title: Android Bluetooth LE connection to heart rate monitor
body: <p>I am absolutely new to android programming and Bluetooth LE. So pls be patient ;)
  I have a few example programs, but they are pretty hard to understand.
  I am currently working on an program, which should display the heart rate, received form a chest strap <code>(Zephyr HXM2)</code> by Bluetooth LE.
  I managed to get a connection and to read characteristics like the serial number string.
  But where I do have problems is in getting the heart rate measurement <code>(UUID = 0x2A37)</code>.</p>
  
  <p>So what my program actually does is:</p>
  
  <p>enabling the notification of the descriptor <code>(UUID =00002902-0000-1000-8000-00805f9b34fb)</code></p>
  
  <pre><code>descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
  mBluetoothGatt.writeDescriptor(descriptor);
  </code></pre>
  
  <p>then I wait for the onCharacteristicChanged Method and do the getvalue function.</p>
  
  <pre><code>BluetoothGattCharacteristic.getValue()
  </code></pre>
  
  <p>First thing I don't know if this is the right way, secondly I get data, but it varies from 2,4 and 6 bytes. Don't know what to do with them.</p>