Datasheet

ATmega164A/PA/324A/PA/644A/PA/1284/P
 2018 Microchip Technology Inc. Data Sheet Complete DS40002070A-page 296
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 ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P has four Fuse bytes. Table 27-3 - Table 27-5
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.
Note: 1. See ”” on page 333 for BODLEVEL Fuse decoding.
BLB1 Mode BLB12 BLB11
1 1 1
No restrictions for SPM or (E)LPM accessing the Boot Loader
section.
2 1 0 SPM is not allowed to write to the Boot Loader section.
3 0 0
SPM is not allowed to write to the Boot Loader section, and
(E)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
(E)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 27-2. Lock Bit protection modes
(1)(2)
(Continued)
Memory Lock bits Protection type
Table 27-3. Extended Fuse byte
Fuse low byte Bit no. Description Default value
– 7 – 1
– 6 – 1
– 5 – 1
– 4 – 1
– 3 – 1
BODLEVEL2
(1)
2 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL1
(1)
1 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL0
(1)
0 Brown-out Detector trigger level 1 (unprogrammed)