带有 Raspberry Pi 3 和 BlueZ 5.39 的 Qt 5.7 QBluetooth LE GATT 服务器示例

Question

我正在尝试在集成了 Broadcom 蓝牙芯片的 Raspberry Pi 3 上运行 Qt 5.7 beta QBluetooth GATT 服务器示例 (https://doc-snapshots.qt.io/qt5-dev/qtbluetooth-heartrate-server-example.html)。

蓝牙在我的 Pi 3 上运行良好，并且 hci0 接口(interface)在重新启动后“正在运行”:

root@raspberrypi:~/bluez-5.39# hciconfig -a
hci0:   Type: BR/EDR  Bus: UART
    BD Address: B8:27:EB:6F:71:A7  ACL MTU: 1021:8  SCO MTU: 64:1
    UP RUNNING PSCAN 
    RX bytes:2316 acl:0 sco:0 events:99 errors:0
    TX bytes:2676 acl:0 sco:0 commands:99 errors:0
    Features: 0xbf 0xfe 0xcf 0xfe 0xdb 0xff 0x7b 0x87
    Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
    Link policy: RSWITCH SNIFF 
    Link mode: SLAVE ACCEPT 
    Name: 'raspberrypi'
    Class: 0x000000
    Service Classes: Unspecified
    Device Class: Miscellaneous, 
    HCI Version: 4.1 (0x7)  Revision: 0xb6
    LMP Version: 4.1 (0x7)  Subversion: 0x2209
    Manufacturer: Broadcom Corporation (15)

我成功下载、编译和安装了最新的 BlueZ 5.39，它包含一个完整的 DBus 接口(interface)，用于 BlueZ BLE 功能:

http://www.kernel.org/pub/linux/bluetooth/bluez-5.39.tar.xz

我已经确认路径中选择的版本是正确的版本:

[bluetooth]# version
Version 5.39

我使用 buildroot 交叉编译 Qt 5.7 并将它的库部署到 Pi。我可以在我的主机上成功构建并在 Pi 上运行生成的可执行文件。

Qt 的 GATT 示例非常简单，我只添加了 2 行“qDebug”来查看一些控制台输出。为了完整起见，我将其粘贴在这里:

#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/qscopedpointer.h>
#include <QtCore/qtimer.h>

#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    QLowEnergyAdvertisingData advertisingData;
    advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
    advertisingData.setIncludePowerLevel(true);
    advertisingData.setLocalName("BlueZ 5 GATT Server");
    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));
    qDebug() << "Beginning to advertise...";
    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());
        qDebug() << "Changing characteristic to: " << value;
        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();
}

轮廓:

TEMPLATE = app
TARGET = qt-gatt

QT += bluetooth
CONFIG += c++11

SOURCES += main.cpp

## Install directory
target.path = /home/pi
INSTALLS += target

当我在全新启动后以 root 身份在 Pi 上运行应用程序时 - 它运行并输出我的打印消息:

root@raspberrypi:/home/pi# ./qt-gatt 
Beginning to advertise...
Changing characteristic to:  "\x00<"
Changing characteristic to:  "\x00="
Changing characteristic to:  "\x00>"
Changing characteristic to:  "\x00?"

没有显示任何错误或警告 - 但我的任何设备都看不到它。我的 iPhone 和 Mac 可以看到其他 BLE 设备，但看不到 Pi。代码将 Pi 设置为“可发现”。

我怎样才能使这项工作/我做错了什么？

Answer 1

您可能已经知道这一点，但我认为 bluetoothd 仍然需要使用 -E 来启动实验模式。

您也可以在 main() 的顶部添加以下行查看来自 QBluetooth 的日志记录.让我们知道您看到或发现了什么。我正在尝试做一件非常相似的事情，现在很幸运……而且日志记录似乎在我的平台上不起作用。

QLoggingCategory::setFilterRules(QStringLiteral("qt.bluetooth* = true"));