Microchip Technology MA160014 Data Sheet
PIC18(L)F2X/4XK22
DS41412F-page 102
2010-2012 Microchip Technology Inc.
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY
MOVLW
D'64’
; number of bytes in erase block
MOVWF
COUNTER
MOVLW
BUFFER_ADDR_HIGH
; point to buffer
MOVWF
FSR0H
MOVLW
BUFFER_ADDR_LOW
MOVWF
FSR0L
MOVLW
CODE_ADDR_UPPER
; Load TBLPTR with the base
MOVWF
TBLPTRU
; address of the memory block
MOVLW
CODE_ADDR_HIGH
MOVWF
TBLPTRH
MOVLW
CODE_ADDR_LOW
MOVWF
TBLPTRL
READ_BLOCK
TBLRD*+
; read into TABLAT, and inc
MOVF
TABLAT, W
; get data
MOVWF
POSTINC0
; store data
DECFSZ
COUNTER ;
done?
BRA
READ_BLOCK
; repeat
MODIFY_WORD
MOVLW
BUFFER_ADDR_HIGH
; point to buffer
MOVWF
FSR0H
MOVLW
BUFFER_ADDR_LOW
MOVWF
FSR0L
MOVLW
NEW_DATA_LOW
; update buffer word
MOVWF
POSTINC0
MOVLW
NEW_DATA_HIGH
MOVWF
INDF0
ERASE_BLOCK
MOVLW
CODE_ADDR_UPPER
; load TBLPTR with the base
MOVWF
TBLPTRU
; address of the memory block
MOVLW
CODE_ADDR_HIGH
MOVWF
TBLPTRH
MOVLW
CODE_ADDR_LOW
MOVWF
TBLPTRL
BSF
EECON1, EEPGD
; point to Flash program memory
BCF
EECON1, CFGS
; access Flash program memory
BSF
EECON1, WREN
; enable write to memory
BSF
EECON1, FREE
; enable Erase operation
BCF
INTCON, GIE
; disable interrupts
MOVLW
55h
Required
MOVWF
EECON2
; write 55h
Sequence
MOVLW
0AAh
MOVWF
EECON2
; write 0AAh
BSF
EECON1, WR
; start erase (CPU stall)
BSF
INTCON, GIE
; re-enable interrupts
TBLRD*-
; dummy read decrement
MOVLW
BUFFER_ADDR_HIGH
; point to buffer
MOVWF
FSR0H
MOVLW
BUFFER_ADDR_LOW
MOVWF
FSR0L
WRITE_BUFFER_BACK
MOVLW
BlockSize
; number of bytes in holding register
MOVWF
COUNTER
MOVLW
D’64’/BlockSize
; number of write blocks in 64 bytes
MOVWF
COUNTER2
WRITE_BYTE_TO_HREGS
MOVF
POSTINC0, W
; get low byte of buffer data
MOVWF
TABLAT
; present data to table latch
TBLWT+*
; write data, perform a short write
; to internal TBLWT holding register.