Bluetooth Low Energy の概要

m_deviceDiscoveryAgent = new QBluetoothDeviceDiscoveryAgent(this);
m_deviceDiscoveryAgent->setLowEnergyDiscoveryTimeout(15000);

connect(m_deviceDiscoveryAgent, &QBluetoothDeviceDiscoveryAgent::deviceDiscovered,
        this, &DeviceFinder::addDevice);
connect(m_deviceDiscoveryAgent, &QBluetoothDeviceDiscoveryAgent::errorOccurred,
        this, &DeviceFinder::scanError);

connect(m_deviceDiscoveryAgent, &QBluetoothDeviceDiscoveryAgent::finished,
        this, &DeviceFinder::scanFinished);
connect(m_deviceDiscoveryAgent, &QBluetoothDeviceDiscoveryAgent::canceled,
        this, &DeviceFinder::scanFinished);
m_deviceDiscoveryAgent->start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod);

void DeviceFinder::addDevice(const QBluetoothDeviceInfo &device)
{
    // If device is LowEnergy-device, add it to the list
    if (device.coreConfigurations() & QBluetoothDeviceInfo::LowEnergyCoreConfiguration) {
        auto devInfo = new DeviceInfo(device);
        auto it = std::find_if(m_devices.begin(), m_devices.end(),
                               [devInfo](DeviceInfo *dev) {
                                   return devInfo->getAddress() == dev->getAddress();
                               });
        if (it == m_devices.end()) {
            m_devices.append(devInfo);
        } else {
            auto oldDev = *it;
            *it = devInfo;
            delete oldDev;
        }
        setInfo(tr("Low Energy device found. Scanning more..."));
        setIcon(IconProgress);
    }
    //...
}

m_control = QLowEnergyController::createCentral(m_currentDevice->getDevice(), this);
connect(m_control, &QLowEnergyController::serviceDiscovered,
        this, &DeviceHandler::serviceDiscovered);
connect(m_control, &QLowEnergyController::discoveryFinished,
        this, &DeviceHandler::serviceScanDone);

connect(m_control, &QLowEnergyController::errorOccurred, this,
        [this](QLowEnergyController::Error error) {
            Q_UNUSED(error);
            setError("Cannot connect to remote device.");
            setIcon(IconError);
        });
connect(m_control, &QLowEnergyController::connected, this, [this]() {
    setInfo("Controller connected. Search services...");
    setIcon(IconProgress);
    m_control->discoverServices();
});
connect(m_control, &QLowEnergyController::disconnected, this, [this]() {
    setError("LowEnergy controller disconnected");
    setIcon(IconError);
});

// Connect
m_control->connectToDevice();

void DeviceHandler::serviceDiscovered(const QBluetoothUuid &gatt)
{
    if (gatt == QBluetoothUuid(QBluetoothUuid::ServiceClassUuid::HeartRate)) {
        setInfo("Heart Rate service discovered. Waiting for service scan to be done...");
        setIcon(IconProgress);
        m_foundHeartRateService = true;
    }
}

    // If heartRateService found, create new service
    if (m_foundHeartRateService)
        m_service = m_control->createServiceObject(QBluetoothUuid(QBluetoothUuid::ServiceClassUuid::HeartRate), this);

    if (m_service) {
        connect(m_service, &QLowEnergyService::stateChanged, this, &DeviceHandler::serviceStateChanged);
        connect(m_service, &QLowEnergyService::characteristicChanged, this, &DeviceHandler::updateHeartRateValue);
        connect(m_service, &QLowEnergyService::descriptorWritten, this, &DeviceHandler::confirmedDescriptorWrite);
        m_service->discoverDetails();
    } else {
        setError("Heart Rate Service not found.");
        setIcon(IconError);
    }

void DeviceHandler::serviceStateChanged(QLowEnergyService::ServiceState s)
{
    switch (s) {
    case QLowEnergyService::RemoteServiceDiscovering:
        setInfo(tr("Discovering services..."));
        setIcon(IconProgress);
        break;
    case QLowEnergyService::RemoteServiceDiscovered:
    {
        setInfo(tr("Service discovered."));
        setIcon(IconBluetooth);

