title: Exception in pyfingerprint python library using r305 sensor
body: <p>I followed the steps given in this <a href="https://sicherheitskritisch.de/2015/03/fingerprint-sensor-fuer-den-raspberry-pi-und-debian-linux-en/" rel="nofollow">link</a>  . But i'm getting the following error:</p>
  
  <pre><code>The fingerprint sensor could not be initialized!
  Exception message: The received packet do not begin with a valid header!
  </code></pre>
  
  <p>I tried changing the tx/rx wires but no use. The same error occurs.
  Please help me to solve this issue.</p>