Stephen Gidge and his roommate have a poorly-lit flight of stairs in their home. That isn’t a big deal during the day, but it is a recipe for late night tumbles. They could have setup some nightlights or installed a new hall light, but they were both experienced with Arduino and so they created these cascading LED star lights instead.

Under each step on their staircase, Gidge and his roommate mounted a strip of white LEDs. When someone approaches the bottom stair, each step lights up in a sequence starting from the bottom and going up. If someone approaches the top stair, the opposite happens and the sequence goes down. In either case, all of the stairs will remain lit for a little while to give the climber enough time to complete their journey. There is also a cooldown delay, so the “down” sequence doesn’t activate when someone reaches the top step as they’re ascending the stairs.

An Arduino Mega controls each LED strip individually via one of 16 transistors, though all of the strips share power. The Arduino detects people using a pair of ultrasonic sensors — one at the top of the stairs and the other at the bottom. That was enough to provide lighting for safe midnight snack runs, but the duo took it one step further by adding music-reactive effects that are great for parties. The Arduino listens for music through a MAX9814 microphone module and flashes the stairs like a massive bass visualizer, enhancing shindig ambiance.