Bluetooth RFCOMM Connection Problems with socket

AnatolyKub · 1 Aug 2019, 10:35

Hello guys. I have to communicate with device via Bluetooth Classic. I can connect to device and send command. If I switch GUI Page, the connection does not lost but socket->state() show me that is unconnected state. What is not correct here? beepBuzzor is in the socketConnected() SLOT and it works after connectToService call. But if I clos my scanningpage in qml and click on the button startMotor from other qml page, the state is unconnected but why? If I put the startMotor button in scanningPage where I have selected the right device, it works. but not on other pages.

BluetoothManager::BluetoothManager(QObject *parent) : QObject(parent)
{
    socket = new QBluetoothSocket(QBluetoothServiceInfo::RfcommProtocol);
}

void BluetoothManager::startDiscovery()
{

    // Check if Bluetooth is available on this device
    if (localDevice.isValid()) {

        qDebug() << "Bluetooth is available on this device";

        //Turn BT on
        localDevice.powerOn();

        // Make it visible to others
        localDevice.setHostMode(QBluetoothLocalDevice::HostDiscoverable);

        //Read local device name & address
        qDebug() << "Local Device:" << localDevice.name() << "(" << "Address:" << localDevice.address() << ")";

        // Create a discovery agent and connect to its signals

        discoveryAgent = new QBluetoothDeviceDiscoveryAgent(this);

        connect(discoveryAgent, SIGNAL(finished()), this, SLOT(deviceDiscoverFinished()));

        // Start a discovery
        // Trick: da es kein DiscoveryTimer für Classic gibt, suchen wir nach LE devices, da BT121 BLE unterstützt.
        // Die Verbindung erfolgt jedoch über RFCOMM sobald man sich mit dem Gerät verbindet.
        discoveryAgent->setLowEnergyDiscoveryTimeout(5000);
        discoveryAgent->start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod);


        qDebug() << "Device discover started";
    }
    else
    {
        qDebug() << "Bluetooth is not available on this device";
    }

}
//SLOT for the finish of device Discovery
void BluetoothManager::deviceDiscoverFinished()
{
    qDebug() << "Device discover finished";

    listOfDevices = discoveryAgent->discoveredDevices();

    qDebug() << "Found new devices:";

    for (int i = 0; i < listOfDevices.size(); i++)
    {
        //Q_OS_IOS / MAC do not need here cuz the run is on android device, delete later
        //We do not find galileo device on MacBook
        #if defined (Q_OS_IOS) || defined (Q_OS_MAC)
        // On MacOS and iOS we get no access to device address,
        // only unique UUIDs generated by Core Bluetooth.

        qDebug() << "getting address from deviceUuid()" << listOfDevices.at(i).name().trimmed()
        << " ( " << listOfDevices.at(i).deviceUuid().toString().trimmed() << " ) ";
        setDevice(listOfDevices.at(i).name().trimmed() + " (" + listOfDevices.at(i).deviceUuid().toString().trimmed() + ")");


        #else

        qDebug() << listOfDevices.at(i).name().trimmed()
                 << " ("
                 << listOfDevices.at(i).address().toString().trimmed()
                 << ")";
        setDevice(listOfDevices.at(i).name().trimmed() + " (" + listOfDevices.at(i).address().toString().trimmed() + ")");

        #endif
    }


}

/**
*   In GUI (QML) user select a device with index i.
*   Create a new socket, using Rfcomm protocol to communicate 
*/

void BluetoothManager::deviceSelected(int i)
{
    selectedDevice = listOfDevices.at(i);

    #if defined (Q_OS_IOS) || defined (Q_OS_MAC)
    qDebug() << "User select a device: " << selectedDevice.name() << " ("
             << selectedDevice.deviceUuid().toString().trimmed() << ")";
#else

    qDebug() << "User select a device: " << selectedDevice.name() << " ("
             << selectedDevice.address().toString().trimmed() << ")";
#endif



    if (localDevice.pairingStatus(selectedDevice.address())== QBluetoothLocalDevice::Paired)
        {
            qDebug() << "Pairing is allready done";
        }
        else
        {
            qDebug() << "Not paired. Please do pairing first for communication with device!";
        }

    selecDevAdress = selectedDevice.address();
    connectToSvc();
    //Connect SIGNALS with SLOTS
    connect(socket, SIGNAL(error(QBluetoothSocket::SocketError)), this, SLOT(socketError(QBluetoothSocket::SocketError)));
    connect(socket, SIGNAL(connected()), this, SLOT(socketConnected()));
    connect(socket, SIGNAL(disconnected()), this, SLOT(socketDisconnected()));
    connect(socket, SIGNAL(readyRead()), this, SLOT(socketRead()));
    connect(socket, SIGNAL(stateChanged(QBluetoothSocket::SocketState)), this, SLOT(socketStateChanged()));
}

void BluetoothManager::connectToSvc()
{
    qDebug() << "Create socket";

