Datasheet

PIC16(L)F1516/7/8/9
DS41452C-page 100  2010-2012 Microchip Technology Inc.
EXAMPLE 11-3: WRITING TO FLASH PROGRAM MEMORY
; This write routine assumes the following:
; 1. 64 bytes of data are loaded, starting at the address in DATA_ADDR
; 2. Each word of data to be written is made up of two adjacent bytes in DATA_ADDR,
; stored in little endian format
; 3. A valid starting address (the least significant bits = 00000) is loaded in ADDRH:ADDRL
; 4. ADDRH and ADDRL are located in shared data memory 0x70 - 0x7F (common RAM)
;
BCF INTCON,GIE ; Disable ints so required sequences will execute properly
BANKSEL PMADRH ; Bank 3
MOVF ADDRH,W ; Load initial address
MOVWF PMADRH ;
MOVF ADDRL,W ;
MOVWF PMADRL ;
MOVLW LOW DATA_ADDR ; Load initial data address
MOVWF FSR0L ;
MOVLW HIGH DATA_ADDR ; Load initial data address
MOVWF FSR0H ;
BCF PMCON1,CFGS ; Not configuration space
BSF PMCON1,WREN ; Enable writes
BSF PMCON1,LWLO ; Only Load Write Latches
LOOP
MOVIW FSR0++ ; Load first data byte into lower
MOVWF PMDATL ;
MOVIW FSR0++ ; Load second data byte into upper
MOVWF PMDATH ;
MOVF PMADRL,W ; Check if lower bits of address are '00000'
XORLW 0x1F ; Check if we're on the last of 32 addresses
ANDLW 0x1F ;
BTFSC STATUS,Z ; Exit if last of 32 words,
GOTO START_WRITE ;
MOVLW 55h ; Start of required write sequence:
MOVWF PMCON2 ; Write 55h
MOVLW 0AAh ;
MOVWF PMCON2 ; Write AAh
BSF PMCON1,WR ; Set WR bit to begin write
NOP ; NOP instructions are forced as processor
; loads program memory write latches
NOP ;
INCF PMADRL,F ; Still loading latches Increment address
GOTO LOOP ; Write next latches
START_WRITE
BCF PMCON1,LWLO ; No more loading latches - Actually start Flash program
; memory write
MOVLW 55h ; Start of required write sequence:
MOVWF PMCON2 ; Write 55h
MOVLW 0AAh ;
MOVWF PMCON2 ; Write AAh
BSF PMCON1,WR ; Set WR bit to begin write
NOP ; NOP instructions are forced as processor writes
; all the program memory write latches simultaneously
NOP ; to program memory.
; After NOPs, the processor
; stalls until the self-write process in complete
; after write processor continues with 3rd instruction
BCF PMCON1,WREN ; Disable writes
BSF INTCON,GIE ; Enable interrupts
Required
Sequence
Required
Sequence