input Voltage, and has no missing codes. 1999 Microchip Technology Inc. Preliminary DS30221A-page 141 PIC16F872 FIGURE 14-16: A/D CONVERSION TIMING BSF ADCON0, GO 1 TCY (TOSC/2)(1) 131 Q4 130 132 A/D CLK 9 A/D DATA 8 ... 7 ... 2 1 0 NEW_DATA OLD_DATA ADRES ADIF GO DONE SAMPLING STOPPED SAMPLE Note 1: 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 instruction to be executed. TABLE 14-10: A/D CONVERSION REQUIREMENTS Param No. 130 Sym Characteristic TAD A/D clock period Min Conditions 1.6 — — µs TOSC based, VREF ≥ 3.0V 3.0 — — µs TOSC based, VREF ≥ 2.0V Standard(F) 2.0 4.0 6.0 µs A/D RC Mode Extended(LF) 3.0 6.0 9.0 µs A/D RC Mode — 12 TAD Note 2 40 — µs 10* — — µs The minimum time is the amplifier settling time. This may be used if the "new" input voltage has not changed by more than 1 LSb (i.e., 20.0 mV @ 5.12V) from the last sampled voltage (as stated on CHOLD). — 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 instruction to be executed. 132 TACQ Acquisition time Q4 to A/D clock start Units Extended(LF) TCNV Conversion time (not including S/H time) (Note 1) TGO Max Standard(F) 131 134 Typ† * † 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. § This specification ensured by design. Note 1: ADRES register may be read on the following TCY cycle. 2: See Section 10.1 for min conditions. DS30221A-page 142 Preliminary 1999 Microchip Technology Inc. PIC16F872 15.0 DC AND AC CHARACTERISTICS GRAPHS AND TABLES The graphs and tables provided in this section are for design guidance and are not tested. In some graphs or tables, the data presented are outside specified operating range (i.e., outside specified VDD range). This is for information only and devices are ensured to operate properly only within the specified range. The data presented in this section is a statistical summary of data collected on units from different lots over a period of time and matrix samples. ’Typical’ represents the mean of the distribution at 25°C. ’Max’ or ’min’ represents (mean + 3σ) or (mean - 3σ) respectively, where σ is standard deviation, over the whole temperature range. Graphs and Tables not available at this time. 1999 Microchip Technology Inc. Preliminary DS30221A-page 143 PIC16F872 NOTES: DS30221A-page 144 Preliminary 1999 Microchip Technology Inc. PIC16F872 16.0 PACKAGING INFORMATION 16.1 Package Marking Information 28-Lead PDIP (Skinny DIP) Example XXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXX PIC16F872-I/SP 9910SAA YYWWNNN 28-Lead SOIC Example XXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXX PIC16F872-I/SO YYWWNNN 9910SAA 28-Lead SSOP Example XXXXXXXXXXXX XXXXXXXXXXXX PIC16F872-I/SS YYWWNNN Legend: MM...M XX...X YY WW NNN Note: * 9910SAA Microchip part number information Customer specific information* Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line thus limiting the number of available characters for customer specific information. Standard OTP marking consists of Microchip part number, year code, week code, facility code, mask rev#, and assembly code. For OTP 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. 1999 Microchip Technology Inc. Preliminary DS30221A-page 145 PIC16F872 28-Lead Plastic Shrink Small Outline (SS) – 209 mil, 5.30 mm (SSOP) E E1 p D B 2 1 n α A c A2 φ A1 L β Units Dimension Limits n p Number of Pins Pitch Overall Height Molded Package Thickness Standoff Overall Width Molded Package Width Overall Length Foot Length Lead Thickness Foot Angle Lead Width Mold Draft Angle Top Mold Draft Angle Bottom A A2 A1 E E1 D L c φ B α β MIN .068 .064 .002 .299 .201 .396 .022 .004 0 .010 0 0 INCHES NOM 28 .026 .073 .068 .006 .309 .207 .402 .030 .007 4 .013 5 5 MAX .078 .072 .010 .319 .212 .407 .037 .010 8 .015 10 10 MILLIMETERS* NOM MAX 28 0.65 1.73 1.85 1.98 1.63 1.73 1.83 0.05 0.15 0.25 7.59 7.85 8.10 5.11 5.25 5.38 10.06 10.20 10.34 0.56 0.75 0.94 0.10 0.18 0.25 0.00 101.60 203.20 0.25 0.32 0.38 0 5 10 0 5 10 MIN *Controlling Parameter Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side. JEDEC Equivalent: MS-150 Drawing No. C04-073 DS30221A-page 146 Preliminary 1999 Microchip Technology Inc. PIC16F872 28-Lead Skinny Plastic Dual In-line (SP) – 300 mil (PDIP) E1 D 2 n 1 α E A2 A L c β B1 A1 eB Units Number of Pins Pitch p B Dimension Limits n p INCHES* MIN NOM MILLIMETERS MAX MIN NOM 28 MAX 28 .100 2.54 Top to Seating Plane A .140 .150 .160 3.56 3.81 4.06 Molded Package Thickness A2 .125 .130 .135 3.18 3.30 3.43 Base to Seating Plane A1 .015 Shoulder to Shoulder Width E .300 .310 .325 7.62 7.87 8.26 Molded Package Width E1 .275 .285 .295 6.99 7.24 7.49 Overall Length D 1.345 1.365 1.385 34.16 34.67 35.18 Tip to Seating Plane L c .125 .130 .135 3.18 3.30 3.43 .008 .012 .015 0.20 0.29 0.38 B1 .040 .053 .065 1.02 1.33 1.65 Lower Lead Width B .016 .019 .022 0.41 0.48 0.56 Overall Row Spacing eB α .320 .350 .430 8.13 8.89 10.92 5 10 15 5 10 15 5 10 15 5 10 15 Lead Thickness Upper Lead Width Mold Draft Angle Top Mold Draft Angle Bottom β 0.38 *Controlling Parameter Notes: Dimension D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side. JEDEC Equivalent: MO-095 Drawing No. C04-070 1999 Microchip Technology Inc. Preliminary DS30221A-page 147 PIC16F872 28-Lead Plastic Small Outline (SO) – Wide, 300 mil (SOIC) E E1 p D B 2 1 n h α 45° c A2 A φ β L Units Dimension Limits n p A1 MIN INCHES* NOM 28 .050 .099 .091 .008 .407 .295 .704 .020 .033 4 .011 .017 12 12 MAX MILLIMETERS NOM 28 1.27 2.36 2.50 2.24 2.31 0.10 0.20 10.01 10.34 7.32 7.49 17.65 17.87 0.25 0.50 0.41 0.84 0 4 0.23 0.28 0.36 0.42 0 12 0 12 MIN Number of Pins Pitch Overall Height A .093 .104 Molded Package Thickness A2 .088 .094 Standoff A1 .004 .012 Overall Width E .394 .420 Molded Package Width E1 .288 .299 Overall Length D .695 .712 Chamfer Distance h .010 .029 Foot Length L .016 .050 φ Foot Angle Top 0 8 c Lead Thickness .009 .013 Lead Width B .014 .020 α Mold Draft Angle Top 0 15 β Mold Draft Angle Bottom 0 15 *Controlling Parameter Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side. JEDEC Equivalent: MS-013 Drawing No. C04-052 DS30221A-page 148 Preliminary MAX 2.64 2.39 0.30 10.67 7.59 18.08 0.74 1.27 8 0.33 0.51 15 15 1999 Microchip Technology Inc. PIC16F872 APPENDIX A: REVISION HISTORY Version Date Revision Description A 1999 This is a new data sheet. However, these devices are similar to the PIC16C72A devices found in the PIC16C62B/72A Data Sheet (DS35008A). APPENDIX B: CONVERSION CONSIDERATIONS Considerations for converting from previous versions of devices to the ones listed in this data sheet are listed in Table B-1. TABLE B-1: CONVERSION CONSIDERATIONS Characteristic PIC16C72A PIC16F872 Pins 28 28 Timers 3 3 Interrupts 8 10 2C Slave) SSP (SPI, I2C Master/Slave) Communication SSP (SPI, I Frequency 20 MHz 20 MHz A/D 8-bit 10-bit CCP 1 1 Program Memory 2K EPROM 2K FLASH RAM 128 bytes 128 bytes EEPROM data None 64 bytes Other In-Circuit Debugger, Low Voltage Programming 1999 Microchip Technology Inc. Preliminary DS30221A-page 149 PIC16F872 NOTES: DS30221A-page 150 Preliminary 1999 Microchip Technology Inc. PIC16F872 INDEX A A/D ..................................................................................... 85 ADCON0 Register ...................................................... 85 ADCON1 Register ...................................................... 86 ADIF bit ...................................................................... 87 Analog Input Model Block Diagram ............................ 89 Analog Port Pins .......................................................... 