Datasheet

Figure 28-5. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read
Lock Bits
0
1
BS2
Fuse High Byte
0
1
BS1
DATA
Fuse Low Byte
0
1
BS2
Extended Fuse Byte
28.8.13. Reading the Signature Bytes
The algorithm for reading the Signature bytes is as follows (Please refer to Programming the Flash for
details on Command and Address loading):
1. Step A: Load Command “0000 1000”.
2. Step B: Load Address Low Byte (0x00 - 0x02).
3. Set OE to “0”, and BS1 to “0”. The selected Signature byte can now be read at DATA.
4. Set OE to “1”.
28.8.14. Reading the Calibration Byte
The algorithm for reading the Calibration byte is as follows (Please refer to Programming the Flash for
details on Command and Address loading):
1. Step A: Load Command “0000 1000”.
2. Step B: Load Address Low Byte, 0x00.
3. Set OE to “0”, and BS1 to “1”. The Calibration byte can now be read at DATA.
4. Set OE to “1”.
28.8.15. Parallel Programming Characteristics
For characteristics of the Parallel Programming, please refer to Parallel Programming Characteristics.
Related Links
Parallel Programming Characteristics on page 407
28.9. Serial Downloading
Both the Flash and EEPROM memory arrays can be programmed using the serial SPI bus while RESET
is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and MISO (output). After
RESET is set low, the Programming Enable instruction needs to be executed first before program/erase
operations can be executed.
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
376