With the code written, power circuitry set up, audio amplifier built, cell network connection tested, accelerometer function verified, and project box 3D printed, what more is left but to assemble it and make sure it all works? And this is precisely what we did - after some delays for family matters and beginning a new school year.

 

When designing the enclosure we wanted to make sure it was as small as possible, so that the user wouldn't have to carry around a huge obtrusive box on their back. After trying a number of configurations we got everything to fit in a 6 by 5 inch box, and by turning the Arduino and SD shield on their sides, the needed depth was only 1 inch. While this is still a far cry from something that a person could wear as (for example) a pendant, as a prototype it strikes a practical balance between form factor and ease of construction.

 

All the components fitted into the box and powered on for testing.

 

The other board with the braided wires leading to it has the "help" and "cancel" buttons. It would be worn on the user's wrist so they can easily access the buttons.

 

The finished project box with the lid in place and screwed down.

And the lid fits! The speaker (for playing an audio tone to alert the user that a fall has been detected) is glued to the underside of the lid, below the grille.