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ATMEGA8U2_14 Datasheet, PDF (258/310 Pages) ATMEL Corporation – 125 Powerful Instructions – Most Single Clock Cycle Execution | |||
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ATmega8U2/16U2/32U2
25.7.12
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 253 for details on Command loading):
1. A: Load Command â0000 0100â.
2. Set OE to â0â, and BS2, BS1 to â00â. The status of the Fuse Low bits can now be read
at DATA (â0â means programmed).
3. Set OE to â0â, and BS2, BS1 to â11â. The status of the Fuse High bits can now be read
at DATA (â0â means programmed).
4. Set OE to â0â, and BS2, BS1 to â10â. The status of the Extended Fuse bits can now be
read at DATA (â0â means programmed).
5. Set OE to â0â, and BS2, BS1 to â01â. The status of the Lock bits can now be read at
DATA (â0â means programmed).
6. Set OE to â1â.
Figure 25-6. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read
Fuse Low Byte
0
Extended Fuse Byte
1
BS2
Lock Bits
0
0
DATA
1
BS1
Fuse High Byte
1
BS2
25.7.13
Reading the Signature Bytes
The algorithm for reading the Signature bytes is as follows (refer to âProgramming the Flashâ on
page 253 for details on Command and Address loading):
1. A: Load Command â0000 1000â.
2. B: Load Address Low Byte (0x00 - 0x02).
3. Set OE to â0â, and BS to â0â. The selected Signature byte can now be read at DATA.
4. Set OE to â1â.
25.7.14
Reading the Calibration Byte
The algorithm for reading the Calibration byte is as follows (refer to âProgramming the Flashâ on
page 253 for details on Command and Address loading):
1. A: Load Command â0000 1000â.
2. B: Load Address Low Byte, 0x00.
3. Set OE to â0â, and BS1 to â1â. The Calibration byte can now be read at DATA.
4. Set OE to â1â.
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