Rainbow Electronics ATtiny43U - Manual (Page 140)

140
8048B–AVR–03/09
ATtiny43U
19.2 Fuse Bytes
The ATtiny43U has three Fuse bytes. Table 19-3 , Table 19-4 and Table 19-5 briefly describe 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 133 .
Notes: 1. See “Alternate Functions of Port B” on page 74 for description of RSTDISBL and DWEN
Fuses. When programming the RSTDISBL Fuse, TBD programming has to be used to change
fuses to perform further programming
2. DWEN must be unprogrammed when Lock Bit security is required. See “Program And Data
Memory Lock Bits” on page 139 .
3. The SPIEN Fuse is not accessible in SPI Programming mode.
4. See “WDT Configuration as a Function of the Fuse Settings of WDTON” on page 52 for
details.
5. See Table 20-5 on page 158 for BODLEVEL Fuse decoding.
Table 19-3. 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 19-4. 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) 5
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)