PIC18F2220/2320/4220/4320
EXAMPLE 6-3:
WRITING TO FLASH PROGRAM MEMORY
MOVLW
D'64
; number of bytes in erase block
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
COUNTER
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
; point to buffer
; Load TBLPTR with the base
; address of the memory block
; 6 LSB = 0
READ_BLOCK
TBLRD*+
MOVFW
; read into TABLAT, and inc
; get data
TABLAT
MOVWF
DECFSZ COUNTER
POSTINC0
; store data and increment FSR0
; done?
GOTO
READ_BLOCK
; repeat
MODIFY_WORD
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
DATA_ADDR_HIGH
FSR0H
DATA_ADDR_LOW
FSR0L
NEW_DATA_LOW
POSTINC0
NEW_DATA_HIGH
INDF0
; point to buffer
; update buffer word and increment FSR0
; update buffer word
ERASE_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
BCF
BSF
BSF
BSF
BCF
MOVLW
MOVWF
MOVLW
MOVWF
BSF
CODE_ADDR_UPPER
TBLPTRU
CODE_ADDR_HIGH
TBLPTRH
CODE_ADDR_LOW
TBLPTRL
EECON1,CFGS
EECON1,EEPGD
EECON1,WREN
EECON1,FREE
INTCON,GIE
55h
; load TBLPTR with the base
; address of the memory block
; 6 LSB = 0
; point to PROG/EEPROM memory
; point to Flash program memory
; enable write to memory
; enable Row Erase operation
; disable interrupts
; Required sequence
; write 55H
EECON2
AAh
EECON2
EECON1,WR
; write AAH
; start erase (CPU stall)
NOP
BSF
INTCON,GIE
; re-enable interrupts
WRITE_BUFFER_BACK
MOVLW
8
; number of write buffer groups of 8 bytes
; point to buffer
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
COUNTER_HI
BUFFER_ADDR_HIGH
FSR0H
BUFFER_ADDR_LOW
FSR0L
PROGRAM_LOOP
MOVLW
MOVWF
8
; number of bytes in holding register
COUNTER
WRITE_WORD_TO_HREGS
MOVFW
MOVWF
TBLWT+*
POSTINC0
TABLAT
; get low byte of buffer data and increment FSR0
; present data to table latch
; short write
; to internal TBLWT holding register, increment
TBLPTR
DECFSZ COUNTER
GOTO WRITE_WORD_TO_HREGS
; loop until buffers are full
DS39599C-page 78
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
