Peer-to-peer between PN532 on RPi and Nexus phone

Question

I am trying to create a simple message exchange between a Nexus 3 phone and a raspberry Pi with an adafruit NFC breakboard (PN532 chip). I have compiled the latest libnfc1.71 library and ran the examples:

pi@raspberrypi ~/libnfc1.7/libnfc-1.7.1/examples $ ./nfc-dep-initiator
NFC device: pn532_uart:/dev/ttyAMA0
 openedD.E.P. (212 kbpspassive mode) target:
       NFCID3: 01  fe  ec  d8  f7  03  c5  2d  00  00
           BS: 00
           BR: 00
           TO: 08
           PP: 32
General Bytes: 46  66  6d  01  01  11  03  02  00  13  04  01  96
Sending: Hello World!
nfc_initiator_transceive_bytes: RF Transmission Error

The error is thrown when I remove the phone from the NFC board, otherwise it just does nothing.

pi@raspberrypi ~/libnfc1.7/libnfc-1.7.1/examples $ ./nfc-dep-target
NFC device: pn532_uart:/dev/ttyAMA0 opened
NFC device will now act as: D.E.P. (undefined baud ratepassive mode) target:
       NFCID3: 12  34  56  78  9a  bc  de  ff  00  00
           BS: 00
           BR: 00
           TO: 00
           PP: 01
General Bytes: 12  34  56  78
Waiting for initiator request...
Initiator request received. Waiting for data...

nfc_target_receive_bytes: Target Released

The code from the android device:

MainActivity extends ActionBarActivity   implements NfcAdapter.CreateNdefMessageCallback, NfcAdapter.OnNdefPushCompleteCallback{
    private NfcAdapter mNfcAdapter = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        if (mNfcAdapter == null) {
            Toast.makeText(this, "NFC is not available", Toast.LENGTH_LONG).show();
            finish();
            return;
        }


        mNfcAdapter.setNdefPushMessageCallback(new NfcAdapter.CreateNdefMessageCallback()
        {
            @Override
            public NdefMessage createNdefMessage(NfcEvent event)
            {
                String text = ("Beam me up, Android!\n\n" +
                        "Beam Time: " + System.currentTimeMillis());
                NdefMessage msg = new NdefMessage(
                        new NdefRecord[] { createMime(
                                "application/vnd.com.example.android.beam", text.getBytes())
                        });
                return msg;
            }

        }, this, this);


      //  mNfcAdapter.setNdefPushMessageCallback(this, this);
        mNfcAdapter.setOnNdefPushCompleteCallback(this,this);
    }



@Override
public void onResume() {
    super.onResume();

    // Check to see that the Activity started due to an Android Beam
    if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
        processIntent(getIntent());
    }
}

@Override
public void onNewIntent(Intent intent) {
    // onResume gets called after this to handle the intent
    setIntent(intent);
}

/**
 * Parses the NDEF Message from the intent and prints to the TextView
 */
void processIntent(Intent intent) {
    EditText textView = (EditText) findViewById(R.id.editText);
    Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
            NfcAdapter.EXTRA_NDEF_MESSAGES);
    // only one message sent during the beam
    NdefMessage msg = (NdefMessage) rawMsgs[0];
    // record 0 contains the MIME type, record 1 is the AAR, if present
    textView.setText(new String(msg.getRecords()[0].getPayload()));
}

public void CloseApp(View view) {
    this.finish();
}

@Override
public void onNdefPushComplete(NfcEvent nfcEvent) {
    EditText editText = (EditText) findViewById(R.id.editText);
    editText.setText("onNdefPushComplete");
}

processIntent never gets called, neither onNdefPushComplete or createNdefMessage

Answer 1

The peer-to-peer examples that you are using are transmitting data at the NFCIP-1 (NFC-DEP) layer. An Android device supports only exchange of NDEF messages through SNEP/NPP, so you would need to implement the missing layers between NFC-DEP and SNEP in order to get P2P communication with an Android device running. The layers are like this (you can get all the specifications from the NFC Forum's website:

+------------------------------------------------+
|        NFC Data Exchange Format (NDEF)         |
+------------------------------------------------+
|     Simple NDEF Exchange Protocol (SNEP)       |
+------------------------------------------------+
|    NFC Logical Link Control Protocol (LLCP)    |
+------------------------------------------------+
|  NFC Data Exchange Protocol (NFC-DEP/NFCIP-1)  |
+------------------------------------------------+

So you have to add the LLCP, SNEP and NDEF layers.