Android Bluetooth Arduino

Question

I'm currently trying to get data from an Arduino to Android using the Bluesmirf module.

Here is my code for the Arduino.

void setup() {

 Serial.begin(115200);

}
void loop() {
   if(Serial.available()){
    char val = Serial.read();
    if(val == '.'){
          Serial.println("t1|x1|x2|x3|x4");
   } 
  }
 }

As you can see, I'm just having it write a long string. Eventually, the string will contain values. If i write a period to the arduino, it will return those values. Here is my Bluetooth Code, its very similar to the one in the Bluetooth Chat Sample:

private class ConnectedThread extends Thread{
    private BluetoothSocket mmSocket;
    private InputStream mmInStream;
    private OutputStream mmOutStream;

    public ConnectedThread(BluetoothSocket socket) {
        // TODO Auto-generated constructor stub
        mmSocket = socket;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        try {
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (Exception e) {
            // TODO: handle exception
        }
        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }

    public void run(){
        byte[] buffer = new byte[1024];
        int bytes;


        while(true){
            try {
                // Garbage collector necessary to prevent data loss
                System.gc();
                bytes = mmInStream.read(buffer);
                Log.d("Value of Output", new String(buffer, 0, bytes)) 

            } catch (IOException e) {
                e.printStackTrace();
                connectionLost();
            }

        }

    }

    public void write(byte[] buffer){
        try{
            mmOutStream.write(buffer);
        } catch(IOException e){
            Log.d("Write", "failed");
        }
    }

    public void cancel(){
        if (mmInStream != null) {
            try{mmInStream.close();}catch(Exception e){}
            mmInStream = null;
        }
        if (mmOutStream != null) {
            try{mmOutStream.close();} catch(Exception e){}
            mmOutStream = null;
        }

        if (mmSocket != null) {
            try{mmSocket.close();}catch(Exception e){}
            mmSocket = null;
        }
    }
}

A few things I want to mention. The System.gc() is there because if I don't put it there, I sometimes get faulty data. Sometimes the data is loss, sometimes it's repeated.

The problem that I'm having is that the output comes back in more than one line. So in my log I'll get something like

The value of Output t1|x1|x

the value of Output 2|x3|x4

Instead of it all in one line. When I connect the arduino to the computer via Bluetooth(bluetooth dongle), the data comes back in one line. How can I ensure that the data comes back in one line.

I have had similar issues using the BluetoothChat example, Arduino, and a BlueGiga WT32 module. I have a feeling this is an issue on the Android side. — user2461391
– user2461391, Commented Aug 22, 2013 at 13:27

Skaard-Solo · Accepted Answer · 2013-08-23 09:47:35Z

1

Well. I had the same issue. To solve it, I used mDinput = new DataInputStream(mmInStream);, then mDinput.readFully(dateBuffer, 0, sizeYouWant);. Then, readFully will return you the buffer only when it is full

Hope this helps

answered Aug 23, 2013 at 9:47

Skaard-Solo

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1 Comment

piyushg91 Over a year ago

This is a great workaround. Thanks! The first few data lines that come back wind up being useless but I can just tell the program to ignore the first few data lines.

ladislas · Accepted Answer · 2013-08-22 07:31:43Z

1

I can try concatenate your data in a "buffer" and check this buffer for the new line/carriage return character. Once it is found, you asign the data to your real variable, clear the buffer and starts all over again. That should do the trick.

Hope it helps! :)

answered Aug 22, 2013 at 7:31

ladislas

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