QBluetoothSocketPrivate::_q_readNotify() 18 error: -1 "Connection timed out"

[ZainMehdi]

Hi I am using qt on an embedded board for communication with an IOS device. The embedded board is runnning qt 5.10 and is in peripheral mode. I am getting the above-mentioned error sometimes and after that Bluetooth Error takes place, with error signal as follows

Error: QLowEnergyController::Error(UnknownError)

Kindly provide any insight as to how can I know the source of this issue. The document says nothing about it.

I get a "Bluetooth Error" as in

function  void Bluetooth::reconnectOnError(QLowEnergyController::Error error)

and after that the app crashes with segmentation fault. I am unable to trace the source as qt is in release mode. Only get disassembler information.

#include "bluetooth.h"

#define log qDebug()<<"["<<__DATE__<<":"<<QTime::currentTime().toString()<<"]"<<"["<<__LINE__<<"]"<<"["<<__FILE__<<"] "

Bluetooth::Bluetooth(mainprocess *main,QObject *parent) :QObject(parent), mainObject(main)
{

    initializeBluetooth();
}

void Bluetooth::initializeBluetooth(){

    try{
        log<<"Initializing Bluetooth...\n";
        //! [Advertising Data]
        advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
        advertisingData.setLocalName("AtlasGo");
        advertisingData.setServices(QList<QBluetoothUuid>() <<QBluetoothUuid::Atlas);


        // For IOS its readonly and for Atlas its write only
        ReadCharacteristicData.setUuid(QBluetoothUuid::ReadCharacteristic);
        ReadCharacteristicData.setProperties(QLowEnergyCharacteristic::Notify);
        ReadCharacteristicDesc.setUuid(QBluetoothUuid::ClientCharacteristicConfiguration);
        ReadCharacteristicDesc.setValue(QByteArray(2,0));
        ReadCharacteristicData.addDescriptor(ReadCharacteristicDesc);



        // For IOS its write only characteristic and for Atlas its read only
        WriteCharactersiticData.setUuid(QBluetoothUuid::WriteCharacteristic);
        WriteCharactersiticData.setProperties(QLowEnergyCharacteristic::Write |QLowEnergyCharacteristic::Notify);
        WriteCharactersiticDesc.setUuid(QBluetoothUuid::AtlasDescriptor);
        WriteCharactersiticDesc.setValue(QByteArray::fromHex("Write").toHex());
        WriteCharactersiticData.addDescriptor(WriteCharactersiticDesc);

        // For IOS its readonly and for Atlas its write only
        ConnectivityData.setUuid(QBluetoothUuid::Connectivity);
        ConnectivityData.setProperties(QLowEnergyCharacteristic::Notify);
        ConnectivityDesc.setUuid(QBluetoothUuid::ClientCharacteristicConfiguration);
        ConnectivityDesc.setValue(QByteArray(2, 0));
        ConnectivityData.addDescriptor(ConnectivityDesc);


        // For IOS its write only characteristic and for Atlas its read only
        TrackerData_Data.setUuid(QBluetoothUuid::TrackingData);
        TrackerData_Data.setProperties(QLowEnergyCharacteristic::Notify);
        TrackerDesc.setUuid(QBluetoothUuid::ClientCharacteristicConfiguration);
        TrackerDesc.setValue(QByteArray(2, 0));
        TrackerData_Data.addDescriptor(TrackerDesc);



        serviceData.setType(QLowEnergyServiceData::ServiceTypePrimary);
        serviceData.setUuid(QBluetoothUuid::Atlas);


        // Adding characteristic to our service
        serviceData.addCharacteristic(ReadCharacteristicData);
        serviceData.addCharacteristic(WriteCharactersiticData);
        serviceData.addCharacteristic(ConnectivityData);
        serviceData.addCharacteristic(TrackerData_Data);



        leController.reset(QLowEnergyController::createPeripheral()); // We are resetting only the pointer here (leController is a scoped pointer)
        service.reset(leController->addService(serviceData));         // Resetting  only the pointer here (service is a scoped pointer)


        while ( localdevice.hostMode()==QBluetoothLocalDevice::HostPoweredOff){

            log<<"Host is powered off";
            system("sudo rfkill unblock 3");
            system("sudo rfkill unblock 0");
            if(localdevice.hostMode()==QBluetoothLocalDevice::HostConnectable)
                break;


        }



        connect(&heartbeatTimer, &QTimer::timeout,mainObject, &mainprocess::TickProvider);
        connect(leController.data(), &QLowEnergyController::disconnected,mainObject,&mainprocess::reconnect);
        connect(leController.data(), &QLowEnergyController::connected,mainObject,&mainprocess::bleConnected);
        connect(service.data(),&QLowEnergyService::characteristicChanged,mainObject,&mainprocess::parseResponse);
        connect(leController.data(), static_cast<void (QLowEnergyController::*)(QLowEnergyController::Error)>(&QLowEnergyController::error),
                this,&Bluetooth::reconnectOnError);

        leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,advertisingData);

        // We have to check if advertising succeeded ot not. If there was an advertising error we will
        // try to reinitialize our bluetooth service
        while (leController->state()!= QLowEnergyController::AdvertisingState){
            resetBluetoothService();
            leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,advertisingData);

