Memory Programming; Program And Data Memory Lock Bits - Atmel AVR AT90CAN32 Manual

25. Memory Programming

25.1

Program and Data Memory Lock Bits

AT90CAN32/64/128
336
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
erased to "1" with the Chip Erase command.
Table 25-1. Lock Bit Byte
Lock Bit Byte
BLB12
BLB11
BLB02
BLB01
LB2
LB1
Note: 1. "1" means unprogrammed, "0" means programmed.
Table 25-2. Lock Bit Protection Modes
Memory Lock Bits
LB Mode LB2
1 1
2 1
3 0
BLB0 Mode BLB02
1 1
2 1
3 0
4 0
BLB1 Mode BLB12
1 1
(1)
Bit No Description
7 –
6 –
5 Boot Lock bit
4 Boot Lock bit
3 Boot Lock bit
2 Boot Lock bit
1 Lock bit
0 Lock bit
(1)(2)
Protection Type
LB1
1 No memory lock features enabled.
Further programming of the Flash and EEPROM is disabled in Parallel and
0 Serial Programming mode. The Fuse bits are locked in both Serial and
Parallel Programming mode.
Further programming and verification of the Flash and EEPROM is disabled
0 in Parallel and Serial Programming mode. The Boot Lock bits and Fuse bits
are locked in both Serial and Parallel Programming mode.
BLB01
No restrictions for SPM (Store Program Memory) or LPM (Load Program
1
Memory) accessing the Application section.
0 SPM is not allowed to write to the Application section.
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
0
section. If Interrupt Vectors are placed in the Boot Loader section, interrupts
are disabled while executing from the Application section.
LPM executing from the Boot Loader section is not allowed to read from the
1 Application section. If Interrupt Vectors are placed in the Boot Loader
section, interrupts are disabled while executing from the Application section.
BLB11
1 No restrictions for SPM or LPM accessing the Boot Loader section.
Table 25-2. The Lock bits can only be
Default Value
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
(1)
(1)
7679H–CAN–08/08