As with our Iduino Mega 2560, the Iduino MEGA R3 is also a microcontroller board based on the ATmega2560. 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, an external power jack, an ICSP header, and a reset button, enabling the board to be plug-and-play.
The Iduino MEGA R3 differs from Iduino Mega 2560 in that it has 3 additional pins, they are SDA, SCL and IOREF,amoung which the IOREF pin can provide the VREF to the board. In addition, considering the compatibility of Iduino MEGA R3 with the series products to come，Iduino MEGA R3 has a port reserved on the left side of IOREF pin.
Input Voltage (recommended): 7-12V
Operating Voltage： 5V
54 Digital I/O Pins：（of which 14 provide PWM output）
16 Analog Input
4 UART (hardware serial ports)
An USB interface
An ICSP header
A power interface
A reset button
DC Current of I/O Pin: 40 mA
DC Current for 3.3V Pin: 50mA
Flash Memory: 256KB of which 8KB is used for bootloader ( Atmega 328)
EEPROM： 4 KB
Clock Speed: 16MHz
For more information, please kindly check our wiki page.