My objective was to create a wearable enclosure for the peculiar set of gubbins I want to use. Appearance is not the main priority, so if it looks a bit rough that’s OK, and can be left for a time if/when the thing works. On the other hand it needs not to break and spill its guts on the street. I can always print a new enclosure if the current one is wearing thin.
My original enclosure ideas were a bust for one reason or another.
The fixed-size bangle idea was aimed at making something that was very easy to put on, and take off. There would be no display, and I was thinking it would be glued together, and charged inductively. This certainly was an easy on/off design, but it was really hard to get a good fit.
I tried a whole bunch of ideas and the best was the following:
Likes and Dislikes
The parts fitted together tightly, and I’m sure with appropriate glue would be strong enough. The opening was too sharp and scratched. The curve did not transition smoothly at the top from one side to the other.
There seemed to be enough room for a pretty large battery, and a non-flexible board with nRF52 and DecaWave module + accel.
It was certainly workable for a first prototype, and could probably have been made from some material that looked less obnoxious.
Of course it didn’t have a display, and was rather thick. A lot of the problem is that, being conservative about power, I selected a big battery. The other problem is that I only know how to make a non-flexible PCB, so there’s a lot of wasted space. Not shown is the vibrator motor.
Watch with off-the-shelf strap
This was a plastic case that could hold an e-ink display as well as the other large components. This version uses an off-the-shelf Fitbit watch strap.
|With strap attached, but no display
|Battery, uC and vibrator installed
|Assembled, but of course – non-operational
I was rather pleased with progress on this version because the strap actually held the two parts together which would be great for test before it was finally glued.
The major show-stopper was that lugs for attaching the strap were way too brittle, and would snap off at the least provocation.
So what now?
The e-ink display has a lot of power advantages. The strap mechanism is cool, but clearly not strong enough. So I probably need to run with the same set of components, but perhaps I can use a smaller battery if I can figure out a wake-up radio of some sort.