Arduino UNO R3 V1 Development Board with USB Cable The Arduino UNO R3  is an open-source embedded development board designed around the ATmega328  microcontroller. As Atmel transitions to surface mount ICs, the DIP package is becoming scarce, prompting the shift to SMD. This board offers the same functionality as the traditional PTH version, with the only difference being the non-removable ATmega328. Ideal for a wide range of projects, it features 14 digital I/O pins (6 with PWM), 6 analog inputs, 32 KB flash memory, 2 KB SRAM, and 1 KB EEPROM. With a clock speed of 16 MHz, it supports a 5V operating voltage and is recommended to be powered by 7-9V DC.