title: Card Emulation, RC522 and Nexus 4's NFC UID
body: <p>I have 2 problems:</p>
  
  <p>First, I want to emulation card and NDEF Message.
  I implemented <code>HostApduService</code> using this code:</p>
  
  <pre><code>public class MyHostApduService extends HostApduService {
  private int messageCount = 0;
     @Override
     public byte[] processCommandApdu(byte[] apdu, Bundle extras) {
           String n1="Hello World";
           byte[] response=n1.getBytes();
           Log.d("HCEDEMO", "Application selected");
           return response;
     }
  
     @Override
     public void onDeactivated(int reason) {
          Log.d("HCEDEMO", "Deactivated: " + reason);
     }
  }
  </code></pre>
  
  <p>When my phone emulates a tag, put it near NFC Reader RC522.
  But these code not run. Is there a problem with AID?
  I used AIDs:</p>
  
  <ul>
  <li>F04E66E75C02D8</li>
  <li>F0394148148100</li>
  <li>D2760000850101</li>
  <li>F222222222</li>
  </ul>
  
  <p>Second, I want to know what is UID of Android Devices's NFC when it communicate with another devices. Nothing is found with Google :(</p>
  
  <p>Could you help me?</p>