Arduino UNO R4 WiFi: specs and pinout
Arduino UNO R4 WiFi: a 5 V Renesas RA4M1 board with an ESP32-S3 module for Wi-Fi and Bluetooth, and a 12x8 LED matrix.
Specs
| Spec | Value | Source |
|---|---|---|
| MCU (main) | Renesas R7FA4M1AB3CFM#AA0 (RA4M1), 48 MHz Arm Cortex-M4, 256 kB flash, 32 kB SRAM | Arduino official documentation p.2, Features |
| Main MCU operating voltage | 5 V (fixed) | Arduino official documentation p.2, Features; p.9, section 5 |
| Recommended VIN | 6 V to 24 V | Arduino official documentation p.7, section 2 Recommended Operating Conditions |
| USB-C input voltage (VUSB) | 4.8 V to 5.5 V (5.0 V typ); do not supply more than 5 V via USB-C | Arduino official documentation p.7, section 2; p.12, section 7 |
| Operating temperature | -40 °C to 85 °C | Arduino official documentation p.7, section 2 |
| GPIO current (RA4M1) | 8 mA maximum per GPIO | Arduino official documentation p.16, section 11.3 Pin Current |
| Wi-Fi/Bluetooth module | ESP32-S3-MINI-1-N8, 3.3 V, Wi-Fi 4 (2.4 GHz), Bluetooth 5 LE | Arduino official documentation p.9, section 6; p.2, Features |
| Level translator between MCUs | TXB0108DQSR (5 V RA4M1 to 3.3 V ESP32-S3) | Arduino official documentation p.8, section 4 Board Topology |
| Qwiic I2C connector voltage | 3.3 V | Arduino official documentation p.14, section 10 Qwiic I2C Connector |
Power
| Value | Source | |
|---|---|---|
| Supply | VIN 6 V to 24 V, or USB-C at 5 V (USB-C must not be fed more than 5 V) | Arduino official documentation p.2 Features; p.7 section 2; p.12 section 7 |
Pinout
The ESP32-S3 module has its own header (section 6.1, p.10) with its own 3.3 V pins; it is not the same as the main headers.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| IOREF | Reference for digital logic V - connected to 5 V | 5 V | Arduino official documentation p.18, 12.1 Analog | |
| +3V3 | +3V3 power rail | 3.3 V | powers the ESP32-S3 module and the Qwiic connector (section 10, p.14) | Arduino official documentation p.18, 12.1 Analog |
| +5V | +5V power rail | 5 V | Arduino official documentation p.18, 12.1 Analog | |
| VIN | Voltage input | 6 V to 24 V (recommended) | Arduino official documentation p.2 Features; p.7, section 2 | |
| A0 | Analog input 0 / DAC | Arduino official documentation p.18, 12.1 Analog | ||
| A1 | Analog input 1 / OPAMP+ | Arduino official documentation p.18, 12.1 Analog | ||
| A2 | Analog input 2 / OPAMP- | Arduino official documentation p.18, 12.1 Analog | ||
| A3 | Analog input 3 / OPAMPOut | Arduino official documentation p.18, 12.1 Analog | ||
| A4 | Analog input 4 / I2C Serial Datal (SDA) | Arduino official documentation p.18, 12.1 Analog | ||
| A5 | Analog input 5 / I2C Serial Clock (SCL) | Arduino official documentation p.18, 12.1 Analog | ||
| SCL | I2C Serial Clock (SCL) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| SDA | I2C Serial Datal (SDA) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| AREF | Analog Reference Voltage | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D13/SCK/CANRX0 | GPIO 13 / SPI Clock / CAN Receiver (RX) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D12/CIPO | GPIO 12 / SPI Controller In Peripheral Out | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D11/COPI | GPIO 11 (PWM) / SPI Controller Out Peripheral In | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D10/CS/CANTX0 | GPIO 10 (PWM) / SPI Chip Select / CAN Transmitter (TX) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D9 | GPIO 9 (PWM~) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D8 | GPIO 8 | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D7 | GPIO 7 | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D6 | GPIO 6 (PWM~) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D5 | GPIO 5 (PWM~) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D4 | GPIO 4 | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D3 | GPIO 3 (PWM~) / Interrupt Pin | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D2 | GPIO 2 / Interrupt Pin | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D1/TX0 | GPIO 1 / Serial 0 Transmitter (TX) | 5 V (RA4M1 logic) | Arduino official documentation p.18, 12.2 Digital | |
| D0/TX0 | GPIO 0 / Serial 0 Receiver (RX) | 5 V (RA4M1 logic) | The source table writes this pin name as D0/TX0 but describes it as Serial 0 Receiver (RX); treat it as RX | Arduino official documentation p.18, 12.2 Digital |
| GND | Ground | Digital header pin 4 | Arduino official documentation p.18, 12.2 Digital | |
| OFF | For controlling power supply | OFF connector pin 1; its pin 2 is Ground (12.3) | Arduino official documentation p.19, 12.3 OFF |
Build with it
Project ideas for the Arduino UNO R4 WiFi. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- A push-button counter that shows the count on the 12x8 LED matrix: Learning project. One push button wired to a digital pin and GND; the LED matrix is on the board (section 8, p.12).
- A rotary encoder that sets the angle of a small servo motor with an Arduino UNO R4 WiFi: Learning project. The servo runs from its own 5 V supply through the buck module with grounds joined; the board only drives the signal line (GPIO current 8 mA, section 11.3).
- A three-button preset selector that moves a servo to three fixed angles with an Arduino UNO R4 WiFi: Learning project. Buttons are inputs only; the servo supply is separate from the board, as in the encoder idea.
- A Wi-Fi doorbell notifier that scrolls a message on the LED matrix with an Arduino UNO R4 WiFi and a tactile push button: A button to ground on a digital pin (internal pull-up, 5 V logic) is read by the RA4M1; the ESP32-S3 Wi-Fi side sends the alert and the 12x8 LED matrix shows a message.
Common mistakes
- Connecting the ESP32-S3 header pins (3.3 V) to RA4M1 pins (5 V) can damage the circuits. (source: Arduino official documentation section 11.2 Pin Voltage, p.16)
- Driving a servo, motor or other high-current load straight from a GPIO: the GPIOs handle 8 mA. Use an external supply. (source: Arduino official documentation section 11.3, p.16)
- Supplying more than 5 V through the USB-C port. (source: Arduino official documentation section 7 USB Connector, p.12)
Not covered by the official source
- Analog rows carry no voltage value in the source.
- No typical current figures are in the manual.
Sources
- Arduino official documentation (Arduino UNO R4 WiFi user manual/datasheet SKU ABX00087, modified 07/11/2026, 24 pp)