Arduino UNO R4 WiFi product image

Arduino UNO R4 WiFi

Nerd Approved:
(5/5)
Review by Joshua Morris on
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Review

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.

✓ Pros

  • ✓48MHz Renesas RA4M1 pairs with ESP32-S3 for simultaneous logic and Wi-Fi
  • ✓Onboard Wi-Fi/BLE, DAC, CAN, and Qwiic cut down on shield stacking
  • ✓Integrated 12x8 LED matrix accelerates debugging in the field
  • ✓USB-C power/programming and UNO footprint stay breadboard-friendly
  • ✓Arduino IDE, web editor, and updated libraries cover most R4 use cases

✗ Cons

  • ✗Idle current ~90 mA with Wi-Fi active, so not ideal for battery-only builds
  • ✗Legacy AVR-specific libraries sometimes need renesas porting
  • ✗Less flash/RAM headroom than full ESP32 dev kits for complex networking

Specifications

MicrocontrollerRenesas RA4M1 (Arm Cortex-M4, 48MHz)
WifiEspressif ESP32-S3 (Wi-Fi + Bluetooth LE)
PowerUSB-C 5V or VIN 7-24V
Digital Pins14 digital (6 PWM, 12-bit DAC output)
Analog Pins6 analog inputs (12-bit ADC)
Led MatrixIntegrated 12x8 red LED matrix
ConnectivityWi-Fi, Bluetooth LE, CAN, Qwiic connector
Dimensions68.85 x 53.34 mm (UNO R3 footprint)
Date First AvailableJune 21, 2023

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