Arduino Nano is a surface mount breadboard embedded version with integrated USB. It is a smallestcompleteand breadboard friendly. It has everything that Diecimila/Duemilanove has (electrically) with more analog input pins and onboard +5V AREF jumper. Physicallyit is missing power jack. The Nano is automatically sense and switch to the higher potential source of powerthere is no need for the power select jumper.

Nano’s got the breadboard-ability of the Boarduino and the Mini+USB with smaller footprint than eitherso users have more breadboard space. It’s got a pin layout that works well with the Mini or the Basic Stamp (TXRXATNGND on one toppower and ground on the other). This new version 3.0 comes with ATMEGA328 which offer more programming and data memory space. It is two layers. That make it easier to hack and more affordable.

You end up paying less with Nano than Mini and USB combined!

Specifications: 

Microcontroller                        Atmel ATmega328

Operating Voltage (logic level)  5 V

Input Voltage (recommended)  7-12 V

Input Voltage (limits)               6-20 V

Digital I/O Pins                        14 (of which 6 provide PWM output)

Analog Input Pins                    8

DC Current per I/O Pin            40 mA

Flash Memory                          32 KB (of which 2KB used by bootloader)

SRAM                                     2 KB

EEPROM                                 1 KB

Clock Speed                           16 MHz

Dimensions                            0.70” x 1.70”