SparkFun Forums

[ederbf]

Hi guys,

I bought the MPR121 Capacitive Touch Sensor Breakout Board and since it can manage 12 capacitive pads, I imagine if would be possible to make something like a notebook trackpad, returning X and Y coordinates to control a mouse cursor.

My great challenge is that I need to make a trackpad that works through 6mm of wood.

I know that is possible to make a single pad be activated through wood, due to capacitive field, but I really need more than a "trigger", I need position of the finger, just like a notebook trackpad. Is there anyway to achieve that?

Thank you in advance.

[Ross Robotics]

The only way I can think of, is to have small capacitive pads that are in a grid. Then when a finger moves over them, have an algorithm determine where the finger is at.

[ederbf]

Hi Codlink,

We have this same idea in mind, just waiting the stuff arrive for start the project. Just thinking about the grid of electrodes, looks like that higher the thickness of the wood, bigger must be the electrode. But soon we will know.

Thank you very much for your answer.

[Ross Robotics]

I would try to have the pads small as possible to get higher accuracy, but there are downfalls, i.e., it would take more processing power.. The only way to do this is trial and error. You may search and see if anyone else has done something similar.

Keep us updated on your progress as I will be doing some capacitive touch projects soon.