All Atmel microcontrollers have a 3-byte signature code which identifies the device. This code can be read in both serial and parallel mode, also when the device is locked. The three bytes reside in a separate address space. For the device signature bytes, there are differences between ATmega328PB and ATmega328 variants, see below table for more detail.
| Part | Signature bytes address | ||
|---|---|---|---|
| 0x000 | 0x001 | 0x002 | |
| ATmega328 | 0x1E | 0x95 | 0x14 |
| ATmega328P | 0x1E | 0x95 | 0x0F |
| ATmega328PB | 0x1E | 0x95 | 0x16 |