    //socket->connectToService(selecDevAdress, QBluetoothUuid(QString("00001101-0000-1000-8000-00805F9B34FB")), QIODevice::ReadWrite);
    //static const QString serviceUuid(QStringLiteral("00001101-0000-1000-8000-00805F9B34FB"));
    socket->connectToService(selectedDevice.address(), QBluetoothUuid(QString("00001101-0000-1000-8000-00805F9B34FB")), QIODevice::ReadWrite);

    //Also works with this line instead of the two above (with declaration of serviceUuid)
    //socket->connectToService(QBluetoothAddress(selectedDevice.address()),QBluetoothUuid(QBluetoothUuid::SerialPort));
    socket->open(QIODevice::ReadWrite);



}

//SLOT wenn Socket verbunden ist

void BluetoothManager::socketConnected()
{

    //qDebug() << ("Connected to: "+socket->peerAddress().toString() +":"+socket->peerPort());
    qDebug() << ("Connected to: "+socket->peerAddress().toString());
    qDebug() << "Socket connected";
    qDebug() << "Local: "
             << socket->localName()
             << socket->localAddress().toString()
             << socket->localPort();
    qDebug() << "Peer: "
             << socket->peerName()
             << socket->peerAddress().toString()
             << socket->peerPort();

    //Do "beep" sound commando after succesfull connection to Galileo device
    beepBuzzor();

}

/**
*   Socket disconnected.
*   Delete socket, free the memory.
*/

//SLOT für Verbindungsabbruch von Socket
void BluetoothManager::socketDisconnected()
{
    qDebug() << "Socket disconnected";
    socket->deleteLater();
}


void BluetoothManager::socketError(QBluetoothSocket::SocketError error)
{
    qDebug() << "Socket error: " << error;
}

void BluetoothManager::socketStateChanged()
{
    int socketState = socket->state();

    if(socketState == QAbstractSocket::UnconnectedState)
    {
        qDebug() << "unconnected";
    }
    else if(socketState == QAbstractSocket::HostLookupState)
    {
        qDebug() << "host lookup";
    }
    else if(socketState == QAbstractSocket::ConnectingState )
    {
        qDebug() << "connecting";
    }
    else if(socketState == QAbstractSocket::ConnectedState)
    {
        qDebug() << "connected";
    }
    else if(socketState == QAbstractSocket::BoundState)
    {
        qDebug() << "bound";
    }
    else if(socketState == QAbstractSocket::ClosingState)
    {
        qDebug() << "closing";
    }
    else if(socketState == QAbstractSocket::ListeningState)
    {
        qDebug() << "listening";
    }
}

//   SLOT when data ready on bluetooth socket
void BluetoothManager::socketRead()
{
    qDebug() << "socketRead()";
    QByteArray recievedData = socket->readAll();

    emit dataRecieved(recievedData);
}

/**
*   Get a string with device info
*/

const QString &BluetoothManager::device() const
{
    return deviceInfo;
}


void BluetoothManager::setDevice(const QString &newDevice)
{
    if (newDevice != deviceInfo) {

        deviceInfo = newDevice;
        emit deviceChanged();
    }
}

void BluetoothManager::beepBuzzor()
{
    QByteArray beep;
    beep.append(QByteArray::fromRawData("\x04\x00\x09\xD0\x07\x32\x00", 7));
    command(beep);
}

void BluetoothManager::startMotor() //this slot I call from qml but nothing happens cuz state unconnected but the connection is established to device! Whats not correct?
{
    qDebug() << "startMotor slot";
    if(socket->state() == QBluetoothSocket::UnconnectedState){
        qDebug() << "Socket Unconnected";
    }
    else{
        qDebug() << "Socket Unonnected";
    }
    socketStateChanged();
    //command(start);
}

void BluetoothManager::command(QByteArray &cmdBuf)
{
socket->write(cmdBuf);
}