Had been talking to xWhatsit about the possibility of using his capsense controllers on regular switches like ALPS, MX, space invaders, or anything with physical contacts other than just IBM capacitative boards like IBM model F's. He mentioned that they should be usable with physical switches and maintain NKRO with diodes used for each key.

Sure, there are other keyboard controllers out there that have similar functionality, but I haven't found any that are anywhere near as simple to program as the xWhatsit given that the configuration utility is completely visual and runs on all major operating systems including Mac, Windows, and Linux.  Configuration consists of pressing a key, it is visualized on a matrix, and you can choose from the dropdown menu what you want to assign the key to.

The idea behind this post is to get the word out that a lot of older keyboards with unique layouts with bad or obsolete controllers could be restored to function, have NKRO, and all of xWhatsit's awesome features that were previously known to be usable only on capsense boards.

Finally got around to building a concept board to test out the theory using an Apple M0110 and it WORKS PERFECTLY, NKRO and all:


Basically followed the guide here as far as wiring goes, but substituted the teensy for the xWhatsit:
http://deskthority.net/workshop-f7/the-apple-m0110-today-t1067.html

...important part is that the diodes go in with the black/silver band marked end of each diode wired towards the ROWs, not the columns, which is exactly the same as the guide above has it pictured.

I use the Model F variant of the controller which supports up to 128 keys (16 columns and 8 rows).  This can be used on full size keyboard that would have more than 16 columns, you'd just need to extend the columns to cover the extra keys, up to one each per intersecting row.  Will eventually get around to making a full size board if anyone is interested in seeing how that would look, or might be easier to make a drawing of how that would look.

If anyone is interested in trying this, I have xWhatsit Model F controllers available for $35 shipped to the USA.  PM me if interested.

1 - Thats awesome, I didn't think it would work with anything but capsense.

2 - I'm not sure your wires are long enough. ;-p

What voltage threshold did you have to use in the controller?

1 - Thats awesome, I didn't think it would work with anything but capsense.

2 - I'm not sure your wires are long enough. ;-p

What voltage threshold did you have to use in the controller?

Ah, I knew the wire length would get brought up! I was so excited to get this thing together that I figured I rather have the wires too long than too short and figured I could always shorten them later.  Also thought it would be good to debunk the idea that the controllers require extensive ground shielding to cancel out signal noise.  They probably do need to be shielded well for use in a capsense board to prevent signal noise, but when used with physical switches, the threshold voltage can be turned way up to eliminate any noise. 

I used the default 681 voltage threshold value but tested that it will work with anything 150 or higher.  The larger you make the value in this instance, the higher the signal to noise ratio.  It's definitely not a narrow range (I usually end up at 110-120) that you have to work with when they are used for capsense boards.

My other thought is that it could be that choosing a lower threshold voltage would allow bad switches (ones that aren't making good internal physical contact) to continue to work since not all of the strobe voltage would need to make it through.  If you think about the capsense board for which these were designed, there is no physical contact electrically even with the hammers.  There is non-electrically-conductive solder mask over each capsense pad.  Haven't tested the revival of bad switches theory though since I don't exactly have any bad switches to work with (just been lucky so far).  Seems like it would be useful if that worked since you wouldn't have to tear a board apart to get at one switch that feels ok, but still isn't working and not having to go and find a replacement.

From memory, Toms controller, from the front and left to right as 2 ground pins, 8 row pins, 2 more ground pins, 16 column pins and then 2 more ground pins.

Works for Model M's too, though only SSKs and Wheelwriters have 16x8 matrixes. You'll still only get 2KRO because of the limitations of the membrane, but also handy if you want to add a solenoid: