Datasheet

 2002-2013 Microchip Technology Inc. DS30487D-page 33
PIC16F87/88
An example of the complete four-word write sequence
is shown in Example 3-5. The initial address is loaded
into the EEADRH:EEADR register pair; the four words
of data are loaded using indirect addressing, assuming
that a row erase sequence has already been
performed.
EXAMPLE 3-5: WRITING TO FLASH PROGRAM MEMORY
; This write routine assumes the following:
; 1. The 32 words in the erase block have already been erased.
; 2. A valid starting address (the least significant bits = '00') is loaded into EEADRH:EEADR
; 3. This example is starting at 0x100, this is an application dependent setting.
; 4. The 8 bytes (4 words) of data are loaded, starting at an address in RAM called ARRAY.
; 5. This is an example only, location of data to program is application dependent.
; 6. word_block is located in data memory.
BANKSEL EECON1 ;prepare for WRITE procedure
BSF EECON1, EEPGD ;point to program memory
BSF EECON1, WREN ;allow write cycles
BCF EECON1, FREE ;perform write only
BANKSEL word_block
MOVLW .4
MOVWF word_block ;prepare for 4 words to be written
BANKSEL EEADRH ;Start writing at 0x100
MOVLW 0x01
MOVWF EEADRH ;load HIGH address
MOVLW 0x00
MOVWF EEADR ;load LOW address
BANKSEL ARRAY
MOVLW ARRAY ;initialize FSR to start of data
MOVWF FSR
LOOP
BANKSEL EEDATA
MOVF INDF, W ;indirectly load EEDATA
MOVWF EEDATA
INCF FSR, F ;increment data pointer
MOVF INDF, W ;indirectly load EEDATH
MOVWF EEDATH
INCF FSR, F ;increment data pointer
BANKSEL EECON1
MOVLW 0x55 ;required sequence
MOVWF EECON2
MOVLW 0xAA
MOVWF EECON2
BSF EECON1, WR ;set WR bit to begin write
NOP ;instructions here are ignored as processor
NOP
BANKSEL EEADR
INCF EEADR, f ;load next word address
BANKSEL word_block
DECFSZ word_block, f ;have 4 words been written?
GOTO loop ;NO, continue with writing
BANKSEL EECON1
BCF EECON1, WREN ;YES, 4 words complete, disable writes
BSF INTCON,GIE ;enable interrupts
Required
Sequence