Qt Bluetooth reconnection problem

[AndreaFurlani]

Hello,
I am developing a bluetooth service with two characteristics: one to let other devices read a list of MAC address and the other to write a command for the program.
Everything is working fine, the only problem is that when I disconnect from the main service and then I reconnect to it, I can see the two services but I can't read or write.
This is the code:

static const QLatin1String serviceUuid("11223344-5566-7788-99aa-bbccddeeff00");
    static const QLatin1String readListUuid("11223344-5566-7788-99aa-bbccddeeff11");
    static const QLatin1String writeListUuid("11223344-5566-7788-99aa-bbccddeeff12");

    // [Advertising Data]
        QLowEnergyAdvertisingData advertisingData;
        advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
        advertisingData.setIncludePowerLevel(true);
        advertisingData.setLocalName("BOX");
        advertisingData.setServices(QList<QBluetoothUuid>() << QBluetoothUuid(serviceUuid));

    // [Service Data]
        QLowEnergyCharacteristicData readList,writeList;

        readList.setUuid(QBluetoothUuid(readListUuid));
        readList.setProperties(QLowEnergyCharacteristic::Read);

        writeList.setUuid(QBluetoothUuid(writeListUuid));
        writeList.setProperties(QLowEnergyCharacteristic::Write);

        const QLowEnergyDescriptorData clientConfig(QBluetoothUuid::CharacteristicUserDescription,QByteArray(2, 0));
        readList.addDescriptor(clientConfig);
        writeList.addDescriptor(clientConfig);

        QLowEnergyServiceData serviceData;
        serviceData.setType(QLowEnergyServiceData::ServiceTypePrimary);
        serviceData.setUuid(QBluetoothUuid(serviceUuid));
        serviceData.addCharacteristic(readList);
        serviceData.addCharacteristic(writeList);


    // [Start Advertising]

        leController.reset(QLowEnergyController::createPeripheral());
        service_list.reset(leController->addService(serviceData));
        leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,advertisingData);



    qCDebug(BLELog) << " Start BLE backend [...] ";

    ConnectionHandler connectionHandler;
    DeviceHandler m_deviceHandler;


    // TODO! Restore debug options.
    GenericDeviceIf::start(debugMode, protocolDebug);

    // Initialize reachable state to unreachable.
    DataModel::getInstance()->setDeviceCategoryReachable(_category, false);

    _endpoints = DataModel::getInstance() ->getEndpointsListByCategory(dataBaseClasses::ENDPOINT_CATEGORY_BLE);

    m_deviceHandler.setDevice(nullptr);
    qDeleteAll(devices);
    devices.clear();

    emit devicesChanged();

    qCDebug(BLELog) << "Scanning for devices...";

    discoveryAgent->start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod);

    emit scanningChanged();

    // [Retrieving the list of devices]

        QLowEnergyCharacteristic characteristic = service_list->characteristic(QBluetoothUuid(readListUuid));
        QString sep = "\n";
        for (const auto &e: _endpoints){
            L.append(QString(e->getName()).toUtf8());
            L.append(QString("\t").toUtf8());
            L.append(QString(e->getMapping()).toUtf8());
            L.append(QString(sep.toUtf8()));
        }
        L.resize(L.size()-1);

        if (L.isEmpty())
            qCDebug(BLELog) << "No endpoints loaded in the list";
        else
            service_list -> writeCharacteristic(characteristic, L) ;


   // [Reconnect to the service when it disconnects]
        auto reconnect = [this , serviceData, advertisingData]()
        {
            service_list.reset(leController->addService(serviceData));
            if (!service_list.isNull()) {
                leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData, advertisingData);
            }
        };

        auto getCommand = [this, serviceData, advertisingData]()
        {
            command = service_list->characteristic(QBluetoothUuid(writeListUuid)).value();
            qCDebug(BLELog) << command;
        };

        QObject::connect(leController.data(), &QLowEnergyController::disconnected, reconnect);
        QObject::connect(service_list.get() , &QLowEnergyService::characteristicChanged, getCommand);

In the header file service_list and leController are defined as follow:

QScopedPointer<QLowEnergyController> leController;
QScopedPointer<QLowEnergyService> service_list;

I based my code following the heart rate server example.

[Ixtl]

@AndreaFurlani
Hi Andrea,

I think 'm facing a same kind of issue (Windows Platform, Mingw8.1 32bits, Qt 5.15.3).

Please, can you share errors messages you got ?

BR
Patrick Babonneau