Datasheet
103
ATtiny13
2535E–AVR–10/04
Fuse Bytes The ATtiny13 has two Fuse bytes. Table 44 and Table 45 describe briefly the functional-
ity 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 13 on page 33 for BODLEVEL Fuse decoding.
2. See “Alternate Functions of Port B” on page 50 for description of RSTDISBL and
DWEN Fuses.
3. DWEN must be unprogrammed when Lock Bit security is required. See “Program
And Data Memory Lock Bits” on page 102.
4. When programming the RSTDISBL Fuse, High-voltage Serial programming has to be
used to change fuses to perform further programming.
Notes: 1. The SPIEN Fuse is not accessible in SPI Programming mode.
2. See “Watchdog Timer Control Register - WDTCR” on page 39 for details. Program-
ming this fues will disable the Watchdog Timer Interrupt.
3. The default value of SUT1..0 results in maximum start-up time for the default clock
source. See Table 5 on page 23 for details.
4. The default setting of CKSEL1..0 results in internal RC Oscillator @ 9.6 MHz. See
Table 4 on page 23 for details.
5. See “System Clock Prescaler” on page 25 for details.
Table 44. Fuse High Byte
Fuse High Byte Bit No Description Default Value
– 7 – 1 (unprogrammed)
– 6 – 1 (unprogrammed)
– 5 – 1 (unprogrammed)
SELFPRGEN 4 Self Programming Enable 1 (unprogrammed)
DWEN
(3)
3 debugWire Enable 1 (unprogrammed)
BODLEVEL1
(1)
2 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL0
(1)
1 Brown-out Detector trigger level 1 (unprogrammed)
RSTDISBL
(4)
0 External Reset disable 1 (unprogrammed)
Table 45. Fuse Low Byte
Fuse Low Byte Bit No Description Default Value
SPIEN
(1)
7
Enable Serial Program
and Data Downloading
0 (programmed, SPI prog.
enabled)
EESAVE 6
EEPROM memory is
preserved through the
Chip Erase
1 (unprogrammed,
EEPROM not preserved)
WDTON
(2)
5
Watchdog Timer always
on 1 (unprogrammed)
CKDIV8
(5)
4 Divide clock by 8 0 (programmed)
SUT1 3 Select start-up time 1 (unprogrammed)
(3)
SUT0 2 Select start-up time 0 (programmed)
(3)
CKSEL1 1 Select Clock source 1 (unprogrammed)
(4)
CKSEL0 0 Select Clock source 0 (programmed)
(4)