Others?
āUser programmableā button/switch. Handling for example via zyncoder library midirouter part, something like MAP BT#1 CC#nn ā¦
And now another āfun to be haveā.
Two expander reserved inputs are assigned, but at least maybe this gives an idea to tinker with:
Port extender chip pins can be used also as outputs in mixed configurations - some are inputs, some are outputs and pins configured as outputs donāt interfere with interrupt logic to INTA/INTB pins. This is important part. Now comes fun part:
Pushbutton and LED, integrated inside or mounted above switch. This button can be used by program as some kind of toggles (state may indicated by LED), even in context (for example on admin screen Start/Stop options toggles), tapping some kind of tempo, doubling as encoder switch, user programmable actions etc. LED can be also used independently by Pi, for example as visual metronome, for Zynthian ābusyā indication (loading programs or samples from card/usb stick) - same way as Zynthian logo does by now on screen. And of course one usage too - programmable LED always helps for debugging hardware/software cooperation 