Hide a button in your button

morganmorgan wrote 01/25/2019 at 02:19 • 3 min read • Like

oh the ideas that pop up when in #Hack Chat .

While batting around some ideas about using clusters of vias as capacitive touch inputs @Morning.Star brought up an excellent point, one that was already in my mind as usual. Haptics are important. Despite the fact I'll likely be the only person using this, designing accessible interfaces >IS< important. Make it a habit.

For this design, I wanted to keep the overall profile as low as possible. This was one of the main reasons to use capsense instead of buttons. The second reason was to "discover" the buttons in the design. The next suggestion from @Morning.Star (jokingly?) was why not use both! ....Why not indeed!

I went digging and found some nice button that checked all the boxes. Flat enough to not obstruct the overall profile, visually there are a pretty good fit for my overall theme and most importantly, flat enough that I though capsense underneath was feasible.

The button
The button

For a test I busted out the ol' #SharpieCAD  and make a simple test board.

Button with sharpied copper clad

The idea here is too keep as much copper as possible around and beneath the button footprint.

Alrigh! Button soldered up! The red & black wires coming down are the for the button and the blue one up top is for capacitive touch. The blue breadboard wire going underneath is connected to the backside ground plane.

This project will be using the ESP32 as always. This is handy as it has a Touch Input peripheral and good example code. Took just a few minutes to have a test working. Only odd this I ran into is the way a the "pad_num" argument for many functions is tied to one specific GPIO but not very clearly explained. Once that was clear the rest of the test code is pretty standard copy & paste from that example.

I'll call that experiment a success. With any luck the project this is going into will be unveiled towards the end of February. Thanks to @Morning.Star for both the common sense reminder of the importance of accessible interface and the silly experiment idea.



Morning.Star wrote 01/28/2019 at 16:44 point

No worries dude. Its always fun kicking ideas around in HC, thanks for writing it up. :-D

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