This variant is for 'standard' model F keyboards, including FAT, F122, ...
For other variants see:
- https://github.com/purdeaandrei/SMDModelFController/tree/extra_columns
- https://github.com/purdeaandrei/SMD4704KishsaverClassModelFController
- https://github.com/listofoptions/TH-XWhatsIt
This project is based on the Through-hole xwhatsit by listofoptions, which is un turn based on the capsense controllers by XWhatsIt (Tom Wong-Cornall). original liscencure holds, as well as CERN OSH (compatible license).
original implementation of Tom Wong-Cornall's controller documented here
http://downloads.cornall.co/ibm-capsense-usb-web/ibm-capsense-usb.html
Working theory of operation is under the previous link.