BLE 广告 UWP 应用程序

Question

我正在尝试制作一个可以扫描 BLE 广告的程序。我一直在查看 Windows-universal-samples，更准确地说是名为 BluetoothAdvertisement 的示例。我想制作一个简单的 UWP 应用程序，它可以扫描 BLE 广告并将它们显示在列表框中。但是我的应用程序根本找不到任何东西，我完全迷路了。

namespace BleDiscAdv2
{

public sealed partial class MainPage : Page
{
    // The Bluetooth LE advertisement watcher class is used to control and customize Bluetooth LE scanning.
    private BluetoothLEAdvertisementWatcher watcher;

    public MainPage()
    {
        this.InitializeComponent();

        // Create and initialize a new watcher instance.
        watcher = new BluetoothLEAdvertisementWatcher();

        //Set the in-range threshold to -70dBm. This means advertisements with RSSI >= -70dBm 
        //will start to be considered "in-range"
        watcher.SignalStrengthFilter.InRangeThresholdInDBm = -70;

        // Set the out-of-range threshold to -75dBm (give some buffer). Used in conjunction with OutOfRangeTimeout
        // to determine when an advertisement is no longer considered "in-range"
        watcher.SignalStrengthFilter.OutOfRangeThresholdInDBm = -75;

        // Set the out-of-range timeout to be 2 seconds. Used in conjunction with OutOfRangeThresholdInDBm
        // to determine when an advertisement is no longer considered "in-range"
        watcher.SignalStrengthFilter.OutOfRangeTimeout = TimeSpan.FromMilliseconds(2000);

    }

    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        // Attach a handler to process the received advertisement. 
        // The watcher cannot be started without a Received handler attached
        watcher.Received += OnAdvertisementReceived;
    }

        private void btStart_Click(object sender, RoutedEventArgs e)
    {
        watcher.Start();
    }

    private async void OnAdvertisementReceived(BluetoothLEAdvertisementWatcher watcher, BluetoothLEAdvertisementReceivedEventArgs eventArgs)
    {
        DateTimeOffset timestamp = eventArgs.Timestamp;
        string localName = eventArgs.Advertisement.LocalName;

        await this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
        {
            lbModtaget.Items.Add("Name of device: " + localName + "\t" + "Time for advertisement: " + timestamp.ToString("hh\:mm\:ss\.fff"));
        });
    }
}
}

谁能告诉我哪里出了问题？我是 BLE 的新手，我已经有一段时间没有编码了。

此致克里斯蒂安

Answer 1

But my application can't find anything at all and I'm totally lost.

请确保您的应用已在 Package.appxmanifest 中启用蓝牙功能。有关详细信息，请参阅 Basic Setup。
请确保运行ning 设备的蓝牙无线电已打开且可用。
有设备在做广告，符合过滤条件。您可以在另一台设备上运行 Bluetooth advertisement official sample 的场景 2 来确保这一点。

通过我这边的测试，你的代码片段可以很好地扫描BLE广告。在您的代码片段中，您没有收听观察者的 Stopped 事件句柄，该事件句柄用于通知应用程序蓝牙 LE 广告扫描已被应用程序或由于错误取消或中止.如果观察者被强制停止，它将不会收到任何广告。

您可以添加Stopped事件句柄来检查是否有BluetoothError。

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    // Attach a handler to process the received advertisement. 
    // The watcher cannot be started without a Received handler attached
    watcher.Received += OnAdvertisementReceived;
    watcher.Stopped += OnAdvertisementWatcherStopped;
}

private async void OnAdvertisementWatcherStopped(BluetoothLEAdvertisementWatcher sender, BluetoothLEAdvertisementWatcherStoppedEventArgs args)
{
    await this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        txtresult.Text = string.Format("Watcher stopped or aborted: {0}", args.Error.ToString());
    });
}

比如RadioNotAvailable可能是运行设备没有开启蓝牙造成的，OtherError可能是蓝牙能力没有开启造成的。如果观察者没有停止并且有广告，您的应用应该可以运行。

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