如何从Android手机向Pi发送NDEF消息

Question

我正在尝试使用nfcpy从我的手机向我的Raspberry Pi发送NDEF消息。

我已经连接了PN532，并且能够打印有关Tag的一些信息。

使用我的Android应用程序我可以将消息发送到另一部手机，但Pi不接收它。

import time
import nfc
import ndef
from threading import Thread
from nfc.clf import RemoteTarget

with nfc.ContactlessFrontend('tty:AMA0') as clf:
        tag = clf.connect(rdwr={'on-connect': lambda tag: False })
        print(tag)
        for record in tag.ndef.record:
                print(record)
        clf.close()

package com.example.t1000;

import android.bluetooth.BluetoothAdapter;
import android.content.Context;
import android.content.Intent;
import android.net.wifi.WifiManager;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.NfcEvent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

public class NFCSender extends AppCompatActivity implements NfcAdapter.CreateNdefMessageCallback {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_nfcsender);

        Intent intent = getIntent();
        StringBuilder stringBuilder = new StringBuilder();

        stringBuilder.append("Now Sending: ");
        stringBuilder.append(intent.getStringExtra(MainActivity.EXTRA_MYMAC));

        String displayedMessage = stringBuilder.toString();

        TextView textView = (TextView) findViewById(R.id.textView);

        textView.setText(displayedMessage);

    }

    @Override
    public NdefMessage createNdefMessage(NfcEvent event) {
        Intent intent = getIntent();
        NdefRecord ndefRecord = NdefRecord.createMime("text/plain", intent.getStringExtra(MainActivity.EXTRA_MYMAC).getBytes());
        NdefMessage ndefMessage = new NdefMessage(ndefRecord);
        return ndefMessage;
    }
}

将一个随附的标签保存到阅读器时，我收到的错误是：

Traceback (most recent call last):
  File "readTag.py", line 11, in <module>
    for record in tag.ndef.record:
AttributeError: 'NoneType' object has no attribute 'record'

与此相反，用我的手机触摸阅读器根本没有给出错误，虽然它仍然给我Type4ATag MIU=255 FWT=0.038664作为输出。

之后，只有在拿走手机时才会出现错误：

Traceback (most recent call last):
  File "readTag.py", line 11, in <module>
    for record in tag.ndef.record:
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/__init__.py", line 278, in ndef
    if ndef.has_changed:
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/__init__.py", line 130, in has_changed
    ndef_data = self._read_ndef_data()
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/tt4.py", line 289, in _read_ndef_data
    if not (hasattr(self, "_ndef_file") or self._discover_ndef()):
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/tt4.py", line 231, in _discover_ndef
    if not self._select_ndef_application():
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/tt4.py", line 197, in _select_ndef_application
    self.tag.send_apdu(0, 0xA4, 0x04, 0x00, self._aid)
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/tt4.py", line 488, in send_apdu
    apdu = self.transceive(apdu)
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/tt4.py", line 437, in transceive
    data = self._dep.exchange(data, timeout)
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/tag/tt4.py", line 123, in exchange
    data = self.clf.exchange(data, (data[1] & 0x3F) * self.fwt)
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/clf/__init__.py", line 1051, in exchange
    rcvd_data = exchange(self.target, send_data, timeout)
  File "/home/pi/.local/lib/python2.7/site-packages/nfc/clf/pn53x.py", line 667, in send_cmd_recv_rsp
    raise nfc.clf.TimeoutError
nfc.clf.TimeoutError

Answer 1

所以，我终于找到了我的错误，这就是我忘记了

NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
nfcAdapter.setNdefPushMessageCallback(this, this);

到我的onCreate方法，之后它工作得很好。