聽取藍芽 LE 廣告

一般聽力

此示例顯示如何偵聽特定廣告。

BluetoothLEAdvertisementWatcher watcher = new BluetoothLEAdvertisementWatcher();

// Use active listening if you want to receive Scan Response packets as well
// this will have a greater power cost.
watcher.ScanningMode = BluetoothLEScanningMode.Active;

// Register a listener, this will be called whenever the watcher sees an advertisement. 
watcher.Received += OnAdvertisementReceived;

watcher.Start();

廣告過濾器：偵聽特定廣告

有時你想聽一個特定的廣告。在這種情況下，監聽包含有效負載的廣告（標識為 0xFFFE）並在廣告中包含字串 Hello World。這可以與建立藍芽 LE 廣告示例配對，以便進行一次 Windows 機器廣告和另一次收聽。

注意：在啟動觀察者之前，請務必設定此廣告過濾器！

var manufacturerData = new BluetoothLEManufacturerData();
manufacturerData.CompanyId = 0xFFFE;

// Make sure that the buffer length can fit within an advertisement payload (~20 bytes). 
// Otherwise you will get an exception.
var writer = new DataWriter();
writer.WriteString("Hello World");
manufacturerData.Data = writer.DetachBuffer();

watcher.AdvertisementFilter.Advertisement.ManufacturerData.Add(manufacturerData);

訊號過濾：聽取近端廣告

有時你只想在裝置廣告進入範圍時觸發你的觀察者。你可以定義自己的範圍，只需注意正常值介於 0 和 -128 之間。

// Set the in-range threshold to -70dBm. This means advertisements with RSSI >= -70dBm 
// will start to be considered "in-range" (callbacks will start in this 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);

回撥

watcher.Received += OnAdvertisementReceived;
watcher.Stopped += OnAdvertisementWatcherStopped;

private async void OnAdvertisementReceived(BluetoothLEAdvertisementWatcher watcher, BluetoothLEAdvertisementReceivedEventArgs eventArgs)
{
    // Do whatever you want with the advertisement

    // The received signal strength indicator (RSSI)
    Int16 rssi = eventArgs.RawSignalStrengthInDBm;
}

private async void OnAdvertisementWatcherStopped(BluetoothLEAdvertisementWatcher watcher, BluetoothLEAdvertisementWatcherStoppedEventArgs eventArgs)
{
    // Watcher was stopped
}

注意：這僅適用於在前臺收聽。