Nearly a year ago, in November 2017, student newspaper The Cornell Daily Sun reported that “students and staff in at least four campus buildings heard a five-second tune, but couldn’t pinpoint exactly where it was coming from.” This went on for over a week, with none other than Rick Astley’s “Never Gonna Give You Up” playing intermittently at an interval of between 32 and 38 minutes apart.
After some of these Rickrolling devices were discovered, they were found to be nothing more than a small piezoelectric speaker with a battery and chip attached. Most seemed to consider this a harmless joke, with director of facilities Henry W. Crans Jr. adding that “I just wish they’d use a battery with a shorter shelf life.”
Now that some time has passed — and perhaps people are a little less annoyed —Joseph Primmer has claimed this mischief as his with an explanation of how these gadgets work. An ATtiny85 microcontroller uses separate outputs for each pin of the piezo speaker in order to produce sound, and between clips, it goes to sleep to save power. He notes that such a device could theoretically power itself for a year or more using its CR2032 battery.
Code is included in the write-up, and it’s quite a simple and inexpensive build if you’d like to try your own version to prank your pals.