PS/2 Keyboard Hardware Protocol Information?

j-r charles asks: "I need to design a 12 key keypad that plugs into a PS2 port INSTEAD of the standard PC keyboard. Does anyone knows the protocol used by IBM, or where to find it?" So why stick with the boring old choices of 88 and 101 keys when you can build your own with as many (or as few) as you like. Has anyone built custom keyboards for their PCs? How difficult was it?

Comments

If you can't find, dissect!

[JediTrainer]

I don't know about finding information, but I have a cheap ($5) converter from the regular (large) keyboard plug to the PS/2 in my hand right now. Therefore, you have 2 possibilities:

1 - ship a converter (like the above, but get a bulk discount from manufacturer) with your unit, much like mouse manufacturers ship a ps/2 -> serial or usb -> ps/2 converter for their hardware. Added bonus of having your keypad work with BOTH the regular and PS/2 plugs

2 - dissect the PS/2 converter mentioned above and learn from it. I don't imagine how it could be that different. Maybe it's as simple as mapping the wires. The converter's only an inch long, so I'm guessing it doesn't have much in there. Then again, I'm not a hardware person, so I don't know.

Re:If you can't find, dissect!

[bluGill]

True, but it sounded like the poster could find specs for AT style keyboards, but not PS/2. Considereing the price on AT to PS/2 keyboards adaptors I can't help but belive that it is just a few wires and no electronics. I would however make sure from one of the adaptors first. (Or just ship with the adaptors)

Here ya go...

[ScottG]

Google.com is your friend. Try any one of these:

http://govschl.ndsu.nodak.edu/~achapwes/PICmicro/P S2/ps2.htm

http://www.nti1.com/ps2-prots.html

http://micro.new21.org/pic/html/tut_ps2/ps2.htm

We should rename "Ask slashdot"...

[Anonymous Coward]

...to "Too lazy or Stupid to use Google".

Re:We should rename "Ask slashdot"...

[FoxIVX]

I'm sick of people jackassing around here, blah blah blahing about how easy it was to find on google... Ask Slashdot isnt just a forum for the poster to find their answer, it's like every other part of /. A place to have a discussion. Cliff posts stories, I assume, that he thinks will spark a good discussion, not based on the ease of finding the answer on google.com. This is "ASK SLASHDOT" NOT "ASK GOOGLE.COM".

Re:Easy!

[penguinboy]

Well, it *is* serial. Even if it was, 6 wires plus shield would not give you 64 combinations (which is obviously wrong for the additional reason that the keyboard interface has to be able to signal uniquely for each of 100+ keys). Power and ground take two wires, so you'd be left with 4, which would allow just 16 combinations.

Which 12 keys?

[unitron]

Are you wanting to use this as some sort of gamepad or did you create an operating system that only recognizes 12 characters?

I just got through googling stuff like "keyboard emulator", "keyboard port wiring", "dummy keyboard" and stuff along those lines looking for info on what circuitry to add to a passive KVM switch so that I can boot one computer, switch the switch, and boot the second with the first still thinking that it has a mouse, keyboard, and monitor attached.

Didn't find much of what I was looking for but found a bunch of links about game controls and using the integrated circuit in keyboards that send the scan codes to the computer as part of custom game controls.

http://www.google.com