BBC Micro:bit wrist holder

This post shows you how to convert a £3 iPod 7 arm band into a wrist or arm holder for a BBC Microbit board and battery. The photo shows the creation with a Microbit and battery pack being modeled by the local electronic’s wear supermodel.

I intend to use the Microbit as assistive technology as a communications aid. The Microbit on the wrist detects a gesture and then communicates this to a second Microbit which is connected to communications device. This second Microbit says ‘hey, there’s been a gesture!’ to the communications device, so acts as a switch. This enables the wearer to control software through hand motion. More details of this work are here.

I need a wrist holder for the Microbit as I am not allowed to just superglue it on to other people according to the University Ethics Committee. I couldn’t find anything suitable for sale, so broke out my sewing kit and made one from an armband aimed at one of the many iPod incarnations. With the Microbit on it, I am reminded of the Power Glove from 1989. Who wouldn’t want one of those? The tagline for the Power Glove was ‘it’s so bad’, which kind of fits.

A friend pointed out that the holder could be used to strap the Microbit on the leg or any other suitable appendage. For instance, you could log accelerometer and temperature data during sports. Use a second Microbit connected to a laptop to wirelessly log the data from the Microbit attached to your body.

I started with a ‘King of Flash New iPod Nano 7th Generation Premium Water Resistant Armband Case’ from eBay for the princely sum of £3.

Remove the plastic iPod holder bit with a few minutes of cutting with a suitably sharp instrument.

You need to sew back one of the plastic belt reinforcements on to the first of the two belt slots.

You can cut off the neoprene with the second slot. If you are using the modified arm band to attach to the wrist, then you can also trim down the length of the belt as it is sized to be long enough to go around a biceps. Even my weedy biceps are much larger than my wrist. Sew on some elastic loops to hold the Microbit board and the battery holder. I bought a 1m piece of 3mm black elastic from eBay to do this.

To get the belt to stick to itself and close the holder, I used some sticky back velcro of the ‘hook’ gender. I stuck two pieces back to back to form a velcro ‘gender bender’. This sticks to the belt part of the velcro on the holder, next to where the board and battery will sit.

The assembled wrist holder with the Microbit and battery pack is shown below. I use a AAA battery holder with a switch on it that I also bought from eBay for about £2 instead of the ‘always on’ battery pack that came with the Microbit. I buy a lot of things from eBay.

If you are worried about the battery pack flying off after a violent wrist motion, you can double secure it with some sticky back velcro between the back of the battery pack and the neoprene of the wrist mount.

There you have it. How to make your own Microbit and battery pack wrist/arm/leg holder. ‘It’s so bad!’