Support for the Arduino IDE 1.0+ (OSX/Win/Linux).
Power supply via USB or External Source-5v or 7-35v (automatic selection).
The DPS 500mA 5V Regulator.
Built-in USB (and serial debugging).
6 I/O Pins (2 are used for USB only if your program actively communicates over USB, otherwise you can use all 6).
8k Flash Memory (about 6k available including the bootloader).
I2C and SPI.
PWM on 3 pins (more possible with the help of the Software PWM).
ADC on 4 pins.
Power LED and Test/Status LED (on Pin0).
Size: 1.8 cm x 2.6 cm .
For programming follow this video https://www.youtube.com/watch?v=O1aLLBAChq4