Windows IoT Project: Wifi Connection Status Indicator

In this Windows 10 IoT project for Raspberry Pi, we are going to create a Wifi Connection status indicator. The whole idea of this project is to have an LED light that indicates whether your Windows IoT device has connected to a specified Wifi network or not. If the LED is off it means that your WiFi network is not available. Flashing LED means the WiFi network is available and a connection attempt is being made. If the LED light is steady ON it means connection has been made.

We will create the app to check the WiFi connection status in VB.NET. This app will will run as background service in your Raspberry Pi running Windows 10 IoT.

Hardware requirements

• Raspberry Pi 2 or 3 with Windows 10 IoT Core installed
• LED light
• Resistor 220Ω (or higher upto 1KΩ)
• Breadboard
• Connector wires

Wiring the LED

Connect the negative end of LED to GPIO 5 and positive end to 3.3V pin using the resistor. Check this link for detailed instructions. Connecting LED to Raspberry Pi GPIO pins

Building the app

Create a new Visual Studio Project in Visual Basic using the template Background Application (IoT). For your app to access the Wi-Fi adapter, the wifiControl DeviceCapability must be added to the AppX manifest. To do this add the following line in manifest file Package.appx.

<DeviceCapability Name="wifiControl" />

All your app code is written inside the StartupTask class. The following are the main functions.

• initGPIO - Initialize the GPIO Controller.
  The initGPIO function gets the GPIO controller, opens the GPIO pin 5 and writes a low value to the pin and also sets the Pin for output. This function is executed only once at the beginnig of the program.
• wifiInit - Access the WiFi adapter.
  The wifiInit function requests access to the WiFi adapters in your device, gets the first adapter (in case you have multiple wifi adapater). It will then scan the adapter for available Wifi networks. This function is executed only once at the beginnig of the program
• wifiConnect - Connect to the WiFi network.WifiConnect function scans through list of available networks to check if the wifi network that you want to connect exists and tries to make a connection to that network using the specified password credentials. This function is executed whenever the wifi connection status changes to not connected (wifiConnected = False)
• SetWifiConnectionStatus - Set Wifi connection status. This function is executed periodically to check if the WiFi connection has been established. It will set the variable wifiConnected to either True or False
• WiFiPollTimer_tick - Periodic Timer to check the connection status and make the LED on, off or blink. The code inside this function is executed every 2 seconds.

The program also uses the following constants

• MYWIFI A string constant to specify the name of your WiFi network.
• PASSWORD Password for your Wifi network.
• INTERVAL The interval in seconds between connection status checks. You may change this value according to your requirements.
• LED_PIN The GPIO pin to which the LED is connected.

Source Code

Here is the full source code of StartupTask class.

Imports Windows.ApplicationModel.Background
Imports Windows.Devices.Gpio
Imports Windows.System.Threading
Imports Windows.Devices.WiFi
Imports Windows.Networking.Connectivity
Imports Windows.Security.Credentials

Public NotInheritable Class StartupTask
    Implements IBackgroundTask

    Const LED_PIN As Short = 5 'GPIO Pin(5) = Physical Pin(29) = WiringPi Pin (21)
    Const INTERVAL As Short = 2    'Interval in seconds
    Const MYWIFI As String = "MyWiFiNetwork-SSID" ' Your wifi ssid
    Const MYPASSWORD As String = "password" 'Your wifi password
    
    Private gpio
    Private pin As GpioPin
    Private pinValue As GpioPinValue
    Private BlinkTimer As ThreadPoolTimer
    Private cancelled As Boolean = False
    Private deferral As BackgroundTaskDeferral = Nothing
    Private FirstAdapter As WiFiAdapter
    Private wifiNetworks As WiFiNetworkReport
    Private mywifinetwork As WiFiAvailableNetwork

    Private networkfound As Boolean = False
    Private connectedProfile As ConnectionProfile

    Private wifiConnected As Boolean = False

    Public Sub Run(taskInstance As IBackgroundTaskInstance) Implements IBackgroundTask.Run
        'Handler for cancelled background task
        AddHandler taskInstance.Canceled, New BackgroundTaskCanceledEventHandler(AddressOf onCanceled)

