Rainbow Electronics ATmega32L - Manual (Page 265)

265
ATmega32(L)
2503C–AVR–10/02
Programming the Lock Bits The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” on page 260 for details on Command and Data loading):
1. A: Load Command “0010 0000”.
2. C: Load Data Low Byte. Bit n = “0” 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 “Programming
the Flash” on page 260 for details on Command loading):
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 “0” and BS1 to “1”. The status of the Lock bits can now be
read at DATA (“0” means programmed).
5. Set OE to “1”.
Figure 132. Mapping between BS1, BS2 and the Fuse- and Lock Bits during Read
Reading the Signature Bytes The algorithm for reading the Signature bytes is as follows (refer to “Programming the
Flash” on page 260 for details on Command and Address loading):
1. A: Load Command “0000 1000”.
2. B: Load Address Low Byte ($00 - $02).
3. Set OE to “0”, and BS1 to “0”. The selected Signature byte can now be read at
DATA.
4. Set OE to “1”.
Reading the Calibration Byte The algorithm for reading the Calibration byte is as follows (refer to “Programming the
Flash” on page 260 for details on Command and Address loading):
1. A: Load Command “0000 1000”.
2. B: Load Address Low Byte, $00.
3. Set OE to “0”, and BS1 to “1”. The Calibration byte can now be read at DATA.
4. Set OE to “1”.
Fuse Low Byte
Lock Bits 0
1
BS2
Fuse High Byte
0
1
BS1
DATA