I’m currently looking at integrating a touchpad in my own keyboard design.
Up until not long ago you could completely trust that touchpads were interface with PS/2 protocol. But I think there is a change to USB. The uncertainty and the fact that Synaptics won’t share specs with end users makes me hesitate to just buy a modern touchpad replacement part.
But with Framework things could be different. The parts are right now not yet available. But if I knew the interface standard I would totally love to utilise the assembly in my design.
PS: I found mentionings of this device path on the net.
/devices/pci0000:00/0000:00:15.3/i2c_designware.2/i2c-2/i2c-PIXA3854:00/0018:093A:0274.0004/input/input9
Seems to indicate i2c for the touchpad. Which means I won’t be able to easily make it show up as a HID device on USB. (Via QMK PS/2 input)