Capacitive Buttons Control All Life


Projects involving Conway’s Game of Life and utilizing a Nokia 3310 screen are quite popular with electronics hobbyists. [Droky] put these two together and went one step further by adding capacitive sensors to control the Game of Life. His work is a great example of how to use the Atmel QTouch capacitive sensor (QT100a datasheet). This chip does the heavy lifting that we’ve seen in other touch sensitive solutions. It operates from 2V-5.5V, requires only three capacitors and a resistor, has a one pin active high output, and sells for around $1 in low quantities. One thing [Droky] overlooked in his board layout is the ground pad on the bottom of the WSON6 chip. He was able to make it work by masking the trace that runs under the chip but you will want to alter the layout in your own designs.

If you’ve used the QT100a before we’d like to hear about your experience, and find out if button debounce handling is necessary with this chip. Let us know in the comments. You can see a video of it in action after the break.


7 thoughts on “Capacitive Buttons Control All Life

  1. I used a QT240 in a simple prototype, and debounce definitely wasn’t necessary. But if it were an actual product, I would have something (ie an On/Off button requiring a 2s hold for on, holding down volume button causes it to keep increasing, etc.)

    Also, interesting quote from avrfreaks forum:

    “I Found this article with an interesting view of why Atmel comes out with a 6-pin AVR pin compatiple to PIC10F2xx.
    QT100 is based on a PIC MCU and now Atmel has replaced QT100 with QT100A that and it’s very likely the QT100A is in fact a pre-programmed ATtiny10.”

  2. I’ve used the QT100A in a project, it’s pretty nice. Easy to use and design with, hard to solder! And no, it doesn’t seem to need debounce, though my implementation was very simple.

  3. Am i the only one who buys 3310 lcd and the metal connectors are not glued directly on the glass but only sandwiched together by the metal and plastic casing?

    I’d really like to find a place where i could find one’s like in this project.

    Thanks if you can help

  4. Has anyone made an Eagle footprint for the QT100A? I tried to load the eagle files from the project’s website, but I get an error 202, which likely means they’re using a cracked version of Eagle. I suppose I could create a footprint myself, but if anyone’s already done it, you’d save me a bit of time.


Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.