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Description: If you need to add user input without using a button, then a capacitive touch interface might be the answer. The AT42QT1010 Capacitive Touch Breakout offers a single capacitive touch button with easy-to-use digital I/O pins.

The AT42QT1010 is a dedicated, single-button capacitive sense chip. The chip handles monitoring a conductive area for touch. As long as a touch (e.g. from a finger) is detected, the AT42QT1010 keeps the output line high. Otherwise, the line is kept low. You just need to provide a power source (1.8V - 5V) and ground for the AT42QT1010 to work. Additionally, a PAD pin is available if you would like to create your own external electrode.

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Comments 14 comments

  • How did you get the LED to be placed upside-down? Was it placed by hand or do you guys have a super duper pick-and-place?

  • I’m trying to make a capacitive flood detector and I’ve run into a problem. I’m applying power to the sensor, waiting 100ms then reading the OUT pin; the process repeats every 5 minutes. Here is the issue I’m experiencing: if my finger (or anything else with high relative permittivity) is on the sensor pad before I power on the sensor, the OUT pin never changes to high; I’ve confirmed the behavior with my oscilloscope. If I power on the sensor, then touch the pad it works fine. Any idea what’s going on?

    • It looks like that is the intended behavior of the chip. I tried it and can confirm what you saw. It seems that the AT42QT1010 does some calibration when you initially apply power and cannot register a touch event if your finger is present on power up. You have to take your finger away for ~1 second before it can start registering touches again.

  • Cool! I’ve been wanting to add touch inputs to replace the paddle on my ham radio Morse keyer (built around an Arduino) but I’ve been too lazy. Now I will. Time to spend money! And even cooler, if I read the datasheet correctly the chip can work by proximity as well as direct touch. So I can just wave my finger over it, maybe?

  • Would you guys consider making a version that could select between momentary or toggle output modes please? I’d love to see this available, Thanks!

    • In the meantime, you could use a flip-flop to turn the momentary output into a toggling one.

      With a CD4013B chip, tie the momentary touchpad output to the clock input of the flip-flop, and tie the !Q output back to the D input. Each time there is a rising edge on the clock input, the flip-flop output will change state - one pulse to turn it on, one pulse to turn it off.

      • Thanks for a the great idea and details Byron! SparkFun, this does not let you off the hook for a turn-key product…

    • Duly noted - a toggle version would be very useful - thank you! Something we can certainly look into.

  • The Hookup guide says that the external electrode can be almost any shape or size… well, is this to be taken literally. I am trying to turn some two foot sheet steel cubes into touch sensors. Possible with this?

  • So… this product is amazing. Just hooked it up, did some test runs for its limits. So far, I’ve been able to detect my finger’s presence through EIGHT MILLIMETERS of plastic. Oh, and did I mention that it’s actually two separate pieces of 4mm thick plastic? Yeah. Phenomenal.


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