The Arduino Nano is a small, complete, breadboard-friendly board based on the ATmega328. This Nano is delivered without soldered headers (these are also not included). This board uses the same chip as the UNO, but comes in a different package. This board has no DC power jack, and is controlled with a Mini- USB cable.
It concerns the 3rd revision (latest) with the following changes:
- Stronger RESET circuit.
- Added SDA and SCL pins at the AREF pin and 2 new pins at the RESET pin, namely the IOREF pin, allowing shields to adapt to the voltage from the board. In the future shields will be compatible with both the 5v and 3.3v version. The 2nd pin is not connected and is reserved for future updates.
This Arduino is a clone, which means that this board was not built in the original factory. The only difference between original and clones is that these Arduino 's are cheaper. All components and circuits are otherwise identical.