ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 353

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Programming the Lock Bits
Reading the Fuse and Lock
Bits
Reading the Signature Bytes
2549K–AVR–01/07
The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” on page 348 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. If LB mode 3 is pro-
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 348 for details on Command loading):
1. A: Load Command “0000 0100”.
2. Set OE to “0”, and BS2, BS1 to “00”. The status of the Fuse Low bits can now be
3. Set OE to “0”, and BS2, BS1 to “11”. The status of the Fuse High bits can now be
4. Set OE to “0”, and BS2, BS1 to “10”. The status of the Extended Fuse bits can
5. Set OE to “0”, and BS2, BS1 to “01”. The status of the Lock bits can now be read
6. Set OE to “1”.
Figure 143. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read
The algorithm for reading the Signature bytes is as follows (refer to “Programming the
Flash” on page 348 for details on Command and Address loading):
1. A: Load Command “0000 1000”.
2. B: Load Address Low Byte (0x00 - 0x02).
3. Set OE to “0”, and BS to “0”. The selected Signature byte can now be read at
4. Set OE to “1”.
grammed (LB1 and LB2 is programmed), it is not possible to program the Boot
Lock bits by any External Programming mode.
read at DATA (“0” means programmed).
read at DATA (“0” means programmed).
now be read at DATA (“0” means programmed).
at DATA (“0” means programmed).
DATA.
Fuse Low Byte
Extended Fuse Byte
Fuse High Byte
Lock Bits
ATmega640/1280/1281/2560/2561
BS2
BS2
0
1
0
1
BS1
0
1
DATA
353