6 Block Diagram ............................................................ 88 Configuring Analog Port Pins ..................................... 90 Configuring the Interrupt ............................................ 87 Configuring the Module .............................................. 87 Conversion Clock ....................................................... 90 Conversions ............................................................... 91 Delays ........................................................................ 89 Effects of a Reset ....................................................... 92 GO/DONE bit ............................................................. 87 Internal Sampling Switch (Rss) Impedence ............... 88 Operation During Sleep ............................................. 92 Sampling Requirements ............................................. 88 Source Impedence ..................................................... 88 Time Delays ............................................................... 89 Absolute Maximum Ratings ............................................. 125 ACK .................................................................................... 62 Acknowledge Data bit ........................................................ 56 Acknowledge Pulse ............................................................ 62 Acknowledge Sequence Enable bit ................................... 56 Acknowledge Status bit ...................................................... 56 ADRES Register ............................................................ 9, 85 Application Note AN578, "Use of the SSP Module in the I2C Multi-Master Environment." ............................... 61 Application Notes AN552 (Implementing Wake-up on Key Strokes Using PIC16CXXX) .................................................... 25 AN556 (Table Reading Using PIC16CXX) ................. 20 Architecture PIC16F872 Block Diagram .......................................... 5 Assembler MPASM Assembler .................................................. 119 B Banking, Data Memory .................................................. 7, 12 Baud Rate Generator ......................................................... 68 BCLIF ................................................................................. 18 BF .................................................................... 54, 62, 71, 73 Block Diagrams A/D ............................................................................. 88 Analog Input Model .................................................... 89 Baud Rate Generator ................................................. 68 Capture ...................................................................... 48 Compare .................................................................... 49 I2C Master Mode ........................................................ 66 I2C Module ................................................................. 61 PWM .......................................................................... 49 SSP (I2C Mode) ......................................................... 61 SSP (SPI Mode) ......................................................... 57 Timer0/WDT Prescaler .............................................. 37 Timer2 ........................................................................ 45 BRG ................................................................................... 68 Brown-out Reset (BOR) ............................... 95, 99, 101, 102 BOR Status (BOR Bit) ................................................ 19 Buffer Full bit, BF ............................................................... 62 Buffer Full Status bit, BF .................................................... 54 Bus Arbitration ................................................................... 78 Bus Collision During a RESTART Condition ...................... 81 1999 Microchip Technology Inc. Bus Collision During a Start Condition ............................... 79 Bus Collision During a Stop Condition ............................... 82 Bus Collision Interrupt Flag bit, BCLIF ............................... 18 Bus Collision Section ......................................................... 78 C Capture/Compare/PWM Capture Block Diagram ................................................... 48 CCP1CON Register ........................................... 47 CCP1IF .............................................................. 48 Mode ................................................................. 48 Prescaler ........................................................... 48 CCP Timer Resources ............................................... 47 Compare Block Diagram ................................................... 49 Mode ................................................................. 49 Software Interrupt Mode .................................... 49 Special Event Trigger ........................................ 49 Special Trigger Output of CCP1 ........................ 49 Section ....................................................................... 47 Special Event Trigger and A/D Conversions ............. 49 Capture/Compare/PWM (CCP) CCP1 RC2/CCP1 Pin ..................................................... 6 PWM Block Diagram ................................................. 49 PWM Mode ................................................................ 49 CCP1CON ......................................................................... 11 CCP1M0 bit ....................................................................... 47 CCP1M1 bit ....................................................................... 47 CCP1M2 bit ....................................................................... 47 CCP1M3 bit ....................................................................... 47 CCP1X bit .......................................................................... 47 CCP1Y bit .......................................................................... 47 CCPR1H Register .................................................... 9, 11, 47 CCPR1L Register ........................................................ 11, 47 CKE ................................................................................... 54 CKP ................................................................................... 55 Clock Polarity Select bit, CKP ............................................ 55 Code Examples Indirect Addressing .................................................... 20 Code Protection ......................................................... 95, 109 Computed GOTO ............................................................... 20 Configuration Bits .............................................................. 95 Conversion Considerations .............................................. 149 D D/A ..................................................................................... 54 Data Memory ....................................................................... 7 Bank Select (RP1:RP0 Bits) .................................. 7, 12 General Purpose Registers ......................................... 7 Register File Map ........................................................ 8 Special Function Registers .......................................... 9 Data/Address bit, D/A ........................................................ 54 DC Characteristics ........................................................... 