I have written a very basic firmware for the HHKB pro 2 using the Adafruit Feather 32u4 Bluefruit LE. It is USB only at the moment, Using NicoHood's HID Library. It should work for any 32u4 micro, at least until bluetooth is added.
I created this because I am modding my own HHKB and adding a lot of new functions: Bluetooth, mini joystick + mouse buttons, Raspberry Pi zero as a usb device which also controls LED's and an IR emmiter. Basically it's a project that will require lots of modification to TMK, or writing my own driver from scratch. When I started with very little information I found it very hard to follow TMK's source to pick out the parts I needed. TMK is written for a lot of different keyboards, and with a lot of functionality and optimization. Thats all very good for actually using the driver, but not as good for getting a foundational understanding of how it all works together, and how the HHKB works.
The goal of sharing this isn't to try to replace TMK, QMK, or other firmwares, but to provide a starting point to understanding the basics. More will be added to it over time. It will continue to serve as something that is supposed to be easy to read, and hopefully educational.
Download:
https://github.com/sexiewasd/HHKBNicoHood HID:
https://github.com/NicoHood/HID
