
258
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P [DATASHEET]
8285E–AVR–02/2013
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 ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/6450A/6450P has three 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.
Notes:
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 27-2.
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
Brown-out Detector trigger level
1 (unprogrammed)
2
Brown-out Detector trigger level
1 (unprogrammed)
1
Brown-out Detector trigger level
1 (unprogrammed)
0
External Reset Disable
1 (unprogrammed)