        }

        // Timer for periodically sending information to IOS
        // Tracking data
        // Connectivity information
        log<<"Starting the Tick Timer Timer";
        heartbeatTimer.start(66);
        //    heartbeatTimer.start(200); Just for testing
    }
    catch(std::exception e)
    {
        log<<"---------------------";
        log<<"Bluetooth Crashed";
        log<<"---------------------";
        log<<"Bluetooth Initialization failed";
        log<<e.what();
        emit recoverBluetooth();
    }


}

void Bluetooth::reconnectOnDisconnect(){


    try{

        log<<"Bluetooth Device Disconnected";
        log<<"Resetting Bluetooth bt.service";


         //resetBluetoothService();
        if(leController->state()!= QLowEnergyController::ConnectedState){
            //leController->disconnectFromDevice();
            leController.reset(QLowEnergyController::createPeripheral());
            service.reset(leController->addService(serviceData));
        }

        if (!service.isNull()){

            if(leController->state()!=QLowEnergyController::AdvertisingState && leController->state()!=QLowEnergyController::ConnectedState){
                leController->startAdvertising(QLowEnergyAdvertisingParameters(),advertisingData,advertisingData);   //, advertisingData);
            }

            // We have to check if advertising succeeded ot not. If there was an advertising error we will
            // try to reinitialize our bluetooth service
            while (leController->state()!= QLowEnergyController::AdvertisingState && leController->state()!= QLowEnergyController::ConnectedState ){
                resetBluetoothService();
                leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,advertisingData);

            }

            connect(service.data(),&QLowEnergyService::characteristicChanged,mainObject,&mainprocess::parseResponse);
            connect(leController.data(), &QLowEnergyController::disconnected,mainObject,&mainprocess::reconnect);
            connect(leController.data(), &QLowEnergyController::disconnected,mainObject,&mainprocess::stopTracker);
            connect(leController.data(), &QLowEnergyController::connected,mainObject,&mainprocess::bleConnected);
            connect(leController.data(), static_cast<void (QLowEnergyController::*)(QLowEnergyController::Error)>(&QLowEnergyController::error),
                    this,&Bluetooth::reconnectOnError);


        }
    }
    catch(std::exception e){

        log<<"---------------------";
        log<<"Bluetooth Crashed";
        log<<"---------------------";
        log<<"Error while handling bluetooth Disconnect";
        log<<e.what();
        emit recoverBluetooth();
    }


}

void Bluetooth::reconnectOnError(QLowEnergyController::Error error){


    try{

        // Have to check this error because of Qt's bug. It throws error when remote device disconnects
        if(error!=QLowEnergyController::RemoteHostClosedError){

            log<<"Bluetooth Error !!";
            log<<"Resetting Bluetooth bt.service";
            log<<"Error: "<<error;

           // resetBluetoothService();

            if(leController->state()!= QLowEnergyController::ConnectedState){
                //leController->disconnectFromDevice();
                leController.reset(QLowEnergyController::createPeripheral());
                service.reset(leController->addService(serviceData));
            }


            if (service!=nullptr){

                if(leController->state()!=QLowEnergyController::AdvertisingState && leController->state()!=QLowEnergyController::ConnectedState){
                    leController->startAdvertising(QLowEnergyAdvertisingParameters(),advertisingData,advertisingData);   //, advertisingData);
                }

                // We have to check if advertising succeeded or not. If there was an advertising error we will
                // try to reinitialize our bluetooth service
                while (leController->state()!= QLowEnergyController::AdvertisingState && leController->state()!= QLowEnergyController::ConnectedState ){
                    //resetBluetoothService();
                    leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,advertisingData);

                }

                // Connections
                connect(service.data(),&QLowEnergyService::characteristicChanged,mainObject,&mainprocess::parseResponse);
                connect(service.data(), QOverload<QLowEnergyService::ServiceError>::of(&QLowEnergyService::error),[=](QLowEnergyService::ServiceError newError){
                    log<<"---------------------";
                    log<<"Bluetooth Service Error:"<<newError;
                    log<<"---------------------";
                });
                connect(leController.data(), &QLowEnergyController::disconnected,mainObject,&mainprocess::reconnect);
                connect(leController.data(), &QLowEnergyController::connected,mainObject,&mainprocess::bleConnected);
                connect(leController.data(), &QLowEnergyController::disconnected,mainObject,&mainprocess::stopTracker);
                connect(leController.data(), static_cast<void (QLowEnergyController::*)(QLowEnergyController::Error)>(&QLowEnergyController::error),
                        this,&Bluetooth::reconnectOnError);


            }
        }
    }

    catch(std::exception e){

        log<<"---------------------";
        log<<"Bluetooth Crashed";
        log<<"---------------------";
        log<<"Error while reconnecting after remote device disconnection";
        log<<e.what();
        emit recoverBluetooth();
    }


}



void Bluetooth::resetBluetoothService(){

    try{

        log<<"Trying to reset bluetooth";
        if(leController->state()==QLowEnergyController::AdvertisingState)
            leController->stopAdvertising();


        // Todo: Use timer
        system("sudo service bluetooth stop");
        QThread::sleep(1);
        system("sudo service bluetooth start");
        QThread::sleep(1);

        log<<"Bluetooth Reset complete";
    }

    catch(std::exception e){
        log<<"---------------------";
        log<<"Bluetooth Crashed";
        log<<"---------------------";
        log<<"Error while resetting bluetooth";
        log<<e.what();
        emit recoverBluetooth();
    }
}