reading serial keypads?

quispqix

can someone help! I have a small foldable keyboard with +/- and data (3 wires) and three serial keypads 4x3 matrix. The chip for the keypad seems to be 'karl-2 8818 CFA taiwan', 3.579545MHz crystal and UCN5810a and a 555. I have tried every BS2 serin code I can think of. I was hoping someone has had some experience, salvaging keypad/boards? the key pads are 12v, gnd, and two wires data in, data out. (moose products inc model sx-3136, I have three) and one keyboard for a Royal DaVinci palm orginizer.
If you can help me read these Id appreciate it!

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It is better to burn out than to fade away,... Because rust, never sleeps!

MaryMc2009

Sometimes letting go is so hard to do...until Ebay came along.

UVNET

Regarding salvaging keypads, perhaps the chip is defective or rejected (and dumped onto surplus market).
THE SWITCHES ARE GOOD so what I would do is code a new chip for the protocol you prefer.
I generally despise (and dispose - of) used carbonized rubber keypads.

Another thing I would do first is look on an o-scope to see if the keypads are sending data and if you know the protocol.
Serial sometimes requires time and patience, lacking that, get what works.

I can not guess at the protocol for your keypad, but I got a 3-pin offbrand PDA keypad on clearance for cheap.
I do not expect any difficulty in reverse engineering it's protocol. Something unique will come out for each key.

-CC1onUVnet

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"No good deed goes unpunished."

quispqix

Okey Dokie!, I see! I was just assuming the BS2 would 'just read it' The other three keypads I can dermel and make my own etch pad contacts. Plus they have parts I can use for other uses. Thanks.

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Post Edited (quispqix) : 10/22/2006 5:02:00 AM GMT