Has anyone actually documented the pinout/protocol anywhere?
I mean the joypad side, not the CPU side (that's already detailed in the PC-FX GA documentation).
There are 7 pins ... 1 power (+5V), 2 ground and 4 data going into an NEC 65612 gate array.
I'm going to assume that that's "reset", "clock", "in" and "out" ... but it'll save a bunch of time screwing around with an Arduino if someone has already documented this somewhere.