DI Y

CIRCUITS

WIRELESS MOTION

SENSING MADE EASY

XBee radios track every hit in roller derby action! By Tom Igoe

Photography by Tom Igoe

I was never much of a sports fan until my friend At first I thought of giving each skater a Wii Remote, Mattie introduced me to the Gotham Girls Roller but the signal isn’t strong enough for an 88'-long Derby ( gothamgirlsrollerderby.com). Once you’ve track. I still wanted to keep it simple, so I paired a 3- seen a good blocker send the opposing team’s jam- axis accelerometer module with an XBee radio from mer sailing into the sidelines with a solid hip check, Digi. The basic XBee is great for wireless sensing you’re hooked. Add all the bad puns in the players’ projects; configuration is easy and its onboard in-nicknames, and you’ve got a sport I just can’t resist. puts mean you don’t need a microcontroller. So, the

Soon, I had to find a way to hack it. If the skaters final part count for each skater module is 3 compo-wore motion sensors, I figured, you could make nents and a couple of sockets on a small board. things react to the action. Sound effects on every In addition to the skater radios, you’ll need a base hit! A synchronized soundtrack! Flames shooting up radio attached to a computer. I outfitted 3 skaters every time a player gets knocked out of bounds! The with radios and set up my laptop to graph the data possibilities are endless. and play sound effects when the players collided.

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