PIC16F870_13 Datasheet, PDF (32/172 Pages) Microchip Technology – 28/40-Pin, 8-Bit CMOS FLASH Microcontrollers

PIC16F870/871
3.10 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
PIC16F870/871 devices via ICSP. Once write protec-
tion 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 program memory reads.
TABLE 3-1: READ/WRITE STATE OF INTERNAL FLASH PROGRAM MEMORY
Configuration Bits
CP1
CP0
WRT
Memory Location
Internal
Read
Internal
Write
ICSP Read ICSP Write
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
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
Yes
No
No
No
Yes
No
Yes
No
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
No
No
Yes
No
Yes
No
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
No
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
TABLE 3-2: REGISTERS ASSOCIATED WITH DATA EEPROM/PROGRAM FLASH
Address
Name
Bit 7 Bit 6 Bit 5 Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on:
POR, BOR
Value on
all other
RESETS
0Bh, 8Bh, INTCON GIE PEIE T0IE INTE RBIE T0IF INTF
10Bh, 18Bh
10Dh
EEADR EEPROM Address Register, Low Byte
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)
Legend:
Note 1:
x = unknown, u = unchanged, r = reserved, - = unimplemented, read as '0'.
Shaded cells are not used during FLASH/EEPROM access.
These bits are reserved; always maintain these bits clear.
RBIF 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
—
—
DS30569C-page 32
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