Arduino Uno

Overview
The Arduino Uno is an Arduino board almost identical in looks, size and shape to the Arduino Duemilanove this board however has the capability to make full use of the USB protocol thanks to its Atmega8U2 (which replaces the FTDI Serial to USB chip) meaning that it can "pretend" to be any other USB device, for example you could program it to be a mouse, keyboard, flash disk, printer or any other USB device. It has got a 10 bit ADC so any sensor connected on the ADC pin will give values between 0 to 1023. 0 meaning 0V and 1023 meaning 5V. The reference voltage is taken by default as 5V so the step size is: Step size = 5/1024 = 4.8828 mV However, we can change the reference voltage as well by connecting the AREF pin on Arduino to our desired voltage.