Connect to PyBluez server using Android SDK

Question

I want to open RFCOMM socket connection between two devices, but nothing that I tried worked. This is what I have:

Python script uses PyBluez to advertise SPP service and waits for connections.
Android application tries to find that service and connect to the device.

Server side

Bluetooth server script advertises serial port profile service. The service UUID used is 00001101-0000-1000-8000-00805F9B34FB.

bluetooth.advertise_service(
    sock=self.server_socket,
    name="My Service",
    service_id=self.service_uuid,
    service_classes=[self.service_uuid, bluetooth.SERIAL_PORT_CLASS],
    profiles=[bluetooth.SERIAL_PORT_PROFILE],
    description="My service description.",
)

Client

I can find the device to which I want to connect. To make a connection, I followed official Android documentation Connect Bluetooth devices / Connect as a client and used the same UUID as used on the server side. However, I get an exception java.io.IOException: read failed, socket might closed or timeout, read ret: -1.

Also, when scanning SDP server of the device that I want to connect to, I do find 00001101-0000-1000-8000-00805F9B34FB service UUID, but it seems to be a default value, as it does not matter whether I advertise the service or not. Also, if I change the service UUID to something else, it does not show up. I tried clearing the cache both on both devices, but ti doesn't not change anything.

Moreover, I tried using BluetoothProfile.ServiceListener to get the information about the advertised services, but it does not find the serial port profile service that I advertise through the Python script that I mentioned earlier.

public class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final BluetoothDevice mmDevice;
    private final BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

    public ConnectThread(BluetoothDevice device, String serviceUuid) {
        BluetoothSocket tempSocket = null;
        mmDevice = device;

        try {
            UUID uuid = UUID.fromString(serviceUuid);
            tempSocket = device.createRfcommSocketToServiceRecord(serviceUuid);
        } catch (IOException e) {
            Log.e("BluetoothClassicModule", "Socket's create() method failed", e);
        }

        mmSocket = tempSocket;
    }

    public void run() {
        bluetoothAdapter.cancelDiscovery();

        try {
            Log.d("BluetoothClassicModule", "[Thread] Began connecting to device " + mmDevice.getName());
            mmSocket.connect();
        } catch (IOException connectException) {
            Log.e("BluetoothClassicModule", "[THREAD] Could not connect to device.", connectException);

            try {
                mmSocket.close();
            } catch (IOException closeException) {
                Log.e("BluetoothClassicModule", "[THREAD] Could not close the client socket.", closeException);
            }
            return;
        }

        Log.d("BluetoothClassicModule", "[THREAD] Connected successfully.");
    }
}

How could I make it work or at least debug this? I want to:

Find the device that advertises service with serial port profile and specific service UUID.
Establish RFCOMM connection to that device from Android application.

Connect to PyBluez server using Android SDK

0 Answers0