Datasheet
293
ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]
8284E–AVR–02/2013
28. Memory programming
28.1 Program and Data Memory Lock Bits
The Atmel ATmega169A/169PA/329A/329PA/3290A/3290PA/649A/649P/6490A/6490P 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.
Note: 1. “1” means unprogrammed, “0” means programmed.
Table 28-1. Lock Bit byte
(1)
.
Lock Bit byte Bit no. Description Default value
7 – 1 (unprogrammed)
6 – 1 (unprogrammed)
BLB12 5 Boot Lock bit 1 (unprogrammed)
BLB11 4 Boot Lock bit 1 (unprogrammed)
BLB02 3 Boot Lock bit 1 (unprogrammed)
BLB01 2 Boot Lock bit 1 (unprogrammed)
LB2 1 Lock bit 1 (unprogrammed)
LB1 0 Lock bit 1 (unprogrammed)
Table 28-2. Lock Bit Protection modes
(1)(2)
.
Memory Lock bits Protection type
LB Mode LB2 LB1
1 1 1 No memory lock features enabled.
210
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)
300
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)
BLB0 Mode BLB02 BLB01
1 1 1 No restrictions for SPM or LPM accessing the Application section.
2 1 0 SPM is not allowed to write to the Application section.
300
SPM is not allowed to write to the Application section, and LPM executing from the
Boot Loader section is not allowed to read from the Application section. If Interrupt
Vectors are placed in the Boot Loader section, interrupts are disabled while
executing from the Application section.
401
LPM executing from the Boot Loader section is not allowed to read from the
Application section. If Interrupt Vectors are placed in the Boot Loader section,
interrupts are disabled while executing from the Application section.
BLB1 Mode BLB12 BLB11
1 1 1 No restrictions for SPM or LPM accessing the Boot Loader section.