Android: Catching BLE Connection Fails/Disconnects?

Question

So I\'m able to connect to a BLE device just fine under normal circumstances. What I want to do is handle abnormal circumstances, like when the connection to a device fails or a

Answer 1

First, if an established connection is dropped you should get a disconnected state change event when the supervision timeout has passed. Otherwise there is some bug in Android.

Now about connection attempts.

Once you create a BluetoothGatt object with connectGatt and specify the auto connect parameter to true OR execute the connect method on an existing BluetoothGatt object, the phone will be in a state where it always and indefinitely tries to connect to the device and reconnect to the device if it disconnects for any reason until you either call disconnect or close on the gatt object.

So if you want to abort the connection after a while, just set up any kind of timer which calls disconnect on the gatt object (or close if you don't need it anymore) when it is triggered.

Also note that the status parameter of the onConnectionStateChange when newState is disconnected is not well-defined. In older Android versions it contains usually 0 or 133 and in newer versions often the Bluetooth standard's error code of the disconnect reason.

Also, if you get a disconnect state change event without previously have got a connected state change event, it usually indicates something has gone wrong in the internal Bluetooth stack (unless you use non-auto connect for which you always get a disconnect state change event after some timeout). Then I'd recommend that you close the gatt object and try again later.