![](http://datasheet.mmic.net.cn/Atmel/AT32AP7000-CTUR_datasheet_96418/AT32AP7000-CTUR_285.png)
285
2545T–AVR–05/11
ATmega48/88/168
28. Memory programming
28.1
Program and data memory lock bits
The Atmel ATmega88/168 provides six Lock bits which can be left unprogrammed (“1”) or can
be programmed (“0”) to obtain the additional features listed in
Table 28-2. The Lock bits can only
be erased to “1” with the Chip Erase command.The Atmel ATmega48 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.
Notes:
1. “1” means unprogrammed, “0” means programmed.
2. Only on ATmega88/168.
Notes:
1. Program the fuse bits and boot lock bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed.
Table 28-1.
Lock bit byte
Bit no.
Description
Default value
7
–
1 (unprogrammed)
6
–
1 (unprogrammed)
5
Boot lock bit
1 (unprogrammed)
4
Boot lock bit
1 (unprogrammed)
3
Boot lock bit
1 (unprogrammed)
2
Boot lock bit
1 (unprogrammed)
LB2
1
Lock bit
1 (unprogrammed)
LB1
0
Lock bit
1 (unprogrammed)
Table 28-2.
Lock bit protection mode
sMemory lock bits
Protection type
LB mode
LB2
LB1
1
No memory lock features enabled.
21
0
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)30
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