Epi 32U4 is a tiny, Arduino-compatible, USB-Type-C dev board powered by the ATmega32U4 microcontroller. We’ve designed it to be as small as practically possible, and it provides quite a few protective features to keep it operating well in noisy environments. That includes a fuse and ESD protection as well as a ferrite bead and a low-pass filter for analog reference in case the power supply is noisy.

Epi 32U4’s diminutive size allows you to incorporate it into just about any project. You can solder it directly to a PCB or use the included headers for a less permanent mounting solution. It is also quite easy to hand wire, as it includes mounting slots that allow you to screw it down before you begin soldering.

Epi 32U4 can act as a USB device, which makes it ideal for projects like compact keyboards, and its Type-C connector helps you future-proofs your designs. It also has more available IO ports than a standard Pro Micro, so it’s appropriate even for projects where space is not at a premium. Finally, its USB D+ and D- lines are broken out, in case your design requires a separate connector.

Features & Specifications

• ATmega32U4
• 16-MHz crystal
• Runs at 4.5 - 5.5 V for the 16 MHz version, down to 2.7 V at 8 MHz
• Castellated pins at 1.27-mm spacing
• ESD and surge protection on USB data lines and power input
• 500-mA polyfuse
• Ferrite bead for power filtration
• Low-pass filter for analog voltage reference
• 24 available IOs
• Protruding USB Type-C port with mounting slots beside it
• LED on pin 13
• Made in the EU

Comparisons

¹ Varistors for ESD and surge protection, a ferrite-bead power filter, and a low-pass filter for analog voltage reference.
² A low-pass filter for analog voltage reference.

Size Comparisons

Pinout Diagram

Support & Documentation

You can find source and documentation files for Epi 32u4 in our GitHub repository.

Manufacturing Plan

Epi 32U4 will be assembled in Sweden, where we will populate German-made PCBs with high-quality components from well-known manufacturers using an open-source Lumen PnP machine. We will then test each unit in our laboratory.

Fulfillment & Logistics

After our production run is complete, we will box everything up and send it along to Crowd Supply’s fulfillment partner, Mouser Electronics, who will handle distribution to backers worldwide. You can learn more about Crowd Supply’s fulfillment service under Ordering, Paying, and Shipping in their guide.

Risks & Challenges

We’ve planned everything thoroughly, but since this is our first campaign, unexpected developments may arise. Part shortages are of course a risk, but availability looks quite good at this stage, and we are prepared to make substitutions if necessary. Our PnP machine is new to us—and a relatively new device in general—so it may take us some time to dial it in properly. Should any of this become too much of a burden, we also have a relationship with a local company that specializes in electronics design and manufacturing. If necessary, we can contract with them for PCBA.