Re: USB Joystick hack, wire lengths, false triggers...


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Posted by Dr. J on March 07, 2002 at 23:12:58:

In Reply to: Re: USB Joystick hack, wire lengths, false triggers... posted by Russ Foster on March 07, 2002 at 21:14:48:

Hey,
I'm emailing this to you as well as posting it on the message board. I also hacked a usb gravis gamepad and had the same problem. I found that if you ground the directional pads separate from the four diamond buttons then you won't get that cross over. It's something about the circuitry. I emailed them and they actually got me in contact with engineer who designed it. He basically said that in order to save space/$ they set up four of the switches to read whether or not the button was pushed with a "directional" ground, or a "button" ground.
BUT... even after I grounded them separately, when I went into windows gaming options and properties I found that multiple key presses at the same time would make it go hay wire, or if I pressed any diagonals, it would also press a key. I emailed Gravis again, and they had no idea why it was getting crossing signals. I tried it on two other gamepads, and triple checked my wiring, and still the same problem everytime. So, I did two things.
1. I hacked my console neogeo controllers to the gravis gamepad (only 4 buttons, so no problem), and used that for neogeo games.
2. I ordered a CH gamepad and hacked that for 10 buttons and found that every button works independently, and no "ghosting." The only problem here is that they cost about $30 afterh S&H. Also, they have somekind of coating over their button sensors that I had to scrape off to get the solder to stick. (I almost ruined one of the CH gamepads.)

I had another Idea, but since I decided on using the CH gamepads I never tried it. I was going to make one 10 button joystick by using 2 gravis gamepads. (so one joystick would plug up with 2 usb ports). Like I said, I never tried it because I really wanted the convenience of one usb plug.

So, my final advice. I'd either go with another option all together, or go with the CH gamepads, because there about the only other gamepad I could find with 10 buttons, and I know they won't give you the weird button problems.
Hope this helps, Jay D.

: Maybe I should have made it clear, that I would like to use 8 buttons...all of column x1 and x2.

: But the problems I am experiencing with just row prevent me from detecting whether it was button #1 or #5 that was pushed.

: With only 4 buttons wired (5,6,7,8) then I only check for presses on 5,6,7,8 and can safely ignore 1,2,3,4.

: -rjf

: ----

: : This is not a MAME question, but hopefully someone can help...

: : I have an USB Gravis Gamepad that I have torn apart and wired up my own buttons. I use these buttons for a quiz-show style game. Each contestant has a button who chimes in when they know the answer. (Addtl info: it's a Visual Basic PC app that checks for the button press).

: : Because of the problems am I having, I am only able to use buttons 5,6,7, and 8.

: : I have a (Radio Shack) button on 5 feet of 20 gauge speaker wire connected to the Gamepad circuit board. With this set up, a button push on button #5 also triggers #1; button #6, triggers #2; button #7, triggers #3; button #8, triggers #4.

: : If two buttons (any two of 5,6,7, or 8) are pushed--then ONLY those two buttons are triggered (the corresponding 1,2,3,4 button cancels).

: : The buttons are arranged on the encoder chip in a 4x3 matrix:

: :


: : x1 x2 x3
: : y1 1 5 9
: : y2 2 6 10
: : y3 3 7 na
: : y4 4 8 na
: :

: : Again, I only have column x2 wired, but a single button press on that row triggers a button in col x1 (unless two or more buttons from x2 are pressed).

: : Any ideas?





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