title: Mifare Ultralight C Authentication in Android (2.3.6)
body: <p>I'm trying to authenticate a Mifare Ultralight C (ISO/IEC 14443-2 and 14443-3 type A compatible) tag.</p>
  
  <p>I send the authentication command with the MifareUltralight.transceive() function provided in Android. I have also checked NfcA.transceive() (IsoDep seems not to be compatible with this kind of tag because this object is for dealing with ISO/IEC 14443-4 tags and that's why I don't use IsoDep.transceive()).</p>
  
  <p>So, when I first send the authentication request command the tag answers the transceive() with AFxxxx..... where I process the tag answer and then I send another transceive() with the response to that answer but... just before sending the transceive() the tag is connected, when it's sent I get a "tag was lost" warning and a "transceive failed".</p>
  
  <p>Also, if I try it with NfcA the same problem happens.</p>
  
  <p>Finally, if I try to send one authentication command after the first one response I get also a "Tag was lost" warning with the transceive fail.</p>
  
  <p>So my question is:</p>
  
  <blockquote>
    <blockquote>
      <p><strong>Why does the NFC tag get lost when I send the second transceive()?</strong>&lt;&lt;</p>
    </blockquote>
  </blockquote>
  
  <p>(It doesn't seem to be a timeout problem because just before sending the second transceive() the connection is open with the tag)
  I made all the stuff in a different Thread from the UI one.</p>
  
  <p>Thanks in advance!</p>