Arduino Mega board from Arduino Officials based on ATmega16U2.  The Official Arduino Mega 2560 is Rev3 development board based on ATmega2560 microcontroller. The board has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analogue inputs, 4 UARTs (hardware serial ports), a 16MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller, simply connect it to a computer with a USB cable or power it with an AC to DC adaptor or battery to get started.

Features:

1. ATmega16U2 instead 8U2 as USB to serial converter
2. 1.0 pinout
3. Stronger RESET circuit
4. 5V operating voltage
5. Input voltage (recommended) range from 7V to 12V
6. Input voltage (limit) range from 6V to 20V
7. 40mA DC current per I/O pin
8. 256KB flash memory of which 8KB used by bootloader
9. 8KB SRAM
10. 4KB EEPROM