Arduino empowers makers’ creativity and passion for innovation with a robust new board that’s perfect for all users, from beginners to experts – allowing anyone to easily connect to the internet and create IoT projects.
Your user-friendly, accessible UNO just took a quantum leap forward: Arduino UNO R4 is a 32-bit microprocessor offering more speed, memory, connectors and connectivity options than any version of the board before. Out of this world, and into the future.
The UNO universe expands with UNO R4 WiFi: the same industry-standard form factor at 5V operating voltage, but with the enhanced performance of a RA4M1 32-bit microcontroller by Renesas with ESP32-S3-MINI coprocessor – for increased computational power, memory and speed – as well as Wi-Fi® and Bluetooth® connectivity, a 12 x 8 LED matrix, and a Qwiic connector.
1】The board is compatible with the official Version.
2】An additional row GPIOs has been added for convenient extra expansion.
3】In the WIFI version, the USB port can be switched between the main chip and ESP32.
Operating Voltage: 5V
Memory: 256KB Flash / 32KB SRAM
Input Voltage: 6-24V
Clock Speed: 48 MHz
Programming Port: USB-C
MCU: RA41M1 from Renesas (Cortex M4)
HID device (emulate a mouse or a keyboard)
Improved power section (up to 24V through VIN)
DAC (12 bits)
WiFi® / Bluetooth® Low Energy
Fully-addressable LED matrix with 96 red LEDs (12×8)
Qwiic I2C connector
RTC (with support for a buffer battery)
Runtime errors diagnostics
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.
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.
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.
The pinout of UNO R4 WiFi is slightly different. See the image below.
Given below is the table of all the IO pins on the UNO R4:
D0 – D13
D3, D5, D6, D9, D10, D11
A0 – A5
RXD: D0, TXD: D1
External Interrupt Pins
SS : D10
COPI : D11
CIPO : D12
SCLK : D13
OPAMP + : A1
OPAMP – : A2
OPAMP OUT: A3
Built-in LED Pin
Pin description of Arduino UNO R4
Arduino UNO R4 Specifications
Given below are the detailed specifications of UNO R4 Minima and WiFi boards.
Renesas RA4M1 (Arm® Cortex®-M4)
ESP32-S3(R4 WiFi only)
Digital I/O Pins
Analog input pins
Circuit operating voltage
Input voltage (VIN)
DC Current per I/O Pin
Main core ESP32-S3 (R4 WiFi only)
48 MHz 240 MHz
RA4M1 ESP32-S3 (R4 WiFi only)
256 kB Flash, 32 kB RAM 384 kB ROM, 512 kB SRAM
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.
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.