Qt 5.11 | Qt Bluetooth | Bluetooth Low Energy Heart Rate Server Example | main.cpp Example File

Qt 5.11.3 Reference Documentation

# main.cpp Example File

heartrate-server/main.cpp

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      #include <QtBluetooth/qlowenergyadvertisingdata.h>
      #include <QtBluetooth/qlowenergyadvertisingparameters.h>
      #include <QtBluetooth/qlowenergycharacteristic.h>
      #include <QtBluetooth/qlowenergycharacteristicdata.h>
      #include <QtBluetooth/qlowenergydescriptordata.h>
      #include <QtBluetooth/qlowenergycontroller.h>
      #include <QtBluetooth/qlowenergyservice.h>
      #include <QtBluetooth/qlowenergyservicedata.h>
      #include <QtCore/qbytearray.h>
      #include <QtCore/qcoreapplication.h>
      #include <QtCore/qlist.h>
      #include <QtCore/qloggingcategory.h>
      #include <QtCore/qscopedpointer.h>
      #include <QtCore/qtimer.h>

      int main(int argc, char *argv[])
      {
          //QLoggingCategory::setFilterRules(QStringLiteral("qt.bluetooth* = true"));
          QCoreApplication app(argc, argv);

          QLowEnergyAdvertisingData advertisingData;
          advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
          advertisingData.setIncludePowerLevel(true);
          advertisingData.setLocalName("HeartRateServer");
          advertisingData.setServices(QList<QBluetoothUuid>() << QBluetoothUuid::HeartRate);

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

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

          const QScopedPointer<QLowEnergyController> leController(QLowEnergyController::createPeripheral());
          const QScopedPointer<QLowEnergyService> service(leController->addService(serviceData));
          leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,
                                         advertisingData);

          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::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);

          auto reconnect = [&leController, advertisingData]() {
              leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,
                                             advertisingData);
          };
          QObject::connect(leController.data(), &QLowEnergyController::disconnected, reconnect);

          return app.exec();
      }