Help Wanted - DIY Capacitive sensor as an interupt

Hi guys,
I am trying to build a low power capacitive sensor using aluminum foil connected to an arduino.
I would need to use the capacitive sensors change in voltage to wake up the arduino from sleep mode.

I have looked into ADC conversion but i cant get it stable enough or figure out how to use it as an interupt.

After alot of research i could only find few forum pages that hinted at what i needed. Any help would be appreciated

Well, to wake the Arduino from sleep, you need an external device.

Sounds like you want a TTP223.

Connect your touch/ proximity plate to the vacant solder pad at the corner next to the black chip.

Could these be used to trigger an interrupt? If so those look almost perfect! Ive ordered some either way

Try tying an interrupt wake GPIO to an inactive state (whichever of Vcc or Gnd that you use) with a 10M resistor. Extend that to a small pad. I'd be willing to bet that touching the pad would trigger the input, even if it's covered in insulation... of course it would not be as reliable as the prox plate. The prox plate will consume some power...

aarg:
The prox plate will consume some power.

Something between 2 and 10 µA it seems. :grinning:

Just tried a basic state change detection with a 1M resistor (don't have 10M atm), it worked pretty well without problems. Still waiting for the touch pad to come in but for now this will work well :slight_smile: Thanks for your help guys