336
7679H–CAN–08/08
AT90CAN32/64/128
25. Memory Programming
25.1 Program and Data Memory Lock Bits
The AT90CAN32/64/128 provides six Lock bits which can be left unprogrammed (“1”) or can be
programmed (“0”) to obtain the additional features listed in Table 25-2. The Lock bits can only be
erased to “1” with the Chip Erase command.
Note: 1. “1” means unprogrammed, “0” means programmed.
Table 25-1. 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 25-2. 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
111
No restrictions for SPM (Store Program Memory) or LPM (Load Program
Memory) 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.
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