How do wearables connect?

[gercer]

Hello!

I have been trying to make a wearable custom board. I have been trying to find some info about it but i don´t find anything useful. I have some questions. 
Working with a nrf52832, SES and SDK15.

1.- First of all I have noticed when i try to pair my mobile to another bluetooth device it shows me the type of device (multimedia, wearable, etc.) How can I configure that?

2.- I have noticed that some smart bands allows you to connect via BT with the car to play music and the smart band still gets the notifications from the phone such as messages and phonecalls. Is it possible to do that with the nrf52832?  How to achieve that?

If you have some useful links it would be awesome, I'm starting to work with BLE so there are some stuff i don´t understand.

Thank you!

[MartinBL]

Hi,

1. This is probably done using the Appearance Characteristic. From the Bluetooth Core Spec:
   
   It is also possible to include Appearance in the advertising packets. This tutorial mentions how you can configure that (the tutorial uses an old SDK, but I believe the method is relevant today). 
2. There are several different versions (often referred to as specifications) of Bluetooth (Wiki) and you should probably read up upon what their differences and capabilities are. Nordic's nRF52 ICs support Bluetooth v4.x and v5. These Bluetooth versions are also known as Bluetooth low energy (BLE). Today, devices that transfer audio, like your car stereo, most likely use Bluetooth v2 or v3, also known as Bluetooth Classic. BLE and Bluetooth Classic devices cannot talk directly to each other, but it could be that your car stereo has both BLE and Bluetooth Classic support. It could also be that your smart band is communicating with the car stereo using your phone as a gateway. 

[gercer]

The demo was in SDK11 using Keil tho.

1.- If anyone is interested i had to add at the end of the advertising_init function:
err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_WATCH_SPORTS_WATCH);
APP_ERROR_CHECK(err_code);

And the different appearances can be shown in the ble_types.h file.

Thanks for the help MartinBL