Building your own trackpad?

[cribbit]

So I've got a crazy, crazy idea. I want to build a trackpad into a keyboard. I've looked at options like taking an apple trackpad and mounting it, but I want to see if I can go deeper than that. I've got time and money to waste, I want to see what I can build. Can I make the case itself a trackpad?

[PJE]

You need a combination of conductors and insulators. You could create a custom touchpad module but you would need to isolate it from a metal enclosure.

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[sinusoid]

I'll just leave this here:

Mildly related:

When that 3d trackpad surfaced around 2007, I remember seeing images that suggested it could be used directly over the keyboard. As in, the area of keys itself. Lots of RF interference I imagine, but damn, it would be nice if it worked.

[cribbit]

Revisiting this topic.

I wonder if it would be viable to wear a ring with an RFID chip in it and mimic a trackpad with that? That also opens up the potential for 3D gestures you wouldn't get with just a trackpad-like surface, especially with multiple rings.

[LazyDog]

Surely it would be easiest to use some laptop pad and figure out how the protocol works?

[cribbit]

Surely it would be easiest to use some laptop pad and figure out how the protocol works?

The case itself tho. So it's more like a keyboard built into a trackpad, than a trackpad built into a keyboard.

[dorkvader]

Surely it would be easiest to use some laptop pad and figure out how the protocol works?

Almost always PS/2.
However its hard to find datasheets / pinouts from elan and alps, and almost impossible for synaptic. I have done a little looking into this and decided it's not really worth my time to figure more out, what with how cheap they are nowadays.

on to the topic at hand: You can look at datasheets for capacitive sense controllers for trackapds / phones . This idea was floated around a little bit with respect to model F / beamspring capsense a few years ago, Unfortunately they are usually too "slow" to be good for keyboard use. However they are just right for trackpad use!

Anyway you can take one of those, and have a look at its ratings: what sort of capacative matrix it can cover, what level of capcitance it can detect, etc. Then you can mix carbon in with your plastic case material (or something) and hook it up to the controller.

Not sure if it would work, but I'd start looking there first.

[hanya]

It looks peoples from Ultimate Hacking Keyboard, have been considered to use Azoteq IQS550 touch screen controller for their touchpad parts.
You can buy this IC from mouser. But you need to design PCB having pattern matrix for the touchpad. The manufacturer provides reference design for the pad, it is the starting point.