The two most important features of a smart watch, for my personal use, are displaying notifications, and displaying a particular integer that my phone knows that is updated every 5 minutes (it's my blood sugar, retrieved by xDrip+, but that's not a terribly important detail).
Notifications seem to be easy, thanks Gadgetbridge!
The display of the integer is where things get difficult, and I'm trying to figure out a good starting approach. My experience with Bluetooth has been that it's really easy to get caught in confusing dead ends where you can't tell whether you have some small bug or your whole approach is wrong, so I'd appreciate some direction before I dive in too deep.
The phone can publish the data in a few ways: it's send out as a broadcast Intent in Android, and it can be accessible through a local Web server, so I can write an Android app that hooks into either of those methods and forward it along to any other method, like advertising with Bluetooth.
Then, I'd write a widget or custom watch face in the Bangle.js that listens for that advertisement and displays the value.
However, if I'm reading things right, then this would interfere with other NRF functions, so Gadgetbridge would stop working? I'd really like to know this before I've written the two ends of this system.
It seems like another approach could be to modify Gadgetbridge, to use the channel it already has set up, but to make a special kind of "notification" that is intercepted in the Bangle.js app and interpreted to mean "save these data into storage." Then my widget could just read from storage and display the value there. Of course, this would mean either maintaining my own fork of Gadgetbridge, or getting my code path merged in for this specific, personal need, neither of which seems great.
Does anyone have any insight or suggestions? There's lots of help for using the sensors built into the Bangle.js, but I haven't found anything clear for doing something like this.
Thanks in advance!