LPC Microcontrollers中的主题 Re: Resistive PCB touch pad

Resistive PCB touch pad

tonysofla — Mon, 29 Aug 2016 16:00:53 GMT

As the LPC11U24 don't have cap-sense, what other ways have been done to get a cheap switch button?

Is using internal pull-up resistor OK, or it needs a weaker 100K external?

Should use pull-down and connect left side pad array to Vdd instead?

I'm using 33ohm series resistors (BOM from USB part) on both traces as static electricity protection.

Plan to use this single pad just for user interaction, can board work fine without a reset switch?
planning to load code using USB bootloader , can you software-reset it over USB anytime?

Re: Resistive PCB touch pad

soledad — Thu, 20 Oct 2016 21:02:25 GMT

Hello Tony,

I made some tests and it is needed an amplifier (transistor). In the web, I found a basic circuit that you can use as reference:

From: http://pcbheaven.com/wikipages/How_a_Touch_Button_works/

I hope this helps!!

Have a great day,
Sol

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