There's also HRA's USB Gamepad Bridge for MSX. Haven't looked too closely at it myself but it's Pi Pico based so hopefully it won't break the bank!
Sorry for the refloat...
Would this be compatible with MSX Trackball? (used in HAL Eddy II)
I can't find any reference of the HTC-001 hardware or compatibility...
I don't think so . The trackball isn't compatible to mouse modus.
If you read the code, the trackball emulation mode is there, explained by NYYRIKKI.
Even incompatible with MSX mouse, the MSX trackball uses the same pins and protocol to send its movement information.
Maybe this mode is unfinished.
I will check, maybe it can be changed on the fly from one mode to the other
Are pure USB (non-PS2 compatible) mice recognized in this project's setup? Or is it only mice that support the PS/2 protocol?
The trackball protocol it self sucks and I strongly suggest to use mouse protocol when possible... but yes, trackball protocol works as well. Only the game uploading feature is quite broken and does not seem to work at all with all Arduinos... How ever this is discontinued as there are better and more simple alternatives now such as JJFS or MSXDISK... also touchpad support could be improved.
You can set up the trackball emulation mode (and save it as default mode if you wish) by using the mouse buttons on power up or by using console.
Modern USB-mice that are not PS/2 backward compatible can not be used.
In general I very kindly suggest to RTFM (readme.txt)
Looks like links are dead again. Where can I find ps2.zip now?
Thanks all!