See this for detail and discussion here.
See this for TMK general info.
There are two options.
You can buy a fully preassembled converter from me here.
Buying Arduino Leonardo and USB Host Shield.
- https://store.arduino.cc/products/arduino-leonardo-with-headers
- https://docs.arduino.cc/retired/shields/arduino-usb-host-shield
- https://www.sparkfun.com/products/9947
See wiki.
https://github.com/tmk/tmk_keyboard/wiki#build-firmware
You can editor keymap and download firmware with web browser.
The converter supports 'HID Boot protocol' only. This means it can host only standard USB keyboard(6KRO).
- Media/System control keys are not recognized.
- 'Fn' key itself cannot be remapped.
Many of NKRO keyboards still can work with the converter in 6KRO mode.