127 Development Support ...................................................... 119 Device Overview .................................................................. 5 Direct Addressing .............................................................. 21 E Electrical Characteristics ................................................. 125 Errata ................................................................................... 3 F Firmware Instructions ...................................................... 111 FSR Register ..................................................... 9, 10, 11, 20 DS30221A-page 151 PIC16F872 G General Call Address Sequence ........................................ 64 General Call Address Support ........................................... 64 General Call Enable bit ...................................................... 56 I I/O Ports ............................................................................. 23 I2C ...................................................................................... 61 I2C Master Mode Reception ............................................... 73 I2C Master Mode Restart Condition ................................... 70 I2C Mode Selection ............................................................ 61 I2C Module Acknowledge Sequence timing .................................. 75 Addressing ................................................................. 62 Baud Rate Generator ................................................. 68 Block Diagram ............................................................ 66 BRG Block Diagram ................................................... 68 BRG Reset due to SDA Collision ............................... 80 BRG Timing ............................................................... 68 Bus Arbitration ........................................................... 78 Bus Collision .............................................................. 78 Acknowledge ...................................................... 78 Restart Condition ............................................... 81 Restart Condition Timing (Case1) ...................... 81 Restart Condition Timing (Case2) ...................... 81 Start Condition ................................................... 79 Start Condition Timing ................................. 79, 80 Stop Condition ................................................... 82 Stop Condition Timing (Case1) .......................... 82 Stop Condition Timing (Case2) .......................... 82 Transmit Timing ................................................. 78 Bus Collision timing .................................................... 78 Clock Arbitration ......................................................... 77 Clock Arbitration Timing (Master Transmit) ................ 77 Conditions to not give ACK Pulse .............................. 62 General Call Address Support ................................... 64 Master Mode .............................................................. 66 Master Mode 7-bit Reception timing .......................... 74 Master Mode Operation ............................................. 67 Master Mode Start Condition ..................................... 69 Master Mode Transmission ........................................ 71 Master Mode Transmit Sequence .............................. 67 Multi-Master Communication ..................................... 78 Multi-master Mode ..................................................... 67 Operation ................................................................... 61 Repeat Start Condition timing .................................... 70 Slave Mode ................................................................ 62 Slave Reception ......................................................... 63 Slave Transmission .................................................... 63 SSPBUF ..................................................................... 62 Stop Condition Receive or Transmit timing ................ 76 Stop Condition timing ................................................. 76 Waveforms for 7-bit Reception .................................. 63 Waveforms for 7-bit Transmission ............................. 64 I2C Module Address Register, SSPADD ............................ 62 I2C Slave Mode .................................................................. 62 ID Locations ............................................................... 95, 109 In-Circuit Serial Programming (ICSP) ........................ 95, 110 INDF ................................................................................... 11 INDF Register .......................................................... 9, 10, 20 Indirect Addressing ...................................................... 20, 21 FSR Register ............................................................... 7 Instruction Format ............................................................ 111 DS30221A-page 152 Instruction Set .................................................................. 111 ADDLW .................................................................... 113 ADDWF .................................................................... 113 ANDLW .................................................................... 113 ANDWF .................................................................... 113 BCF ......................................................................... 113 BSF .......................................................................... 113 BTFSC ..................................................................... 114 BTFSS ..................................................................... 114 CALL ........................................................................ 114 CLRF ....................................................................... 114 CLRW ...................................................................... 114 CLRWDT ................................................................. 114 COMF ...................................................................... 115 DECF ....................................................................... 115 DECFSZ .................................................................. 115 GOTO ...................................................................... 115 INCF ........................................................................ 115 INCFSZ .................................................................... 115 IORLW ..................................................................... 116 IORWF ..................................................................... 116 MOVF ...................................................................... 116 MOVLW ................................................................... 116 MOVWF ................................................................... 116 NOP ......................................................................... 116 RETFIE .................................................................... 117 RETLW .................................................................... 117 RETURN .................................................................. 117 RLF .......................................................................... 117 RRF ......................................................................... 117 SLEEP ..................................................................... 117 SUBLW .................................................................... 