How to use devicepicker for Bluetooth in VB?

Question

Would like to use the DevicePicker class in Visual Basic to find the characteristics of the available Bluetooth interfaces.

Are there clear examples of its usage?

Answer 1

This test with BluetoothSelectDevices works on my OS (Windows 10 22H2), except for the Callback (not really needed...) :

Dim bsdp As BLUETOOTH_SELECT_DEVICE_PARAMS = New BLUETOOTH_SELECT_DEVICE_PARAMS()
bsdp.dwSize = Marshal.SizeOf(GetType(BLUETOOTH_SELECT_DEVICE_PARAMS))
bsdp.hwndParent = Me.Handle
'bsdp.pszInfo = "Information"
bsdp.fShowAuthenticated = True
bsdp.fShowUnknown = True
bsdp.fShowRemembered = True
'bsdp.fAddNewDeviceWizard = True
DeviceCallbackProc = New PfnDeviceCallback(AddressOf DeviceCallback)
bsdp.pfnDeviceCallback = DeviceCallbackProc
Dim bRet = BluetoothSelectDevices(bsdp)
If (bRet) Then
    ' Assuming 1 device is returned
    Dim pDevices As New BLUETOOTH_DEVICE_INFO()
    pDevices = CType(Marshal.PtrToStructure(bsdp.pDevices, pDevices.GetType()), BLUETOOTH_DEVICE_INFO)

    ' sAddress = "8C:D1:7B:BC:30:30"
    Dim sAddress = String.Join(":", BitConverter.GetBytes(pDevices.Address).Take(6).Reverse().[Select](Function(b) b.ToString("X2")))
    Dim sName = pDevices.szName

    ' ex : COD_MAJOR_PHONE and COD_PHONE_MINOR_SMART : see bthdef.h for all codes
    Dim nCODMajor = GET_COD_MAJOR(pDevices.ulClassofDevice)
    Dim nCODMinor = GET_COD_MINOR(pDevices.ulClassofDevice)

    BluetoothSelectDevicesFree(bsdp)
End If

With Declarations :

   <DllImport("Bthprops.cpl", SetLastError:=True, CharSet:=CharSet.Unicode)>
   Public Shared Function BluetoothSelectDevices(ByRef pbtsdp As BLUETOOTH_SELECT_DEVICE_PARAMS) As Boolean
   End Function

   <DllImport("Bthprops.cpl", SetLastError:=True, CharSet:=CharSet.Unicode)>
   Public Shared Function BluetoothSelectDevicesFree(ByRef pbtsdp As BLUETOOTH_SELECT_DEVICE_PARAMS) As Boolean
   End Function

   Public Delegate Function PfnDeviceCallback(pvParam As IntPtr, ByRef pDevice As BLUETOOTH_DEVICE_INFO) As Boolean


   <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)>
   Public Structure BLUETOOTH_SELECT_DEVICE_PARAMS
       Public dwSize As Integer
       Public cNumOfClasses As Integer
       Public prgClassOfDevices As IntPtr
       Public pszInfo As String
       Public hwndParent As IntPtr
       Public fForceAuthentication As Boolean
       Public fShowAuthenticated As Boolean
       Public fShowRemembered As Boolean
       Public fShowUnknown As Boolean
       Public fAddNewDeviceWizard As Boolean
       Public fSkipServicesPage As Boolean
       Public pfnDeviceCallback As PfnDeviceCallback 'PFN_DEVICE_CALLBACK
       Public pvParam As IntPtr
       Public cNumDevices As Integer
       Public pDevices As IntPtr

       Public ReadOnly Property Devices As BLUETOOTH_DEVICE_INFO()
           Get
               If cNumDevices > 0 Then
                   Dim devs = New BLUETOOTH_DEVICE_INFO(cNumDevices - 1) {}

                   For idevice = 0 To cNumDevices - 1
                       devs(idevice) = CType(Marshal.PtrToStructure(New IntPtr(pDevices.ToInt64() + idevice * Marshal.SizeOf(GetType(BLUETOOTH_DEVICE_INFO))), GetType(BLUETOOTH_DEVICE_INFO)), BLUETOOTH_DEVICE_INFO)
                   Next

                   Return devs
               End If
               Return New BLUETOOTH_DEVICE_INFO(-1) {}
           End Get
       End Property

       Public ReadOnly Property Device As BLUETOOTH_DEVICE_INFO
           Get
               If cNumDevices > 0 Then
                   Dim lDevice As BLUETOOTH_DEVICE_INFO = Marshal.PtrToStructure(pDevices, GetType(BLUETOOTH_DEVICE_INFO))
                   Return lDevice
               End If
               Return New BLUETOOTH_DEVICE_INFO()
           End Get
       End Property
   End Structure
   
    <StructLayout(LayoutKind.Sequential)>
    Structure SYSTEMTIME
        Public wYear As UShort
        Public wMonth As UShort
        Public wDayOfWeek As UShort
        Public wDay As UShort
        Public wHour As UShort
        Public wMinute As UShort
        Public wSecond As UShort
        Public wMilliseconds As UShort
    End Structure
    
    <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)>
    Public Structure BLUETOOTH_DEVICE_INFO
        Public dwSize As UInteger
        Public Address As ULong
        Public ulClassofDevice As UInteger
        Public fConnected As Boolean
        Public fRemembered As Boolean
        Public fAuthenticated As Boolean
        Public stLastSeen As SYSTEMTIME
        Public stLastUsed As SYSTEMTIME
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=248)>
        Public szName As String
    End Structure
    
    Public COD_FORMAT_BIT_OFFSET = (0)
    Public COD_MINOR_BIT_OFFSET = (2)
    Public COD_MAJOR_BIT_OFFSET = (8 * 1)
    Public COD_SERVICE_BIT_OFFSET = (8 * 1 + 5)

    Public COD_FORMAT_MASK = (&H3)
    Public COD_MINOR_MASK = (&HFC)
    Public COD_MAJOR_MASK = (&H1F00)
    Public COD_SERVICE_MASK = (&HFFE000)

    Public Function GET_COD_FORMAT(_cod As UInteger)
        Return ((_cod And COD_FORMAT_MASK) >> COD_FORMAT_BIT_OFFSET)
    End Function

    Public Function GET_COD_MINOR(_cod As UInteger)
        Return ((_cod And COD_MINOR_MASK) >> COD_MINOR_BIT_OFFSET)
    End Function

    Public Function GET_COD_MAJOR(_cod As UInteger)
        Return ((_cod And COD_MAJOR_MASK) >> COD_MAJOR_BIT_OFFSET)
    End Function

    Public Function GET_COD_SERVICE(_cod As UInteger)
        Return ((_cod And COD_SERVICE_MASK) >> COD_SERVICE_BIT_OFFSET)
    End Function
    
    Public Shared DeviceCallbackProc As PfnDeviceCallback = Nothing

    Public Shared Function DeviceCallback(pvParam As IntPtr, ByRef pDevice As BLUETOOTH_DEVICE_INFO) As Boolean
        ' Never reached...
        Return True
    End Function

Answer 2

I am trying to programmatically get the recognizable names of the BT interfaces connected to the computer, to match them to the COMxy names so that the program first recognizes (recognizable names) the interfaces it wants to work with AND then try and connect (COMxy) to them in the "transparent UART" mode.

Easy said but not done...

Answer 3

Thank you Castorix31.

I have to check my application's environment. It is a simple "forms-based VB application". I will try your suggestion during the next few days.

Merci

Answer 4

Castorix31,

Thank you indeed. I used your suggestions and when I imported the required components, it worked IMMEDIATELY.