Feature:

• It is a smallest, complete, and breadboard friendly board. It has everything that Diecimila/Duemilanove has (electrically) with more analog input pins and onboard +5V AREF jumper.

• Nano's got the breadboard-ability of the Boarduino and the Mini+USB with smaller footprint than either, so users have more breadboard space. It's got a pin layout that works well with the Mini or the Basic Stamp (TX, RX, ATN, GND on one top, power and ground on the other).

• The Nano can be powered via the Mini-B USB connection, 7-12V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.

Input and OutputEach of the 14 digital pins on the Nano can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. Some pins have specialized functions:Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the CH340G USB chip.