MEGA128CAN Datasheet, PDF(336/413 Page) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

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MEGA128CAN Datasheet, PDF (336/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

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Programming the Lock Bits

Reading the Fuse and

Lock Bits

The algorithm for programming the Lock bits is as follows (refer to âProgramming the

Flashâ on page 331 for details on Command and Data loading):

1. A: Load Command â0010 0000â.

2. C: Load Data Low Byte. Bit n = â0â programs the Lock bit. If LB mode 3 is pro-

grammed (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.

The algorithm for reading the Fuse and Lock bits is as follows (refer to âProgramming

the Flashâ on page 331 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 fo 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 161. 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

Reading the Signature Bytes

Fuse High Byte

1

BS1

BS2

The algorithm for reading the Signature bytes is as follows (refer to âProgramming the

Flashâ on page 331 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.

Reading the Calibration Byte

The algorithm for reading the Calibration byte is as follows (refer to âProgramming the

Flashâ on page 331 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.

336 AT90CAN128

4250EâCANâ12/04

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