Arduino UNO R4 Minima (China Version)

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UNO R4 Minima development board Improved Version Compatible with Arduino UNO R4

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.

Arduino’s continued commitment to making technology accessible to everyone was the inspiration behind Arduino UNO R4 Minima: the new addition to the brand’s community-supported ecosystem offers powerful technology at an affordable price. Packing more computational power, memory and speed in the familiar form factor of the UNO at 5V operating voltage, it allows users to easily upgrade projects made with the UNO R3 or the Leonardo. What’s more, thanks to a RA4M1 microcontroller by Renesas, it can leverage two new off-the-shelf peripherals, CAN BUS and (12 bit) DAC: perfect for automation or audio projects.


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)
  • CAN bus
  • DAC (12 bits)
  • Op amp


【Product Show】

Package Contains

UNO-R4-Minima-B x1

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 Type Pin Number
Digital Pins D0 – D13
PWM Pins D3, D5, D6, D9, D10, D11
DAC Pin A0
Power output 3.3V, 5V
Analog Pins A0 – A5
Serial Pins(UART) RXD: D0, TXD: D1
External Interrupt Pins D2, D3
SPI Pins SS : D10
COPI : D11
CIPO : D12
SCLK : D13
I2C protocol SDA: A4
OPAMP – : A2
Built-in LED Pin D13
Pin description of Arduino UNO R4



Arduino UNO R4 Specifications

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

Microcontroller Renesas RA4M1 (Arm® Cortex®-M4)
WiFi-Bluetooth module ESP32-S3(R4 WiFi only)
Pins Digital I/O Pins 14
Pins Analog input pins 6(14-bit)
DAC 1(12-bit)
PWM pins 6(8-bit)
Communication UART 1
I2C 1
Power Circuit operating voltage 5 V
Input voltage (VIN) 6-24 V
DC Current per I/O Pin 8 mA
Clock speed Main core
ESP32-S3 (R4 WiFi only)
48 MHz
240 MHz
Memory RA4M1
ESP32-S3 (R4 WiFi only)
256 kB Flash, 32 kB RAM
384 kB ROM, 512 kB SRAM
Dimensions Width 68.58 mm
Length 53.44 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.

Symbol Min Max Ideal Unit
Vin pin 6 24 7.0 V
USB C 4.8 5.5 5 V
DC Jack 6 24 7.0 V
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


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