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 with the R3 version are:
ATmega16U2 instead 8U2 as USB-to-Serial converter.
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. Features:
- Microcontroller: ATmega2560
- Operating Voltage: 5V
- Input Voltage (recommended): 9V
- Input Voltage (limits): 7-18V
- Digital I/O Pins: 54 (of which 14 provide PWM output)
- Analog Input Pins: 16
- DC Current per I/O Pin: 40 mA
- DC Current for 3.3V Pin: 50 mA
- DC Current for 5V Pin: 800 mA
- Flash Memory: 256 KB of which 8 KB used by bootloader
- SRAM: 8 KB
- EEPROM: 4 KB
- Clock Speed 16 MHz