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ATMEGA8_14 Datasheet, PDF (226/331 Pages) ATMEL Corporation – High-performance, Low-power Atmel | |||
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ATmega8(L)
Programming the
Fuse High Bits
The algorithm for programming the Fuse high bits is as follows (refer to âProgramming the Flashâ
on page 222 for details on Command and Data loading):
1. A: Load Command â0100 0000â
2. C: Load Data Low byte. Bit n = â0â programs and bit n = â1â erases the Fuse bit
3. Set BS1 to â1â and BS2 to â0â. This selects high data byte
4. Give WR a negative pulse and wait for RDY/BSY to go high
5. Set BS1 to â0â. This selects low data byte
Programming the Lock
Bits
The algorithm for programming the Lock Bits is as follows (refer to âProgramming the Flashâ on
page 222 for details on Command and Data loading):
1. A: Load Command â0010 0000â
2. C: Load Data Low byte. Bit n = â0â programs the Lock bit
3. Give WR a negative pulse and wait for RDY/BSY to go high
The Lock Bits can only be cleared by executing Chip Erase.
Reading the Fuse and
Lock Bits
The algorithm for reading the Fuse and Lock Bits is as follows (refer to âProgramming the Flashâ
on page 222 for details on Command loading):
1. A: Load Command â0000 0100â
2. Set OE to â0â, BS2 to â0â, and BS1 to â0â. The status of the Fuse Low bits can now be
read at DATA (â0â means programmed)
3. Set OE to â0â, BS2 to â1â, and BS1 to â1â. The status of the Fuse High bits can now be
read at DATA (â0â means programmed)
4. Set OE to â0â, BS2 to â0â, and BS1 to â1â. The status of the Lock Bits can now be read at
DATA (â0â means programmed)
5. Set OE to â1â
Figure 108. Mapping Between BS1, BS2 and the Fuse- and Lock Bits During Read
Fuse low byte
Lock bits
0
0
DATA
1
Fuse high byte
1
BS1
BS2
2486AAâAVRâ02/2013
226
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