Arduino Uno R4 Series
The Arduino Uno R4 is the 4th generation of the iconic Uno — now with a 32-bit ARM Cortex-M4 processor.
Variants
| Model | MCU | Wireless | LED Matrix | Best For |
|---|---|---|---|---|
| Uno R4 Minima | RA4M1 (Cortex-M4, 48 MHz) | No | No | GPIO, sensors, motor control |
| Uno R4 WiFi | RA4M1 + ESP32-S3 | WiFi + BLE | 12×8 red LED | IoT, web server, wireless |
Key Specs (both)
- 256 KB Flash, 32 KB SRAM
- 14 digital I/O, 6 analog in, DAC (12-bit), CAN bus
- 5V operating voltage, USB-C
- Arduino IDE 2.3+ required
- Shield-compatible with Uno R3
Quick Start
- Install Arduino IDE 2.3+
- Connect Uno R4 via USB-C
- Select board: Tools → Board → Arduino Uno R4 WiFi (or Minima)
- Upload the Blink example
R4 WiFi Specific
- ESP32-S3 co-processor for WiFi/BLE
- Built-in RTC (real-time clock)
- Qwiic/Stemma I2C connector
- Onboard LED matrix: use
Arduino_LED_Matrixlibrary
Common Issues
- Board not detected — R4 needs Arduino IDE 2.3+, older versions do not recognize it
- Upload errors — Double-tap reset button to enter bootloader mode
- Shield compatibility — Most R3 shields work, but 5V-only shields may need level checking