PIC18F2XK20/4XK20
DS41297F-page 22
Advance Information
2009 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-
Memory”. As with code memory, the ID locations must
be erased before being modified.
When VDD is below the minimum for Bulk Erase
operation, ID locations can be cleared with the Row
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.
0000
8E A6
9C A6
84 A6
BSF EECON1, EEPGD
BCF EECON1, CFGS
BSF EECON1, WREN
Step 2: Set Table Pointer to ID. Load write buffer with 8 bytes and write.
0000
1101
1111
0000
0E 20
6E F8
0E 00
6E F7
0E 00
6E F6
<MSB><LSB>
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.
