PIC16F1938_13 Datasheet, PDF (115/488 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver

PIC16(L)F1938/9
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 (common RAM)
;
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
XORLW
ANDLW
BTFSC
GOTO
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,
;
MOVLW
MOVWF
MOVLW
MOVWF
BSF
NOP
NOP
55h
EECON2
0AAh
EECON2
EECON1,WR
; Start of required write sequence:
; Write 55h
;
; 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 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
MOVWF
MOVLW
MOVWF
BSF
NOP
NOP
55h
EECON2
0AAh
EECON2
EECON1,WR
; Start of required write sequence:
; Write 55h
;
; 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.
; after write processor continues with 3rd instruction
BCF
EECON1,WREN ; Disable writes
BSF
INTCON,GIE
; Enable interrupts
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DS40001574C-page 115