Chipmaker Arduino ... Uno series of microcontroller boards. The series is the company’s most popular product line. The Uno R4 replaces the product line’s previous flagship chip, the Uno R3.

The previous generation Arduino UNO R3 used the 8-bit microcomputer ATmega328P as the MCU, but the Arduino UNO R4 is equipped with the ' Renesas RA4M1 ' that includes a 32-bit Arm Cortex-M4 core.