Spoke Ink is a booster pack for MSP430 LaunchPad that attaches to the spokes of your bicycle wheel. Using an array of 32 RGB LEDs and a magnetic sensor, this booster pack projects produce a bright and upright image right from the spokes of your wheel. You can create the image from any bitmap with software.
This booster pack has one row of LEDs and able to create eye illusion pattern known as persistence of vision (POV) phenomenon when bicycle wheel rotate. To generate a persistent image, Spoke Ink and the MSP430 have to light up in the exact same radial position with each turn of the wheel. And, they have to be able to do so no matter how fast the biker is going and how quickly the wheel is rotating. This dynamic adjustment is achieved by triggering interrupts based on a small magnetic sensor that trips each time the booster pack passes a small magnet glued to the stationary part of the bicycle.
The bike POV project is powered by 3 AA batteries and is designed by George Netscher, Ryan Bartling, and Valerie LaBounta.