118 SUBWF .................................................................... 118 SWAPF .................................................................... 118 XORLW ................................................................... 118 XORWF ................................................................... 118 Summary Table ....................................................... 112 INTCON ............................................................................. 11 INTCON Register ............................................................... 14 GIE Bit ....................................................................... 14 INTE Bit ..................................................................... 14 INTF Bit ..................................................................... 14 PEIE Bit ..................................................................... 14 RBIE Bit ..................................................................... 14 RBIF Bit ............................................................... 14, 25 T0IE Bit ...................................................................... 14 T0IF Bit ...................................................................... 14 Inter-Integrated Circuit (I2C) .............................................. 53 Internal Sampling Switch (Rss) Impedence ....................... 88 Interrupt Sources ....................................................... 95, 105 Block Diagram ......................................................... 105 Interrupt on Change (RB7:RB4 ) ............................... 25 RB0/INT Pin, External .......................................... 6, 106 TMR0 Overflow ........................................................ 106 Interrupts Bus Collision Interrupt ................................................ 18 Synchronous Serial Port Interrupt .............................. 16 Interrupts, Context Saving During .................................... 106 Interrupts, Enable Bits Global Interrupt Enable (GIE Bit) ....................... 14, 105 Interrupt on Change (RB7:RB4) Enable (RBIE Bit) ........................................................... 14, 106 Peripheral Interrupt Enable (PEIE Bit) ....................... 14 RB0/INT Enable (INTE Bit) ........................................ 14 TMR0 Overflow Enable (T0IE Bit) ............................. 14 1999 Microchip Technology Inc. PIC16F872 Interrupts, Flag Bits Interrupt on Change (RB7:RB4) Flag (RBIF Bit) ..................................................... 14, 25, 106 RB0/INT Flag (INTF Bit) ............................................. 14 TMR0 Overflow Flag (T0IF Bit) .......................... 14, 106 K KeeLoq Evaluation and Programming Tools ................. 122 L Loading of PC .................................................................... 20 M Master Clear (MCLR) ........................................................... 6 MCLR Reset, Normal Operation ................ 99, 101, 102 MCLR Reset, SLEEP ................................. 99, 101, 102 Memory Organization Data Memory ............................................................... 7 Program Memory ......................................................... 7 MPLAB Integrated Development Environment Software . 119 Multi-Master Communication ............................................. 78 Multi-Master Mode ............................................................. 67 O OPCODE Field Descriptions ............................................ 111 OPTION ............................................................................. 11 OPTION_REG Register ..................................................... 13 INTEDG Bit ................................................................ 13 PS2:PS0 Bits ............................................................. 13 PSA Bit ....................................................................... 13 RBPU Bit .................................................................... 13 T0CS Bit ..................................................................... 13 T0SE Bit ..................................................................... 13 OSC1/CLKIN Pin ................................................................. 6 OSC2/CLKOUT Pin ............................................................. 6 Oscillator Configuration ................................................ 95, 97 HS ...................................................................... 97, 101 LP ....................................................................... 97, 101 RC ................................................................ 97, 98, 101 XT ...................................................................... 97, 101 Oscillator, WDT ................................................................ 107 Output of TMR2 ................................................................. 45 P P (Stop bit) ......................................................................... 54 Packaging ........................................................................ 145 Paging, Program Memory .............................................. 7, 20 PCL Register ...................................................... 9, 10, 11, 20 PCLATH Register .............................................. 9, 10, 11, 20 PCON Register .................................................... 11, 19, 100 BOR Bit ...................................................................... 19 POR Bit ...................................................................... 19 PICDEM-1 Low-Cost PICmicro Demo Board ................... 121 PICDEM-2 Low-Cost PIC16CXX Demo Board ................ 121 PICDEM-3 Low-Cost PIC16CXXX Demo Board .............. 121 PICSTART Plus Entry Level Development System ...... 121 PIE1 Register ............................................................... 11, 15 PIE2 Register ............................................................... 11, 17 Pinout Descriptions PIC16F872 ................................................................... 6 PIR1 Register ..................................................................... 16 PIR2 Register ..................................................................... 18 POP ................................................................................... 20 1999 Microchip Technology Inc. PORTA .......................................................................... 6, 11 Analog Port Pins .......................................................... 6 Initialization ................................................................ 23 PORTA Register ........................................................ 23 RA3, RA0 and RA5 Port Pins .................................... 23 RA4/T0CKI Pin ...................................................... 6, 23 RA5/SS/AN4 Pin .......................................................... 6 TRISA Register .......................................................... 23 PORTA Register .................................................................. 9 PORTB .......................................................................... 6, 11 PORTB Register ........................................................ 25 Pull-up Enable (RBPU Bit) ......................................... 13 RB0/INT Edge Select (INTEDG Bit) .......................... 13 RB0/INT Pin, External ......................................... 6, 106 RB3:RB0 Port Pins .................................................... 