UNO R3 form-factor board built around a 48MHz Renesas RA4M1 with onboard ESP32-S3 Wi-Fi/BLE, USB-C power, Qwiic connector, and a 12x8 LED matrix—ideal for connected prototypes without stacking extra shields.

I leaned hard on the UNO R4 WiFi for a pair of fall workshops, and it still earns its spot as my default connected Uno. The 48MHz Renesas RA4M1 handles sensor sampling while the onboard ESP32-S3 streams data to an MQTT broker over WPA3 without stuttering, and USB-C finally means I can power a breadboard from the same cable as my laptop. The Qwiic connector saved me time in class—students snapped on IMUs and environmental sensors without soldering or jumper spaghetti—and the 12x8 LED matrix made it trivial to show status icons and error states. Libraries that expect AVR registers still need minor tweaks, but the official ArduinoCore-renesas package covers most of the common APIs now. Idle draw is around 90 mA with Wi-Fi on, so it’s not a coin-cell board, yet for mains-powered IoT builds or rapid prototyping the R4 WiFi remains the sweet spot in 2025.

UNO R4 WiFi combines 48MHz Renesas RA4M1 with ESP32-S3 for connected projects. Includes USB-C, Qwiic connector, and 12x8 LED matrix without extra shields.

Arduino UNO R4 WiFi Development Board with ESP32-S3

Arduino UNO R4 WiFi

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Arduino UNO R4 WiFi