Datasheet

169
8197C–AVR–05/11
ATtiny261A/461A/861A
18.2 Fuse Bytes
The device has three fuse bytes. Table 18-3, Table 18-4 and Table 18-5 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.
Notes: 1. Enables SPM instruction. See “Self-Programming the Flash” on page 163.
Notes: 1. See “Alternate Functions of Port B” on page 65 for description of RSTDISBL and DWEN
Fuses. After programming the RSTDISBL fuse, parallel programming must be used to change
fuses and allow further programming.
2. DWEN must be unprogrammed when Lock Bit security is required. See “Program And Data
Memory Lock Bits” on page 168.
3. The SPIEN Fuse is not accessible in SPI programming mode.
4. Programming this fues will disable the Watchdog Timer Interrupt. See “WDTCR – Watchdog
Timer Control Register” on page 46 for details.
5. See Table 19-6 on page 189 for BODLEVEL Fuse decoding.
Table 18-3. Fuse Extended Byte
Fuse High 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 18-4. Fuse High Byte
Fuse High Byte Bit No Description Default Value
RSTDISBL
(1)
7 External Reset disable 1 (unprogrammed)
DWEN
(2)
6 DebugWIRE Enable 1 (unprogrammed)
SPIEN
(3))
6
Enable Serial Program and Data
Downloading
0 (programmed, SPI prog.
enabled)
WDTON
(4)
4 Watchdog Timer always on 1 (unprogrammed)
EESAVE 3
EEPROM memory is preserved
through the Chip Erase
1 (unprogrammed, EEPROM
not preserved)
BODLEVEL2
(5)
2 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL1
(5)
1 Brown-out Detector trigger level 1 (unprogrammed)
BODLEVEL0
(5)
0 Brown-out Detector trigger level 1 (unprogrammed)