Wearable IMU, coin-cell, BLE or other RF
Tazling last edited by
I've got an app in mind, using an Arduino MCU (my tool of choice, I realise ymmv), where it would be very handy to have wireless IMU in multiple places. With moving parts -- especially human parts -- trailing wire harnesses and repeated flexing are really a PITA. So hmmm, I've been surveying the marketplace. So far it's pretty frustrating.
mbientlabs makes what looks like the ideal gizmo (a little spendy, but perfect features and packaging). however, I cannot find any low-level info about how the thing actually communicates. mbient has buried it under mountains of OO SDK to help me develop for Windows, iOS, Android etc. Not interested. Just want to exchange some bytes (or at most a JSON dialogue over HTTP) with the BLE device.
I found some dandy coin-powered IMU with no BLE, only i2c. I found some big clunky RF solutions -- but no one wants a mint tin strapped to their ankle or wrist. anyway, in the course of this treasure hunt I found this group... and thought y'all would be the perfect people to ask.
does anyone have a line on a subminiature, wearable, coin cell powered, 6-axis accelerometer/gyro with BLE (or other low-power radio) whose communication protocol is simple enough that I could interrogate it from a BLE (or other low power radio) equipped Arduino? If there was already an Arduino library for it, that would be just icing on the cake! if it had smart enough power management to make the coin cell last longer than 24 hours of continuous use, that would be gilding on the icing.
@tazling Sure. Some of the new nordic based Tiles sport a 3 year battery life from tiny coincells and yet can be activated remotely via wireless: https://www.nordicsemi.com/News/2019/10/Tile-employs-nRF52810-to-provide-ultra-low-power-connectivity
For less battery life but more sensors, there are a number of nRF52 based watches with sensors built-in and OLED screen. Is that more of what you're after?
I don't know whether any of them have open source code you can poke and play with though, which I suspect is probably what you're after. i.e. you could probably hack one of the smart watches, but you'd have to completely recode it from scratch. Unfortunately, with all the paranoia about security, I'm doubting you'll find much that will let you change it. In that sense, we've gone backward.
What exactly would you most want?
https://forum.mysensors.org/topic/9305/mysensors-smart-watch might be of interest