Datasheet

PIC24FJ64GA004 FAMILY
DS39881E-page 52  2010-2013 Microchip Technology Inc.
5.5.2 PROGRAMMING A SINGLE WORD
OF FLASH PROGRAM MEMORY
If a Flash location has been erased, it can be pro-
grammed using table write instructions to write an
instruction word (24-bit) into the write latch. The
TBLPAG register is loaded with the 8 Most Significant
Bytes of the Flash address. The TBLWTL and TBLWTH
instructions write the desired data into the write latches
and specify the lower 16 bits of the program memory
address to write to. To configure the NVMCON register
for a word write, set the NVMOPx bits (NVMCON<3:0>)
to ‘0011’. The write is performed by executing the unlock
sequence and setting the WR bit (see Example 5-4).
EXAMPLE 5-4: PROGRAMMING A SINGLE WORD OF FLASH PROGRAM MEMORY
; Setup a pointer to data Program Memory
MOV #tblpage(PROG_ADDR), W0 ;
MOV W0, TBLPAG ;Initialize PM Page Boundary SFR
MOV #tbloffset(PROG_ADDR), W0 ;Initialize a register with program memory address
MOV #LOW_WORD_N, W2 ;
MOV #HIGH_BYTE_N, W3 ;
TBLWTL W2, [W0] ; Write PM low word into program latch
TBLWTH W3, [W0++] ; Write PM high byte into program latch
; Setup NVMCON for programming one word to data Program Memory
MOV #0x4003, W0 ;
MOV W0, NVMCON ; Set NVMOP bits to 0011
DISI #5 ; Disable interrupts while the KEY sequence is written
MOV #0x55, W0 ; Write the key sequence
MOV W0, NVMKEY
MOV #0xAA, W0
MOV W0, NVMKEY
BSET NVMCON, #WR ; Start the write cycle
NOP ; 2 NOPs required after setting WR
NOP ;