Datasheet
2010-2012 Microchip Technology Inc. DS41419D-page 115
PIC16(L)F1824/1828
EXAMPLE 11-5: WRITING TO FLASH PROGRAM MEMORY
; This write routine assumes the following:
; 1. The 16 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 = 000) is loaded in ADDRH:ADDRL
; 4. ADDRH and ADDRL are located in shared data memory 0x70 - 0x7F
;
BCF INTCON,GIE ; Disable ints so required sequences will execute properly
BANKSEL EEADRH ; Bank 3
MOVF ADDRH,W ; Load initial address
MOVWF EEADRH ;
MOVF ADDRL,W ;
MOVWF EEADRL ;
MOVLW LOW DATA_ADDR ; Load initial data address
MOVWF FSR0L ;
MOVLW HIGH DATA_ADDR ; Load initial data address
MOVWF FSR0H ;
BSF EECON1,EEPGD ; Point to program memory
BCF EECON1,CFGS ; Not configuration space
BSF EECON1,WREN ; Enable writes
BSF EECON1,LWLO ; Only Load Write Latches
LOOP
MOVIW FSR0++ ; Load first data byte into lower
MOVWF EEDATL ;
MOVIW FSR0++ ; Load second data byte into upper
MOVWF EEDATH ;
MOVF EEADRL,W ; Check if lower bits of address are '000'
XORLW 0x07 ; Check if we're on the last of 8 addresses
ANDLW 0x07 ;
BTFSC STATUS,Z ; Exit if last of eight words,
GOTO START_WRITE ;
MOVLW 55h ; Start of required write sequence:
MOVWF EECON2 ; Write 55h
MOVLW 0AAh ;
MOVWF EECON2 ; Write AAh
BSF EECON1,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 to complete.
; After write processor continues with 3rd instruction.
INCF EEADRL,F ; Still loading latches Increment address
GOTO LOOP ; Write next latches
START_WRITE
BCF EECON1,LWLO ; No more loading latches - Actually start Flash program
; memory write
MOVLW 55h ; Start of required write sequence:
MOVWF EECON2 ; Write 55h
MOVLW 0AAh ;
MOVWF EECON2 ; Write AAh
BSF EECON1,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 EECON1,WREN ; Disable writes
BSF INTCON,GIE ; Enable interrupts
Required
Sequence
Required
Sequence