bluetooth with android and raspberrypi

Question

All that I would like to do is connect my andriod tab to my raspberrypi. I have searched and I am using code found in examples but I am still having troubles. I can establish communication between the two when I run my python script on the pi and use Blueterm on my android device. I can even send and receive strings.

However with my own androaid app I am having trouble and getting an exception when trying to connect. Any help would be greatly appreciated.

python code:

from bluetooth import *

server_sock=BluetoothSocket( RFCOMM )
server_sock.bind(("",PORT_ANY))
server_sock.listen(1)

port = server_sock.getsockname()[1]

uuid = "94f39d29-7d6d-437d-973b-fba39e49d4ee"

x = 0

while x<3:
        print "Waiting for connection on RFCOMM channel %d" % port

        client_sock, client_info = server_sock.accept()
        print "Accepted connection from ", client_info
        x = 1

        while x == 1:
                try:
                        data = client_sock.recv(1024)
                        if len(data) == 0: break
                        print "received [%s]" % data

                        if data == 'temp':
                                data = str(read_temp())+'!'
                        elif data == 'a':
                                data = 'A A A!'
                        elif data == 'b':
                                data = 'B B B'
                        else:
                                data = 'WTF!'
                                x = 5
                        client_sock.send(data)
                        print "sending [%s]" % data

                except IOError:
                        pass


except KeyboardInterrupt:

                        print "disconnected"

                        client_sock.close()
                        server_sock.close()
                        print "all done"

                        break

if x == 5:
        print "disconnected"
        client_sock.close()
        server_sock.close()
        print "all done"

Android Code:

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import java.io.IOException;
import java.util.Set;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {

    Button tryBluetoothButton;
    BluetoothSocket mmSocket = null;
    BluetoothDevice mmDevice = null;
    BluetoothAdapter mBluetoothAdapter;

    public void tryBT(View view) {
        Log.i("myStuff", "Button Clicked");
        sendBtMsg("a");
    }

    public void sendBtMsg(String msg2send) {

        UUID uuid = UUID.fromString("94f39d29-7d6d-437d-973b-fba39e49d4ee");

        try {
            mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
            mmSocket.connect();
            Log.i("myStuff", "Conected OK!");

        } catch (IOException e) { }{

            Log.i("myStuff", "EXCEPTION THROWN");
            }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tryBluetoothButton = (Button) findViewById(R.id.tryBluetoothButton);

        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

        if (!mBluetoothAdapter.isEnabled()) {
            Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBluetooth, 0);
            Log.i("myStuff", "Bluetooth Enabled");
        } else {
            Log.i("myStuff", "Bluetooth Already Enabled");
        }

        Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
        if (pairedDevices.size() > 0) {
            for (BluetoothDevice device : pairedDevices) {
                if (device.getName().equals("raspberrypi"))
                {
                    mmDevice = device;
                    Log.i("myStuff", "Device equals " + device.getName());
                    break;
                }
            }
        }
    }
}

Log from Android Studio when I run the app

01-20 16:33:42.983 8994-8994/paul.piconnect2 I/myStuff: Bluetooth Already Enabled
01-20 16:33:43.003 8994-8994/paul.piconnect2 I/myStuff: Device equals raspberrypi
01-20 16:33:48.889 8994-8994/paul.piconnect2 I/myStuff: Button Clicked
01-20 16:33:50.831 8994-8994/paul.piconnect2 I/myStuff: EXCEPTION THROWN
01-20 18:30:53.092 12714-12714/paul.piconnect2 I/myStuff: EXCEPTION THROWN
                                                      java.io.IOException: read failed, socket might closed or timeout, read ret: -1
                                                          at android.bluetooth.BluetoothSocket.readAll(BluetoothSocket.java:582)
                                                          at android.bluetooth.BluetoothSocket.readInt(BluetoothSocket.java:593)
                                                          at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:378)
                                                          at paul.piconnect2.MainActivity.sendBtMsg(MainActivity.java:35)
                                                          at paul.piconnect2.MainActivity.tryBT(MainActivity.java:25)
                                                          at java.lang.reflect.Method.invokeNative(Native Method)
                                                          at java.lang.reflect.Method.invoke(Method.java:515)
                                                          at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:270)
                                                          at android.view.View.performClick(View.java:4633)
                                                          at android.view.View$PerformClick.run(View.java:19270)
                                                          at android.os.Handler.handleCallback(Handler.java:733)
                                                          at android.os.Handler.dispatchMessage(Handler.java:95)
                                                          at android.os.Looper.loop(Looper.java:146)
                                                          at android.app.ActivityThread.main(ActivityThread.java:5602)
                                                          at java.lang.reflect.Method.invokeNative(Native Method)
                                                          at java.lang.reflect.Method.invoke(Method.java:515)
                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
                                                          at dalvik.system.NativeStart.main(Native Method)

I have been searching for a solution and will continue to do so. I have the raspberry pi and the samsung tab paired. I even have the tab as a trusted device. I am good with the python code because when I run blueterm with my tab I get the expected response when I type in "a" or "b". Any help would be great. Thank you.

Answer 1

Given the exception that is being thrown and confirming via comments that permissions are set correctly, perhaps this is an issue that's addresssed in these existing answers:

IOException: read failed, socket might closed - Bluetooth on Android 4.3

BluetoothSocket.connect() throwing exception "read failed"