         'Continue background task execution
        deferral = taskInstance.GetDeferral()

         'Initialize GPIO
        initGPIO()

         'Initialize Wifi
        wifiInit()

         'Create a periodic timer
        BlinkTimer = ThreadPoolTimer.CreatePeriodicTimer(New TimerElapsedHandler(AddressOf WiFiPollTimer_tick), TimeSpan.FromSeconds(INTERVAL))

    End Sub

    Private Async Sub wifiInit()
        Dim wifiaccess As WiFiAccessStatus

         'Request access to the wifi adapters
        wifiaccess = Await WiFiAdapter.RequestAccessAsync()

        If wifiaccess = WiFiAccessStatus.Allowed Then
         'Find all WiFi adapters
            Dim result = Await WiFiAdapter.FindAllAdaptersAsync()
            If (result.Count >= 1) Then
                FirstAdapter = result(0)
                 'Scan for available Wifi networks
                Await FirstAdapter.ScanAsync
                wifiNetworks = FirstAdapter.NetworkReport
            End If
        End If

    End Sub

    Private Async Sub wifiConnect(wifinetwork As WiFiAvailableNetwork)
        Dim result As WiFiConnectionResult
        Dim credential As New PasswordCredential
        credential.Password = MYPASSWORD

         'FirstAdapter.Disconnect()
        result = Await FirstAdapter.ConnectAsync(wifinetwork, WiFiReconnectionKind.Automatic, credential)
        If result.ConnectionStatus = WiFiConnectionStatus.Success Then
            Debug.WriteLine("Connected Now... ")
            wifiConnected = True
        End If

    End Sub

    Private Async Sub SetWifiConnectionStatus(ssid As String)
        connectedProfile = Await FirstAdapter.NetworkAdapter.GetConnectedProfileAsync()
        If Not (connectedProfile Is Nothing) AndAlso connectedProfile.GetNetworkNames(0) = ssid Then
            Debug.WriteLine("Connected to Wifi")
            wifiConnected = True
        Else
            wifiConnected = False
            Debug.WriteLine("Disconnected..")
        End If

    End Sub

    Private Sub onCanceled(sender As IBackgroundTaskInstance, reason As BackgroundTaskCancellationReason)
        cancelled = True
    End Sub

    Sub WiFiPollTimer_tick(state As Object)

        If Not cancelled AndAlso Not (FirstAdapter Is Nothing) Then
            If wifiNetworks Is Nothing Then
                 'If there are no available networks turn LED OFF
                pinValue = GpioPinValue.High
                pin.Write(pinValue)
                networkfound = False
            Else
                If networkfound = False Then
                     'If there are available networks in range
                    For Each AvailableNetwork In wifiNetworks.AvailableNetworks
                        'if wifi network is available in range
                        If AvailableNetwork.Ssid = MYWIFI Then
                            networkfound = True
                            mywifinetwork = AvailableNetwork
                        End If
                    Next

                Else

		  SetWifiConnectionStatus(mywifinetwork.Ssid)
		  If wifiConnected = False Then
		      wifiConnect(mywifinetwork)
		      If (pinValue = GpioPinValue.High) Then
		   	  pinValue = GpioPinValue.Low
		      Else
			  pinValue = GpioPinValue.High
		      End If
		      pin.Write(pinValue)

		  Else
		     Debug.WriteLine(mywifinetwork.Ssid)
		     If pinValue <> GpioPinValue.Low Then
			 pinValue = GpioPinValue.Low
			 pin.Write(pinValue)
		     End If
		  End If
            End If
        End If

        Else
             'if the task is cancelled
             'Stop the timer and finish execution
            BlinkTimer.Cancel()
            deferral.Complete()
        End If
    End Sub

    Private Sub initGPIO()
         'Get the default GPIO controller
        gpio = GpioController.GetDefault()

        If Not gpio Is Nothing Then
             'Open a connection to the GPIO Pin
            pin = gpio.openpin(LED_PIN)
            pinValue = GpioPinValue.High

             'Write Pin value low to turn OFF LED
            pin.Write(pinValue)

             'Set the pin for output
            pin.SetDriveMode(GpioPinDriveMode.Output)
        End If

    End Sub

End Class

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