25 RB7:RB4 Interrupt on Change ................................. 106 RB7:RB4 Interrupt on Change Enable (RBIE Bit) ........................................................... 14, 106 RB7:RB4 Interrupt on Change Flag (RBIF Bit) ..................................................... 14, 25, 106 RB7:RB4 Port Pins .................................................... 25 TRISB Register .......................................................... 25 PORTB Register .................................................................. 9 PORTC .......................................................................... 6, 11 Block Diagram ........................................................... 27 PORTC Register ........................................................ 27 RC0/T1OSO/T1CKI Pin ............................................... 6 RC1/T1OSI Pin ............................................................ 6 RC2/CCP1 Pin ............................................................. 6 RC3/SCK/SCL Pin ....................................................... 6 RC4/SDI/SDA Pin ........................................................ 6 RC5/SDO Pin .............................................................. 6 RC6 Pin ....................................................................... 6 RC7 Pin ....................................................................... 6 TRISC Register ......................................................... 27 PORTC Register .................................................................. 9 Postscaler, WDT Assignment (PSA Bit) ................................................ 13 Rate Select (PS2:PS0 Bits) ....................................... 13 Power-on Reset (POR) ........................ 95, 99, 100, 101, 102 Oscillator Start-up Timer (OST) ......................... 95, 100 POR Status (POR Bit) ............................................... 19 Power Control (PCON) Register .............................. 100 Power-down (PD Bit) ........................................... 12, 99 Power-up Timer (PWRT) ................................... 95, 100 Time-out (TO Bit) ................................................. 12, 99 Time-out Sequence on Power-up .................... 103, 104 PR2 .................................................................................... 11 PR2 Register ............................................................... 10, 45 Prescaler, Timer0 Assignment (PSA Bit) ................................................ 13 Rate Select (PS2:PS0 Bits) ....................................... 13 PRO MATE II Universal Programmer ........................... 121 Product Identification System .......................................... 158 Program Counter Reset Conditions ..................................................... 101 Program Memory ................................................................. 7 Interrupt Vector ............................................................ 7 Paging ................................................................... 7, 20 Program Memory Map ................................................. 7 Reset Vector ................................................................ 7 Program Verification ........................................................ 109 Programming Pin (VPP) ....................................................... 6 Programming, Device Instructions ................................... 111 PUSH ................................................................................. 20 DS30221A-page 153 PIC16F872 R R/W .................................................................................... 54 R/W bit ............................................................................... 62 R/W bit ............................................................................... 63 Read/Write bit, R/W ........................................................... 54 Receive Enable bit ............................................................. 56 Receive Overflow Indicator bit, SSPOV ............................. 55 Register File ......................................................................... 7 Register File Map ................................................................. 8 Registers FSR Summary ........................................................... 11 INDF Summary .......................................................... 11 INTCON Summary ..................................................... 11 OPTION Summary ..................................................... 11 PCL Summary ............................................................ 11 PCLATH Summary .................................................... 11 PORTB Summary ...................................................... 11 SSPSTAT ................................................................... 54 STATUS Summary .................................................... 11 Summary ...................................................................... 9 TMR0 Summary ......................................................... 11 TRISB Summary ........................................................ 11 Reset ............................................................................ 95, 99 Block Diagram ............................................................ 99 Reset Conditions for All Registers ........................... 102 Reset Conditions for PCON Register ....................... 101 Reset Conditions for Program Counter .................... 101 Reset Conditions for STATUS Register ................... 101 Restart Condition Enabled bit ............................................ 56 Revision History ............................................................... 149 S S (Start bit) ......................................................................... 54 SCK .................................................................................... 57 SCL .................................................................................... 62 SDA .................................................................................... 62 SDI ..................................................................................... 57 SDO ................................................................................... 57 SEEVAL Evaluation and Programming System ............ 122 Serial Clock, SCK ............................................................... 57 Serial Clock, SCL ............................................................... 62 Serial Data Address, SDA .................................................. 62 Serial Data In, SDI ............................................................. 57 Serial Data Out, SDO ......................................................... 57 Slave Select, SS ................................................................ 57 SLEEP .................................................................. 95, 99, 108 SMP ................................................................................... 54 Software Simulator (MPLAB-SIM) .................................... 120 Special Features of the CPU .............................................. 95 Special Function Registers .................................................. 9 Speed, Operating ................................................................. 1 SPI Master Mode .............................................................. 58 Master Mode Timing .................................................. 58 Serial Clock ................................................................ 