I'm developing a 'smart watch' which is connected via BLE to an app on a phone.
My idea is to show the direction on the watch so the user doesn't have to remove the phone from their pocket while using their favorite application (Waze, Google Maps, ...)
Is there any standard to send navigation information (turn left/right, ...) to a smart device over BLE?
It seems there are apps that do this, but they are fully custom: https://www.youtube.com/watch?v=naAhe7DTKYM. I'm checking on the side of Android Auto, but it seems to me it's only by USB cable.
Off the top of my head there are two services that you can use for this purpose:-
Location and Navigation Service (Used mostly for outdoor):-
"The Location and NavigationService(LN Service)exposes location and navigation-related data from a Location and Navigation sensor (Server)intended for outdoor activity applications."
Indoor Positioning Service (Used mostly for indoor):-
"The Indoor Positioning Service exposes location information to support mobile devices to position themselves in an environment where GNSS signals are not available, for example in indoor premises. The location information is mainly exposed via advertising and the GATT-based service is primarily intended for configuration."
If both are not 100% suitable for your application, then you can create your custom profile that contains one or both of these services in addition to a custom service (turn left/right etc). This way, any watch can connect to the phone and get the adopted services info, and for any additional info watch can add support for the custom service.