With a little bit of experience with the Twilio API under my belt, I went to the Signal Developer Conference to see what I could learn from the sessions, as well as pick the brains of professionals in that industry.


It’s somewhat liberating to admit that I don’t know much about things like network performance under high load, and the community was, for the most part, happy to answer my questions.  As interesting as that was though, I’m a hacker at heart and as soon as I heard that they were distributing the HackPacks, I made a beeline for the counter for some hands-on fun.

The Hardware

The HackPacks consisted of a customized Cocoon backpack, a few LittleBits components, an 8×8 NeoPixel NeoMatrix, and a tshirt.  Fully assembled outside of the backpack, the electronics look like this.


The backpacks were specially modded for the conference so the LED panel could be affixed to the outside via a velcro diffuser patch.  The rest of the electronics are tucked safely inside, connected via wires through the grommet in the corner.

The Software

After tossing around some ideas, I settled on implementing TicTacToe.  Our kits didn’t come with any buttons or other input hardware, and I’d left all my toys at home, so I wrote it a very simple AI that plays against itself.  Optimal TicTacToe strategy is actually kind of boring to watch, so I made it pick a random empty spot for each move.  When a win condition is satisfied, it plays a little animation, and starts a new game.

This is a pretty simple, 200-line project, and the source is on github.  As you can see, the 8×8 matrix doesn’t have enough pixels for me to do actual X’s or O’s.  So, I scaled it up to use four of these boards, for 16×16 pixels.  Here it is behind a textured acrylic panel and paper I’m using as a diffuser.  The diffuser is closer to the lights on the left side so there is less scattering than the right side.


While checking out some of the other projects people were working on, I saw someone playing with a particle system library.  It required a few tweaks to work with what we had, but the effect is really cool and I’ll have to play with it some more later. It’s too bad the ideal distance for the flame effect isn’t really compatible with the backpack setup, but maybe it will work well in something like a lamp.

Future Work

The LittleBit system is a cute and convenient toy, but at the end of the day, I’m still going back to my Uno and breadboard for development.  When I want something smaller, it’s hard to beat the much lower cost and size of the Trinket or Pro Trinket, both under $10.  With the LittleBits system, the Arduino module alone is $36, more than I am willing to pay for each little idea I want to keep.


That said, I think it’s a good introduction to circuits for kids, so I gave it to a cousin in middle school. My code can run off the Pro Trinket and I may add a controller for more interesting games.

Categories: Projects

Leave a Reply