Datasheet

3. Load data using programming instructions 7b. A bit value of “0” will program the corresponding lock
bit, a “1” will leave the lock bit unchanged.
4. Write Lock bits using programming instruction 7c.
5. Poll for Lock bit write complete using programming instruction 7d, or wait for t
WLRH
(refer to table
Parallel Programming Characteristics, VCC = 5V ±10% in chapter Parallel Programming
Characteristics).
28.10.23. Reading the Fuses and Lock Bits
1. Enter JTAG instruction PROG_COMMANDS.
2. Enable Fuse/Lock bit read using programming instruction 8a.
3. – To read all Fuses and Lock bits, use programming instruction 8f.
– To only read Extended Fuse byte, use programming instruction 8b.
– To only read Fuse high byte, use programming instruction 8c.
– To only read Fuse low byte, use programming instruction 8d.
– To only read Lock bits, use programming instruction 8e.
28.10.24. Reading the Signature Bytes
1. Enter JTAG instruction PROG_COMMANDS.
2. Enable Signature byte read using programming instruction 9a.
3. Load address 0x00 using programming instruction 9b.
4. Read first signature byte using programming instruction 9c.
5. Repeat steps 3 and 4 with address 0x01 and address 0x02 to read the second and third signature
bytes, respectively.
28.10.25. Reading the Calibration Byte
1. Enter JTAG instruction PROG_COMMANDS.
2. Enable Calibration byte read using programming instruction 10a.
3. Load address 0x00 using programming instruction 10b.
4. Read the calibration byte using programming instruction 10c.
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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