批量传输和 Android USB API

Posted 2023-04-17

【中文标题】批量传输和 Android USB API

【英文标题】：BulkTransfer & Android USB API

【发布时间】：2017-02-28 10:10:58

【问题描述】：

我有一个程序，我尝试通过 USB 将我的 android 设备连接到网络摄像头。我在一些事情上遇到了麻烦，即正确传输数据。我尝试过使用 bulkTransfer，但似乎没有人意识到它正在被使用。我一直在尝试找到可能对我有帮助的示例，例如here，但没有一个对我有帮助-它们的结构似乎比我的要好，但是每当我在加载时切换程序崩溃。

我相当有信心我的字节声明也不正确，我应该以某种方式将我的数据转发到那里，但我不确定如何。在如何数据传输和如何构建我的代码方面的任何帮助将不胜感激。

一些声明：

private byte[] bytes = 1,2;
private static int TIMEOUT = 0;
private boolean forceClaim = true;

在创建时：

UsbDevice device = (UsbDevice) getIntent().getParcelableExtra(UsbManager.EXTRA_DEVICE);
    UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
    HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList();
    Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
    while(deviceIterator.hasNext()) 
        device = deviceIterator.next();
        PendingIntent mPermissionIntent = PendingIntent.getBroadcast(this,0,new Intent(ACTION_USB_PERMISSION), 0);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        registerReceiver(mUsbReceiver, filter);
        mUsbManager.requestPermission(device, mPermissionIntent);
        UsbDeviceConnection connection = mUsbManager.openDevice(device);
        Log.d("CAM Connection", " " + connection);
        Log.d("CAM UsbManager", " " + mUsbManager);
        Log.d("CAM Device", " " + device);



        UsbInterface intf = device.getInterface(0);
        Log.d("CAM_INTF Interface!!!!", " " +  intf );
        UsbEndpoint endpoint = intf.getEndpoint(0);
        Log.d("CAM_END Endpoint", " " +  endpoint );

        connection.claimInterface(intf, forceClaim);
        StringBuilder sb = new StringBuilder();
        if(connection.bulkTransfer(endpoint,bytes,bytes.length,TIMEOUT) < 2)
            Log.d("test", "");
       //Log.d("BULK", ""+ connection.bulkTransfer(endpoint, bytes, bytes.length, TIMEOUT)); //do in another thread
    

附加相关代码：

 private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() 

    public void onReceive(Context context, Intent intent) 
        String action = intent.getAction();
        if (ACTION_USB_PERMISSION.equals(action)) 
            synchronized (this) 
                UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);

                if (intent.getBooleanExtra(EXTRA_PERMISSION_GRANTED, false)) 
                    if(device != null)



                        //call method to set up device communication
                    
                
                else 
                    Log.d("Deny:", "permission denied for device " + device);
                
            
        
    
;

【参考方案1】：

您的问题之一是寻找端点。 endpoint0 用于控制任务，您应该在代码中找到适当的 IN 和 OUT 端点。

 UsbInterface usbInterfaceTemp = null;
        usbInterface = null;
        endpointIN = null;
        endpointOUT = null;
        for (int i = 0; i < usbGotPermiDVC.getInterfaceCount(); i++) 

            usbInterfaceTemp = usbGotPermiDVC.getInterface(i);
            if (usbInterfaceTemp.getEndpointCount() >= 2) 

                for (int j = 0; j < usbInterfaceTemp.getEndpointCount(); j++) 

                    UsbEndpoint usbEndpointTemp = usbInterfaceTemp.getEndpoint(j);

                    if (usbEndpointTemp.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) 

                        if (usbEndpointTemp.getDirection() == UsbConstants.USB_DIR_IN) 

                            endpointIN = usbEndpointTemp;

                         else if (usbEndpointTemp.getDirection() == UsbConstants.USB_DIR_OUT) 

                            endpointOUT = usbEndpointTemp;

                        
                    
                
            
        

        if (endpointIN != null && endpointOUT != null) 
            usbInterface = usbInterfaceTemp;
        

        if (usbInterface == null) 
            return;
        


        usbDeviceConnection = usbManager.openDevice(usbSelectedDevice);

        if (!(usbDeviceConnection != null && usbDeviceConnection.claimInterface(usbInterface, true))) 
            usbDeviceConnection = null;
            return;
        

        usbDeviceConnection.controlTransfer(0x21, 34, 0, 0, null, 0, 0);
        usbDeviceConnection.controlTransfer(0x21, 32, 0, 0, new byte[](byte) 0x80,
                0x25, 0x00, 0x00, 0x00, 0x00, 0x08, 7, 0);

        Toast.makeText(getApplicationContext(), "Device opened and Interface claimed!", Toast.LENGTH_SHORT).show();

其中usbGotPermiDVC为获得USB访问权限的设备。