Resistive PCB touch pad

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Resistive PCB touch pad

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tonysofla
Contributor I

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?

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soledad
NXP Employee
NXP Employee

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:

pastedImage_2.png

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

I hope this helps!!


Have a great day,
Sol

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