Microchip Technology DV164136 Data Sheet

 2007-2012 Microchip Technology Inc.

DS39778E-page 103

7.5.2

FLASH PROGRAM MEMORY WRITE 
SEQUENCE (WORD 
PROGRAMMING).

The PIC18F87J11 family of devices have a feature that
allows programming a single word (two bytes). This
feature is enable when the WPROG bit is set. If the
memory location is already erased, the following
sequence is required to enable this feature:
1.

Load the Table Pointer register with the address
of the data to be written

2.

Write the 2 bytes into the holding registers and
perform a table write

3.

Set the WREN bit (EECON1<2>) to enable byte
writes.

4.

Disable interrupts.

5.

Write H

'

55

'

 to EECON2.

6.

Write H

'

AA

'

 to EECON2.

7.

Set the WR bit. This will begin the write cycle.

8.

The CPU will stall for duration of the write for T

IW

(see Parameter 

9.

Re-enable interrupts.

MOVLW    CODE_ADDR_UPPER 

; Load TBLPTR with the base address

MOVWF    TBLPTRU

MOVLW    CODE_ADDR_HIGH

MOVWF    TBLPTRH

MOVLW    CODE_ADDR_LOW

MOVWF    TBLPTRL

MOVLW    DATA0

MOVWF    TABLAT

TBLWT*+

MOVLW    DATA1

MOVWF    TABLAT

TBLWT*

PROGRAM_MEMORY

BSF

EECON1, WPROG 

; enable single word write

BSF

EECON1, WREN 

; enable write to memory

BCF

INTCON, GIE 

; disable interrupts

MOVLW

H'55'

Required

MOVWF

EECON2

 

; write H'55'

Sequence MOVLW

H'AA'

MOVWF

EECON2

; write H'AA'

BSF

EECON1, WR 

; start program (CPU stall)

BSF

INTCON, GIE

; re-enable interrupts

BCF

EECON1, WPROG 

; disable single word write

BCF

EECON1, WREN 

; disable write to memory