PIC16F720-ESLASHML datasheet(165/244 Pages) MICROCHIP

165 / 244 page

 2010 Microchip Technology Inc.

DS41430A-page 165

PIC16F/LF720/721

EXAMPLE 18-2:

WRITING TO FLASH PROGRAM MEMORY

; This write routine assumes the following:

; 1. A valid starting address (the least significant bits = ‘00000’)is loaded in ADDRH:ADDRL

; 2. The 64 bytes of data are loaded, starting at the address in DATADDR

; 3. ADDRH, ADDRL and DATADDR are all located in shared data memory 0x70 - 0x7f

;

BANKSEL PMADRH

; Bank 3

MOVF

ADDRH,W

; Load initial address

MOVWF

PMADRH

;

MOVF

ADDRL,W

;

MOVWF

PMADRL

;

MOVF

DATAADDRL,W

; Load initial data address

MOVWF

FSR0L

;

MOVF

DATAADDRH,W

; Load initial data address

MOVWF

FSR0H

;

LOOP

MOVIW

INDF0++

; Load first data byte into lower

MOVWF

PMDATL

;

MOVIW

INDF0++

; Load second data byte into upper

MOVWF

PMDATH

;

BSF

PMCON1,WREN

; Enable writes

BSF

PMCON1,LWLO

; Only Load Write Latches

MOVLW

55h

; Start of required write sequence:

MOVWF

PMCON2

; Write 55h

MOVLW

AAh

;

MOVWF

PMCON2

; Write AAh

BSF

PMCON1,WR

; Set WR bit to begin write

NOP

; Any instructions here are ignored as processor

; halts to begin write sequence

NOP

; processor will stop here and wait for write complete

; after write processor continues with 3rd instruction

MOVF

PMADR,W

; Check if lower five bits of address are ‘11111’

XORLW

0x1F

; Check if we’re on the last of 8 addresses

ANDLW

0x1F

;

BTFSC

STATUS,Z

; Exit if last of 32 words,

GOTO

START_WRITE

;

INCF

PMADR,F

; Still loading latches Increment address

GOTO

LOOP

; Write next latches

START_WRITE

BCF

PMCON1,LWLO

; No more Latches only; Actually start write

MOVLW

55h

; Start of required write sequence:

MOVWF

PMCON2

; Write 55h

MOVLW

AAh

;

MOVWF

PMCON2

; Write AAh

BSF

PMCON1,WR

; Set WR bit to begin write

NOP

; Any instructions here are ignored as processor

; halts to begin write sequence

NOP

; processor will stop here and wait for write complete

; after write processor continues with 3rd instruction

BCF

PMCON1,WREN

; Disable writes

PIC16F720-E/ML Datasheet(PDF) 165 Page - Microchip Technology

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