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Qt笔记
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Qt笔记---使用Qt开发BLE(Bluetooth low energy)程序
在Qt项目中开发BLE通信程序，即低功耗蓝牙设备通信，关于蓝牙设备的通信分为普通蓝牙设备和低功耗蓝牙设备，此文只介绍低功耗蓝牙设备的连接通信方式。 开发环境：系统：win10 Qt：5.15.2 MSVC：2019
注：使用此版本之前使用过其他低版本的Qt和MSVC，会出现搜索不到设备以及一些各种其他的问题，最后使用此版本功能正常。 使用方法 1.在工程的pro文件中添加对蓝牙模块的支持QT += bluetooth
扫描BLE设备需要用到QBluetoothDeviceDiscoveryAgent类，通过start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod)函数发现低功耗设备。将扫描出的设备信息放到链表中。 BluetoothDeviceService.h #include #include #include class BluetoothDeviceService : public QObject { Q_OBJECT public: explicit BluetoothDeviceService(QObject *parent = nullptr); private slots: // 发现的BLE设备信息 void onDeviceDiscovered(const QBluetoothDeviceInfo &deviceInfo); // 搜索设备时出错 void onDeviceDiscoverError(QBluetoothDeviceDiscoveryAgent::Error error); private: // 设备发现对象 QBluetoothDeviceDiscoveryAgent *m_deviceDiscoveryAgent; // 保存发现的BLE设备信息 QList *m_deviceInfoList; // 保存服务的uuid QList m_uuidList; // 蓝牙控制器 QLowEnergyController *m_control; // 控制器连接计时器 QTimer m_controlTimer; // 蓝牙服务 QLowEnergyService *m_service; QList m_charList; QLowEnergyCharacteristic m_character; QLowEnergyDescriptor m_descriptor; };BluetoothDeviceService.cpp #include "BluetoothDeviceService.h" BluetoothDeviceService::BluetoothDeviceService(QObject *parent) : QObject{parent}, m_control(NULL), m_service(NULL) { m_deviceDiscoveryAgent = new QBluetoothDeviceDiscoveryAgent(this); m_deviceInfoList = new QList(); // 设置搜索设备超时 20s m_deviceDiscoveryAgent->setLowEnergyDiscoveryTimeout(20000); connect(m_deviceDiscoveryAgent, &QBluetoothDeviceDiscoveryAgent::deviceDiscovered, this, &BluetoothDeviceService::onDeviceDiscovered); connect(m_deviceDiscoveryAgent, SIGNAL(error(QBluetoothDeviceDiscoveryAgent::Error)), this, SLOT(onDeviceDiscoverError(QBluetoothDeviceDiscoveryAgent::Error))); connect(&m_controlTimer, &QTimer::timeout, [this](){ emit sigDebugLog(QString::fromLocal8Bit("蓝牙控制器连接设备超时！")); disconnectDevice(); }); } void BluetoothDeviceService::onDeviceDiscovered(const QBluetoothDeviceInfo &deviceInfo) { if (deviceInfo.coreConfigurations() & QBluetoothDeviceInfo::LowEnergyCoreConfiguration) { // 添加对发现的BLE设备名称过滤，只保留需要名称的设备 if (deviceInfo.name().contains(QString::fromLocal8Bit("过滤名称"))) { emit sigDebugLog(QString::fromLocal8Bit("发现一个蓝牙设备:%1--地址:%2").arg(deviceInfo.name()).arg(deviceInfo.address().toString())); // 保存设备信息 m_deviceInfoList->append(deviceInfo); emit sigDiscovered(deviceInfo); } } } void BluetoothDeviceService::disconnectDevice() { if(m_controlTimer.isActive()) m_controlTimer.stop(); if(m_control) { m_control->disconnectFromDevice(); delete m_control; m_control = NULL; } if(m_service){ delete m_service; m_service = NULL; } }
通过双击界面上的设备列表，将设备列表的索引传到设备信息链表中，创建对应的蓝牙控制器。 void BluetoothDeviceService::connectDevice(int iRow) { // 只保存当前选中设备的服务uuid，删除其他 m_uuidList.clear(); //创建蓝牙控制器对象 m_control = QLowEnergyController::createCentral(m_deviceInfoList->at(iRow)); if (m_control == NULL) { emit sigDebugLog(QString::fromLocal8Bit("创建蓝牙控制器失败！")); } else { emit sigDebugLog(QString::fromLocal8Bit("创建蓝牙控制器成功！")); } connect(m_control, SIGNAL(connected()), this, SLOT(onControlConnected())); connect(m_control, SIGNAL(disconnected()), this, SLOT(onControlDisconnected())); connect(m_control, SIGNAL(serviceDiscovered(QBluetoothUuid)), this, SLOT(onServiceDiscovered(QBluetoothUuid))); connect(m_control, SIGNAL(discoveryFinished()), this, SLOT(onControlDiscoveryFinished())); connect(m_control, SIGNAL(error(QLowEnergyController::Error)), this, SLOT(onControlError(QLowEnergyController::Error))); // 开始计时控制器的连接超时 m_controlTimer.start(10000); // 发起连接 m_control->connectToDevice(); } 4.