I spent today, and most of this evening, developing and testing both a new Picade firmware and a quick and dirty update script which should let you easily get it installed hopefully without even opening up your Picade.
Complete instructions for the process are here: https://github.com/pimoroni/Picade-Sketch/tree/master/update
You’ll need either a keyboard to type in the necessary commands, or a network connection to your Picade so you can do so remotely.
Note: RetroPie by default shows up on your network as RETROPIE and the default SSH login is the same as Raspbian:
I’ve made some quite significant changes to how buttons are handled, which should improve the performance of multiple simultaneous button presses, and repeated button presses.
I’d really love any feedback, especially from fighter aficionados.
Other changes include the ability to hold the volume buttons to ramp the volume up/down, auto-saving of volume level.
This is all open-source, albeit fairly ugly code. I have tried to make the Arduino sketch as beginner-friendly as possible, with some comments at the top to guide you through things like remapping and turning the Vol Up/Down buttons into extra game buttons.