Basic button wiring

[exhar]

I've been working on and off on a small 1P control panel (just to keep myself busy), and i've got a question with the button wiring.
I'm gonna use a gamepad hack, and it's a Gravis Gamepad Pro USB. My question then is.. if i'm not gonna daisy-chain the grounds but rather run two wires from each 'button' on the gamepad to the pushbuttons.. do i need to know which of the two is ground? or can i just wire whichever to the common and the no on the cherry switch? (being as i assume each individual loop will be complete)
I can't seem to find any schematics for the gravis gamepad pro usb, and i can't tell a diode from a tuna sandwich.
If at all anyone could help me out on this, or if anyone has the schematics for the gravis gamepad pro usb (which are and which aren't grounds), it'd be much appreciated.

Toodles.
m

[Kitbasher]

I just finished using a Gravis gamepro USB for my first arcade controller.  Worked fine.  I decided not to worry about trying to trace the circuits to find out if there is actually a common ground.  Since that pad works by a button closing the contacts on the circuit board I simply soldiered my wires to the bare contacts, cimped spade connectors to the wires and then hooked them to the microswitches.  If you do not have the tools or the soldiering skills, there is a guy who is selling hacked Gravis Gamepad Pro USB pad by the name of Gnateye.  He posts in the for sale trade area.
Later

[Druin]

Yes, if you are just going to wire each of the switch contacts directly to the  new external switch contacts without any ground chaining etc, you don't need to worry what's what.  A switch doesn't care which terminal is ground or signal, just that when you press it, it completes the connection between the contacts.

So if you have button A on a gamepad, it has 2 contacts.  If you solder a wire to contact 1, and another wire to contact 2, then wire those to a cherry switch (N.O. normally open, press to make contact), no problem.

[exhar]

Ok, great. That's exactly what i needed to know.
Thanks alot Kitbasher and Druin.

[SNAAAKE]

why gravis pad at all..there are tons of other pads(usb onces) that are very easy to work with.Just a suggestion .

[exhar]

Yeah i figured as much, but hey.. it was a really cheap pad.
Sides, it's a 'do as i go' kinda project, and it's extremely imperfect in every sense of the word (yet it looks fantastic, my ability to cover up mistakes is beyond imaginable).
Anywho, just a simple 1/32 holes here and there and i was good to go.
I already did the whole soldering and put it all together.. it works great.

Again, thanks to everyone for posting.

[eightbit]

Talk about cheap joysticks. I bought a 6 button game pad from circuit city yesterday for $1. I took it apart and it looks like it will work great for my mini-mame project.

[exhar]

i went for the gravis gpp usb namely because i wanted six player buttons and at least three "function" buttons. sides, i've always used gravis and it's always been quite good.
and actually this pad isn't all that bad for a single player project. despite the fact the gravis xperience software is over ten megs, it's actually pretty useful. auto-loads button settings according to what executable you launch, and you can hotset pretty much everything, including double hotsets and multiple hotsets.
another plus, i guess, is the fact the usb cord is extremely long.

anywho, another question here. i might later on work on a two player project, or even a cabinet. no pad hacks here. so the question is.. is there software for keyboard encoders that allows hotsets?
hotsetting just completely blew me out of the water. heh.

[eightbit]

I don't know about hotsets but its fairly simple in mame to load a custom key configuration for each rom.