DSPIC33F datasheet(35/80 Pages) MICROCHIP

35 / 80 page

Preliminary

DS70152D-page 35

dsPIC33F/PIC24H PROGRAMMING SPECIFICATION

FIGURE 3-3:

ENTERING ENHANCED ICSP™ MODE

3.4

Blank Check

The term “Blank Check” implies verifying that the

device has been successfully erased and has no

programmed memory locations. A blank or erased

memory location is always read as a ‘1’.

The Device ID registers (0xFF0000:0xFF0002) can be

ignored by the Blank Check since this region stores

device information that cannot be erased. The device

Configuration registers are also ignored by the Blank

Check. Additionally, all unimplemented memory space

should be ignored from the Blank Check.

The QBLANK command is used for the Blank Check. It

determines if the code memory is erased by testing

these memory regions. A ‘BLANK’ or ‘NOT BLANK’

response is returned. If it is determined that the device

is not blank, it must be erased before attempting to

program the chip.

3.5

Code Memory Programming

3.5.1

PROGRAMMING METHODOLOGY

Code memory is programmed with the PROGP

command. PROGP programs one row of code memory

starting from the memory address specified in the

command. The number of PROGP commands required

to program a device depends on the number of write

blocks that must be programmed in the device.

A flowchart for programming code memory is shown in

Figure 3-4. In this example, all 88K instruction words of

a dsPIC33F/PIC24H device are programmed. First, the

number of commands to send (called ‘RemainingC-

mds’ in the flowchart) is set to 1368 and the destination

address (called ‘BaseAddress’) is set to ‘0’. Next, one

write block in the device is programmed with a PROGP

command. Each PROGP command contains data for

one row of code memory of the dsPIC33F/PIC24H.

After the first command is processed successfully,

‘RemainingCmds’ is decremented by ‘1’ and compared

with ‘0’. Since there are more PROGP commands to

send, ‘BaseAddress’ is incremented by 0x80 to point to

the next row of memory.

On the second PROGP command, the second row is

programmed. This process is repeated until the entire

device is programmed..

MCLR

PGD

PGC

VDD

P14

b31

b30

b29

b28

b27

...

Program/Verify Entry Code = 0x4D434850

P1A

P1B

P18

P19

001

000

VIH

Note:

If a bootloader needs to be programmed,

the bootloader code must not be pro-

grammed into the first page of code mem-

ory. For example, if a bootloader located at

address 0x200 attempts to erase the first

page, it would inadvertently erase itself.

Instead, program the bootloader into the

second page, e.g. 0x400.

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