发现蓝牙服务发现蓝牙服务要在蓝牙控制器连接成功后进行，在搜索服务之前做了1秒的延时处理。 void BluetoothDeviceService::onControlConnected() { // 停止连接计时 m_controlTimer.stop(); emit sigDebugLog(QString::fromLocal8Bit("蓝牙控制器连接成功，开始搜索蓝牙服务！")); m_uuidList.clear(); QThread::msleep(1000); //搜索服务 m_control->discoverServices(); } 5.发现蓝牙服务后保存其服务uuid void BluetoothDeviceService::onServiceDiscovered(const QBluetoothUuid &newService) { emit sigDebugLog(QString::fromLocal8Bit("发现一个蓝牙服务-uuid:").append(newService.toString())); m_uuidList.append(newService); } 6.创建蓝牙服务在发现蓝牙服务结束后，延时创建蓝牙服务。蓝牙服务创建成功以后开始获取服务详情，也加了延时。 void BluetoothDeviceService::onControlDiscoveryFinished() { emit sigDebugLog(QString::fromLocal8Bit("蓝牙服务搜索结束！")); QThread::msleep(1000); createService(0); } void BluetoothDeviceService::createService(int iRow) { // 创建服务 m_service = m_control->createServiceObject(m_uuidList.at(iRow),this); if (m_service == NULL) { emit sigDebugLog(QString::fromLocal8Bit("创建蓝牙服务失败！")); } else { emit sigDebugLog(QString::fromLocal8Bit("创建蓝牙服务成功！")); //监听服务状态变化 connect(m_service,SIGNAL(stateChanged(QLowEnergyService::ServiceState)) ,this,SLOT(onServiceStateChanged(QLowEnergyService::ServiceState))); //服务的characteristic变化，有数据传来 connect(m_service,SIGNAL(characteristicChanged(QLowEnergyCharacteristic,QByteArray)) ,this,SLOT(onServiceCharacteristicChanged(QLowEnergyCharacteristic,QByteArray))); //描述符成功被写 connect(m_service,SIGNAL(descriptorWritten(QLowEnergyDescriptor,QByteArray)) ,this,SLOT(onDescriptorWritten(QLowEnergyDescriptor,QByteArray))); // connect(m_service, SIGNAL(error(QLowEnergyService::ServiceError)), this, SLOT(onServiceError(QLowEnergyService::ServiceError))); QThread::msleep(1000); //服务详情发现函数 m_service->discoverDetails(); } } 7.在发现蓝牙服务后，对每个特征进行处理，包括配置描述符和存储具有写入权限的特征。 void BluetoothDeviceService::onServiceStateChanged(QLowEnergyService::ServiceState newState) { Q_UNUSED(newState); QLowEnergyCharacteristic bleCharacteristic; //发现服务 if(m_service->state() == QLowEnergyService::ServiceDiscovered){ m_charList = m_service->characteristics(); for(int i=0; iwriteDescriptor(m_descriptor,QByteArray::fromHex("0100")); } if (bleCharacteristic.properties() & QLowEnergyCharacteristic::WriteNoResponse || bleCharacteristic.properties() & QLowEnergyCharacteristic::Write) { m_character = bleCharacteristic; } } } } } 8.接收数据 void BluetoothDeviceService::onServiceCharacteristicChanged(QLowEnergyCharacteristic characteristic, QByteArray newValue) { Q_UNUSED(characteristic); int len = newValue.size(); if(len > 0){ emit sigDebugLog(QString("rec:").append(newValue.toHex())); } } 9.发送数据 void BluetoothDeviceService::sendCmd(const QByteArray &data) { if (m_service) { m_service->writeCharacteristic(m_character, data, QLowEnergyService::WriteWithResponse); } } 10.总结关于一些延时的处理，发现运行时会出现崩溃的问题，因此加入了一些延时。最后附上一张完整执行过程。
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