Epi 32U4

An extremely compact, Arduino-compatible ATmega32U4 USB Type-C dev board

Jun 09, 2023

Project update 3 of 9

A Quick Review of Similar Boards

by rallekralle

Hola, and welcome to our second weekly update! This time we will compare Epi 32U4 to some similar boards.

You’ve seen this size-comparison illustration on the campaign page no doubt, as well as the spec comparisons. I’ll go through them in order…

The classic Pro Micro clone. Who doesn’t love it? It’s affordable and does the job, but it’s getting a bit outdated with that USB Micro-B port. And it doesn’t have all its pins broken out either. Though, most of the time that doesn’t matter. For protective features, it only has the standard 500-mA polyfuse on the USB power line.

But the Pro Micro led to the development of better boards. The Elite-C series from Keeb, for example. It’s the same form factor as the Pro Micro, but it has USB Type-C, a reset button, and extra pins. And it’s castellated. (I used to think the term was "crenelated", like castle battlement walls, but apparently it’s "castellated" when talking electronics.) The Elite-C does not have any voltage converters, however, or obvious protective features over the Pro Micro. It is very thin, with the USB port middle-mounted, making it ideal for its original purpose: controlling DIY keyboards.

Sparkfun developed the original Pro Micro, and they’ve been building on it every since. Their latest version, from what I can tell, is Qwiic Pro Micro. It has most of the features of the Elite-C V4, along with a voltage converter and a connector for Sparkfun’s Qwiic I²C system. Though with all that, it doesn’t have any more pins broken out than the standard Pro Micro, and the USB Type-C port is not middle-mounted, which it a little thicker.

µduino (Microduino) is extremely impressive, and I’d get one immediately if they were still available. This is, as far as I know, still the smallest Arduino-compatible board ever made. Somehow, developer Dave managed to cram all the features of the original Pro Micro, and more, into barely more than a square centimeter. With that said, I don’t think it’s too practical to use. The pins are crammed together in a 1.27-mm double-row header, which I imagine makes soldering tricky. And I have no idea how you’d mount it without of gluing it down permanently.

Beetle, then. One of DFRobot’s well-known boards. It has a unique shape to say the least. Looks quite neat. Though it still uses the Micro-B port, has few usable pins, and lacks voltage regulators and other notable features. The large pseudo-castellated pads makes soldering to it a breeze, though, which is ideal for beginners. It has its applications for sure.

Which brings us to the PICO. It was released in 2018 and claimed to be the smallest Arduino-compatible board ever. (For the record, that’s the year after the µduino came out.) It has a voltage converter, a reset button, and an onboard RGB LED which is cool. It’s the smallest board I know of that uses standard 2.54-mm headers. But that also prevents it from having too many pins broken out. And, like the µduino, it’s unavailable at the moment.

I’m not going to describe the Epi here. The campaign page does that nicely on its own. But I will note that none of the boards I’ve written about above appear to be CE or UKCA marked.

That’s it for today. Have a great weekend and a happy Pride Month!

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Epi 32U4 is part of Microchip Get Launched

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