Wearable Timing Bracer by Mike Hord

In this project, you’ll make a glowing wrist timer that’s perfect for a LARP costume. I have a lot of friends who participate in live action roleplaying (LARP) games. As a concept it’s similar to tabletop roleplaying, except there are no turns, there’s no dice, and everything happening around you has a component of reality to it. One of the elements of the game is timed effects; for instance, a spell may put you to sleep for 10 minutes, pin you in place for 1 minute, or make you laugh uncontrollably for 5 minutes. Since the game takes place in a fantasy wonderland, using a wristwatch to time an effect is an anachronism that detracts from the sense of the game.


This project includes both sewing and electronics. I’ve separated the supplies into two lists for convenience. You can find the craft supplies at any reasonably well-stocked sewing supply or fabric store.


Since the measurements for the crafting portion will vary according to preference and the wearer’s size, much of this project requires a “try it and see” approach. I’m also assuming that you’re comfortable enough with sewing that I don’t need to explain every step of the sewing portion. If you’ve never done an etextiles project before, I suggest that you first check out these excellent tutorials to help with the fundamentals.


You’ll need to download the Simple for Mobile app to your smartphone to change the timing settings. This app acts like a browser for Simple-based projects. It’s available for both iPhone and Android and is free to download. Using the app is pretty simple:

When your bracer is powered up and your Simple has been programmed with the project code, open the For Mobile app and you should see a list item titled “Bracer of Time.” Touch that list item to bring up the interface for the bracer, shown in Figure 9-9, where you can enter the desired delay in seconds for each timer, as well as store the values in flash memory on the bracer so they persist after power down.


You should now have a complete magical timing bracer! I hope you find some need for it. I recommend looking through the full code and the comments left there. You’ll find some useful tricks for linearizing the output of an LED, so that it appears to fade smoothly and evenly from all the way off to all the way on, as well as some goodies about executing code in a loop without a lot of busy waiting.

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