57 Serial Data In ............................................................. 57 Serial Data Out .......................................................... 57 Serial Peripheral Interface (SPI) ................................ 53 Slave Mode Timing .................................................... 59 Slave Mode Timing Diagram ...................................... 59 Slave Select ............................................................... 57 SPI clock .................................................................... 58 SPI Mode ................................................................... 57 SPI Clock Edge Select, CKE .............................................. 54 SPI Data Input Sample Phase Select, SMP ....................... 54 DS30221A-page 154 SPI Module Slave Mode ................................................................ 59 SS ...................................................................................... 57 SSP .................................................................................... 53 Block Diagram (SPI Mode) ........................................ 57 RA5/SS/AN4 Pin .......................................................... 6 RC3/SCK/SCL Pin ....................................................... 6 RC4/SDI/SDA Pin ........................................................ 6 RC5/SDO Pin ............................................................... 6 SPI Mode ................................................................... 57 SSPADD .................................................................... 62 SSPBUF .............................................................. 58, 62 SSPCON1 ................................................................. 55 SSPCON2 ................................................................. 56 SSPSR ................................................................ 58, 62 SSPSTAT ............................................................ 54, 62 SSP I2C SSP I2C Operation .................................................... 61 SSP Module SPI Master Mode ....................................................... 58 SPI Slave Mode ......................................................... 59 SSPCON1 Register ................................................... 61 SSP Overflow Detect bit, SSPOV ...................................... 62 SSPADD Register ........................................................ 10, 11 SSPBUF ...................................................................... 11, 62 SSPBUF Register ................................................................ 9 SSPCON Register ............................................................... 9 SSPCON1 .................................................................... 55, 61 SSPCON2 .......................................................................... 56 SSPEN ............................................................................... 55 SSPIF .......................................................................... 16, 63 SSPM3:SSPM0 ................................................................. 55 SSPOV .................................................................. 55, 62, 73 SSPSTAT .............................................................. 11, 54, 62 SSPSTAT Register ............................................................ 10 Stack .................................................................................. 20 Overflows ................................................................... 20 Underflow .................................................................. 20 Start bit (S) ......................................................................... 54 Start Condition Enabled bit ................................................ 56 STATUS Register ........................................................ 11, 12 C Bit ........................................................................... 12 DC Bit ........................................................................ 12 IRP Bit ....................................................................... 12 PD Bit .................................................................. 12, 99 RP1:RP0 Bits ............................................................. 12 TO Bit .................................................................. 12, 99 Z Bit ........................................................................... 12 Stop bit (P) ......................................................................... 54 Stop Condition Enable bit .................................................. 56 Synchronous Serial Port .................................................... 53 Synchronous Serial Port Enable bit, SSPEN ..................... 55 Synchronous Serial Port Interrupt ...................................... 16 Synchronous Serial Port Mode Select bits, SSPM3:SSPM0 ................................................................. 55 T T1CKPS0 bit ...................................................................... 41 T1CKPS1 bit ...................................................................... 41 T1CON ............................................................................... 11 T1CON Register .......................................................... 11, 41 T1OSCEN bit ..................................................................... 41 T1SYNC bit ........................................................................ 41 T2CKPS0 bit ...................................................................... 45 T2CKPS1 bit ...................................................................... 45 T2CON Register .......................................................... 11, 45 1999 Microchip Technology Inc. PIC16F872 TAD ..................................................................................... 90 Timer0 Clock Source Edge Select (T0SE Bit) ........................ 13 Clock Source Select (T0CS Bit) ................................. 13 Overflow Enable (T0IE Bit) ........................................ 14 Overflow Flag (T0IF Bit) ..................................... 14, 106 Overflow Interrupt .................................................... 106 RA4/T0CKI Pin, External Clock ................................... 6 Timer1 ................................................................................ 41 RC0/T1OSO/T1CKI Pin ............................................... 6 RC1/T1OSI Pin ............................................................ 6 Timers Timer0 External Clock .................................................... 38 Interrupt ............................................................. 37 Prescaler ............................................................ 38 Prescaler Block Diagram ................................... 37 Section ............................................................... 37 T0CKI ................................................................. 38 Timer1 Asynchronous Counter Mode ............................ 43 Capacitor Selection ............................................ 43 Operation in Timer Mode ................................... 42 Oscillator ............................................................ 43 Prescaler ............................................................ 43 Resetting of Timer1 Registers ........................... 43 Resetting Timer1 using a CCP Trigger Output .. 43 Synchronized Counter Mode ............................. 