256
Atmel ATmega16/32/64/M1/C1 [DATASHEET]
7647K–AVR–12/13
Notes: 1.
Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2.
2.
“1” means unprogrammed, “0” means programmed
25.2
Fuse Bits
the fuses and how they are mapped into the Fuse bytes. Note that the fuses are read as logical zero, “0”, if they are
programmed.
Note:
1.
Table 25-3.
Lock Bit Protection Modes
(1)(2).
BLB0 Mode
BLB02
BLB01
1
No restrictions for SPM or LPM accessing the Application section.
2
1
0
SPM is not allowed to write to the Application section.
3
0
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.
4
0
1
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
No restrictions for SPM or LPM accessing the Boot Loader section.
2
1
0
SPM is not allowed to write to the Boot Loader section.
3
0
SPM is not allowed to write to the Boot Loader section, and LPM executing from
the Application section is not allowed to read from the Boot Loader section. If
Interrupt Vectors are placed in the Application section, interrupts are disabled
while executing from the Boot Loader section.
4
0
1
LPM executing from the Application section is not allowed to read from the Boot
Loader section. If Interrupt Vectors are placed in the Application section,
interrupts are disabled while executing from the Boot Loader section.
Table 25-4. Extended Fuse Byte
Extended Fuse Byte
Bit No
Description
Default Value
-
7
-
1 (unprogrammed)
-
6
-
1 (unprogrammed)
PSCRB
5
PSC reset behavior
1 (unprogrammed)
PSCRVA
4
PSCOUTnA reset value
1 (unprogrammed)
PSCRVB
3
PSCOUTnB reset value
1 (unprogrammed)
2
Brown-out detector trigger level
1 (unprogrammed)
1
Brown-out detector trigger level
1 (unprogrammed)
0
Brown-out detector trigger level
1 (unprogrammed)