Android Tutorial Tutorial Android and Raspberry Debian in BT

MarcoRome

Expert
Licensed User
Hi all. In this example we have Raspberry Pi Rasbian and Android App ( communicate via BlueTooth ).

Through Android we give the command to access and turn off/on the LED, and from the Raspberry we read in Android the status of the LED.


The code B4J ( Library JavaObject + jBluetooth + jPi4J + jRandomAccessFile )

B4X:
'Non-UI application (console / server application)
#Region  Project Attributes
    #CommandLineArgs:
    #MergeLibraries: True
#End Region

#AdditionalJar: bluecove-gpl-2.1.1-SNAPSHOT
#AdditionalJar: bluecove-bluez-2.1.1-SNAPSHOT

Sub Process_Globals
    Private bt As Bluetooth
    Private astream As AsyncStreams
    
    Private controller As GpioController
    Private Pin1 As GpioPinDigitalOutput
    
    Dim timer1 As Timer
    
End Sub

Sub AppStart (Args() As String)
    'Per connettersi via BT
    'SetSystemProperty("bluecove.debug", "true")
    bt.Initialize("bt")
    If bt.IsEnabled = False Then
        Log("Bluetooth not available1")
        ExitApplication
    End If
    Log($"My address: ${GetBluetoothAddress}"$)
    bt.Listen

    'Per inizializzare e settare i PIN da controllare
    controller.Initialize
    Pin1.Initialize(1, False) 'GpioPinDigitalOutput --> GPIO18 Vedi schema Libreria jPi4J
    
    timer1.Initialize("timer1",2000)
      
    StartMessageLoop
    
End Sub


'Ok
Sub timer1_Tick
    If Pin1.State = True Then
        Pin1.State = False
        astream.Write(Array As Byte(1, 0))
    Else
        Pin1.State = True
        astream.Write(Array As Byte(1, 1))
    End If
    Log(Pin1.State)
End Sub


Sub bt_Connected (Success As Boolean, Connection As BluetoothConnection)
    If Success Then
        If astream.IsInitialized Then
            astream.Close
        End If
        Log($"Connected to: ${Connection.Name} - ${Connection.MacAddress}"$)
        astream.InitializePrefix(Connection.InputStream, True, Connection.OutputStream, "astream")
        bt.Listen
    Else
        Log("Error connecting...")
    End If
End Sub

'Per Input da Raspberry
Sub Switch_StateChange(Checked As Boolean)
    If astream.IsInitialized Then
        Dim index As Int =  switches.IndexOf(Sender)
        Dim State As Byte
        If Checked Then State = 1 Else State = 0
        astream.Write(Array As Byte(index, State))
    End If
End Sub

'Per input da Android
Private Sub Astream_NewData (Buffer() As Byte)
'    'Dim ledNumber As Int = Buffer(0)
'    Dim state As Boolean = Buffer(1) = 1
'    Pin1.State = state
    
    Dim state As Boolean = Buffer(1) = 1
    Pin1.State = state
    
    If state = True Then     
        timer1.Enabled = True
    Else
        timer1.Enabled = False
    End If
End Sub

Private Sub AStream_Error
    AStream_Terminated
End Sub

Private Sub AStream_Terminated
    Log("Connected terminated")
End Sub

Private Sub GetBluetoothAddress As String
    Dim jo As JavaObject = bt
    Dim raw As String = jo.GetFieldJO("device").RunMethod("getBluetoothAddress", Null)
    Dim sb As StringBuilder
    sb.Initialize
    For i = 0 To raw.Length - 1 Step 2
        If sb.Length > 0 Then sb.Append(":")
        sb.Append(raw.SubString2(i, i + 2))
    Next
    Return sb.ToString
End Sub
The Code B4A ( Library JavaObject + RandomAccessFile + Serial )
B4X:
#Region  Project Attributes
    #ApplicationLabel: Raspberry BT
    #VersionCode: 1
    #VersionName:
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: portrait
    #CanInstallToExternalStorage: False
#End Region

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

Sub Process_Globals
    Private astream As AsyncStreams
    Private serial As Serial
    Private connected As Boolean
End Sub

Sub Globals
    Private txtMAC As EditText
    Private lblState As Label
    Private txtLogs As EditText
    Private btnConnect As Button
    Private btnDisconnect As Button

    Private btn_accendi As Button
    Private lbl_led As Label
    
    Dim stato_led As Int
End Sub

Sub Activity_Create(FirstTime As Boolean)
    If FirstTime Then
        serial.Initialize("serial")
    End If
    Activity.LoadLayout("1")
    txtMAC.Text = "B8:27:EB:D6:79:DF"
End Sub

Sub Activity_Resume
    UpdateState
End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

Sub UpdateState
    btnConnect.Enabled = serial.IsEnabled And Not(connected)
    btnDisconnect.Enabled = connected
    btn_accendi.Enabled = connected
'    For Each v As View In pnlSwitches
'        v.Enabled = connected
'    Next
    If connected Then
        lblState.TextColor = Colors.Green
        lblState.Text = "Connected"
        
    Else
        lblState.TextColor = Colors.Red
        lblState.Text = "Not connected"
    End If
End Sub


'ON / OFF led
Sub btn_accendi_Click
    
    'If Checked Then state = 1 Else state = 0
    'astream.Write(Array As Byte(v.Switch.Tag, state))
    'ON
    Dim c2 As ColorDrawable
    If stato_led = 1 Then
        astream.Write(Array As Byte(1, 0))
        stato_led = 0
        c2.Initialize2(Colors.Red,50dip,1dip,Colors.White)
        txtLogs.Text = $"State Remote Led 1 is OFF"$
    Else
        astream.Write(Array As Byte(1, 1))
        stato_led = 1
        c2.Initialize2(Colors.Green,50dip,1dip,Colors.White)
        txtLogs.Text = $"State Remote Led 1 is ON"$
    End If
    lbl_led.Background = c2
    
End Sub

Sub btnConnect_Click
    Try
        serial.Connect(txtMAC.Text)
    Catch
        Log(LastException)
        ToastMessageShow(LastException.Message, True)
    End Try
End Sub

Sub Serial_Connected (Success As Boolean)
    Log($"Connected ${Success}"$)
    If Success Then
        If astream.IsInitialized Then astream.Close
        astream.InitializePrefix(serial.InputStream, True, serial.OutputStream, "astream")
        connected = True
        UpdateState
    End If
End Sub

Sub btnDisconnect_Click
    serial.Disconnect
    astream.Close
    connected = False
    UpdateState
End Sub

Sub astream_NewData (Buffer() As Byte)
    Dim state As String
    If Buffer(1) = 1 Then state = "ON" Else state = "OFF"
    txtLogs.Text = $"State Remote Led ${Buffer(0)} is ${state}"$
    Dim c2 As ColorDrawable
    If Buffer(1) = 1 Then
        c2.Initialize2(Colors.Green,50dip,1dip,Colors.White)
    Else
        c2.Initialize2(Colors.Red,50dip,1dip,Colors.White)
    End If
    lbl_led.Background = c2
    
End Sub

Sub astream_Error
    astream_Terminated
End Sub

Sub astream_Terminated
    connected = False
    UpdateState
End Sub
 
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