Android Question B4A Library [B4X] BLE 2 - Bluetooth Low Energy : Send / Receive Data

Dim s As String = "abc"
Dim b() As Byte = s.GetBytes("utf8") 'or ASCII

#Region  Project Attributes 
    #ApplicationLabel: BleTest
    #VersionCode: 1
    #VersionName: 
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes 
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
    Private xui As XUI
    Dim rp As RuntimePermissions
    Private ble As BleManager2
    Private rp As RuntimePermissions

    Private SERVICE_UUID As String = "6e400001-b5a3-f393-e0a9-e50e24dcca9e"
    Private WRITE_UUID As String = "6e400002-b5a3-f393-e0a9-e50e24dcca9e"
    Private NOTIFY_UUID As String = "6e400003-b5a3-f393-e0a9-e50e24dcca9e"
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Private btnSend As Button
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    If FirstTime Then
        ble.Initialize("ble")
    End If
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub Button1_Click
    'xui.MsgboxAsync("Hello world!", "B4X")
    StartScan
End Sub

Sub btnSend_Click
    ble.WriteData(SERVICE_UUID, WRITE_UUID, "A".GetBytes("UTF8"))
    Log("TX: A")
End Sub

Sub StartScan
    rp.CheckAndRequest(rp.PERMISSION_ACCESS_FINE_LOCATION)
    Wait For Activity_PermissionResult (Permission As String, Result As Boolean)

    If Result Then
        ble.Scan(Array As String())
    End If
End Sub

Sub ble_DeviceFound (Name As String, Id As String, AdvertisingData As Map, RSSI As Double)
    Log("Trovato: " & Name)

    If Name = "Remote" Then
        ble.StopScan
        ble.Connect(Id)
    End If
End Sub

Sub ble_ServicesDiscovered (Services As List)
    Log("Services OK")

    Sleep(300)

    ble.SetNotify(SERVICE_UUID, NOTIFY_UUID, True)
    Log("Notify attivato")
End Sub

Sub ble_Connected (Services As List)
    Log("Connesso!")
    CallSubDelayed(Me, "EnableNotify")
End Sub

Sub ble_CharacteristicChanged (ServiceId As String, CharacteristicId As String, Value() As Byte)
    Log("RAW RX: " & BytesToString(Value, 0, Value.Length, "UTF8"))
End Sub

Sub EnableNotify
    Log("Attivo notify...")
    Sleep(500)

    'ble.SetIndication(SERVICE_UUID, NOTIFY_UUID, True)
    ble.SetNotify(SERVICE_UUID, NOTIFY_UUID, True)
End Sub

#Region  Project Attributes 
    #ApplicationLabel: BleTest
    #VersionCode: 1
    #VersionName: 
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: unspecified
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes 
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
    Private xui As XUI
    Dim rp As RuntimePermissions
    Private ble As BleManager2
    Private rp As RuntimePermissions
    Private DeviceName="Remote" As String
    Private SERVICE_UUID As String = "6e400001-b5a3-f393-e0a9-e50e24dcca9e"
    Private WRITE_UUID   As String = "6e400002-b5a3-f393-e0a9-e50e24dcca9e"
    Private NOTIFY_UUID  As String = "6e400003-b5a3-f393-e0a9-e50e24dcca9e"
    
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Private btnSend As Button
    Private edtCommand As EditText
    Private lblAnswer As Label
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    If FirstTime Then
        ble.Initialize("ble")
    End If
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub btnScan_Click
    Wait For (StartScan) Complete (Result As Boolean)
    btnSend.Enabled=Result
End Sub

Sub btnSend_Click
    Log("Sent : " & edtCommand.Text)
    ble.WriteData(SERVICE_UUID, WRITE_UUID,edtCommand.Text.GetBytes("UTF8"))
    lblAnswer.Text=""
End Sub

Sub StartScan As ResumableSub
    rp.CheckAndRequest(rp.PERMISSION_ACCESS_FINE_LOCATION)
    Wait For Activity_PermissionResult (Permission As String, Result As Boolean)

    If Result Then
        ble.Scan(Array As String())
    End If
    Return Result
End Sub

Sub ble_DeviceFound (Name As String, Id As String, AdvertisingData As Map, RSSI As Double)
    Log("Found: " & Name)

    If Name = DeviceName Then
        ble.StopScan
        ble.Connect(Id)
    End If
End Sub

Sub ble_ServicesDiscovered (Services As List)
    Log("Services OK")

End Sub

Sub ble_Connected (Services As List)
    Log("Connected!")
    Sleep(1000)
    ble.SetNotify(SERVICE_UUID, NOTIFY_UUID, True)
    Log("Notify activated")
End Sub

Sub ble_DataAvailable (sid As String, Characteristics As Map)
    'Log("Data available>" & sid & "<")
    Dim b() As Byte = Characteristics.Get(NOTIFY_UUID)
    Log(b.Length)
    If b<>Null Then
        lblAnswer.Text = BytesToString(b, 0, b.Length, "utf8")
        Log(lblAnswer.Text)
    End If
End Sub

[/code}

the Log:

** Activity (main) Pause, UserClosed = true **
** Activity (main) Create (first time) **
** Activity (main) Resume **
Found: Remote
Found: 
Discovering services.
Connected!
Setting descriptor. Success = true
writing descriptor: true
Notify activated
Sent : A
7
Sent: A
20
A SRX3,102838,3135,9  <<< two caracters are missing, but for longer answers, only 20 chars are got

Sub btnSend_Click
    Log("Sent : " & edtCommand.Text)
    ble.WriteData(SERVICE_UUID, WRITE_UUID,edtCommand.Text.GetBytes("UTF8"))
    lblAnswer.Text=""
    Sleep(10000)
    ble.ReadData(SERVICE_UUID)
End Sub

Sub btnSend_Click
    Log("Sent : " & edtCommand.Text)
    ble.WriteData(SERVICE_UUID, WRITE_UUID,edtCommand.Text.GetBytes("UTF8"))
    lblAnswer.Text=""
    discard=True
End Sub

Sub ble_DataAvailable (sid As String, Characteristics As Map)
    
    Dim b() As Byte = Characteristics.Get(NOTIFY_UUID)
    
    If b<>Null Then
        lblAnswer.Text = BytesToString(b, 0, b.Length, "utf8")
        Log(lblAnswer.Text)
        If discard=True Then 
          ble.ReadData(SERVICE_UUID)
          discard=False
        End If
    End If
    btnSend.Enabled=True
End Sub
[code]