I don't know. This is my first keyboard firmware. Anyway, the EM85F684A is a really obscure MCU, so there was no other way than to start completely from scratc

I don't know. This is my first keyboard firmware. Anyway, the EM85F684A is a really obscure MCU, so there was no other way than to start completely from scratch, to have FOSS development/flashing tooling and the firmware itself. There's nothing pre-existing available online. I've never heard about Elan before starting this project. It would have certainly been easier to support a more common MCU. Certainly more than half of the effort went into reverse engineering and figuring out the unknowns.