Arduino Welcomes a New Addition to the UNO Family: The UNO R4

March 28, 2023 by Jake Hertz

As modular electronics become more popular in professional electronics, a new Arduino has hit the market.

In recent years, modular electronics have become increasingly popular in both hobbyist and professional design circles. The concept of building electronic systems from interchangeable, pre-manufactured components offers many advantages, including faster prototyping, easier maintenance, and greater flexibility in design. One of the most well-known and widely used modular electronic systems is the Arduino platform, which provides a user-friendly way to create interactive electronic projects.


Arduino UNO R4

Arduino UNO R4. Image used courtesy of Arduino


Yesterday, Arduino bolstered its lineup with a new addition to the popular UNO family: the UNO R4. In this article, we will dive deeper into the features and capabilities of the Arduino UNO R4 as well as the hardware that underlies it.


Arduino UNO R4

A member of the UNO family, the UNO R4 maintains the same form factor, shield compatibility, and 5 V operating voltage as its predecessor. Software compatibility is also a priority, with most existing libraries and examples working interoperably on the new board. Beyond this, the R4 represents a marked improvement in performance over the R3 and other UNO predecessors.

From a computing perspective, the UNO R4 is powered by the Renesas RA4M1 32-bit microcontroller based on an Arm Cortex-M4 core. Unlike the UNO R3, which was built on the AVR-based ATmega328P, UNO R4 is now built on an Arm core, resulting in a 3x in performance—including an increase in processing power, memory, and functionality. Additionally, from R3 to R4, Arduino has upgraded SRAM from 2 kB to 32 kB and Flash memory from 32 kB to 256 kB to support more complex projects.

Other improvements include a USB-C port instead of a USB port, and the maximum power supply voltage has been raised to 24 V with an enhanced thermal design. The board additionally includes a Controller Area Network (CAN) bus and a Serial Peripheral Interface (SPI) port.

From a connectivity perspective, the board will be released in two versions, the UNO R4 Wi-Fi and UNO R4 Minima, with the former offering Wi-Fi and Bluetooth Low Energy connectivity through an Espressif S3 Wi-Fi module. The latter provides a cost-effective option for those seeking the new microcontroller without additional features.


Renesas RA4M1

At the heart of the new Arduino UNO R4 is a powerful microcontroller: the Renesas RA4M1.

THE RA4M1 is built around a high-performance 48 MHz Arm Cortex-M4 core supported by 25 6kB Flash memory, 32 kB SRAM, and 8 kB data Flash to store data as EEPROM. The RA4M1 MCU is also built on a highly efficient low-power process and is supported by an open and flexible ecosystem concept called the Flexible Software Package (FSP). FSP is built on FreeRTOS, which can be expanded to use other RTOSes and middleware.


RA4M1 block diagram

RA4M1 block diagram. Image used courtesy of Renesas. (Click image to enlarge)


In addition to its LCD controller and touch sensing capabilities, the RA4M1 MCU also includes a 14-bit A/D converter, USB 2.0 Full Speed, CAN 2.0B, SCI (UART, Simple SPI, Simple I2C), and SPI/I2C multi-master interface.

One of the key advantages of the RA4M1 MCU is its low power consumption, making it suitable for battery-powered devices. It also offers high performance and flexibility, with the ability to support various software packages and middleware, making it easy to customize and optimize for specific applications.

Overall, the Renesas RA4M1 group of microcontrollers offers a powerful and flexible solution for HMI designs that require a large number of capacitive touch channels and a segment LCD controller. It also offers low power consumption and a wide range of features and scalability options.

Industry Impact

Arduino offers an early access program for the UNO R4; otherwise, the device will become available in late May 2023. As electronic design using modular components finds more traction in the industry, this new Arduino product seems to come at the right time. With a transition from an AVR-based MCU to an Arm-based solution, the Arduino UNO R4 aims to marry the simplicity and ease of Arduino with the performance of Arm. The result may be a powerful solution for improved modular designs in the professional world.