The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital
input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a
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 Uno differs from all preceding boards in that it does not use the FTDI
USB-to-serial driver chip. Instead, it features the Atmega8U2 programmed as a USB-to-serial converter.