Hello.
We are using a long copper rod attached to the PAD connection of the AT42QT1011 touch sensor (about 1/8" diameter x 3 feet long, going around the perimeter of the machine). Overall, this has worked well. But there appear to be circumstances, perhaps related to the proximity of moving metal parts, or motor power demands on the machine, in which the sensor is getting signaled.
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We’ve changed the board to low power mode in order to decrease sensitivity.
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We’re put the board on its own 3v power supply (sharing a ground with the Arduino power) which has reduced the level of interference and false signals when the motors were kicking in.
I’ve tried reading through the AT42QT1011 datasheet regarding the behavior of the chip, electrodes and sensitivity (ground planes, ground traces, and other things I don’t really understand). And I presume that some of that information relates more to the designer of the Sparkfun board than it does to the user of the board, but I don’t really know.
So there are a few things I’m wondering if anyone happens to know.
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Is there a way to measure, using either a multimeter or oscilloscope, the strength of signal through the rod to the PAD? I’d like to diagnose the signal as the machinery is moving to see if/what effects there are.
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Might it help to put the board inside of an enclosure to shield from nearby electronic interference (a simple aluminum box or Faraday bag/box)? or perhaps some insulation around the rod?
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Might there be a way to decrease sensitivity/increase resistance, perhaps by adding a resistor in parallel with the wire to the PAD? I’m grasping at straws at this point.
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Perhaps there’s another suggestion that I am completely oblivious of?
Thank you very much for any input.
Kind Regards,
Jerry.