Ground help...

[Super Cameraman]

Sorry to make two threads for the same project, but this doesn't really have to do with guitar string.

I'm wiring a USB gamepad up to a Guitar Heroish controller.

The main problem is that for some reason, the controller appears to have 2 or even 3 grounds. It might not actually be the real GROUND but it's all I have, I think. I need 6 buttons wired to the controller, but all 6 need to have the a common ground. I found 4 that have a common ground. The other 2 have their own grounds.

Is this even possible? Does anyone know of a USB gamepad with 6 buttons on the same ground? Getting this to work could make or break this project.

[Skyone]

Commons and grounds are called as so for a reason, there are never two grounds or commons in one circuit - your said points are not ground nor common.

What the big problem? Just jump the two button traces for each button.

[Kurt_]

Use this: http://pinouts.ru/Slots/USB_pinout.shtml

Using that, you can trace the connection pin 4 makes with this device to the common ground.

[Super Cameraman]

I'm sorry, I'm a real newb when it comes to wiring... Let me try to explain this better.

I think the controller has some sort of grid, so it's not like each button has 2 unique leads. Some of them share one lead, others just have 2 other leads. I'm sorry if it's not easy to understand.

Skyone, could you explain that better? What does "jump the traces" mean? Do you mean follow the traces to see where the lead? I did, and I got three grounds. (Well not grounds, but you get it.)

Kurt... what?

[Kurt_]

1) Using that pinout, determine what kind of USB cable you have.
2) Find the pin for ground.
3) Using the continuity test on your multimeter, connect one probe to the ground pin on the USB cable (or USB jack on your device) and touch the other probe on the board until you find a spot that has continuity with the pin.

This is your common ground.

Your problem may be that there are additional components you're missing in the way, and that some of your "ground" spots are close to, but not actually, the common ground.

[Skyone]

Just making the point that your buttons don't HAVE to hook up to one common point.

[Super Cameraman]

Kurt: I don't have a multimeter. Is there an alternative?

Skyone: Yes, I do have to have a common ground. The way this will work is that a guitar string will be ground, and when the string touches points on the fret board, the circuit is completed, making a "button."

I could make the string into sections like this.

- non conductive
= conductive

--=====--======--======--======-

Maybe that makes sense. I don't feel like drawing a diagram.

[bacteria]

1) There are two things you primarily use a multimeter for - voltage testing and testing contacts/traces to check what connects to what.

My multimeter is ok but not brilliant for checking contacts (sounds like morse code!), so I made my own - two AA batteries, a 3v LED on the positive wire (only works one way round, so make sure it is the right way before soldering it in place). I attached a small bulldog clip to the positive wire and one to the negative one, so they can clip wires to test contacts - for testing traces, as you want, do the same thing but connect the wires to paperclips. Cheap and reliable!

2) No problem with using the guitar string as a contact, however (using the above suggestion) connect the testing wires to the farthest points on your guitar string(s). If the LED is fairly bright, you are ok; if the light is weak or off, then the guitar string will not work for your application.

[Super Cameraman]

I also need to see what button comes up on the computer when I touch the wires together. Wouldn't it just be easier to take a single wire and start touching points together to see what button they make?

(I actually tried that, but I'll try it again. I rrreaaally don't want to take all the wires off, but I guess I have to.)


Also, solder won't stick to the board. Is this normal? In fact... solder wont stick to a lot of things I try to solder.

[loup]

Also, solder won't stick to the board. Is this normal? In fact... solder wont stick to a lot of things I try to solder.

There is probably a coating on several parts of the board that you will have to scratch off in order to solder to it. Also, when soldering, don't heat up the solder with your iron, heat up the pieces you want to solder together, and then push the solder into those pieces (heat up the wire and pad at the same time and while heating it, push the solder into both the wire and pad.)

[Super Cameraman]

Thanks for the tips.

I don't think this gamepad is usable because the highest amount of buttons with the same lead is 4: Buttons 1, 2, 3 and 5. 4 and 6 use their own ground...


Hacking a keyboard is hard, right?

Also, what about those boards used for MAME's? Like a KeyWiz or something. Would that be better to use? Where can I get a really cheap one? I only need 6 buttons!

[Kurt_]

Hacking a keyboard is hard. Hacking a keyboard PCB is easy. The contacts are neatly in a row on the bottom, and would work great with your purpose. You could almost have one button for every fret and every string if you so desired.

The program you're referring to is keyhook.exe. Basically, you press a key and it tells you which one you pressed.

There's a link for it in the Arcade Sticky, at the bottom of Khagg's link.

[Super Cameraman]

I've been researching keyboard hacking for about a half hour now... It seems extremely hard! But all I need is 6 buttons, so would soldering right to the little board in the corner the keyboard work? How do I get the black stuff off it?

[Kurt_]

It's really easy! Some keyboard have all sorts of crazy features. If you're using one of those, it won't be so easy.

If you have a keyboard, especially an older one, it's a simple design. The keyboard PCB has gold contacts similar to a Nintendo game or a computer card. I believe these are called "card edge" somethings. I know the connectors are called card edge connectors.

If you find one of these, it's a simple 2 wires for each button (or connection).

[Super Cameraman]

The connections are black. I connected what I think is ground with one of them that I scraped the black off and I got "`578" but now I get nothing.