Sunday, August 7, 2016

Twinkle the Starfish (retrospective)

This was a project I did as a present for my young son last christmas. At the time he was really into the Octonauts. There's an episode that features a deep sea starfish called Twinkle who is lost and needs the Octonauts to help her find her way home. My son really loved this episode, so I thought it would be cool to give him his very own Twinkle with blinky eyes. I had a Gemma and some neopixels sitting around from a previous project, so electronically speaking, this project was in the bag, just needed to do some sewing.

I made a star shaped section for Twinkle's front, added a mouth and some embellishment and cut two neopixel-sized holes for the eyes. I hand stitched two black felt circles on the front of these holes that in turn had smaller holes cut into them about 4mm in diameter; big enough such that when the neopixels sat behind the black felt, the LEDs would poke through. I used a single rectangle of felt to make a sewed circuit that connected up two neo pixels and a clicky momentary button to the Gemma. I powered the whole thing using a small 300mA lipo battery. I then stitched this to the back of star such that the neopixels were positioned over the eyes and the button was Twinkle's nose. I then machine sewed this all to the back half of another star (back-to-back) and folded the whole thing inside out and stuffed it with stuffing.

Unfortunately, I didn't really have enough time to put in a proper switch on the battery line, or think about a good way to recharge it, so I left a small finger sized hole on one corner of the star so I could reach in and pull the battery out when needed and so I could switch it on and off using the very small switch on the Gemma. This was probably the most disappointing part of the final design: next time I need to look into how to design this properly with a click switch connected to the battery.

For the code, I setup Twinkle to run in two 'modes'. In the first mode, Twinkle's eyes would just run a predefined pattern. Pressing her nose would cycle through the available patterns: a rainbow sequence and pink lights that would fade in and out. In the second mode, Twinkle's eyes would display a single colour, and pressing her nose would cycle through a list of available colours. To switch between modes, one holds down Twinkle's nose for one second.

The neopixels are surprisingly bright: me and my son like to turn off all the lights and use Twinkle as a colourful torch to explore around in the dark (pretending we are deep under the ocean in the 'midnight' zone). Great fun!

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