ATMEGA8L ATMEL [ATMEL Corporation], ATMEGA8L Datasheet - Page 229

• Manufacturer Part Number: ATMEGA8L
• Description: 8-bit AVR with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Programming the Fuse High
Bits
Programming the Lock Bits
Reading the Fuse and Lock
Bits
2486M–AVR–12/03
The algorithm for programming the Fuse high bits is as follows (refer to “Programming
the Flash” on page 225 for details on Command and Data loading):
1. A: Load Command “0100 0000”.
2. C: Load Data Low byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
3. Set BS1 to “1” and BS2 to “0”. This selects high data byte.
4. Give WR a negative pulse and wait for RDY/BSY to go high.
5. Set BS1 to “0”. This selects low data byte.
The algorithm for programming the Lock Bits is as follows (refer to “Programming the
Flash” on page 225 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.
The algorithm for reading the Fuse and Lock Bits is as follows (refer to “Programming
the Flash” on page 225 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
3. Set OE to “0”, BS2 to “1”, and BS1 to “1”. The status of the Fuse High bits can
4. Set OE to “0”, BS2 to “0”, and BS1 to “1”. The status of the Lock Bits can now be
5. Set OE to “1”.
Figure 108. Mapping Between BS1, BS2 and the Fuse- and Lock Bits During Read
now be read at DATA (“0” means programmed).
now be read at DATA (“0” means programmed).
read at DATA (“0” means programmed).
Fuse low byte
Fuse high byte
Lock bits
BS2
0
1
BS1
0
1
ATmega8(L)
DATA
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