Datasheet

273
8023F–AVR–07/09
ATmega325P/3250P
Notes: 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 24-6 on page 268
for details.
3. See ”WDTCR – Watchdog Timer Control Register” on page 51 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 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 for the default clock source.
See ”System and Reset Characterizations” on page 308 for details.
2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz. See Table 8-6 on
page 33 for details.
3. The CKOUT Fuse allow the system clock to be output on PORTE7. See ”Clock Output Buffer”
on page 35 for details.
4. See ”System Clock Prescaler” on page 35 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.
Table 25-4. 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 25-7 on
page 275 for details)
0 (programmed)
(2)
BOOTSZ0 1
Select Boot Size (see Table 25-7 on
page 275 for details)
0 (programmed)
(2)
BOOTRST 0 Select Reset Vector 1 (unprogrammed)
Table 25-5. 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)