N00b Button Wiring Question

[schmitty]

I am mostly done with a keyboard hack on my first cabinet, but I want to use two different control panels and be able to switch them easily.  I have two questions:

1- On Doc's Modular Mame site (http://www.beersmith.com/mame/wiring.htm) , I like how he uses Rj45 for his connections.  How does he get away with only one wire per button and one ground connection?  Is it because he's using an IPAC-2?  If I used RJ45 I'd need to dedicate 2 wires to each button...  No idea how ground works in this application.

2- I suspect that Molex may be the better way to go - are there any good how-to's out there specific to cabinet building?

Thanks in advance!
-Schmitty

[fatfingers]

I think he "gets away" with only one wire per button and only one ground because he just failed to mention that what he really did is run that one ground (pin one) to all of his buttons/switches.

[shardian]

If he was using a common ground, then yes he was using a keyboard encoder such as the IPAC. With a keyboard hack, you are connecting two points on a matrix, so yes each button would require two wires to go to the keyboard.
I'm not sure how many keys you are using, but a pin header and an IDE cable might be your best bet for a modular interface.

[MYX]

It is the interface. With the key emulators and joy emulators, there is no matrixing as in the KB hack. So all buttons report to one ground. If you were to spend $20 for a GGG ecoWIZ you'd be better off than doing the KB Hack. I did it years ago and sure it works...sort of. But God help you if you try to play 2 player or a game like robotron. You will quickly learn why the keyboard hack is no good. In most cases you can get 3 may be 4 simultaneous key presses. If you are playing robotron (2 joys) and moving at a diagonal while shooting at a diagonal that is 4 buttons. Just a thought.

But then again, I always enjoyed the look on peoples faces when I told them that I hacked a keyboard to make my CP. You did what!?!

[schmitty]

Ah- I see.  Thanks guys.  As a point of reference for anyone who reads this down the line, so far, I am not having issues with multiple key presses.   I followed Marshall Brooks' guide http://www.mameworld.net/emuadvice/keyhack2.html
(It's rather long, but the gist of it is to put each potentially conflicting control on a separate row of your matrix.)  I have an 18x8 matrix keyboard, so I was able to eaasily assign to joysticks and 12 buttons (six per player) to their own row.


Two follow-up questions -
1- for future reference, what's a "GGG ecoWIZ" - no hits googling so i figure it must stand for something.
2- I like the IDE idea since I have a dozen of them laying around.  Where would you track down a socket for them to plug into, though?  Mouser?  And what is the right terminology for the piece?  A "IDE Pin Header"?

Thanks for bearing through the N00b questions - I post my results for the future benefit of other N00bs.
-Schmitty

[monkeybomb]

1- for future reference, what's a "GGG ecoWIZ" - no hits googling so i figure it must stand for something.

http://wiki.arcadecontrols.com/wiki/Keyboard_Encoders#KeyWiz_Eco_2

[MYX]

1- for future reference, what's a "GGG ecoWIZ" - no hits googling so i figure it must stand for something.

http://wiki.arcadecontrols.com/wiki/Keyboard_Encoders#KeyWiz_Eco_2

Groovy Game Gear
Here is a LINK to Randy's GGG site. He makes the stuff. He is also on the board here.