Accelerometer Poi


Even if you’ve never attended a rave, you have probably seen one portrayed on film or television. Those glowing spheres-on-a-string being swung around are called poi, and [Matt Keeter] has designed a pair with an accelerometer upgrade. Poi have a long history and were originally made from plants, but contemporary examples usually feature some kind of light, whether it’s fire, LEDs, or even glowsticks tied to shoelaces.

This build required double-sided PCBs and [Matt] had to custom make the protective covering that slips over the board. The poi are powered by 2 AA batteries fed into a 5V boost regulator. But wait, no microcontroller and no PWM? Actually, we think it’s quite clever that [Matt] took the output from the accelerometer and fed into an inverting amplifier. This keeps the voltage constant while allowing the accelerometer to vary the current. Had he used PWM, the fast motion of the swinging poi would instead produce a blinking effect.

An additional trimmer potentiometer accounts for variability in the accelerometers’ output by adjusting the default brightness. If the recent recap of Burning Man has you excitedly planning to attend next summer, you’d probably find plenty of opportunities to use these in the desert.

PoiPlay – LED Poi

PoiPlay is an elegant mix of new technology and traditional medium. Poi, Maori for ball, is a traditional form of juggling originating in New Zealand. In poi, a ball at the end of a rope or chain is swung in circular motion to develop visual patterns. Often augmented by flame, and more recently LEDs and glow sticks.

The PoiPlay device has 28 RGB LEDs in a 1 foot long enclosure at the end of a rope. They have a 1mbit per second bidirectional wireless interface, three Atmel processors, a lithium ion battery, and a charger. The base station controls not only the PoiPlay but the music as well. All the control software that resides on the PC was written in Perl and communicates via USB port under Cygwin.

They have built the devices to be individually addressable with the capability of being grouped by subnet. This feature isn’t supported by the software yet, but they say it should be done by the next show in 2009.

The site, while pretty offers very little information. Some construction shots would be fantastic. Go check it out though, the pictures are mesmerizing.

[thanks Jm]