Datasheet

© 2008 Microchip Technology Inc. DS39631E-page 263
PIC18F2420/2520/4420/4520
23.5 Program Verification and
Code Protection
The overall structure of the code protection on the
PIC18 Flash devices differs significantly from other
PIC
®
devices.
The user program memory is divided into five blocks.
One of these is a boot block of 2 Kbytes. The remainder
of the memory is divided into four blocks on binary
boundaries.
Each of the five blocks has three code protection bits
associated with them. They are:
• Code-Protect bit (CPn)
• Write-Protect bit (WRTn)
• External Block Table Read bit (EBTRn)
Figure 23-5 shows the program memory organization
for 16 and 32-Kbyte devices and the specific code pro-
tection bit associated with each block. The actual
locations of the bits are summarized in Table 23-3.
FIGURE 23-5: CODE-PROTECTED PROGRAM MEMORY FOR
PIC18F2420/2520/4420/4520
TABLE 23-3: SUMMARY OF CODE PROTECTION REGISTERS
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
300008h CONFIG5L — — — —CP3
(1)
CP2
(1)
CP1 CP0
300009h CONFIG5H CPD CPB — — — — — —
30000Ah CONFIG6L — — — —WRT3
(1)
WRT2
(1)
WRT1 WRT0
30000Bh CONFIG6H WRTD WRTB WRTC
— — — — —
30000Ch CONFIG7L
— — — — EBTR3
(1)
EBTR2
(1)
EBTR1 EBTR0
30000Dh CONFIG7H — EBTRB — — — — — —
Legend: Shaded cells are unimplemented.
Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set.
MEMORY SIZE/DEVICE
Block Code Protection
Controlled By:
16 Kbytes
(PIC18F2420/4420)
32 Kbytes
(PIC18F2520/4520)
Address
Range
Boot Block Boot Block
000000h
0007FFh
CPB, WRTB, EBTRB
Block 0 Block 0
000800h
001FFFh
CP0, WRT0, EBTR0
Block 1 Block 1
002000h
003FFFh
CP1, WRT1, EBTR1
Unimplemented
Read ‘0’s
Block 2
004000h
005FFFh
CP2, WRT2, EBTR2
Block 3
006000h
007FFFh
CP3, WRT3, EBTR3
Unimplemented
Read ‘0’s
1FFFFFh
(Unimplemented Memory Space)