So, I pulled off my Piano Stairs hack this past weekend using parts from Adafruit! Specifically, a Raspberry Pi, an Arduino Uno, and a bunch of photoresistors. I used flashlights on each stair, across from the photoresistors, in order to up the contrast and make it way more robust. (Without flashlights, you get effects like people casting shadows on stairs they’re not actually standing on, etc.)
Now, that was for a hackathon, but I think I have an opportunity to install this semi-permanently (well, maybe a few days or a few weeks) elsewhere on campus. However, the problem with flashlights is that the batteries only last a few hours, and I’d like to just be able to plug something in.