 2010 Microchip Technology Inc.

DS39991A-page 9

PIC24FXXKA2XX

3.5

Erasing Program Memory

To erase the program memory (all of code memory,

data memory and Configuration bits, including the

code-protect bits), set the NVMCON to 4064h and then

execute the programming cycle.

Figure 3-6 illustrates the ICSP programming process

for Bulk Erase. This process includes the ICSP

command code, which must be transmitted (for each

instruction), LSB first, using the PGCx and PGDx pins

(see Figure 3-2).

Table 3-4 provides the steps for executing serial

instruction for the Bulk Erase mode.

FIGURE 3-6:

BULK ERASE FLOW

TABLE 3-4:

SERIAL INSTRUCTION EXECUTION FOR CHIP ERASE

Note:

Program memory must be erased before

writing any data to program memory.

End

Set the WR bit to Initiate Erase

Write 4064h to NVMCON SFR

Delay P11 + P10 Time

Start

Command

(Binary)

Data

(Hex)

Description

Step 1: Exit the Reset vector.

0000

0000

0000

000000

040200

000000

NOP

GOTO

0x200

NOP

Step 2: Set the NVMCON to erase the entire program memory.

0000

0000

24064A

883B0A

MOV

#0x4064, W10

MOV

W10, NVMCON

Step 3: Set the TBLPAG and perform dummy table write to select the erased memory.

0000

0000

0000

0000

0000

0000

200000

880190

200000

BB0800

000000

000000

MOV

#<PAGEVAL>, W0

MOV

W0, TBLPAG

MOV

#0x0000, W0

TBLWTL W0, [W0]

NOP

NOP

Step 4: Initiate the erase cycle.

0000

0000

0000

A8E761

000000

000000

BSET

NVMCON, #WR

NOP

NOP

Step 5: Repeat this step to poll the WR bit (bit 15 of NVMCON) until it is cleared by the hardware.

0000

0000

0000

0000

0000

0000

0001

0000

000000

040200

000000

803B02

883C22

000000

<VISI>

000000

NOP

GOTO

0x200

NOP

MOV

NVMCON, W2

MOV

W2, VISI

NOP

Clock out the contents of the VISI register.

NOP