13 reading the signature bytes, 14 reading the calibration byte – Rainbow Electronics ATmega64C1 User Manual
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7647A–AVR–02/08
ATmega32/64/M1/C1
1.
A: Load Command “0000 0100”.
2.
Set OE to “0”, BS2 to “0” and BS1 to “0”. The status of the Fuse Low bits can now be
read at DATA (“0” means programmed).
3.
Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can now be
read at DATA (“0” means programmed).
4.
Set OE to “0”, BS2 to “1”, and BS1 to “0”. The status of the Extended Fuse bits can now
be read at DATA (“0” means programmed).
5.
Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be read at
DATA (“0” means programmed).
6.
Set OE to “1”.
Figure 24-6. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read
24.8.13
Reading the Signature Bytes
The algorithm for reading the Signature bytes is as follows (refer to
for details on Command and Address loading):
1.
A: Load Command “0000 1000”.
2.
B: Load Address Low Byte (0x00 - 0x02).
3.
Set OE to “0”, and BS1 to “0”. The selected Signature byte can now be read at DATA.
4.
Set OE to “1”.
24.8.14
Reading the Calibration Byte
The algorithm for reading the Calibration byte is as follows (refer to
for details on Command and Address loading):
1.
A: Load Command “0000 1000”.
2.
B: Load Address Low Byte, 0x00.
3.
Set OE to “0”, and BS1 to “1”. The Calibration byte can now be read at DATA.
4.
Set OE to “1”.
Lock Bits
0
1
BS2
Fuse High Byte
0
1
BS1
DATA
Fuse Low Byte
0
1
BS2
Extended Fuse Byte