shmups.system11.org

I'm planning on building a compact jamma system similar to a regular console, and I'd like to be able to use certain types of existing controllers.

The problem I'm facing is how to revert the signals from the controller back to the common ground / every button has its own wire, type of thing (similar to neo geo I think).

For example a saturn controller has chips inside which encode what buttons are being pressed and send it as a data signal.. and then the saturn knows to take that and do the correct button...

The easiest thing would be to rewire the controller, which I've done in the past, but I'd just like the neatness of keeping everything intact.

I'm thinking I'd probably need my own little circuit on the other end of the controller to take the signal and decode it... I'm not sure where to start though.

This is way overkill in my opinion (trying to decode the wire protocol of a console controller simply to convert it to single button signal/ground connections). You'd be better off just soldering signal and ground wires directly to the controller's pcb button contacts, and then route those wires to your jamma connector (maybe use a serial cable or printer cable since you'll need one for every button/direction of the pad). Yuck.

it´s not only overkill, it also produces worse results than the easy method. Having the signal encoded and decoded afterwards produces an, although minimal, amount of lag. One of the benefits of playing PCBs is you get rid of the lag, it seems rather absurd to get that back on purpose, just so your controllers look neat. If you want neatness, Jamma is not the way to go.

thanks for the feedback, I've read more info and it's not a good idea, the best thing I could do for that is use neo geo joysticks, but I'm going to just end up rewiring some old controllers I have.
I was using the top of a pizza box folded in half with holes punched in it for a while...
(i have a vert cabinet, but need a little compact system I can use for horizontal games and portability without detangling jamma harness / psu's all the time)