![](http://datasheet.mmic.net.cn/Atmel/AT32AP7000-CTUR_datasheet_96418/AT32AP7000-CTUR_286.png)
286
2545T–AVR–05/11
ATmega48/88/168
Notes:
1. Program the fuse bits and boot lock bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed.
28.2
Fuse bits
describe briefly the functionality of all 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.
Table 28-3.
Lock bit protection mode
s(1)(2). Only Atmel ATmega88/168.
BLB0 mode
BLB02
BLB01
11
1
No restrictions for SPM or LPM accessing the application
section.
2
1
0
SPM is not allowed to write to the application section.
30
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.
40
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
11
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.
30
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.
40
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 28-4.
Extended fuse byte for mega48.
Extended fuse byte
Bit no.
Description
Default value
–7
–
1
–6
–
1
–5
–
1
–4
–
1
–3
–
1
–2
–
1
–1
–
1
SELFPRGEN
0
Self programming enable
1 (unprogrammed)