BLE connectGatt() method is not reporting anything in BluetoothGattCallback....?

Question

Can somebody please check the problem with this code. I have implemented a service and passes a BluetoothDevice object to it (There is no error/Problem in BluetoothDevice object passing through intent). Then, in the onStartCommand(), i am calling deviceToConnect.connectGatt(this,false,mGattCallback). But my BluetoothGattCallback() is not working (Not printing anything). Code is simple and straight forward. Can somebody help me to debug it.

EDIT: i am doing Le device Scan in MainActivity() and passing device object to a service to connect to the device.

public class PairedBleService extends Service
{
    private BluetoothGatt mConnectedGatt;
    @Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        Toast.makeText(this, "Service Started", Toast.LENGTH_SHORT).show();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // TODO Auto-generated method stub
        super.onStartCommand(intent, flags, startId);

        BluetoothDevice deviceToConnect = (BluetoothDevice) intent.getParcelableExtra(DEVICE_TO_CONNECT);
        mConnectedGatt = deviceToConnect.connectGatt(this, false, mGattCallback);

        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        Toast.makeText(this, "Service End", Toast.LENGTH_SHORT).show();
        super.onDestroy();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

    private BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {

    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_CONNECTED) {
            Toast.makeText(getApplicationContext(), "Peripheral connected", Toast.LENGTH_LONG).show();
        } else if (status == BluetoothGatt.GATT_SUCCESS && newState == BluetoothProfile.STATE_DISCONNECTED) {
            Toast.makeText(getApplicationContext(), "Peripheral Disconnected", Toast.LENGTH_LONG).show();
        } else if (status != BluetoothGatt.GATT_SUCCESS) {
            gatt.disconnect();
        }
    }
}

Edit: I tried to connect my beacon (Peripheral) with standard android bluetooth s/w and there i am able to make connection. But there it is asking for Pairing pin and once putting the pin it is connected and shown in Paired bluetooth device. Is there any method like connectGatt where we can ask "pairing pin" to the user... I am unable to understand what i am missing.

Answer 1

Your onBind method is returning null and hence your main activity is not able to communicate with your service.

Your code should be as per the below,

@ PairedBleService

public class LocalBinder extends Binder 
{
    PairedBleService getService() 
    {
        return PairedBleService.this;
    };
};

@Override
public IBinder onBind(Intent intent) 
{
    // TODO Auto-generated method stub
    return mBinder;
};

private final IBinder mBinder = new LocalBinder();

@ Main Activity

//put this inside onServiceConnected

PairedBleService bleService = ((PairedBleService.LocalBinder) service).getService();

// Your code for connecting with BLE device
....................................
....................................

Answer 2

The edit does help. You want to pair from within the app...

BluetoothDevice has a createBond() method as of API level 19 (4.4) so this leaves out 4.3 which was the first BLE Android version, but there aren't many of those left.

That should pop up the PIN dialog for the user. Once the device is successfully bonded you can then connect. To know when bonding has completed or not you need to have a BroadcastReceiver that is registered to listen to ACTION_BOND_STATE_CHANGED. The Intent that comes in has EXTRA_BOND_STATE which can be BOND_BONDED, BOND_BONDING_, or BOND_NONE.

So in your onStartCommand you want to getBondState() and if it is BOND_NON you want to createBond(). If it is BOND_BONDING you need to wait for the bonding with the BroadcastReceiver and connect once it is bonded. If it is BOND_BONDED then you can connect.