- The UNO R3 is the best board to get started with electronics and coding. If this is your first experience with electronics and coding, the UNO is the most robust board you can start playing with. The UNO R3 is the most used and documented board of the whole Arduino family. The UNO R3 is a microcontroller board based on the ATmega328P. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz quartz crystal, 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.