Android + Arduino Bluetooth Data Transfer



Answers

I was getting the same thing. I went into 'Settings'->'Wireless and Networks'->'Bluetooth Settings' and paired the device. When I went back and re-ran my code, it connected, no exception. I put controls in my UI for displaying the paired devices, I'm going to see if I can code to manage pairing devices from my UI.

Question

I can get my Android app to connect via Bluetooth to my Arduino. However no data can be transmitted between them. Below is my setup and code:

HTC Android v2.2, Bluetooth mate gold modem, Arduino Mega (ATmega1280)

Android Java code:

package com.example.BluetoothExample;

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.TextView;
import android.widget.EditText;  
import android.widget.Button;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;

public class BluetoothExampleActivity extends Activity {
  TextView myLabel;
  EditText myTextbox;
  BluetoothAdapter mBluetoothAdapter;
  BluetoothSocket mmSocket;
  BluetoothDevice mmDevice;
  OutputStream mmOutputStream;
  InputStream mmInputStream;
  Thread workerThread;
  byte[] readBuffer;
  int readBufferPosition;
  int counter;
  volatile boolean stopWorker;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Button openButton = (Button)findViewById(R.id.open);
    Button sendButton = (Button)findViewById(R.id.send);
    Button closeButton = (Button)findViewById(R.id.close);
    myLabel = (TextView)findViewById(R.id.label);
    myTextbox = (EditText)findViewById(R.id.entry);

    //Open Button
    openButton.setOnClickListener(new View.OnClickListener() {
      public void onClick(View v) {
        try {
          findBT();
          openBT();
        }
        catch (IOException ex) { }
      }
    });

    //Send Button
    sendButton.setOnClickListener(new View.OnClickListener() {
      public void onClick(View v) {
        try {
          sendData();
        }
        catch (IOException ex) {
            showMessage("SEND FAILED");
        }
      }
    });

    //Close button
    closeButton.setOnClickListener(new View.OnClickListener() {
      public void onClick(View v) {
        try {
          closeBT();
        }
        catch (IOException ex) { }
      }
    });
  }

  void findBT() {
    mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if(mBluetoothAdapter == null) {
      myLabel.setText("No bluetooth adapter available");
    }

    if(!mBluetoothAdapter.isEnabled()) {
      Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
      startActivityForResult(enableBluetooth, 0);
    }

    Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
    if(pairedDevices.size() > 0) {
      for(BluetoothDevice device : pairedDevices) {
        if(device.getName().equals("FireFly-108B")) {
          mmDevice = device;
          break;
        }
      }
    }
    myLabel.setText("Bluetooth Device Found");
  }

  void openBT() throws IOException {
    UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb"); //Standard //SerialPortService ID
    mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);    
    mmSocket.connect();
    mmOutputStream = mmSocket.getOutputStream();
    mmInputStream = mmSocket.getInputStream();
    beginListenForData();
    myLabel.setText("Bluetooth Opened");
  }

  void beginListenForData() {
    final Handler handler = new Handler(); 
    final byte delimiter = 10; //This is the ASCII code for a newline character

    stopWorker = false;
    readBufferPosition = 0;
    readBuffer = new byte[1024];
    workerThread = new Thread(new Runnable() {
      public void run() {
         while(!Thread.currentThread().isInterrupted() && !stopWorker) {
          try {
            int bytesAvailable = mmInputStream.available();            
            if(bytesAvailable > 0) {
              byte[] packetBytes = new byte[bytesAvailable];
              mmInputStream.read(packetBytes);
              for(int i=0;i<bytesAvailable;i++) {
                byte b = packetBytes[i];
                if(b == delimiter) {
                  byte[] encodedBytes = new byte[readBufferPosition];
                  System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
                  final String data = new String(encodedBytes, "US-ASCII");
                  readBufferPosition = 0;

                  handler.post(new Runnable() {
                    public void run() {
                      myLabel.setText(data);
                    }
                  });
                }
                else {
                  readBuffer[readBufferPosition++] = b;
                }
              }
            }
          } 
          catch (IOException ex) {
            stopWorker = true;
          }
         }
      }
    });

    workerThread.start();
  }

  void sendData() throws IOException {
    String msg = myTextbox.getText().toString();
    msg += "\n";
    //mmOutputStream.write(msg.getBytes());
    mmOutputStream.write('A');
    myLabel.setText("Data Sent");
  }

  void closeBT() throws IOException {
    stopWorker = true;
    mmOutputStream.close();
    mmInputStream.close();
    mmSocket.close();
    myLabel.setText("Bluetooth Closed");
  }

  private void showMessage(String theMsg) {
        Toast msg = Toast.makeText(getBaseContext(),
                theMsg, (Toast.LENGTH_LONG)/160);
        msg.show();
    }
}

Arduino Code:

#include <SoftwareSerial.h>

int bluetoothTx = 45;
int bluetoothRx = 47;

SoftwareSerial bluetooth(bluetoothTx, bluetoothRx);

void setup() {
  //pinMode(45, OUTPUT);
  //pinMode(47, INPUT);
  pinMode(53, OUTPUT);
  //Setup usb serial connection to computer
  Serial.begin(9600);

  //Setup Bluetooth serial connection to android
  bluetooth.begin(115200);
  bluetooth.print("$$$");
  delay(100);
  bluetooth.println("U,9600,N");
  bluetooth.begin(9600);
}

void loop() {
  //Read from bluetooth and write to usb serial
  if(bluetooth.available()) {
  char toSend = (char)bluetooth.read();
  Serial.print(toSend);
  flashLED();
  }

  //Read from usb serial to bluetooth
  if(Serial.available()) {
  char toSend = (char)Serial.read();
  bluetooth.print(toSend);
  flashLED();
  }
}

void flashLED() {
  digitalWrite(53, HIGH);
  delay(500);
  digitalWrite(53, LOW);
}

I've tried using 115200 and 9600 for the baud rates, and I've tried setting the bluetooth rx and tx pins as input/output and output/input. The Arduino is receiving serial data from the PC but can't send it to the Android (I can see this because of the flashLED() method).

The Android can't send any data at all to the Arduino. However they are both connected because the green light on the modem turns on and goes off and the red led flashes when I close the connection. The sendData() method doesn't throw an exception because otherwise showMessage("SEND FAILED"); would appear.

I also have this in my manifest .xml

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="8" />

Any help would be greatly appreciated!

Code taken from:

http://bellcode.wordpress.com/2012/01/02/android-and-arduino-bluetooth-communication/




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