Bluetooth LE Devices

Bluetooth Low Energy (Bluetooth LE) is a wireless communication technology designed for short-range, low-power data transfer. It enables reliable connections while using minimal energy. Here are some Bluetooth LE devices, D600, S550 and S370.

Discovering Bluetooth LE Devices

The Device Manager drives the Bluetooth LE experience and communication with the Socket Mobile Bluetooth LE based devices. To interact with the Device Manager register a handler to the Capture Helper event: DeviceManagerArrival.

Here is an example on how you can register this handle:

public MainPage()
{
    InitializeComponent();

    // initialize CaptureHelper
    capture = new CaptureHelper();

    // register for the Capture Helper events
    capture.DeviceManagerArrival += Capture_DeviceManagerArrival;
}

The Device Manager has a property called “favorite” to configure and identify the Bluetooth LE devices that needs to be discovered. Favorite can be a single value or a semi-colon separated list. It can be a combination of any of the following values:

Favorites

Value	Description
*	Discover and connect to the first available Bluetooth LE devices
Unique Device Identifier	Identifier for a specific Bluetooth LE devices
“”	Empty for when the app is not interested in Bluetooth LE devices

The “favorite” property can be set as follow:

private void Capture_DeviceManagerArrival(object sender, CaptureHelper.DeviceArgs e)
{
    e.CaptureDevice.SetFavoritesAsync("*");
}

Each value in the favorite list represents a Bluetooth LE device. To start the auto discovery for Bluetooth LE devices devices set favorite to a valid value. Auto discovery will stop if the number of devices represented in the favorite are connected.

If favorite is set to empty, auto discovery will not be triggered. Please note that setting favorite to empty, will not disconnect an already connected device. However, if the device gets disconnected, then auto discovery will not start until favorite is set to a valid value.

Once a Bluetooth LE device is discovered, a connection is established. After this it can be used to read NFC cards or barcodes. To interact with the device, register a handler to the Capture Helper event: DeviceArrival.:

public MainPage()
{
    InitializeComponent();

    // initialize CaptureHelper
    capture = new CaptureHelper();

    // register for the Capture Helper events
    capture.DeviceArrival += Capture_DeviceArrival;

}

Note

You can programmatically disconnect a Bluetooth LE (or Bluetooth Classic) device by using the following SetDisconnectAsync() method on a received device via the Capture Helper’s DeviceArrival event.:

CaptureHelperDevice device;

// Device arrival handler
private void Capture_DeviceArrival(object sender, CaptureHelper.DeviceArgs e)
{
    device = e.CaptureDevice;
}

private async void DisconnectDevice()
{
    await device.SetDisconnectAsync();
}

Manual Discovery

This feature lists all the Bluetooth LE devices available in the vicinity by running the discovery process for a specified time. Using the Device Manager, to trigger a manual discovery, use the StartDeviceDiscoveryAsync(duration) along with the duration in milliseconds. Manual discovery runs for the specified duration and sends a DeviceDiscovered event each time a Socket Mobile Bluetooth LE device is discovered. Discovery stops automatically once the duration in milliseconds has been reached and sends a DiscoveryEnded event.

The Device Manager’s favorites should be empty before triggering a manual discovery, else it will return a ESKT_FAVORITENOTEMPTY error because the auto discovery is running.

You can start the manual discovery using a button as follow.:

CaptureHelperDevice deviceManager;

private void Capture_DeviceManagerArrival(object sender, CaptureHelper.DeviceArgs e)
{
    deviceManager = e.CaptureDevice;
}

private async void Button_TriggerScan(object sender, EventArgs e)
{
    await deviceManager.StartDeviceDiscoveryAsync(5000);
}

To receive the list of the discovered devices, register a handler to the Capture Helper event: DeviceDiscovered.:

public MainPage()
{
    InitializeComponent();

    // initialize CaptureHelper
    capture = new CaptureHelper();

    // register for the Capture Helper events
    capture.DeviceDiscovered += Capture_DeviceDiscovered;

}

private void Capture_DeviceDiscovered(object sender, CaptureHelper.DeviceDiscoveredArgs e)
{
    string deviceDiscovered = e.Device;
}

The handler will receive a string each time a Socket Mobile Bluetooth LE device is discovered. This deviceDiscovered string will have a format similar to the one shown below.:

{
    \"name\":\"S550\",
    \"identifierUUID\":\"aca92313-bc43-0000-0000-000000000000\",
    \"serviceUUID\":\"7a4375c9-f7c7-4e22-9afd-16v68fc588ca\"
}

Using the identifierUUID, you can connect to a specific Bluetooth LE device. See Connect to Specific Bluetooth LE Device.

To be notified when the discovery ends, register a handler to the Capture Helper DiscoveryEnded event.:

public MainPage()
{
    InitializeComponent();

    // initialize CaptureHelper
    capture = new CaptureHelper();

    // register for the Capture Helper events
    capture.DiscoveryEnded += Capture_DiscoveryEnded;
}

private void Capture_DiscoveryEnded(object sender, CaptureHelper.DiscoveryEndedArgs e)
{
    Debug.WriteLine("DiscoveryEnded");
}

Connect to Specific Bluetooth LE Device

The Unique Device Identifier can be acquired via a Manual Discovery or directly from a connected device. It is used to connect to a specific Bluetooth LE device.

From Manual Discovery, you can extract the identifierUUID from the string received via the Capture Helper DeviceDiscovered event.:

private void Capture_DeviceDiscovered(object sender, CaptureHelper.DeviceDiscoveredArgs e)
{
    string deviceDiscovered = e.Device;

    // extract identifierUUID
    deviceDiscovered = jsonString.Replace("\\\"", "\"");
    var jsonDict = JsonConvert.DeserializeObject<Dictionary<string, string>>(deviceDiscovered);
    string deviceIdentifier = jsonDict["identifierUUID"];
}

Alternatively, you can retrieve the Unique Device Identifier from a connected Bluetooth LE device via the Capture Helper DeviceArrival event.:

private void Capture_DeviceArrival(object sender, CaptureHelper.DeviceDiscoveredArgs e)
{
    CaptureHelperDevice device = e.CaptureDevice;

    // get identifierUUID
    device.GetDeviceIdentifierAsync().ContinueWith(result =>
    {
        string deviceIdentifier = result.Result.Identifier;
    });
}

To establish a connection, set the Device Manager’s favorite as shown below.:

{
    // deviceManager: device received via the Capture helper's DeviceManagerArrival event
    // deviceIdentifier: Unique device identifier
    deviceManager.SetFavoritesAsync(deviceIdentifier);
}

Reading Data

Once the connection is established successfully, data read from the device (NFC card. Smartphone wallet card, or Barcode) can be received by registering a handler to the Capture Helper event: DecodedData.:

public MainPage()
{
    InitializeComponent();

    // initialize CaptureHelper
    capture = new CaptureHelper();

    // register for the Capture Helper events
    capture.DecodedData += Capture_DecodedData;

}