he Arduino Mega ADK is a microcontroller board based on the ATmega2560. It has a USB host interface to connect with Android based phones.
It is compatible with Android's Accessory Development Kit examples. It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button.
The ADK is based on the Mega 2560. Plus it has an USB Host circuit that enable this board to communicate with USB Devices, and give them power supply.
Additional features coming with the R3 version are: 1.0 pinout: added SDA and SCL pins for TWI communication placed near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board and the second one is a not connected pin, that is reserved for future purposes. stronger RESET circuit. The product is sold in its retail packaging.
For information on using the board with the Android OS, see Google's ADK documentation.