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android bluetooth can't connect

I've been having this problem for a while and haven't been able to figure it out.

I have a android application that puts all paired devices in a listview. When you click one of the list items, it will initiate a request to connect to that bluetooth device.

I can get the list of devices with their addresses no problem. The problem is that once I try to connect I get an IOException on socket.connect();

The error message is as follows: "connect read failed, socket might closed or timeout, read ret: -1"

Here is my code. ANY suggestions would be appreciated. I'm pretty stuck on this.

fyi: the "onEvent" methods is a library that simplifies callbacks...that part works. When the user clicks on a list items this method is called "public void onEvent(EventMessage.DeviceSelected event)"

public class EcoDashActivity extends BaseActivity {

public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");


private BluetoothAdapter mBluetoothAdapter;
private int REQUEST_ENABLE_BT = 100;
private ArrayList<BluetoothDevice> mDevicesList;
private BluetoothDeviceDialog mDialog;
private ProgressDialog progressBar;
private int progressBarStatus = 0;
private Handler progressBarHandler = new Handler();


@Override
public void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.main);

    mDevicesList = new ArrayList<BluetoothDevice>();

    // Register the BroadcastReceiver
    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    registerReceiver(mReceiver, filter);

    setupBluetooth();
}

private void setupBluetooth() {
    mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if (mBluetoothAdapter == null) {
        // Device does not support Bluetooth
        Toast.makeText(this, "Device does not support Bluetooth", Toast.LENGTH_SHORT).show();
    }

    if (!mBluetoothAdapter.isEnabled()) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    } else {
        searchForPairedDevices();
        mDialog = new BluetoothDeviceDialog(this, mDevicesList);
        mDialog.show(getFragmentManager(), "");
    }

}

private void searchForPairedDevices() {

    Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
    // If there are paired devices
    if (pairedDevices.size() > 0) {
        // Loop through paired devices
        for (BluetoothDevice device : pairedDevices) {
            // Add the name and address to an array adapter to show in a ListView
            mDevices.add(device.getName() + "\n" + device.getAddress());
            mDevicesList.add(device);
        }
    }
}


private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        // When discovery finds a device
        if (BluetoothDevice.ACTION_FOUND.equals(action)) {
            // Get the BluetoothDevice object from the Intent
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            // Add the name and address to an array adapter to show in a ListView
            mDevicesList.add(device);
        }
    }
};


@Override
protected void onDestroy() {
    super.onDestroy();
    unregisterReceiver(mReceiver);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_ENABLE_BT) {
        if (resultCode == RESULT_OK) {
            Toast.makeText(this, "BT turned on!", Toast.LENGTH_SHORT).show();
            searchForPairedDevices();

            mDialog = new BluetoothDeviceDialog(this, mDevicesList);
            mDialog.show(getFragmentManager(), "");
        }
    }

    super.onActivityResult(requestCode, resultCode, data);
}


public void onEvent(EventMessage.DeviceSelected event) {

    mDialog.dismiss();

    BluetoothDevice device = event.getDevice();

    ConnectThread connectThread = new ConnectThread(device);
    connectThread.start();
}


public class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final BluetoothDevice mmDevice;

    public ConnectThread(BluetoothDevice device) {
        // Use a temporary object that is later assigned to mmSocket,
        // because mmSocket is final
        BluetoothSocket tmp = null;
        mmDevice = device;

        // Get a BluetoothSocket to connect with the given BluetoothDevice
        try {
            // MY_UUID is the app's UUID string, also used by the server code
            tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
        } catch (IOException e) { }
        mmSocket = tmp;
    }

    public void run() {
        setName("ConnectThread");
        // Cancel discovery because it will slow down the connection
        mBluetoothAdapter.cancelDiscovery();

        try {
            // Connect the device through the socket. This will block
            // until it succeeds or throws an exception
            Log.d("kent", "trying to connect to device");
            mmSocket.connect();
            Log.d("kent", "Connected!");
        } catch (IOException connectException) {
            // Unable to connect; close the socket and get out
            try {
                Log.d("kent", "failed to connect");

                mmSocket.close();
            } catch (IOException closeException) { }
            return;
        }

        Log.d("kent", "Connected!");
    }

    /** Will cancel an in-progress connection, and close the socket */
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) { }
    }
}

Here is my logcat. Pretty short.

07-22 10:37:05.129: DEBUG/kent(17512): trying to connect to device
07-22 10:37:05.129: WARN/BluetoothAdapter(17512): getBluetoothService() called with no BluetoothManagerCallback
07-22 10:37:05.129: DEBUG/BluetoothSocket(17512): connect(), SocketState: INIT, mPfd: {ParcelFileDescriptor: FileDescriptor[98]}
07-22 10:37:40.757: DEBUG/dalvikvm(17512): GC_CONCURRENT freed 6157K, 9% free 62793K/68972K, paused 7ms+7ms, total 72ms
07-22 10:38:06.975: DEBUG/kent(17512): failed to connect
07-22 10:38:06.975: DEBUG/kent(17512): read failed, socket might closed or timeout, read ret: -1

That last line is in the "Catch" section of a try/catch...I'm just logging the error message.

Please note, there is about a 20 second gap between "trying to connect to device" and "failed to connect"

like image 712
Kent Andersen Avatar asked Jul 20 '13 15:07

Kent Andersen


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2 Answers

The jelly bean bluetooth stack is markedly different from the other versions.

This might help: http://wiresareobsolete.com/wordpress/2010/11/android-bluetooth-rfcomm/

In gist: The UUID is a value that must point to a published service on your embedded device, it is not just randomly generated. The RFCOMM SPP connection you want to access has a specific UUID that it publishes to identify that service, and when you create a socket it must match the same UUID.

If you are targeting 4.0.3 device and above , use fetchUuidsWithSdp() and getUuids() to find all the published services and their associated UUID values. For backward compatibility read the article

like image 140
Vrashabh Irde Avatar answered Sep 24 '22 00:09

Vrashabh Irde


I got the same error message after connecting the socket a second time. I simply checked if the socket is already connected.

if(!mmSocket.isConnected())
            mmSocket.connect();

I was testing on Android 4.4.2 (Moto G).

like image 27
marnaish Avatar answered Sep 25 '22 00:09

marnaish