287
2467S–AVR–07/09
ATmega128
Notes:
1. Program the fuse bits before programming the Lock bits.
2. “1” means unprogrammed, “0´means programmed
Fuse Bits
The ATmega128 has three fuse bytes.
describe briefly the functionality of
all the fuses and how they are mapped into the fuse bytes. Note that the fuses are read as logi-
cal zero, “0”, if they are programmed.
Notes:
1. See
“ATmega103 and ATmega128 Compatibility” on page 4
for details.
2. See
“Watchdog Timer Control Register – WDTCR” on page 56
for details.
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 116.
Lock Bit Protection Modes (Continued)
Memory Lock Bits
Protection Type
Table 117.
Extended Fuse Byte
Extended Fuse Byte
Bit No.
Description
Default Value
–
7
–
1
–
6
–
1
–
5
–
1
–
4
–
1
–
3
–
1
–
2
–
1
M103C
1
ATmega103 compatibility mode
0 (programmed)
WDTON
0
Watchdog Timer always on
1 (unprogrammed)