        const QLowEnergyCharacteristic hrChar =
                m_service->characteristic(QBluetoothUuid(QBluetoothUuid::CharacteristicType::HeartRateMeasurement));
        if (!hrChar.isValid()) {
            setError("HR Data not found.");
            setIcon(IconError);
            break;
        }

        m_notificationDesc = hrChar.descriptor(QBluetoothUuid::DescriptorType::ClientCharacteristicConfiguration);
        if (m_notificationDesc.isValid())
            m_service->writeDescriptor(m_notificationDesc, QByteArray::fromHex("0100"));

        break;
    }
    default:
        //nothing for now
        break;
    }

    emit aliveChanged();
}

void DeviceHandler::updateHeartRateValue(const QLowEnergyCharacteristic &c, const QByteArray &value)
{
    // ignore any other characteristic change -> shouldn't really happen though
    if (c.uuid() != QBluetoothUuid(QBluetoothUuid::CharacteristicType::HeartRateMeasurement))
        return;

    auto data = reinterpret_cast<const quint8 *>(value.constData());
    quint8 flags = *data;

    //Heart Rate
    int hrvalue = 0;
    if (flags & 0x1) // HR 16 bit? otherwise 8 bit
        hrvalue = static_cast<int>(qFromLittleEndian<quint16>(data[1]));
    else
        hrvalue = static_cast<int>(data[1]);

    addMeasurement(hrvalue);
}

QLowEnergyAdvertisingData advertisingData;
advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
advertisingData.setIncludePowerLevel(true);
advertisingData.setLocalName("HeartRateServer");
advertisingData.setServices(QList<QBluetoothUuid>() << QBluetoothUuid::ServiceClassUuid::HeartRate);
bool errorOccurred = false;
const std::unique_ptr<QLowEnergyController> leController(QLowEnergyController::createPeripheral());
auto errorHandler = [&leController, &errorOccurred](QLowEnergyController::Error errorCode) {
        qWarning().noquote().nospace() << errorCode << " occurred: "
            << leController->errorString();
        if (errorCode != QLowEnergyController::RemoteHostClosedError) {
            qWarning("Heartrate-server quitting due to the error.");
            errorOccurred = true;
            QCoreApplication::quit();
        }
};
QObject::connect(leController.get(), &QLowEnergyController::errorOccurred, errorHandler);

std::unique_ptr<QLowEnergyService> service(leController->addService(serviceData));
leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,
                               advertisingData);
if (errorOccurred)
    return -1;

QLowEnergyCharacteristicData charData;
charData.setUuid(QBluetoothUuid::CharacteristicType::HeartRateMeasurement);
charData.setValue(QByteArray(2, 0));
charData.setProperties(QLowEnergyCharacteristic::Notify);
const QLowEnergyDescriptorData clientConfig(QBluetoothUuid::DescriptorType::ClientCharacteristicConfiguration,
                                            QByteArray(2, 0));
charData.addDescriptor(clientConfig);

QLowEnergyServiceData serviceData;
serviceData.setType(QLowEnergyServiceData::ServiceTypePrimary);
serviceData.setUuid(QBluetoothUuid::ServiceClassUuid::HeartRate);
serviceData.addCharacteristic(charData);

QTimer heartbeatTimer;
quint8 currentHeartRate = 60;
enum ValueChange { ValueUp, ValueDown } valueChange = ValueUp;
const auto heartbeatProvider = [&service, &currentHeartRate, &valueChange]() {
    QByteArray value;
    value.append(char(0)); // Flags that specify the format of the value.
    value.append(char(currentHeartRate)); // Actual value.
    QLowEnergyCharacteristic characteristic
            = service->characteristic(QBluetoothUuid::CharacteristicType::HeartRateMeasurement);
    Q_ASSERT(characteristic.isValid());
    service->writeCharacteristic(characteristic, value); // Potentially causes notification.
    if (currentHeartRate == 60)
        valueChange = ValueUp;
    else if (currentHeartRate == 100)
        valueChange = ValueDown;
    if (valueChange == ValueUp)
        ++currentHeartRate;
    else
        --currentHeartRate;
};
QObject::connect(&heartbeatTimer, &QTimer::timeout, heartbeatProvider);
heartbeatTimer.start(1000);