Microcontroller Boards
Keyboards & Input Devices

Epi 32U4

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

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Epi 32U4 is an Arduino-compatible, ATmega32U4-based microcontroller board with a pinout based on the Pro Micro. All pins are broken out to castellated holes with 1.27-mm spacing. We designed Epi 32U4 to accommodate noisy environments—even without voltage regulators—thanks to a ferrite power filter, a fuse, ESD protection, and surge protection. With an ATmega32U4 at its core, it can act as a USB device, which makes it perfect for keyboards and other space-constrained projects that require a compact controller.

Features & Specifications


Epi 32U4Pro microElite-C V4Qwiic Pro microµduinoBeetlePICO
Manufacturer Ping Hobbyelektronik Various Keeb Sparkfun µduino DFrobot Mellbell
Footprint22.75 x 12.75 mm 33 x 17.75 mm 33 x 17.75 mm 33 x 17.75 mm 12 x 12 mm 20 x 22 mm 15.25 x 15.25 mm
USB Type-CYes No Yes Yes No No No
Castellated pinsYes No Yes Yes No Arguably No
IO available23 21 24 21 20 10 12
Voltage regulatorNo Yes No Yes Yes No Yes
Protective featuresSeveral ¹ None None None Some ² None None
Screw mountingYes No No No No No No
Open SourceYes Yes Unclear Yes Somewhat Unclear Unclear
AvailabilitySoon Plentiful Available Available Unavailable Available Unavailable

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.

Pinout Diagram

Made by Rasmus at Ping Hobbyelektronik using Paul Tol's muted, colorblind-safe palette CC-BY 4.0 2023

Open Source

You can find source files for Epi 32U4 in our GitHub repository. Source files for the previous version are also available.

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In the Press



"[T]his new dev board called the Epi 32U4 might be the smallest ATmega platform we’ve seen so far."


"This tiny board is Arduino-compatible and offers USB Type-C connectivity, making it an excellent choice for makers and hobbyists."


"The board has many features that make it an excellent choice for many projects, such as robotics, home automation, and IoT."

About the Team

Ping Hobbyelektronik

Kalmar, Sweden  ·  rallekralle11  ·  ping-el.se

A nerd with too much free time...

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