Light up your nighttime bike ride with this persistence of vision display from Adafruit.
In the past couple of weeks, we’ve seen numerous Maker projects focused around bicycles. To recount just a few, there’s been a smart helmet with turn signals and automatic brake lights, a smartphone-controlled handlebar lighting system, and most recently added to the list of bright ideas (no pun intended), Adafruit’s persistence of vision (POV) for your wheels.
The brainchild of Becky Stern, this POV display allows riders to illuminate the night as they pedal their way along the road or sidewalk. As the tires rotate, a series of embedded lights flash, ultimately conjuring up an image in the viewers’ minds. The project is comprised of two DotStar LED strips attached to a wheel spoke — one facing in each direction — driven by a 5V Pro Trinket (ATmega328) and powered by a 3xAA battery pack affixed near its hub.
To get started, Stern cut a half-meter strip of LEDs, leaving 36 pixels on both halves. She then tinned the solder pads and silicone coated wires to the input end of the freshly cut piece, alternating sides for each wire to help prevent a short circuit.
“If you have a 5V Pro Trinket to spare, we strongly encourage you to build a prototype of your circuit on a solderless breadboard. Not only will you get a chance to test out your solder joints connecting the LED strips, but you can have a duplicate system for programming where you can easily make changes,” she advises.
In terms of coding, the POV uses the same program as Phillip Burgess’ Genesis Poi project. Adafruit not only lays out the installation process on their page, but has made the sketches for the bike wheel available on GitHub. The bike POV requires the Adafruit DotStar library for Arduino as well.
From there, Stern trimmed off the header pins, and tinned the wires attached to the LED strips. These four wires are soldered to the Pro Trinket. After testing the circuit, it’s imperative to waterproof it before sticking it onto the bike. Those wishing to save power can also employ an optional switch and/or vibration sensor, which will only trigger the lights when in motion.
How do the electronic stay on, you ask? As challenging as it may be, the battery pack is anchored near the hub by steel zip ties, while plastic zip ties keep the LED strip and Pro Trinket tightly onto the spokes of the wheel.
Pretty cool, right? Head over to Adafruit’s official step-by-step tutorial, and watch Stern’s latest work in action below!