cross-posted from: https://lemmy.world/post/37481146

I'm making a custom keyboard with a Raspberry Pi Pico as the MCU, and i don't understand what all the different pins are for and how they should be wired up to my key matrix and trackpoint.

My current understanding is that GPIO are normal pins that can be wired to the rows and columns, but what of VBUS, VSYS, 3V3, and all the others that aren't just GPIO or GND? And how should the ground pins be used here?

The schematic currently doesn't include the trackpoint because i'm planning to hand wire it and the MCU to the PCB, so i can put them under the PCB in the case and i don't have to try to fit them onto the board. Is there a better way to connect these that won't require adding a bunch of space to the board to fit the MCU?