HiLetgo Mega2560 R3 ATMEGA16U2 CH340 Microcontroller Board Development Board Compatible to Arduino With USB Cable Main chip: Atmega16U2, 100% compatible to Arduino This Mega2560 is compatible with most shields designed for the Arduino Duemilanove or Diecimila. 54 digital input/output pins, including 16 analog inputs, 4 UARTs (hardware serial ports), Clock Speed: 16 MHz Stronger RESET circuit.Use 5.5 * 2.1mm DC barrel jack (compatible with 5.5 * 2.5mm DC barrel jack) Improved and expert version: 1.0 pinout: added SDA and SCL pins that are 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.