DSPIC30F2012AT20ISLASHP datasheet(51/205 Pages) MICROCHIP

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DS70139E-page 49

dsPIC30F2011/2012/3012/3013

5.6

Programming Operations

A complete programming sequence is necessary for

programming or erasing the internal Flash in RTSP

mode. A programming operation is nominally 2 msec in

duration and the processor stalls (waits) until the oper-

ation is finished. Setting the WR bit (NVMCON<15>)

starts the operation and the WR bit is automatically

cleared when the operation is finished.

5.6.1

PROGRAMMING ALGORITHM FOR

PROGRAM FLASH

The user can erase or program one row of program

Flash memory at a time. The general process is:

Read one row of program Flash (32 instruction

words) and store into data RAM as a data

“image”.

Update the data image with the desired new

data.

Erase program Flash row.

Setup NVMCON register for multi-word,

program Flash, erase, and set WREN bit.

Write address of row to be erased into

NVMADRU/NVMDR.

Write ‘55’ to NVMKEY.

Write ‘AA’ to NVMKEY.

Set the WR bit. This begins erase cycle.

CPU stalls for the duration of the erase cycle.

The WR bit is cleared when erase cycle

ends.

Write 32 instruction words of data from data

RAM “image” into the program Flash write

latches.

Program 32 instruction words into program

Flash.

Setup NVMCON register for multi-word,

program Flash, program, and set WREN

bit.

Write ‘55’ to NVMKEY.

Write ‘AA’ to NVMKEY.

Set the WR bit. This begins program cycle.

CPU stalls for duration of the program cycle.

The WR bit is cleared by the hardware

when program cycle ends.

Repeat steps 1 through 5 as needed to program

desired amount of program Flash memory.

5.6.2

ERASING A ROW OF PROGRAM

MEMORY

Example 5-1 shows a code sequence that can be used

to erase a row (32 instructions) of program memory.

EXAMPLE 5-1:

ERASING A ROW OF PROGRAM MEMORY

; Setup NVMCON for erase operation, multi word write

; program memory selected, and writes enabled

MOV

#0x4041,W0

;

MOV

W0,NVMCON

; Init NVMCON SFR

; Init pointer to row to be ERASED

MOV

#tblpage(PROG_ADDR),W0

;

MOV

W0,NVMADRU

; Initialize PM Page Boundary SFR

MOV

#tbloffset(PROG_ADDR),W0

; Intialize in-page EA[15:0] pointer

MOV

W0, NVMADR

; Initialize NVMADR SFR

DISI

; Block all interrupts with priority <7 for

; next 5 instructions

MOV

#0x55,W0

MOV

W0,NVMKEY

; Write the 0x55 key

MOV

#0xAA,W1

;

MOV

W1,NVMKEY

; Write the 0xAA key

BSET

NVMCON,#WR

; Start the erase sequence

NOP

; Insert two NOPs after the erase

NOP

; command is asserted

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