ATmega48PA/88PA/168PA/328P
27. Memory Programming
27.1 Program And Data Memory Lock Bits
The ATmega88PA/168PA/328P provides six Lock bits which can be left unprogrammed (“1”) or
can be programmed (“0”) to obtain the additional features listed in Table 27-2. The Lock bits can
only be erased to “1” with the Chip Erase command. The ATmega48PA has no separate Boot
Loader section. The SPM instruction is enabled for the whole Flash if the SELFPRGEN fuse is
programmed (“0”), otherwise it is disabled.
Table 27-1. Lock Bit Byte(1)
Lock Bit Byte
Bit No
Description
–
Default Value
7
6
5
4
3
2
1
0
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
–
BLB12(2)
Boot Lock bit
Boot Lock bit
Boot Lock bit
Boot Lock bit
Lock bit
BLB11(2)
BLB02(2)
BLB01(2)
LB2
LB1
Lock bit
Notes: 1. “1” means unprogrammed, “0” means programmed.
2. Only on ATmega88PA/168PA/328P.
Table 27-2. Lock Bit Protection Modes(1)(2)
Memory Lock Bits
Protection Type
LB Mode
LB2
LB1
1
1
1
No memory lock features enabled.
Further programming of the Flash and EEPROM is disabled in
Parallel and Serial Programming mode. The Fuse bits are
locked in both Serial and Parallel Programming mode.(1)
2
1
0
0
0
Further programming and verification of the Flash and EEPROM
is disabled in Parallel and Serial Programming mode. The Boot
Lock bits and Fuse bits are locked in both Serial and Parallel
Programming mode.(1)
3
Notes: 1. Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed
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8161D–AVR–10/09
ATMEL [ ATMEL ]
