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Epi controller

A new open-source controller with tiny footprint: Epi by u/rallekralle11.

KBD.news
Published December 8, 2022
Creators! Feel free to tip me off about your keyboard related projects to bring them to 100K readers.

Named after the Epipactis genus or orchids, the Epi by Rasmus (aka rallekralle11) is a tiny controller barely wider than the USB-C connector.

Announced and open sourced in late October, the first prototypes arrived and proved to be working fine.

This is something I've been working on for a while. It's based on the Atmega32U4 but is quite a lot smaller than a Pro Micro and has more pins broken out. The pin spacing is 1,27mm which lets the entire thing be tiny. You can see how it's barely wider than the USB-C port – rallekralle11.

Pic:

Specs

  • Atmega32U4 chip
  • 23(?) GPIO pins
  • 1.27mm pin spacing
  • Dimensions: 23x12.5mm
  • castellated pins
  • Data line ESD protection
  • USB-C connector sunk into the board, and slightly protruding from the end for panel mounting
  • Holes where M2 bolts can be used to hold it in place

Pic:

Despite the tiny footprint, it has most features of a classic Pro Micro:

Only thing it lacks are TX/RX LEDs, voltage regulators and a fuse. None of which should matter for a keyboard. Otherwise it's the same as a Pro Micro but smaller and with more usable pins.

So no integrated voltage regulator, only runs at 4.5-5.5V (down to 2.7 if you make it with an 8MHz crystal, or use the internal oscillator) which is totally fine for USB. No RX/TX/power LEDs either, only one on pin 13 for testing.

Resources

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Published on Thu 8th Dec 2022. Featured in KBD #106 (source).

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