The Arduino UNO, first announced at our own Maker Faire, is one of the — if not the — most recognizable icons of the maker movement. It was an Uno-like board, the Diecimila, that got this humble author excited about hacking on electronics projects, and I’ve continued my love affair with the brand ever since. Imagine my excitement when I learned during Arduino Day 2023 of the company’s plans to release an R4 version of the venerable board, which built on the familiar form factor, while also promising new features to sate the needs of today’s hungry hardware hacker.

The R4 WiFi (this is how they have chosen to brand it — I of course know the term should be hyphenated) maintains the outward appearance of a typical UNO — including of course that critical shield compatibility, as well as the 5V operating voltage expected by most shields — but a closer look reveals that the new board has a number of tricks up its sleeve. The first one is a bit of a giveaway, considering the name: integrated Wi-Fi via an ESP32-S3 coprocessor (which means Bluetooth/BLE too!) — in fact, the ESP32 can even be reprogrammed, giving you two MCUs for the price of one! A new partnership with Renesas brings a 32-bit RA4M1 as the primary MCU, making this the first 32-bit UNO form factor offering from Arduino, and bringing with it a significant performance boost over the R3. Other more subtle upgrades include a USB-C port for programming and Human Interface Devices (HID) capabilities (meaning the R4 can act like a keyboard or mouse), and a QWIIC connector for easy connection to sensors and actuators without a shield or breadboard.

The Arduino UNO R4 WiFi represents a significant step forward compared to the venerable R3.

During pre-release promotion, the R4 was typically pictured with a large yellow rectangle obscuring part of the board — which was made to look like “just part of the design treatment,” but was clearly hiding something. I was lucky enough to interview Arduino co-founder Massimo Banzi some time ago and learned what it was, but have been bound by embargo until today (and, the 1.0.1 release of the R4 board package, which is required to take advantage of it, wasn’t available until today anyway). The area “under the yellow rectangle” is in fact a 12×8 LED matrix, which brings all kinds of exciting possibilities to the board, without any additional external hardware. Example code includes displaying a single frame, cycling through animations, and even running a full Conway’s Game of Life simulation! An LED Matrix Editor tool even lets you define graphics and animations visually, to facilitate its use.

An integrated 12×8 LED matrix brings all kinds of exciting possibilities to the board.

Although the software was only released today, we tried to put the board through its paces with as many of the “usual” UNO-type examples that we could think of, and everything worked well, despite the shift in architecture away from 8-bit AVR. An early adopters program put boards in the hands of open-source library and project maintainers to help ensure any incompatibilities could be resolved before launch.

Overall, the R4 WiFi represents such a significant step forward compared to the venerable R3 that it’s easy to recommend it as a first board for the current generation of makers. The R3 has not been discontinued, but given identical pricing and robust compatibility, it’s almost impossible not to want to take advantage of all that the new board offers for the same price. And if price is a concern, the UNO R4 Minima is available for $20, without the Wi-Fi, LEDs, or Qwiic connector. Both boards are available today from Arduino and authorized distributors.

Standout features: 

  • 32-bit Cortex-M4 MCU
  • ESP32-S3 coprocessor with Wi-Fi and Bluetooth
  • legacy shield and library compatibility
  • 12×8 LED matrix!!!