Datasheet

292
8025M–AVR–6/11
ATmega48P/88P/168P
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
The ATmega48P/88P/168P has three Fuse bytes. Table 28-4 - Table 28-7 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 Modes
(1)(2)
. Only ATmega88P/168P/328P.
BLB0 Mode BLB02 BLB01
111
No restrictions for SPM or LPM 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
111
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.
300
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.
401
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 ATmega48P
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)