Hello all!
This is my first forum post and I registered here because I need some help and guidance in the project I'm currently working on.
I am trying to design and build a countertop to my kitchen using recycled glass and concrete. It should be lit from underneath by a large LED matrix where the LEDs are multiplexed so the whole countertop will work like a screen. This seems to work fine in my first prototype but I want to add more functionality to it by integrating capacitive touch sensor close to the surface in the concrete layer. By doing that I hope to get a really cool, unique countertop where I for example can have light following the dishcloth when wiping the surface. Alot of other functions can also be added then the hardware is built.
This is what the first prototype looks like:
I am not very experienced in arduino but I think I've got a hang of the basics.. I have a method for adding zink layers on the glass pieces (some of it will be removed when sanding the surface) that should build up the sensor area but I dont really know how this should be designed and controlled by the arduino.
I'm thinking of using a diamond pattern like the ITO-layers in a smartphone. This will however be quite complicated to get in place since the spacing between squares seems to be quite important. By having the small passages between the squares it will also be tricky to ensure all of them are so deep down in the concrete so I will not break them when sanding the surface. If there are other alternatives I am very interested! Is it possible to have the layers overlapping it would be alot easier.. I have looked in to wiretouch where they are using a simple net of wires and get quite impressive results.
Now to the embarrassing part. I have tried to built a very simple version of the wire mesh but I cannot really get it to work. Basically what I do is looping over the rows and setting one of them high at a time, the rest are grounded. In a nestled for loop I am reading the values from the columns and I cannot really se any difference if the crosspoint is touch or not. Am I missing something important here? :-[ In the case with the diamond pattern all rows and columns that are not activated or read should as I understund it be grounded so they will form a large ground plate, is this also necessary when using wires? The area would be tiny anyway... I have also tried to add capacitors between the sensing wires and ground as I read somewhere..
I also tried to do the same thing but using stripes of aluminium foil instead of wires, with this setup I can clearly see when a crosspoint is touched, the problem here is that all of the crosspoints seem to be affected almost as much as the touched one...
If someone has any experience of homebuilt capacitive touchscreens I would be really happy for some help! Of course also from you without experience but some ideas of what can be my problem...
Thanks in advance!
Best regards Olle