通过ATMega16 USB-Uart在Android与ATMega16单片机之间建立串行通信

Question

我们目前设置的组件包括：

1)一种每次处理卡时读取卡并发送唯一代码的硬件装置。该系统由射频识别读卡器、ATMega16单片机和PL2303 UART组成，用于与安卓设备进行串行通信.

2)当硬件设备处理卡时接收唯一代码(由微控制器发送)的Android应用程序。

用于接收来自硬件的唯一代码的代码：

代码使用Android USB主机API

    package com.example.admin.hardware;
    import android.content.Context;
    import android.content.Intent;
    import android.hardware.usb.UsbDevice;
    import android.hardware.usb.UsbDeviceConnection;
    import android.hardware.usb.UsbEndpoint;
    import android.hardware.usb.UsbInterface;
    import android.hardware.usb.UsbManager;
    import android.support.v7.app.ActionBarActivity;
    import android.os.Bundle;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.widget.TextView;
    import android.widget.Toast;

    public class MainActivity extends ActionBarActivity {
    UsbManager manager;
    byte[] bytes;
    UsbEndpoint end;
    UsbInterface inter;
    UsbDevice device;
    UsbDeviceConnection conn;
    TextView data;

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

    Intent intent = getIntent();
    device = (UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
    if(device == null)
    {
        Toast.makeText(this, "NO DEVICE CONNECTED!", Toast.LENGTH_LONG).show();
    }
    else
    {
        data = (TextView) findViewById(R.id.data);
        String name = device.getDeviceName();
        //int vendorID = device.getVendorId();

        inter = device.getInterface(0);
        int i = inter.getEndpointCount();
        end = inter.getEndpoint(0);

        Toast.makeText(this, "Name Of The "+name, Toast.LENGTH_LONG).show();

        //RETURNS 128 if USB_DIR_IN and 0 if USB_DIR_OUT
        int direction = end.getDirection();
        Toast.makeText(this, "Direction of The EndPoint "+String.valueOf(direction), Toast.LENGTH_LONG).show();
            manager = (UsbManager) getSystemService(Context.USB_SERVICE);
            conn = manager.openDevice(device);

            conn.claimInterface(inter, true);
            new Thread(new Runnable(){
                @Override
                public void run() {
                    try {
                        conn.bulkTransfer(end, bytes, 32, 0);
                    }
                    catch(Exception e){
                        data.setText(e.getMessage());
                    }
                }
            }).start();

    }


}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
    }

我希望看到的：

从硬件设备接收的数据应存储在字节数组中。

实际发生了什么：

该程序提供“缓冲区启动或长度超出界限”错误！

任何帮助都将不胜感激！

Answer 1

您从不初始化数组bytes。

使用byte[] bytes = new byte[32];。

如果您需要更改数组的长度，那么conn.bulkTransfer(end, bytes, bytes.length, 0);是安全的。