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ATMEGA328P-20AU Datasheet, PDF (303/420 Pages) ATMEL Corporation – 8-bit Atmel Microcontroller with 4/8/16K Bytes In-System Programmable Flash | |||
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ATmega48P/88P/168P
1. A: Load Command â0010 0000â.
2. C: Load Data Low Byte. Bit n = â0â programs the Lock bit. If LB mode 3 is programmed
(LB1 and LB2 is programmed), it is not possible to program the Boot Lock bits by any
External Programming mode.
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.
28.7.12
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 298 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 â1â, and BS1 to â0â. The status of the Extended Fuse bits can now
be read at DATA (â0â means programmed).
5. 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).
6. Set OE to â1â.
Figure 28-6. 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
Fuse High Byte
1
BS1
BS2
28.7.13
Reading the Signature Bytes
The algorithm for reading the Signature bytes is as follows (refer to âProgramming the Flashâ on
page 298 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 BS1 to â0â. The selected Signature byte can now be read at DATA.
4. Set OE to â1â.
8025MâAVRâ6/11
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