The content of the Signature Row fuses (SIGROW) is preprogrammed and cannot be altered. SIGROW holds information such as device ID, serial number, and factory calibration values.
All AVR microcontrollers have a three-byte device ID that identifies the device. This device ID can be read in both serial and parallel mode, also when the device is locked. The three bytes reside in the Signature Row. The signature bytes are given in the following table.
| Device Name | Signature Bytes Address | ||
|---|---|---|---|
| 0x00 | 0x01 | 0x02 | |
| ATmega1609 | 0x1E | 0x94 | 0x26 |
| ATmega1608 | 0x1E | 0x94 | 0x27 |
| ATmega809 | 0x1E | 0x93 | 0x2A |
| ATmega808 | 0x1E | 0x93 | 0x26 |