Datasheet

PIC18F2XXX/4XXX FAMILY

DS39622L-page 22  2010 Microchip Technology Inc.

3.4 ID Location Programming

The ID locations are programmed much like the code

memory. The ID registers are mapped in addresses,

200000h through 200007h. These locations read out

normally even after code protection.

Table 3-8 demonstrates the code sequence required to

write the ID locations.

In order to modify the ID locations, refer to the method-

ology described in Section 3.2.1 “Modifying Code

Memory”. As with code memory, the ID locations must

be erased before being modified.

TABLE 3-8: WRITE ID SEQUENCE

Note: The user only needs to fill the first 8 bytes

of the write buffer in order to write the ID

locations.

4-Bit

Command

Data Payload Core Instruction

Step 1: Direct access to code memory and enable writes.

0000

8E A6

9C A6

BSF EECON1, EEPGD

BCF EECON1, CFGS

Step 2: Load write buffer with 8 bytes and write.

0000

1101

1111

0000

0E 20

6E F8

0E 00

6E F7

0E 00

6E F6

00 00

MOVLW 20h

MOVWF TBLPTRU

MOVLW 00h

MOVWF TBLPTRH

MOVLW 00h

MOVWF TBLPTRL

Write 2 bytes and post-increment address by 2.

Write 2 bytes and start programming.

NOP - hold PGC high for time P9 and low for time P10.