Datasheet

179
8246A–AVR–11/09
ATtiny2313A/4313
20.2 Fuse Bits
The ATtiny2313A/4313 has three Fuse bytes. Table 20-3, Table 20-4 and Table 20-5 describe
briefly the functionality 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.
Note: 1. Enables SPM instruction. See “Self-Programming the Flash” on page 172.
Notes: 1. The SPIEN Fuse is not accessible in serial programming mode.
2. See “WDTCSR – Watchdog Timer Control and Status Register” on page 44 for details.
3. Never ship a product with the DWEN Fuse programmed regardless of the setting of Lock bits.
A programmed DWEN Fuse enables some parts of the clock system to be running in all sleep
modes. This may increase the power consumption.
4. See Table 21-5 on page 198 for BODLEVEL Fuse decoding.
5. See “Alternate Functions of Port A” on page 61 for description of RSTDISBL Fuse.
Table 20-3. Fuse Extended Byte
Fuse Extended
Byte
Bit
No Description Default Value
7 – 1 (unprogrammed)
6 – 1 (unprogrammed)
5 – 1 (unprogrammed)
4 – 1 (unprogrammed)
3 – 1 (unprogrammed)
2 – 1 (unprogrammed)
1 – 1 (unprogrammed)
SELFPRGEN
(1)
0 Self Programming Enable 1 (unprogrammed)
Table 20-4. Fuse High Byte
Fuse High Byte
Bit
No Description Default Value
DWEN
(3)
7 debugWIRE Enable 1 (unprogrammed)
EESAVE 6
EEPROM memory is preserved
through the Chip Erase
1 (unprogrammed, EEPROM
not preserved)
SPIEN
(1)
5
Enable Serial Program and Data
Downloading
0 (programmed, SPI prog.
enabled)
WDTON
(2)
4 Watchdog Timer always on 1 (unprogrammed)
BODLEVEL2
(4)
3 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL1
(4)
2 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL0
(4)
1 Brown-out Detector trigger level 1 (unprogrammed)
RSTDISBL
(5)
0 External Reset disable 1 (unprogrammed)