使用Usbserial示例无法通过usb接收数据

Question

我正在使用以下链接https://github.com/felHR85/SerialPortExample中的UsbSerial示例。我想从照片中显示的设备接收来自usb的数据。

设备基本上是一台通过串口发送计数器数据的计数器。

我可以从中连接设备和开放端口，但无法从中读取数据流。以下是使用的代码。代码没有给出任何错误

主要活动类

public class MainActivity extends AppCompatActivity {

    /*
     * Notifications from UsbService will be received here.
     */
    private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            switch (intent.getAction()) {
                case UsbService.ACTION_USB_PERMISSION_GRANTED: // USB PERMISSION GRANTED
                    Toast.makeText(context, "USB Ready", Toast.LENGTH_SHORT).show();
                    break;
                case UsbService.ACTION_USB_PERMISSION_NOT_GRANTED: // USB PERMISSION NOT GRANTED
                    Toast.makeText(context, "USB Permission not granted", Toast.LENGTH_SHORT).show();
                    break;
                case UsbService.ACTION_NO_USB: // NO USB CONNECTED
                    Toast.makeText(context, "No USB connected", Toast.LENGTH_SHORT).show();
                    break;
                case UsbService.ACTION_USB_DISCONNECTED: // USB DISCONNECTED
                    Toast.makeText(context, "USB disconnected", Toast.LENGTH_SHORT).show();
                    break;
                case UsbService.ACTION_USB_NOT_SUPPORTED: // USB NOT SUPPORTED
                    Toast.makeText(context, "USB device not supported", Toast.LENGTH_SHORT).show();
                    break;
            }
        }
    };
    private UsbService usbService;
    private TextView display;
    private EditText editText;
    private MyHandler mHandler;
    private final ServiceConnection usbConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName arg0, IBinder arg1) {
            usbService = ((UsbService.UsbBinder) arg1).getService();
            usbService.setHandler(mHandler);
        }

        @Override
        public void onServiceDisconnected(ComponentName arg0) {
            usbService = null;
        }
    };

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

        mHandler = new MyHandler(this);
        display = (TextView) findViewById(R.id.textView1);
        editText = (EditText) findViewById(R.id.editText1);
        Button sendButton = (Button) findViewById(R.id.buttonSend);
        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (!editText.getText().toString().equals("")) {
                    String data = editText.getText().toString();
                    if (usbService != null) { // if UsbService was correctly binded, Send data
                        display.append(data);
                        usbService.write(data.getBytes());
                    }
                }
            }
        });
    }

    @Override
    public void onResume() {
        super.onResume();
        setFilters();  // Start listening notifications from UsbService
        startService(UsbService.class, usbConnection, null); // Start UsbService(if it was not started before) and Bind it
    }

    @Override
    public void onPause() {
        super.onPause();
        unregisterReceiver(mUsbReceiver);
        unbindService(usbConnection);
    }

    private void startService(Class<?> service, ServiceConnection serviceConnection, Bundle extras) {
        if (!UsbService.SERVICE_CONNECTED) {
            Intent startService = new Intent(this, service);
            if (extras != null && !extras.isEmpty()) {
                Set<String> keys = extras.keySet();
                for (String key : keys) {
                    String extra = extras.getString(key);
                    startService.putExtra(key, extra);
                }
            }
            startService(startService);
        }
        Intent bindingIntent = new Intent(this, service);
        bindService(bindingIntent, serviceConnection, Context.BIND_AUTO_CREATE);
    }

    private void setFilters() {
        IntentFilter filter = new IntentFilter();
        filter.addAction(UsbService.ACTION_USB_PERMISSION_GRANTED);
        filter.addAction(UsbService.ACTION_NO_USB);
        filter.addAction(UsbService.ACTION_USB_DISCONNECTED);
        filter.addAction(UsbService.ACTION_USB_NOT_SUPPORTED);
        filter.addAction(UsbService.ACTION_USB_PERMISSION_NOT_GRANTED);
        registerReceiver(mUsbReceiver, filter);
    }

    /*
     * This handler will be passed to UsbService. Data received from serial port is displayed through this handler
     */
    private static class MyHandler extends Handler {
        private final WeakReference<MainActivity> mActivity;

        public MyHandler(MainActivity activity) {
            mActivity = new WeakReference<>(activity);
        }

        @Override
        public void handleMessage(Message msg) {
            mActivity.get().display.append("Handle:");
            switch (msg.what) {
                case UsbService.MESSAGE_FROM_SERIAL_PORT:
                    String data = (String) msg.obj;
                    mActivity.get().display.append(data);
                    break;
            }
        }
    }
}

Answer 1

我知道这有点晚了，但只是为了帮助其他可能遇到类似问题的人，您是否找到了解决问题的方法？如果没有，我看不到与您引用的示例中描述的服务（USBService.java）对应的其他java文件。同一个文件包含以下代码片段，您希望调试它以找出出错的地方（可能是字节到字符串转换的问题等）。希望这会有所帮助。

    /*
 *  Data received from serial port will be received here. Just populate onReceivedData with your code
 *  In this particular example. byte stream is converted to String and send to UI thread to
 *  be treated there.
 */
private UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback()
{
    @Override
    public void onReceivedData(byte[] arg0)
    {
        try
        {
            String data = new String(arg0, "UTF-8");
            if(mHandler != null)
                mHandler.obtainMessage(MESSAGE_FROM_SERIAL_PORT,data).sendToTarget();
        } catch (UnsupportedEncodingException e)
        {
            e.printStackTrace();
        }
    }
};