Android Tutorial Android Bluetooth / BluetoothAdmin Tutorial

Erel · Feb 7, 2012

Better implementation based on B4XPages:

[B4XPages] Bluetooth Chat Example

Updated implementation, based on B4XPages of https://www.b4x.com/android/forum/threads/android-bluetooth-bluetoothadmin-tutorial.14768/#content. The code is much simpler compared to the previous example. Note that you can call Serial.Listen without making the device discoverable. This is useful...

www.b4x.com

Tutorial was rewritten in April 2018.
We will create a chat example between two Android devices.

All the non-UI code is implemented in a class named BluetoothManager. It is initialized in Service_Create of the starter service.

It is always better to implement communication related code in a service or a class initialized from a service. This way the communication state is not affected by the activities more complicated state.

The activities call the class methods directly. Calling the activities subs is done with CallSub. Remember that CallSub doesn't do anything if the activity is paused.

The first activity, the main activity, shows two buttons. One for searching other devices and one for listening for connections.

Searching other devices requires a "dangerous" permissions (see the runtime permissions tutorial for more information).
Note that you need to add the permission in the manifest editor:

B4X:

AddPermission(android.permission.ACCESS_FINE_LOCATION)

B4X:

Sub btnSearchForDevices_Click
   rp.CheckAndRequest(rp.PERMISSION_ACCESS_FINE_LOCATION)
   Wait For Activity_PermissionResult (Permission As String, Result As Boolean)
   If Result = False Then
       ToastMessageShow("No permission...", False)
       Return
   End If
   Starter.Manager.SearchForDevices
End Sub

The second button sends an intent to the OS to make the device discoverable and then calls Serial.Listen.

Once a connection is established:
1. AsyncStreams is initialized in prefix mode (see the AsyncStreams tutorial for more information).
2. The ChatActivity is started.

Notes

- In this example we send text messages. Use B4XSerializator to send more complex types.

Scantech · Oct 21, 2015

Erel said:
Are you sure that there are no bluetooth devices near you?

The DeviceFound event is raised as a result of the native API. It will only add devices reported by the OS.

I will do some more investigating. I was in the apartment when I did a search. Not Sure how many other Bluetooth devices are around me. When Away from the apartments it is working properly.

FrankBerra · Nov 17, 2015

Note for Android M users:
Discovering doesn't work until you add the following lines to manifest

B4X:

AddPermission(android.permission.ACCESS_COARSE_LOCATION)
AddPermission(android.permission.ACCESS_FINE_LOCATION)

More info: http://developer.android.com/about/...android-6.0-changes.html#behavior-hardware-id

techknight · Nov 17, 2015

Why they would put that in the locations permission is completely asinine, because this could lead into a false sense of "insecurity" when installing an app and someone actually looks at the permissions. "Why does it need to know my location?" phrase... GRRR google....

Anyways... Can someone try on Android M if location is disabled, if BT discovery still works?

FrankBerra · Nov 17, 2015

Yes it works

DavideV · Nov 18, 2015

techknight said:
Why they would put that in the locations permission is completely asinine, because this could lead into a false sense of "insecurity" when installing an app and someone actually looks at the permissions. "Why does it need to know my location?" phrase... GRRR google....

Anyways... Can someone try on Android M if location is disabled, if BT discovery still works?

I agree with you about the permissions, too much for bluetooth discovery in my opinion.
Could be for ibeacon?
isn't it a sort of bluetooth localization?

Erel · Nov 18, 2015

DavideV said:
Could be for ibeacon?

Actually, the location permission is not required to discover iBeacons: https://www.b4x.com/android/forum/t...acon-devices-with-ble2-library.60151/#content

DavideV · Nov 18, 2015

Erel said:
Actually, the location permission is not required to discover iBeacons: https://www.b4x.com/android/forum/t...acon-devices-with-ble2-library.60151/#content

Thanks Erel to clarify that

Gagandeep Singh · Mar 22, 2016

Everytime i try to connect to any Bluetooth device i get this error,Please tell me where am i going wrong?

Erel · Mar 22, 2016

You need to run this example on two Android devices.

Mitesh_Shah · Apr 13, 2016

HI CAN ANY ONE TRY IN NEW ANDROID OS 6.0 ?

I AM TRY IT IN MY LENOVO K3 NOTE PHONE - ANDROID 6.0 IT'S NOT WORKING. GETTING ERROR DEVICE NOT FOUND

BUT IT'S WORK IN KITKAT AND LOLLIPOP Version

REGARD

MITESH

Erel · Apr 13, 2016

Please do not write ALL CAPS messages.

Are you using B4A v5.80?

Mitesh_Shah · Apr 14, 2016

Hi Sir

I am use B4A V3.0 now

Erel · Apr 14, 2016

You need to add this permission with the manifest editor: android.permission.ACCESS_COARSE_LOCATION

Mitesh_Shah · Apr 15, 2016

Thank u sir

Will try It

Mitesh_Shah · May 18, 2016

HI Erel

I m add >>android.permission.ACCESS_COARSE_LOCATION to Region Module Attributes but, getting Compiling Error.

Parsing code. Error
Error parsing program.
Error description: Attribute not supported: android
Occurred on line: 10
#Androidermission.ACCESS_COARSE_LOCATION

Erel · May 18, 2016

You need to add it in the manifest editor: Project - Manifest Editor:

B4X:

AddPermission(android.permission.ACCESS_COARSE_LOCATION)

Mitesh_Shah · May 19, 2016

Thnk's Sir

Now It's Working

red30 · Sep 20, 2016

I use your example. The data is transmitted. Not working reception ... What am I doing wrong?

B4X:

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

'Activity module
Sub Process_Globals
    Dim AStream As AsyncStreams
    Dim bc As ByteConverter
End Sub

Sub Globals
    Dim readings As EditText
    Dim label1 As Label


End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("2")
    readings.Color = Colors.black
    If AStream.IsInitialized = False Then
        'AStream.InitializePrefix(Main.serial1.InputStream, True, Main.serial1.OutputStream, "AStream")
        AStream.Initialize(Main.Serial1.InputStream, Main.Serial1.OutputStream, "AStreams")
    End If
End Sub

Sub AStreams_NewData (Buffer() As Byte)
    readings.Text=Buffer
    label1.Text=("Data: " & bc.HexFromBytes(Buffer))
End Sub

Sub AStream_Error
    ToastMessageShow("Connection is broken.", True)
End Sub

Sub AStream_Terminated
    AStream_Error
End Sub

Sub Activity_Resume
  
End Sub

Sub Activity_Pause (UserClosed As Boolean)
    If UserClosed Then
        AStream.Close
    End If
End Sub

Sub LightOn_Click
    AStream.Write(Array As Byte(0x00,0x05,0x3f))
End Sub

Erel · Sep 20, 2016

What is not working? NewData is not raised?

red30 · Sep 20, 2016

What is not working? NewData is not raised?

Yes! NewData is not raised...

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