All Atmel microcontrollers have a three-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 ID, namely the device signature bytes, there are differences between ATmega324PB and ATmega324 variants. See below table for more detail.
| Part | Signature Bytes Address | ||
|---|---|---|---|
| 0x000 | 0x001 | 0x002 | |
| ATmega324A | 0x1E | 0x95 | 0x15 |
| ATmega324P | 0x1E | 0x95 | 0x08 |
| ATmega324PA | 0x1E | 0x95 | 0x11 |
| ATmega324PB | 0x1E | 0x95 | 0x17 |