Guide to Arduino UNO R4 Pinout & Specs(Minima & WiFi)

Last updated on March 4th, 2024 at 02:06 pm

The most awaited fourth-generation UNO board and the successor of the popular R3 board– the Arduino UNO R4 has been recently released and is available at online stores for purchase.

Arduino UNO R4 Minima
Arduino UNO R4 Minima

The new Arduino UNO R4 has two variants; UNO R4 Minima(without the wireless module) and UNO R4 WiFi(with WiFi plus Bluetooth module). Both are identical in terms of pinout, form factor, and specifications. The only difference is the presence of the ESP32 module and onboard LED Matrix in R4 WiFi. (Read more differences)

Arduino UNO R4 WiFi
Arduino UNO R4 WiFi

Watch the review video below:

What’s new in Arduino UNO R4?

So what’s different in UNO R4 than the previous R3 board?

The first significant change is the presence of the most awaited USB-C port.

The Arduino UNO R4 takes a giant leap in terms of the onboard microcontroller. Atmega328p is replaced with the powerful 32-bit Arm Cortex-M4 microcontroller(Renesas RA4M1) that can run up to 48 MHz.

The next big update is the memory: 256 kB Flash, 32 kB RAM, and 8 kB of EEPROM, 4 times the UNO R3.

Arduino UNO R4 Minima hardware overview
Arduino UNO R4 Minima hardware overview

The new UNO supports the CAN bus protocol with one pure 12-bit DAC channel. As for the analog pins, they can have a resolution of up to 14-bit as opposed to the 10-bit resolution in Arduino UNO R3.

All the features mentioned above are available in both R4 Minima and R4 WiFi. Whereas UNO R4 WiFi also features a built-in ESP32-S3 chip, 12×8 LED matrix, and a Qwiic I2C connector.

Arduino UNO R4 WiFi hardware overview
Arduino UNO R4 WiFi hardware overview

To learn more differences between Arduino UNO R3 and R4, click here.

Arduino UNO R4 Pinout

Since the UNO R4 is identical to all UNO boards in terms of the form factor and pin layout, there is not a huge difference in the pinout as far as the R3 is concerned. Although R4 Minima and WiFi have a slight difference in their pinouts.

Given below is the pinout diagram of the UNO R4 Minima.

Arduino UNO R4 Minima Pinout
Arduino UNO R4 Minima Pinout

The pinout of UNO R4 WiFi is slightly different. See the image below.

Arduino UNO R4 WiFi Pinout
Arduino UNO R4 WiFi Pinout

Given below is the table of all the IO pins on the UNO R4:

Pin TypePin Number
Digital PinsD0 – D13
PWM PinsD3, D5, D6, D9, D10, D11
Power output3.3V, 5V
Analog PinsA0 – A5
Serial Pins(UART)RXD: D0, TXD: D1
External Interrupt PinsD2, D3
SPI PinsSS : D10
COPI : D11
CIPO : D12
SCLK : D13
I2C protocolSDA: A4
OPAMP – : A2
Built-in LED PinD13
Pin description of Arduino UNO R4

Arduino UNO R4 Specifications

Given below are the detailed specifications of UNO R4 Minima and WiFi boards.

MicrocontrollerRenesas RA4M1 (Arm® Cortex®-M4)
WiFi-Bluetooth moduleESP32-S3(R4 WiFi only)
PinsDigital I/O Pins14
PinsAnalog input pins6(14-bit)
PWM pins6(8-bit)
PowerCircuit operating voltage5 V
Input voltage (VIN)6-24 V
DC Current per I/O Pin8 mA
Clock speedMain core
ESP32-S3 (R4 WiFi only)
48 MHz
240 MHz
ESP32-S3 (R4 WiFi only)
256 kB Flash, 32 kB RAM
384 kB ROM, 512 kB SRAM
DimensionsWidth68.58 mm
Length53.44 mm
Specifications of Arduino UNO R4 Minima and WiFi

How to power Arduino UNO R4?

You can power the UNO R4 either using a USB C cable, Vin pin, or the barrel jack. The USB voltage should be around 5V. Vin pin accepts voltage anywhere between 6 to 24 volts.

Since the Vin pin is internally connected to the barrel jack, you can use an adapter to power the board.

Vin pin6247.0V
USB C4.85.55V
DC Jack6247.0V
Ways to power the Arduino UNO R4 board

How much memory does UNO R4 have?

Both Arduino UNO R4 Minima and WiFi feature 256 kB of FLASH memory(8 times more than the UNO R3), 32 kB of SRAM(16 times more), and 8 kB of EEPROM(8 times more). The main clock frequency of the board is around 48 MHz.

This is due to the presence of the main microcontroller, “Renesas RA4M1” on both boards.

The R4 WiFi variant has an onboard ESP32-S3 chip. The chip features 384 kB of ROM and 512 kB of SRAM.

How to access the ESP32-S3 chip on R4 WiFi?

The ESP32-S3 chip has two main functions here: giving the board WiFi+Bluetooth functionality and acting as a serial bridge for the main microcontroller.

So using its wireless connectivity feature is easy; by utilizing the WiFiS3 library that is built into the UNO R4 Core. There are many examples available on the official website of Arduino UNO.

But accessing the ESP32-S3 chip and using it separately isn’t very easy. Read the tutorial here.


Download the datasheet of UNO R4 from here:


Download the Schematic of UNO R4 from here:

Arduino UNO R4 Dimensions

The dimensions of UNO R4 are 68.58 mm in length and 53.44 mm in width. See the image below:

Arduino UNO R4 Dimensions
Arduino UNO R4 Dimensions

Arduino UNO R4 Price

Arduino UNO R4 Minima is priced at $20, whereas the UNO R4 WiFi at $27.50 on the official website of Arduino. You can get them from Amazon also:

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Ankit Negi

I am an electrical engineer by profession who loves to tinker with electronic devices and gadgets and have been doing so for over six years now. During this period, I have made many projects and helped thousands of students through my blog and YouTube videos. I am active on Linkedin.

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