
299
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
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 Atmel ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P has four Fuse bytes.
mapped into the Fuse bytes. Note that the fuses are read as logical zero, “0”, if they are
programmed.
Note:
BLB1 Mode
BLB12
BLB11
11
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.
30
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.
40
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
2
Brown-out Detector trigger level
1 (unprogrammed)
1
Brown-out Detector trigger level
1 (unprogrammed)
0
Brown-out Detector trigger level
1 (unprogrammed)