PIC16F877-20L Datasheet, PDF (46/218 Pages) Microchip Technology – 28/40-Pin 8-Bit CMOS FLASH Microcontrollers

PIC16F87X
4.9 FLASH Program Memory Write
Protection
The configuration word contains a bit that write protects
the FLASH program memory, called WRT. This bit can
only be accessed when programming the PIC16F87X
device via ICSP. Once write protection is enabled, only
an erase of the entire device will disable it. When
enabled, write protection prevents any writes to FLASH
program memory. Write protection does not affect pro-
gram memory reads.
TABLE 4-1: READ/WRITE STATE OF INTERNAL FLASH PROGRAM MEMORY
Configuration Bits
CP1
CP0
WRT
0
0
x
0
1
0
0
1
0
0
1
1
0
1
1
1
0
0
1
0
0
1
0
1
1
0
1
1
1
0
1
1
1
Memory Location
All program memory
Unprotected areas
Protected areas
Unprotected areas
Protected areas
Unprotected areas
Protected areas
Unprotected areas
Protected areas
All program memory
All program memory
Internal
Read
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Internal
Write
No
No
No
Yes
No
No
No
Yes
No
No
Yes
ICSP Read ICSP Write
No
No
Yes
No
No
No
Yes
No
No
No
Yes
No
No
No
Yes
No
No
No
Yes
Yes
Yes
Yes
TABLE 4-2: REGISTERS ASSOCIATED WITH DATA EEPROM/PROGRAM FLASH
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
0Bh, 8Bh, INTCON GIE PEIE T0IE INTE RBIE
10Bh, 18Bh
10Dh
EEADR EEPROM Address Register, Low Byte
T0IF
INTF
10Fh
EEADRH —
—
— EEPROM Address, High Byte
10Ch
EEDATA EEPROM Data Register, Low Byte
10Eh
EEDATH —
— EEPROM Data Register, High Byte
18Ch
EECON1 EEPGD —
—
— WRERR WREN WR
18Dh
EECON2 EEPROM Control Register2 (not a physical register)
8Dh
PIE2
—
(1)
—
EEIE BCLIE
—
—
0Dh
PIR2
—
(1)
—
EEIF BCLIF
—
—
Legend: x = unknown, u = unchanged, r = reserved, - = unimplemented, read as '0'.
Shaded cells are not used during FLASH/EEPROM access.
Note 1: These bits are reserved; always maintain these bits clear.
Bit 0
RBIF
Value on:
POR,
BOR
Value on
all other
RESETS
0000 000x 0000 000u
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
xxxx xxxx uuuu uuuu
RD x--- x000 x--- u000
—
—
CCP2IE -r-0 0--0 -r-0 0--0
CCP2IF -r-0 0--0 -r-0 0--0
DS30292D-page 46
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