The Arduino Uno R3 is a microcontroller board based on the ATmega328P. It has 6 digital input/output pins and 6 analog inputs/output pins, 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 a AC-to-DC adapter or battery to get started.

The Arduino Uno R3 controller boards requires the CNC shield to control a CNC machine. These two boards together with the stepper drivers forms the controller of the CNC machine and all the motors, sensors and switches connects to it.

The Arduino Uno R3 board is sold without firmware and can very easily be loaded onto the board by downloading the Arduino Development Environment from http://arduino.cc/en/Main/Software and uploading your firmware to the board via USB.