An attempt to get battery level from Bluetooth classic device (headsets) using Window's UWP APIs
OS: Windows 10 Build 18363
Devices 🎧 : Sony WH-CH510 and FireBolt BH1200
Windows wasn't showing battery level of the headphones even though it correctly showed up on a different machine running an updated version of windows. So the Journey began to get it via Windows Runtime APIs.
Support for accessing bluetooth devices is there in Windows Runtime APIs. It is exposed to C# via UWP in Windows.Devices.Bluetooth namespace. Also, as a bonus, you don't need to make an UWP App in order to use these APIs. You can very well access these WinRT APIs in any WPF/.NET App by including the DLLs
My tool is a simple .NET console app 🖥️
Ref: https://blogs.windows.com/windowsdeveloper/2017/01/25/calling-windows-10-apis-desktop-application/
The program gets the battery level of a classic bluetooth device, since there is no built in function to get that via WinRT APIs. For BLE devices, you can simply use built in functions Windows.Devices.Bluetooth.GenericAttributeProfile
We take the classic rfcomm approach to get what we need. A bluetooth device has several rfcomm channels (music, voice) to which we can connect to. Once we establish a connection, the device broadcasts certain AT Commands to which we can listen and respond to.
AT Commands Ref: https://radekp.github.io/qtmoko/api/modememulator-controlandstatus.html
The particular command we are interested in is IPHONEACCEV command. Although it is an APPLE specific command, a lot of manufacturers use the same command to emit their battery level info.
Ref: https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf
Build and make sure your device is paired and is disconnected.
Thanks.