Iduino MEGA R3
From Geeetech Wiki
Introduction
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.