PIC18F1230 MICROCHIP [Microchip Technology], PIC18F1230 Datasheet - Page 202

• Manufacturer Part Number: PIC18F1230
• Description: 18/20/28-Pin, Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F1230/1330
19.5.1
The program memory may be read to or written from
any location using the table read and table write
instructions. The Device ID may be read with table
reads. The Configuration registers may be read and
written with the table read and table write instructions.
In normal execution mode, the CPx bits have no direct
effect. CPx bits inhibit external reads and writes. A
block of user memory may be protected from table
writes if the WRTx Configuration bit is ‘0’. The EBTRx
bits control table reads. For a block of user memory
with the EBTRx bit set to ‘0’, a table read instruction
that executes from within that block is allowed to read.
FIGURE 19-6:
DS39758B-page 200
Results: All table writes disabled to Blockn whenever WRTx = 0.
TBLPTR = 0008FFh
Register Values
PROGRAM MEMORY
CODE PROTECTION
PC = 000FFEh
PC = 001800h
TABLE WRITE (WRTx) DISALLOWED
Advance Information
Program Memory
TBLWT*
TBLWT*
A table read instruction that executes from a location
outside of that block is not allowed to read and will result
in reading ‘0’s. Figures 19-6 through 19-8 illustrate table
write and table read protection.
Note:
000000h
0007FFh
000800h
000FFFh
001000h
001FFFh
Code protection bits may only be written to
a ‘0’ from a ‘1’ state. It is not possible to
write a ‘1’ to a bit in the ‘0’ state. Code
protection bits are only set to ‘1’ by a full
chip erase or block erase function. The full
chip erase and block erase functions can
only be initiated via ICSP operation or an
external programmer.
Configuration Bit Settings
WRTB, EBTRB = 11
WRT0, EBTR0 = 01
WRT1, EBTR1 = 11
© 2006 Microchip Technology Inc.