Electronics > Microcontrollers

Touch Application - Microchip PIC and Atmel ATXMEGA


Nice to meet you all.

From the topic title you can see two micro vendor – I already watched the video #63 and I found out it was very interesting and with info worthy to be eared

Now the question about those two device is related to the Touch functionalities they can have inside

My main interested is in white good appliance, in this field I saw a lot of different technologies for implementing a very simple touch dashboard or front panel (for an oven, a washing machine, etc etc)

1)   Spring
2)   PCB glued on the surface
3)   Capacitive film made by polyester and a silver paste as conductive element and connected to the electronic board using a connector

Do you have any experience in this field?

Considering the title devices, do you have any experience using those devices with this kind of touch technology?

Have you have designed or tested something like that and especially something that was using the (3) technology example?

Thanks a lot for any reply or question you may have for me

Capacitive input I have used has always been the kind where copper traces are covered by a pane of glass. It works well for places where hands may be wet or a splash of water may happen to the panel surface. The design is fairly simple to implement as well. All it takes is to design the pattern on the PCB and then when assembling a pane of glass is put on top of the traces.

A PDF on how to implement touch controls without physical contact with the electronics.


Dear Ptricks

Thanks a lot for your reply, i never used silabs devices, I'm more familiar with cypress ones

From the technologies point of view, i experienced in the past all the 3 solutions I listed (so the 2nd one, I think is the one you are referring to, copper trace/pads made directly on a PCB that is below a glass panel or a plastic panel).

Now I'm trying to experience some more devices and I'm in the middle of the doubt between Pic and ATX - my main worry is related to the solution number 3, capacitive foil solution.

If you check any application note of any supplier, they'll tell you that you have to guarantee as much as possible distance between tracks from the sensing pad but, on the polyester foil solution, you have all the signal track that goes from the sensing pad to the foil tail connector itself almost parallel and very close, so it's very important to be able to filter noise, sensing and mutual couplings

So, I'm looking for any feedback about this specific sensing device (silver paste touch foil - generally speaking, it's like the ITO used above tft but it's cheaper that ITO because it is not transparent) together with PIC or ATX devices

Any feedback is appreciated  :)

Thanks to everybody

I can't tell you anything about the specific foil method, however I've used the ATmega in a touch application before, just using a PCB as the insulator.

Works well, however the code integration is a little bit of a pain, particularly if you're integrating it with other real time control applications. 

Hopefully they've fixed it now, but the Atmel example project use to only work on Atmel Studio 4, even when version 5 had been out for about 2 years.

The pics are of a little low cost display system that's been working happily in my car for 2 years now.  I never really finished it off though.


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