Datasheet

260
ATmega325/3250/645/6450
2570K–AVR–04/07
Notes: 1. Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed
Fuse Bits The ATmega325/3250/645/6450 has three Fuse bytes. Table 109 - Table 111 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: 1. See Table 17 on page 42 for BODLEVEL Fuse decoding.
2. Port G, PG5 is input only. Pull-up is always on. See “Alternate Functions of Port G”
on page 74.
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 108. Lock Bit Protection Modes
(1)(2)
(Continued)
Memory Lock Bits Protection Type
Table 109. Extended Fuse Byte
Extended Fuse Byte Bit No Description Default Value
–7– 1
–6– 1
–5– 1
–4– 1
–5– 1
BODLEVEL1
(1)
2 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL0
(1)
1 Brown-out Detector trigger level 1 (unprogrammed)
RSTDISBL
(2)
0 External Reset Disable 1 (unprogrammed)