The Adafruit GEMMA has three available digital I/O pins, but thanks to the technique of Charlieplexing you can drive up to six LEDs with those pins, one at a time. In general, charlieplexing allows n tri-state pins to control n^2-n LEDs. My example Arduino sketch in github/charlieplex generates 8-bit PWM for each of the six LEDs, although it does require the full CPU to do it. Here is a short video of it in action, showing the smooth fades on and off.
My sewable sequins are made from 0805 surface mount LEDs and small metal beads from a local shop. Becky Stern of Adafruit has a great tutorial on making LED sequins — I used smaller LEDs than Becky, so I had a harder time putting them together and had to build a small jig with a piece of wire to support the bead while soldering it under a microscope. If you don’t need the small size, Adafruit’s premade LED sequins are a much easier way to add them to your project.
Every Wednesday is Wearable Wednesday here at Adafruit! We’re bringing you the blinkiest, most fashionable, innovative, and useful wearables from around the web and in our own original projects featuring our wearable Arduino-compatible platform, FLORA. Be sure to post up your wearables projects in the forums or send us a link and you might be featured here on Wearable Wednesday!