This week’s EYE ON NPI (video) is a new spin on an old familiar classic, it’s Arduino’s UNO R4 Minima and R4 WiFi Boards, now in stock at DigiKey for folks who want a 5V microcontroller board with classic UNO-compatibility but a ton more speed, flash and RAM!

The UNO R4 comes in two flavors, the Minima is low cost, only $20, whereas the UNO R4 WiFi is $27.50 and adds WiFi and BLE via an ESP32-S3 plus a cute monochrome LED grid for scrolling messages or displaying status icons.

This pair of dev boards look just like those classic Arduino boards you probably learned to code and hack on, they’ve been around for almost 20 years, the first board looked very similar, but had a RS232 serial port instead of USB, and all through-hole components. Through various iterations and improvements, the original board was redesigned to add USB and update to the ATmega168 with the Diecimila and then the ATmega328 plus auto-power-switching Duemilanove in 2009. In 2010 the most popular Arduino to date was released, the UNO, which updated the USB port to use an ATmega16u2 and through various small revisions added the IOref pin to allow 3V power/logic and separate I2C pins since A4/A5 were no longer always connected to a TWI peripheral.

Since about 2012, which was the release date of the UNO R3, not a lot has happened with that particular configuration/shape. Arduino the company has released a ton more boards but in different form factors, all  available at DigiKey: Nano, Due, MKR, Portenta etc. and you should definitely check them out! But it’s also a big deal when the main workhorse of the family gets a respin. Particularly since the new R4 takes a very different direction than the previous UNOs: instead of just upgrading the atmegaxx8 chipset, Arduino has gone with the totally different ARM Cortex-based RA4M series which we’ve covered on a previous EYE ON NPI.

In that video we covered a lot about the chip itself, so check it out if you’re interested in the specifics of that chip family.

The chip itself is a similar family to the ARM Cortex M0-based SAMD21 ‘Arduino Zero‘ but thanks to the Renesas version of this core, we now get the 5V-run RA4M.  From Arduino’s description, here are some of the updates

• Hardware compatibility with UNO form factor: The UNO R4 Minima maintains the same form factor, pinout, and 5 V operating voltage as its predecessor, the UNO R3. This ensures a seamless transition for existing shields and projects, leveraging the extensive and unique ecosystem already established for the Arduino UNO.
• Expanded memory and faster clock: Prepare for more precise calculations and the ability to handle complex projects with ease. The UNO R4 Minima boasts increased memory and a faster clock speed, empowering you to tackle demanding tasks effortlessly.
• Extra on-board peripherals: The UNO R4 Minima introduces a range of on-board peripherals, including a 12-bit DAC, CAN BUS, and OP AMP. These additional components provide you with expanded capabilities and flexibility in your designs.
• Extended 24 V tolerance: The UNO R4 Minima now supports a wider input voltage range, allowing power supplies up to 24 V. This enables seamless integration with motors, LED strips, and other actuators, simplifying your projects by utilizing a single power source.
• SWD connector: Debugging is a critical aspect of any project. Simply connect an external debugger to the UNO R4 Minima and effortlessly monitor the inner workings of your system. Stay in control and gain valuable insights.
• HID support: The UNO R4 Minima comes with built-in HID (Human Interface Device) support, enabling it to simulate a mouse or keyboard when connected to a computer via a USB cable. This convenient feature makes it a breeze to send keystrokes and mouse movements to a computer, enhancing usability and functionality.

Some are not particularly new: USB HID support was already added with the Arduino Leonardo, and SWD connectors have been available on the Zero. Some are quite nice additions: USB Type C replaces the chonky B or Micro B, CAN bus support historically requires a separate MCP2515 chip now just needs a transceiver.

The SAMD21 had a DAC, but only 10 bits whereas this one is 12. And 24V DC input with a buck converter for the 5V power rail means you can power motors and larger LED arrays directly. And of course, this is one of the few ARM Cortex chips that can run at 5V.

Adding a new core to the Arduino IDE & ecosystem is no small task, but often the initial work of getting one chip in the family added means that new boards can easily use the same board support package.

Check out the renesas-core over on GitHub to see the libraries that have already been ported to RA4 / RA6 family. But given there’s now three chips in this family, we expect support for Renesas will continue.

One of the great reasons to use Arduino is once your prototype is up and running, you can use the UNO R4 design files to respin your very own open-source hardware variants thanks to the published CAD files!

At $20 a piece, these new Arduino UNO R4s are a great price for the high quality you get from Arduino – and there’s lots of them in stock at DigiKey for immediate shipment! Grab both the UNO R4 Minima and UNO R4 WiFi, and they’ll ship immediately so you can get started moving your 8-bit micro projects to Cortex-M4 by tomorrow afternoon.

See this video: