Android + Arduino Bluetooth Data Transfer

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();     } } 

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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/

Answer 1

Just solved the problem for anyone else who came across this page.

Seems that my Arduino doesn't like me using digital pins for serial communication, I use TX and RX instead with this code taken from http://jondontdoit.blogspot.com.au/2011/11/bluetooth-mate-tutorial.html, also seems that 9600 is a good baud instead of 115200.

/***********************  Bluetooth test program ***********************/ //TODO //TEST THIS PROGRAM WITH ANDROID, //CHANGE PINS TO RX AND TX THO ON THE ARDUINO! //int counter = 0; int incomingByte;  void setup() {   pinMode(53, OUTPUT);   Serial.begin(9600); }  void loop() {   // see if there's incoming serial data:   if (Serial.available() > 0) {     // read the oldest byte in the serial buffer:     incomingByte = Serial.read();     // if it's a capital R, reset the counter     if (incomingByte == 'g') {       digitalWrite(53, HIGH);       delay(500);       digitalWrite(53, LOW);       delay(500);       //Serial.println("RESET");       //counter=0;     }   }    //Serial.println(counter);   //counter++;    //delay(250); } 

Answer 2

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.