Beginner keyboard hack help

[Kaeru the Frog]

I've just taken appart a keyboard. The PCB has 27 connectors which only seem to be grouped together based on where screws are needed. How can I figure out which one connect rows in the matrix and which ones connect columns? The first 8 connect to one side of the contact sheet, 18 to the other, and one to nothing. Does 8x18 sound right? Does that mean 8 individual inputs allowed?

[tom61]

My best recommendation about keyboard hacking is this: Don't! Hack a gamepad or get a keyboard encoder instead. Much, much easier.

[seaner]

Look up the datasheets online for the matrix decoder chip. You can use an ohm-meter to beep out the traces and figure out which pin goes where.

[Zeitgeist]

As far as an18x8 matrix does it really matter?
IMHO The best thing to do is download either ghostkey (dos) or virtua keyboard (windoze) & map the inputs.
http://www.arcadecontrols.com/arcade_downloads.shtml#Utilities
You can then solder leads to your pcb & check what inputs cause key blocking & ghosting & what do not.
Doing this, I was able to get one of my projects, using an old gateway keyboard pcb, to be ghost/block free except for fire button #6 on the player 2 side.
I can hit any diagonal with both sticks & press all six buttons on player one side as well as the first five on player 2 without any conflicts whatsoever.
For the price of the keyboard ($0) I can live with this.
It will take quite a while to test this, but if a keyboard hack is your choice, then this is what you must do or else you may have a situation where you can not move up when player 2 presses button one etc...
Of course you will have to remap the default inputs in mame to match your control panel inputs.
I do have to agree with tom61 however, a gamepad hack or an ipac or keywiz is the way to go.

[AlanS17]

I don't think a keyboard hack is such a great idea. Even if you can do it, it's probably not worth the effort. There may be places to skimp in your project, but this probably shouldn't be one of them. Shell out the extra $25 and buy a J-Pac or an I-Pac or something. If you have to hack something, hack a game controller. With a project that's going to cost 100's of dollars, anyways, why go cheap on one of the most important parts?

[Kaeru the Frog]

Its just going to be a cheap 1 player panel. Less than 50 dollars for controls fram Happs, encoder from an extra keyboard laying around, and some scrap wood. Just something to get my feet wet.

Look up the datasheets online for the matrix decoder chip.

Unfortunatley its covered with a gob of epoxy.

[MrArcade]

Here is a good page on the subject...

http://www.mameworld.net/emuadvice/keyhack2.html

[Tiger-Heli]

Does 8x18 sound right? Does that mean 8 individual inputs allowed?

From my experience, 18x8 sounds possible, although you are probably looking at 2 columns being only the Windows Menu keys or not used, so probably 16x8.  18x8 would mean 18 individual (non-ghosting/blocking) inputs, but you would need to choose them selectively.  However, even 16x8 allows a Street Fighter set-up if you follow the tricks on the MameWorld page that Mr. Arcade mentioned.

[Chad]

Hacking is good.  I followed a GREAT article that will show you EVERYTHING you need to know.

http://people.smu.edu/cmadding/mame/downloads/keyboard%20hack.zip

You can read a bout my experience here:

http://people.smu.edu/cmadding/mame/cabinet.html

I have more downloads on my site for this. I have hacked several keyboards for others and using the grid I made I do not have any problems with ghosting or blocking.

Hope this helps.

[Nervous]

Well, this might work...  

http://www.flightsim.com/cgi/kds?$=main/howto/kevssim.htm

Scroll down about half way to the fourth picture (under flight controls).

[FractalWalk]

How can I figure out which one connect rows in the matrix and which ones connect columns?

First of all I think a keyboard hack is inferior to an encoder. It takes a long time, it's messier, it's hard to do and depending upon your soldering skills, the results may require frequent repairs.  

I did a hack and got it working but then after the third time a connection either shorted to its neighbor or became disconnected, I scrapped it and bought an IPAC. I wish I hadn't messed with the hack in the first place, but if you got lots of time, good soldering skills and the right tools then a hack might work for you.  

To answer your question specifically, download and install keyhook
http://www.arcadecontrols.com/arcade_downloads.shtml#Utilities

Take a piece of wire with both ends stripped and short across a row and a column one by one to see what combination produces which keystroke. Then from your mapping you can determine what will block and what won't.

[AlanS17]

If you must hack something, I have seen a couple of super cheapo programmable PS2 passthru game controllers out there. It's the best of both worlds. You get your stable PS2 connection and an easy (well easier) solder job.

They were like $8 at Electronics Boutique at the mall where I live (south Texas). I can't promise that you'll find one so easily, but I came across it by accident and EB is a national chain.

All the buttons are already isolated, the thing is cheap, you get a passthru, and it's programmable through hardware. How much simpler could it get??