42 T1CON ............................................................... 41 TMR1H .............................................................. 43 TMR1L ............................................................... 43 Timer2 Block Diagram ................................................... 45 Postscaler .......................................................... 45 Prescaler ............................................................ 45 T2CON ............................................................... 45 Timing Diagrams A/D Conversion ........................................................ 142 Acknowledge Sequence Timing ................................. 75 Baud Rate Generator with Clock Arbitration .............. 68 BRG Reset Due to SDA Collision .............................. 80 Brown-out Reset ...................................................... 134 Bus Collision Start Condition Timing ....................................... 79 Bus Collision During a Restart Condition (Case 1) .... 81 Bus Collision During a Restart Condition (Case2) ..... 81 Bus Collision During a Start Condition (SCL = 0) ...... 80 Bus Collision During a Stop Condition ....................... 82 Bus Collision for Transmit and Acknowledge ............. 78 Capture/Compare/PWM ........................................... 136 CLKOUT and I/O ...................................................... 133 I2C Bus Data ............................................................ 140 I2C Bus Start/Stop bits ............................................. 139 I2C Master Mode First Start bit timing ........................ 69 I2C Master Mode Reception timing ............................ 74 I2C Master Mode Transmission timing ....................... 72 Master Mode Transmit Clock Arbitration .................... 77 Power-up Timer ....................................................... 134 Repeat Start Condition ............................................... 70 Reset ........................................................................ 134 SPI Master Mode ....................................................... 58 SPI Slave Mode (CKE = 1) ........................................ 59 SPI Slave Mode Timing (CKE = 0) ............................ 59 Start-up Timer .......................................................... 134 Stop Condition Receive or Transmit .......................... 76 Time-out Sequence on Power-up .................... 103, 104 1999 Microchip Technology Inc. Timer0 ..................................................................... 135 Timer1 ..................................................................... 135 Wake-up from SLEEP via Interrupt ......................... 109 Watchdog Timer ...................................................... 134 TMR0 ................................................................................. 11 TMR0 Register ..................................................................... 9 TMR1CS bit ....................................................................... 41 TMR1H .............................................................................. 11 TMR1H Register .................................................................. 9 TMR1L ............................................................................... 11 TMR1L Register ................................................................... 9 TMR1ON bit ....................................................................... 41 TMR2 ................................................................................. 11 TMR2 Register ..................................................................... 9 TMR2ON bit ....................................................................... 45 TOUTPS0 bit ..................................................................... 45 TOUTPS1 bit ..................................................................... 45 TOUTPS2 bit ..................................................................... 45 TOUTPS3 bit ..................................................................... 45 TRISA ................................................................................ 11 TRISA Register .................................................................. 10 TRISB ................................................................................ 11 TRISB Register .................................................................. 10 TRISC ................................................................................ 11 TRISC Register .................................................................. 10 U UA ...................................................................................... 54 Update Address, UA .......................................................... 54 W Wake-up from SLEEP ................................................ 95, 108 Interrupts ......................................................... 101, 102 MCLR Reset ............................................................ 102 Timing Diagram ....................................................... 109 WDT Reset .............................................................. 102 Watchdog Timer (WDT) ............................................. 95, 107 Block Diagram ......................................................... 107 Enable (WDTE Bit) .................................................. 107 Programming Considerations .................................. 107 RC Oscillator ........................................................... 107 Time-out Period ....................................................... 107 WDT Reset, Normal Operation .................. 99, 101, 102 WDT Reset, SLEEP .................................. 99, 101, 102 Waveform for General Call Address Sequence ................. 64 WCOL .................................................. 55, 69, 71, 73, 75, 76 WCOL Status Flag ............................................................. 69 Write Collision Detect bit, WCOL ....................................... 55 WWW, On-Line Support ...................................................... 3 DS30221A-page 155 PIC16F872 NOTES: DS30221A-page 156 1999 Microchip Technology Inc. PIC16F872 ON-LINE SUPPORT Systems Information and Upgrade Hot Line Microchip provides on-line support on the Microchip World Wide Web (WWW) site. The web site is used by Microchip as a means to make files and information easily available to customers. To view the site, the user must have access to the Internet and a web browser, such as Netscape or Microsoft Explorer. Files are also available for FTP download from our FTP site. The Systems Information and Upgrade Line provides system users a listing of the latest versions of all of Microchip's development systems software products. Plus, this line provides information on how customers can receive any currently available upgrade kits.The Hot Line Numbers are: 1-800-755-2345 for U.S. and most of Canada, and 1-480-786-7302 for the rest of the world. Connecting to the Microchip Internet Web Site 981103 The Microchip web site is available by using your favorite Internet browser to attach to: www.microchip.com The file transfer site is available by using an FTP service to connect to: ftp://ftp.microchip.com The web site and file transfer site provide a variety of services. Users may download files for the latest Development Tools, Data Sheets, Application Notes, User’s Guides, Articles and Sample Programs. A variety of Microchip specific business information is also available, including listings of Microchip