Instead of using the standard pro micro, I used the sparkfun pro micro usb-c controller and qwiic port to connect the pimoroni trackball as shown below. Currently the common crkbd doesn't support i2c ...

This trackball, RA-TRACKBALL-2, uses red Opto boards, A052-1011-00, and not a green PS/2 Opto board pair. The green board pair can suffer from backspin. USB+PS2 Mouse MCU controller, HT82M98A, runs at ...

Instead, [jns] focused on reverse engineering the keyboard and trackball, collectively known as the OID (Operator Input Device) for use via USB. In the video, [jns] goes into more detail about ...

The case, which contains a Teensy to translate the encoder signals into USB commands, is a bit on the large side, but that’s to be expected for a trackball.