PIC18F6585 Datasheet, PDF (92/496 Pages) Microchip Technology – 64/68/80-Pin High-Performance, 64-Kbyte Enhanced Flash Microcontrollers with ECAN Module

PIC18F6585/8585/6680/8680
5.5.1
FLASH PROGRAM MEMORY WRITE
SEQUENCE
The sequence of events for programming an internal
program memory location should be:
1. Read 64 bytes into RAM.
2. Update data values in RAM as necessary.
3. Load table pointer with address being erased.
4. Do the row erase procedure.
5. Load table pointer with address of first byte
being written.
6. Write the first 8 bytes into the holding registers
with auto-increment.
7. Set the EECON1 register for the write operation:
• set EEPGD bit to point to program memory;
• clear the CFGS bit to access program memory;
• set WREN to enable byte writes.
8. Disable interrupts.
9. Write 55h to EECON2.
10. Write 0AAh to EECON2.
11. Set the WR bit. This will begin the write cycle.
12. The CPU will stall for duration of the write (about
5 ms using internal timer).
13. Execute a NOP.
14. Re-enable interrupts.
15. Repeat steps 6-14 seven times to write 64 bytes.
16. Verify the memory (table read).
This procedure will require about 40 ms to update one
row of 64 bytes of memory. An example of the required
code is given in Example 5-3.
Note:
Before setting the WR bit, the Table
Pointer address needs to be within the
intended address range of the eight bytes
in the holding register.
EXAMPLE 5-3: WRITING TO FLASH PROGRAM MEMORY
READ_BLOCK
MODIFY_WORD
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
D’64
COUNTER
high(BUFFER_ADDR)
FSR0H
low(BUFFER_ADDR)
FSR0L
upper(CODE_ADDR)
TBLPTRU
high(CODE_ADDR)
TBLPTRH
low(CODE_ADDR)
TBLPTRL
TBLRD*+
MOVF
MOVWF
DECFSZ
BRA
TABLAT, W
POSTINC0
COUNTER
READ_BLOCK
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
MOVLW
MOVWF
high(DATA_ADDR)
FSR0H
low(DATA_ADDR)
FSR0L
low(NEW_DATA)
POSTINC0
high(NEW_DATA)
INDF0
; number of bytes in erase block
; point to buffer
; Load TBLPTR with the base
; address of the memory block
; read into TABLAT, and inc
; get data
; store data
; done?
; repeat
; point to buffer
; update buffer word
DS30491C-page 90
 2004 Microchip Technology Inc.