275
ATmega16M1/32M1/64M1 [DATASHEET]
8209E–AVR–11/2012
Notes:
1. Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed.
27.2
Fuse bits
the functionality of all the fuses and how they are mapped into the Fuse bytes. Note that the fuses are read as log-
ical zero, “0”, if they are programmed.
Table 27-3.
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 27-4.
Extended Fuse byte.
Extended Fuse byte
Bit no.
Description
Default value
-
7
-
1 (unprogrammed)
-
6
-
1 (unprogrammed)
PSCRB
5
PSC reset behaviour
1 (unprogrammed)
PSCRVA
4
PSCOUTnA reset value
1 (unprogrammed)
PSCRVB
3
PSCOUTnB reset value
1 (unprogrammed)