How to get proper values from Polar heart rate monitor

Question

My android application is getting data from Polar Heart Rate Monitor through Bluetooth connection. My problem is that I am getting such a string: ��������������������������������������������������

My code for getting the data:

 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, "ASCII");

                                readBufferPosition = 0;

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

    workerThread.start();

I tried to change this line in few ways but I am still getting incorrect data:

 final String data = new String(encodedBytes, "ASCII");

How can I solve this issue ?

Please help !!!

Answer 1

The sensor doesn't give you printable strings (like e.g. NMEA does) but binary data that you need to parse. You could look into the MyTracks Polar Sensor data parser for inspiration.

You are using available and read incorrectly (but the way you use you could have luck most of the time).