sales offices, distributors and factory representatives. Other data available for consideration is: • Latest Microchip Press Releases • Technical Support Section with Frequently Asked Questions • Design Tips • Device Errata • Job Postings • Microchip Consultant Program Member Listing • Links to other useful web sites related to Microchip Products • Conferences for products, Development Systems, technical information and more • Listing of seminars and events 1999 Microchip Technology Inc. Trademarks: The Microchip name, logo, PIC, PICmicro, PICSTART, PICMASTER, PRO MATE and MPLAB are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FlexROM and fuzzyLAB are trademarks and SQTP is a service mark of Microchip in the U.S.A. All other trademarks mentioned herein are the property of their respective companies. Preliminary DS30221A-page 157 PIC16F872 READER RESPONSE It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please FAX your comments to the Technical Publications Manager at (480) 786-7578. Please list the following information, and use this outline to provide us with your comments about this Data Sheet. To: Technical Publications Manager RE: Reader Response Total Pages Sent From: Name Company Address City / State / ZIP / Country Telephone: (_______) _________ - _________ FAX: (______) _________ - _________ Application (optional): Would you like a reply? Device: PIC16F872 Y N Literature Number: DS30221A Questions: 1. What are the best features of this document? 2. How does this document meet your hardware and software development needs? 3. Do you find the organization of this data sheet easy to follow? If not, why? 4. What additions to the data sheet do you think would enhance the structure and subject? 5. What deletions from the data sheet 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? 8. How would you improve our software, systems, and silicon products? DS30221A-page 158 Preliminary 1999 Microchip Technology Inc. PIC16F872 PIC16F872 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. -X /XX XXX Device Temperature Range Package Pattern Examples: a) b) Device PIC16F872, PIC16F872T;VDD range 4.0V to 5.5V PIC16LF872, PIC16LF872T;VDD range 2.0V to 5.5V F LF T = CMOS FLASH = Low Power CMOS FLASH = in tape and reel - SOIC, SSOP, packages only. Temperature Range blank I = 0°C to = -40°C to Package SO SP SS = = = Pattern QTP, SQTP, Code or Special Requirements (blank otherwise) 70°C +85°C c) d) PIC16F872-I/SP 301 = Industrial temp., PDIP package, 20MHz, normal VDD limits, QTP pattern #301. PIC16F872-I/SO = Industrial temp., SOIC package, 20 MHz, normal VDD limits. PIC16F872/P = Industrial temp., PDIP package, 10MHz, normal VDD limits. PIC16LF872-I/SS = Industrial temp., SSOP package, DC - 20MHz, extended VDD limits. (Commercial) (Industrial) SOIC Skinny plastic dip SSOP Sales and Support Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. 2. 3. Your local Microchip sales office The Microchip Corporate Literature Center U.S. FAX: (480) 786-7277 The Microchip Worldwide Site (www.microchip.com) Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products. 1999 Microchip Technology Inc. Preliminary DS30221A-page 159 WORLDWIDE SALES AND SERVICE AMERICAS AMERICAS (continued) ASIA/PACIFIC (continued) Corporate Office Toronto Singapore Microchip Technology Inc. 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-786-7200 Fax: 480-786-7277 Technical Support: 480-786-7627 Web Address: http://www.microchip.com Microchip Technology Inc. 5925 Airport Road, Suite 200 Mississauga, Ontario L4V 1W1, Canada Tel: 905-405-6279 Fax: 905-405-6253 Microchip Technology Singapore Pte Ltd. 200 Middle Road #07-02 Prime Centre Singapore 188980 Tel: 65-334-8870 Fax: 65-334-8850 Atlanta Microchip Asia Pacific Unit 2101, Tower 2 Metroplaza 223 Hing Fong Road Kwai Fong, N.T., Hong Kong Tel: 852-2-401-1200 Fax: 852-2-401-3431 Microchip Technology Inc. 500 Sugar Mill Road, Suite 200B Atlanta, GA 30350 Tel: 770-640-0034 Fax: 770-640-0307 Boston Microchip Technology Inc. 5 Mount Royal Avenue Marlborough, MA 01752 Tel: 508-480-9990 Fax: 508-480-8575 Chicago Microchip Technology Inc. 333 Pierce Road, Suite 180 Itasca, IL 60143 Tel: 630-285-0071 Fax: 630-285-0075 Dallas Microchip Technology Inc. 4570 Westgrove Drive, Suite 160 Addison, TX 75248 Tel: 972-818-7423 Fax: 972-818-2924 Dayton Microchip Technology Inc. Two Prestige Place, Suite 150 Miamisburg, OH 45342 Tel: 937-291-1654 Fax: 937-291-9175 Detroit Microchip Technology Inc. Tri-Atria Office Building 32255 Northwestern Highway, Suite 190 Farmington Hills, MI 48334 Tel: 248-538-2250 Fax: 248-538-2260 Los Angeles Microchip Technology Inc. 18201 Von Karman, Suite 1090 Irvine, CA 92612 Tel: 949-263-1888 Fax: 949-263-1338 New York Microchip Technology Inc. 150 Motor Parkway, Suite 202 Hauppauge, NY 11788 Tel: 631-273-5305 Fax: 631-273-5335 San Jose Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955 ASIA/PACIFIC Hong Kong Taiwan, R.O.C Microchip Technology Taiwan 10F-1C 207 Tung Hua North Road Taipei, Taiwan, ROC Tel: 886-2-2717-7175 Fax: 886-2-2545-0139 EUROPE Beijing United Kingdom Microchip Technology, Beijing Unit 915, 6 Chaoyangmen Bei Dajie Dong Erhuan Road, Dongcheng District New China Hong Kong Manhattan Building Beijing 100027 PRC Tel: 86-10-85282100 Fax: 86-10-85282104 Arizona Microchip Technology Ltd. 505 Eskdale Road Winnersh Triangle Wokingham Berkshire, England RG41 5TU Tel: 44 118 921 5858 Fax: 44-118 921-5835 India Denmark Microchip Technology Inc. India Liaison Office No. 6, Legacy, Convent Road Bangalore 560 025, India Tel: 91-80-229-0061 Fax: 91-80-229-0062 Microchip Technology Denmark ApS Regus Business Centre Lautrup hoj 1-3 Ballerup DK-2750 Denmark Tel: 45 4420 9895 Fax: 45 4420 9910 Japan France Microchip Technology Intl. Inc. Benex S-1 6F 3-18-20, Shinyokohama Kohoku-Ku, Yokohama-shi Kanagawa 222-0033 Japan Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Arizona Microchip Technology SARL Parc d’Activite du Moulin de Massy 43 Rue du Saule Trapu Batiment A - ler Etage 91300 Massy, France Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Korea Germany Microchip Technology Korea 168-1, Youngbo Bldg. 3 Floor Samsung-Dong, Kangnam-Ku Seoul, Korea Tel: 82-2-554-7200 Fax: 82-2-558-5934 Arizona Microchip Technology GmbH Gustav-Heinemann-Ring 125 D-81739 München, Germany Tel: 49-89-627-144 0 Fax: 49-89-627-144-44 Shanghai Arizona Microchip Technology SRL Centro Direzionale Colleoni Palazzo Taurus 1 V. Le Colleoni 1 20041 Agrate Brianza Milan, Italy Tel: 39-039-65791-1 Fax: 39-039-6899883 Microchip Technology RM 406 Shanghai Golden Bridge Bldg. 2077 Yan’an Road West, Hong Qiao District Shanghai, PRC 200335 Tel: 86-21-6275-5700 Fax: 86 21-6275-5060 Italy 11/15/99 Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999. The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs and microperipheral products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified. All rights reserved. © 1999 Microchip Technology Incorporated. Printed in the USA. 12/99 Printed on recycled paper. Information contained in this publication regarding device applications and the like is intended for suggestion only and may be superseded by updates. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. The Microchip logo and name are registered trademarks of Microchip Technology Inc. in the U.S.A. and other countries. All rights reserved. All other trademarks mentioned herein are the property of their respective companies. DS30221A-page 160 1999 Microchip Technology Inc.