onDeviceDisconnected - inconsistent reason

[ghost]

I'm getting different reasons inside the ConnectionObservers onDeviceDisconnected callback for different devices in case of disconnecting some BLE devices from the phone (disconnecting them from the power outlet).

• OnePlus 5: Android 9 -> REASON_TIMEOUT
• Samsung Galaxy S21 FE: Android 13 -> REASON_SUCCESS
• Google Pixel 3: Android 12 -> REASON_SUCCESS

The main issue with this is that if I disconnect from a device using the disconnect() from the BleManager, I also get a REASON_SUCCESS on the onDeviceDisconnected callback.

Maybe the different Android version is the issue, I'm not sure. Can you help me take a look at it, how to solve it?

Thanks, Tamas

[krioru]

I have the same issue.

I have a battery powered peripheral/server device and I use phone to connect to it and read its characteristics. If I remove device's battery, I get the SUCCESS reason on disconnection event.

If I try to connect to device which is not powered or out of reach, i get the UNKNOWN reason on disconnection event.

[philips77]

I'll look into that, thanks.

[philips77]

The intended reason should be TERMINATE_PEER_USER, I believe, when you kill the connected device. In worst case TIMEOUT.

[krioru]

Removing the battery and going out of reach both give SUCCESS reason on my Android 13 phone. In both cases the reason should be TIMEOUT, because it's not a 'graceful disconnection'.

[philips77]

There is this method called at some point: https://github.com/NordicSemiconductor/Android-BLE-Library/blob/839cbb3ac11b6b03d0dbc57f5aa523e19805ef62/ble/src/main/java/no/nordicsemi/android/ble/BleManagerHandler.java#L2810-L2820 If the reported status is 0, then success is reported. I'll try to modify it so SUCCESS is only reported when the disconnection was triggered by the user.

[philips77]

Btw, what messages do you get on WARNING level just before getting the event from the log(...) method?

[krioru]

I don't see any warning logs. I retrieve the reason from stateAsFlow() flow.

Here's the logs that I receive when I remove power from the peripheral device:

BluetoothGatt           D  onClientConnectionState() - status=0 clientIf=12 device=CC86EC_3
BluetoothC...Connection D  [Callback] Connection state changed with status: 0 and new state: 0 (DISCONNECTED)
BluetoothC...Connection I  Disconnected
BluetoothC...Connection D  gatt.close()
BluetoothGatt           D  close()
BluetoothGatt           D  unregisterApp() - mClientIf=12
BluetoothAdapter        I  STATE_ON
BluetoothAdapter        I  STATE_ON
BluetoothAdapter        I  STATE_ON
BluetoothC...Connection D  onServicesInvalidated()
BluetoothC...er:connect D  Disconnect reason: SUCCESS

The last log line is called whenever stateAsFlow() emits a new value.

Like this:

stateJob = bleConnectionManager?.stateAsFlow()?.onEach { managerState ->

  if (managerState is ConnectionState.Disconnected) {
    Log.d("$TAG:connect", "Disconnect reason: ${managerState.reason}")
  }

}?.cancellable()?.launchIn(scope)

[krioru]

Ok, I checked on two other devices running Android 10 and Android 8 and they do have that warning log and they report the correct reason:

D  [Callback] Connection state changed with status: 8 and new state: 0 (DISCONNECTED)
W  Error: (0x8): GATT CONN TIMEOUT
I  Disconnected
D  gatt.close()
D  onServicesInvalidated()
D  Disconnect reason: TIMEOUT

So it looks like it's an Android 12/13+ issue. Maybe also Android 11?