Atmel ATmega128 User Manual

288
2467S–AVR–07/09
ATmega128
Notes: 1. The SPIEN fuse is not accessible in SPI Serial Programming mode.
2. The CKOPT fuse functionality depends on the setting of the CKSEL bits. See “Clock
Sources” on page 37
for details.
3. The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 112 on page 284
4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of lock bits
and the JTAGEN Fuse. A programmed OCDEN Fuse enables some parts of the clock system
to be running in all sleep modes. This may increase the power consumption.
5. If the JTAG interface is left unconnected, the JTAGEN fuse should if possible be disabled. This
to avoid static current at the TDO pin in the JTAG interface.
Notes: 1. The default value of SUT1..0 results in maximum start-up time. See Table 14 on page 42 for
details.
2. The default setting of CKSEL3..0 results in Internal RC Oscillator @ 1 MHz. See Table 6 on
page 37 for details.
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if
Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.
Latching of Fuses The Fuse values are latched when the device enters Programming mode and changes of the
fuse values will have no effect until the part leaves Programming mode. This does not apply to
Table 118. Fuse High Byte
Fuse High
Byte Bit No. Description Default Value
OCDEN
(4)
7 Enable OCD 1 (unprogrammed, OCD
disabled)
JTAGEN
(5)
6 Enable JTAG 0 (programmed, JTAG enabled)
SPIEN
(1)
5 Enable Serial Program and
Data Downloading
0 (programmed, SPI prog.
enabled)
CKOPT
(2)
4 Oscillator options 1 (unprogrammed)
EESAVE 3 EEPROM memory is preserved
through the Chip Erase
1 (unprogrammed, EEPROM not
preserved)
BOOTSZ1 2 Select Boot Size (see Table 112
for details)
0 (programmed)
(3)
BOOTSZ0 1 Select Boot Size (see Table 112
for details)
0 (programmed)
(3)
BOOTRST 0 Select Reset Vector 1 (unprogrammed)
Table 119. Fuse Low Byte
Fuse Low
Byte Bit No. Description Default Value
BODLEVEL 7 Brown out detector trigger level 1 (unprogrammed)
BODEN 6 Brown out detector enable 1 (unprogrammed, BOD disabled)
SUT1 5 Select start-up time 1 (unprogrammed)
(1)
SUT0 4 Select start-up time 0 (programmed)
(1)
CKSEL3 3 Select Clock source 0 (programmed)
(2)
CKSEL2 2 Select Clock source 0 (programmed)
(2)
CKSEL1 1 Select Clock source 0 (programmed)
(2)
CKSEL0 0 Select Clock source 1 (unprogrammed)
(2)

Atmel ATmega128 Specifications

General

Brand	Atmel
Model	ATmega128
Category	Microcontrollers
Language	English