Is there a common communication protocol between smartwatches and Android phones?

Question

I am very unhappy with my Fossil Q hybrid watch (no screen, tracks activity & sleep and button functions) but honestly it looks good. The app keeps crashing though. I would like to make my own Android app to extract all kinds of data (for future analysis). Before investing a lot of time, I tried to do some research on how to access the watch. It operates obviously on BLE. But all the documentation is either about Wear OS or actual smartwatches with more advanced functionality. Search engines fail to distinguish between what I am looking for and most popular results.

I was wondering, if there are any known communication protocols between apps and smartwatches, where I can start experimenting? BTW, HCI snoop log reports all traffic but it doesn't look like anything to me. But I can also try to hack it (if it is not encrypted...).

Answer 1

I remember that I have found once a info on dev site regarding the heart rate tracking but I cant find it. Anyway I have found one thing that might help you: https://developers.google.com/fit/android/ble-sensors Unfortunately this is "fit" reference site, which data might be obsolete, afaik the regular updates might come to API reference: https://developers.google.com/android/reference/com/google/android/gms/fitness/SensorsApi

Answer 2

You can start by reading code and documentation of the GadgetBridge project: https://codeberg.org/Freeyourgadget/Gadgetbridge/

They support some of the "Q Hybrid" watches to some extent