Arduino UNO R4 with ESP32S3 onboard announced

Recently, there was some exciting news for hardware enthusiasts, as the popular development board, Arduino UNO R3, is getting an upgraded version.

Arduino UNO R4

Arduino UNO R4

Click to view Arduino UNO R3

The most significant upgrade is its chip, which has finally been upgraded from an 8-bit microcontroller to a 32-bit processor. It uses Renesas’ SoC RA4M1.


Renesas is a leading global microcontroller supplier that offers professional and innovative embedded design and complete semiconductor solutions to improve people’s work and lifestyle through billions of interconnected intelligent devices. Renesas’ products serve various applications such as automotive, industrial, infrastructure, and IoT, and include analog power devices, SoC products, and microcontrollers.

The RA4M1 uses an Arm Cortex-M4 core running at 48MHz, with 32KB SRAM and 256KB Flash. Compared to the previous Arduino UNO R3 that used the AVR architecture of ATmega328P running at 20MHz with 2KB SRAM and 32KB Flash, the progress is huge.


Another significant improvement is that the operating voltage of Arduino UNO R4 is still 5V. The maximum power supply voltage can reach 24V, which means that the new R4 uses a better voltage conversion chip. The R4 also improves heat dissipation, and its temperature performance may be better.

The new version, Arduino UNO R4, also offers new protocols such as support for the CAN bus protocol and a 12-bit analog DAC. It also supports the USB 2.0 full-speed protocol with a speed of up to 12Mbps. The previous large USB Type-B connector has been replaced with the widely used USB Type-C connector. This means that in the future, the R4 may be able to simulate a USB drive like the “Micro:bit” and allow users to drag and drop program uploads.

There are two versions of UNO R4: Arduino UNO R4 Wi-Fi and Arduino UNO R4 Minima.

The Wi-Fi version has an ESP32S3 onboard from Espressif Systems, providing Wi-Fi and Bluetooth functions. The Minima is the version without Wi-Fi.

To be honest, having an onboard ESP32S3 is a bit surprising.

In terms of hardware compatibility, the pins, voltage, and size are all consistent with UNO R3. If you have previously purchased products in the UNO ecosystem, you can continue to use them, and Arduino has promised that most libraries and examples are compatible with UNO R3. Only some programs optimized for the AVR architecture need to be ported. The official library porting and substitution plan has already begun.

Overall, I think that Arduino UNO R4 is a very sincere upgrade.

The official summary of the UNO series’ biggest advantages are:

Standard form factor

UNO has always been this size, with unchanged I/O pin positions and definitions. Arduino has been excellent at backward compatibility in this regard.

Shield compatibility

Arduino expands its functionality through shields, greatly enriching its playability, and you can continue to use shields on R4.

5V operating voltage

I like the 5V voltage because when using a development board with a 3.3V operating voltage, you need to consider the voltage problem to prevent burning out the chip. The universality of the 5V voltage is better, and in most cases, you don’t have to worry about burning out the development board. Also, you’ll find that most sensors and modules are actually 5V, so if you want to use a 5V sensor on a 3.3V development board, you need to think about it more.

Outstanding robustness

The stability and durability of Arduino UNO are the strongest I have seen. I have hardly encountered any situations where the Arduino UNO burned out. On the other hand, I have seen many cases where the Raspberry Pi inexplicably malfunctioned and stopped working. As long as you don’t use it too recklessly, it’s not easy to break an Arduino. The Arduino UNO may be the development board that has been with you for the longest time.

This time, Arduino has achieved the following updates:

Maintained compatibility with the previous generation, both in terms of hardware and software, to a certain extent. To be honest, this is not an easy task, especially for domestic development boards, which have done a very poor job in this regard. Maintaining compatibility in terms of size and I/O interfaces is actually quite difficult. This is like how Windows can run software from ten years ago, while many systems cannot.

The pursuit of performance is very restrained. While keeping up with current performance, compatibility and stability are given top priority. I also like this point because it hits the pain points. This makes Arduino a very reassuring partner that is always with us, rather than something that is discarded after a new generation of products is released.

I think compatibility and stability are the foundation and conscience of a development board. Only when these are done well can we talk about other things. It can be said that Arduino has a very clear understanding of its positioning.

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