ATMEGA8515 Datasheet, PDF (177/254 Pages) ATMEL Corporation – 8-bit AVR Microcontroller with 8K Bytes In-System Programmable Flash

Memory
Programming
Program and Data
Memory Lock bits
2512G–AVR–03/05
ATmega8515(L)
The ATmega8515 provides six Lock bits which can be left unprogrammed (“1”) or can
be programmed (“0”) to obtain the additional features listed in Table 82. The Lock bits
can only be erased to “1” with the Chip Erase command.
Table 81. Lock Bit Byte⁽¹⁾
Lock Bit Byte
Bit no
7
6
BLB12
5
BLB11
4
BLB02
3
BLB01
2
LB2
1
LB1
0
Description
–
–
Boot Lock bit
Boot Lock bit
Boot Lock bit
Boot Lock bit
Lock bit
Lock bit
Default Value
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
Note: 1. “1” means unprogrammed, “0” means programmed
Table 82. Lock Bit Protection Modes⁽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
2
1
0
disabled in Parallel and Serial Programming mode. The
Fuse bits are locked in both Serial and Parallel
Programming mode.⁽¹⁾
Further programming and verification of the Flash and
3
0
0
EEPROM is disabled in Parallel and Serial Programming
mode. The 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.
SPM is not allowed to write to the Application section, and
LPM executing from the Boot Loader section is not
3
0
0
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.
LPM executing from the Boot Loader section is not
4
0
1
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
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