A new open-source controller with tiny footprint: Epi by u/rallekralle11.
KBD.news Published December 8, 2022
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.
23(?) GPIO pins
1.27mm pin spacing
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
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.