Arduino Open-Source Single Board Computer Boards - Arduino A000073, The Arduino Uno SMD is a microcontroller board based on the ATmega328. 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 adaptor 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. Arduino Uno SMD A000073 Board Rev3