ATMEGA261 datasheet(172/226 Pages) ATMEL

172 / 226 page

172

7753E–AVR–06/10

ATtiny261/ATtiny461/ATtiny861

22.2

Fuse Bytes

The ATtiny261/461/861 has three Fuse bytes. Table 22-3, Table 22-4 and Table 22-5 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. See “Alternate Functions of Port B” on page 63 for description of RSTDISBL and DWEN

Fuses.

2. DWEN must be unprogrammed when Lock Bit security is required. See “Program And Data

Memory Lock Bits” on page 171.

3. The SPIEN Fuse is not accessible in SPI Programming mode.

4. See “WDTCR – Watchdog Timer Control Register” on page 46 for details.

5. See Table 23-4 on page 190 for BODLEVEL Fuse decoding.

6. When programming the RSTDISBL Fuse, High-voltage Serial programming has to be used to

change fuses to perform further programming.

Table 22-3.

Fuse Extended Byte

Fuse High Byte

Bit No

Description

Default Value

1 (unprogrammed)

SELFPRGEN

Self-Programming Enable

1 (unprogrammed)

Table 22-4.

Fuse High Byte

Bit No

Description

Default Value

RSTDISBL(1)

External Reset disable

1 (unprogrammed)

DWEN(2)

DebugWIRE Enable

1 (unprogrammed)

SPIEN(3)

Enable Serial Program and Data

Downloading

0 (programmed, SPI prog.

enabled)

WDTON(4)

Watchdog Timer always on

1 (unprogrammed)

EESAVE

EEPROM memory is preserved

through the Chip Erase

1 (unprogrammed, EEPROM

not preserved)

BODLEVEL2(5)

Brown-out Detector trigger level

1 (unprogrammed)

BODLEVEL1(5)

Brown-out Detector trigger level

1 (unprogrammed)

BODLEVEL0(5)

Brown-out Detector trigger level

1 (unprogrammed)

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