I’ve made a capacitive sense wall using bare conductive paint, copper wire, an Arduino, and a series of posters. The Arduino is hooked up to a mac mini which interprets logs from the running Arduino program and loads video or image content. The installation works really well 98.3% of the time. Unfortunately, every once in a while the sensors give bad readings for an extended period of time. They’ll eventually return to their normal state with no human intervention. I haven’t been able to consistently recreate this issue and have little idea of the root cause. It’s deeply troubling.
What could be causing bad sensor readings? Sun spots? Planetary alignment? Is it a warning signal for an imminent alien invasion? I just don’t know.
First off: that’s a very cool display. Congratulations.
Second: the link to your Arduino Hookup JPG is the same as The Wall JPG.
Capacitive sense is highly susceptible to noise. Those long copper tape connections will effectively act as antennae picking up any radiated signal nearby. You might check around for a refrigerator, fan, air conditioner or some other appliance that might conduct or radiate electrical noise. See if you can correlate when the appliance is active (e.g. refrigerator compressor running) with when your display is not working. Once you have identified the culprit, see if you can move it further away from your display. Or you can at least post a note saying “If appliance is running, display will be erratic!”
Note that it is possible that the noise is conducted through the power lines rather than radiated, but given the long strips of copper tape and the fact that it’s capacitive sense, I would bet on radiated.
Instead moving the appliance, you could shield the long copper runs. It looks cool, but it is really hindering your setup. Cover them up with some type of metal mesh/screen and then ground it.
Maybe for an experiment, you could run more copper lines that are grounded next to the signal lines…
Thanks for the help guys. Unfortunately, I haven’t been able to isolate the problem to one specific appliance. There are several microwaves, refrigerators, network devices, ice machines, computers, and other stuff within very close distance to the wall. I’m guessing one or more (or maybe all) of these devices are interfering with the wall. Thanks again, Joe
Have you tried altering the sensing code to only activate by a “doubleclick” of a particular duration or timing? That way you could eliminate any false triggers that don’t fit a specific pattern. Kind of a “software filter” of the input signal.
You could also try adding a diode between the sensor and arduino to block any signal lower than 0.6v. If the interference level is less than that, the diode won’t pass it. I had that trouble on a KITT-like scanner using a 555 and 4017 chips. The wire between them was long, and picked up RF interference. The inline diode fixed it so only the pulses from the 555 got through.
