Datasheet
261
ATmega325/3250/645/6450
2570K–AVR–04/07
Note: 1. The SPIEN Fuse is not accessible in serial programming mode.
2. The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 104 on
page 258 for details.
3. See “WDTCR – Watchdog Timer Control Register” on page 45 for details.
4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of
Lock bits and 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 dis-
abled. This to avoid static current at the TDO pin in the JTAG interface.
Note: 1. The default value of SUT1..0 results in maximum start-up time for the default clock
source. See Table 16 on page 40 for details.
2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz. See
Table 7 on page 28 for details.
3. The CKOUT Fuse allow the system clock to be output on PORTE7. See “Clock Out-
put Buffer” on page 30 for details.
4. See “System Clock Prescaler” on page 31 for details.
Table 110. 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)
WDTON
(3)
4 Watchdog Timer always on 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)
(2)
BOOTSZ0 1
Select Boot Size (see Table 112
for details) 0 (programmed)
(2)
BOOTRST 0 Select Reset Vector 1 (unprogrammed)
Table 111. Fuse Low Byte
Fuse Low Byte Bit No Description Default Value
CKDIV8
(4)
7 Divide clock by 8 0 (programmed)
CKOUT
(3)
6 Clock output 1 (unprogrammed)
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 1 (unprogrammed)
(2)
CKSEL0 0 Select Clock source 0 (programmed)
(2)