PIC16F/LF1946/47
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
EEADRH
ADDRH,W
EEADRH
ADDRL,W
EEADRL
; Disable ints so required sequences will execute properly
; Bank 3
; Load initial address
;
;
;
BANKSEL
MOVF
MOVWF
MOVF
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
LOW DATA_ADDR ; Load initial data address
FSR0L
HIGH DATA_ADDR ; Load initial data address
;
FSR0H
;
EECON1,EEPGD
EECON1,CFGS
EECON1,WREN
EECON1,LWLO
; Point to program memory
; Not configuration space
; Enable writes
BCF
BSF
BSF
; Only Load Write Latches
LOOP
MOVIW
MOVWF
MOVIW
MOVWF
FSR0++
EEDATL
FSR0++
EEDATH
; Load first data byte into lower
;
; Load second data byte into upper
;
MOVF
EEADRL,W
0x07
0x07
STATUS,Z
START_WRITE
; Check if lower bits of address are '000'
; Check if we're on the last of 8 addresses
;
; Exit if last of eight words,
;
XORLW
ANDLW
BTFSC
GOTO
MOVLW
MOVWF
MOVLW
MOVWF
BSF
55h
EECON2
0AAh
EECON2
EECON1,WR
; Start of required write sequence:
; Write 55h
;
; Write AAh
; 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
GOTO
EEADRL,F
LOOP
; Still loading latches Increment address
; Write next latches
START_WRITE
BCF
EECON1,LWLO
; No more loading latches - Actually start Flash program
; memory write
MOVLW
55h
EECON2
0AAh
EECON2
EECON1,WR
; Start of required write sequence:
; Write 55h
;
MOVWF
MOVLW
MOVWF
BSF
; Write AAh
; Set WR bit to begin write
; Any instructions here are ignored as processor
; halts to begin write sequence
; Processor will stop here and wait for write complete.
NOP
NOP
; after write processor continues with 3rd instruction
; Disable writes
; Enable interrupts
BCF
BSF
EECON1,WREN
INTCON,GIE
2010 Microchip Technology Inc.
Preliminary
DS41414A-page 115
MICROCHIP [ MICROCHIP ]
