使用Android与USB HID设备通信

Question

我是USB和Android的新手,所以如果我不清楚自己解释,请原谅我.

我有一个USB HID设备,我可以在Windows中与之通信.我正在尝试使用运行Android 3.1的Acer Iconia A500平板电脑建立通信.

我能够找到设备,枚举它,获得它唯一可用的接口,获得唯一可用的端点(0),并确定它是什么类型的端点(从设备到主机传输中断).

我对USB规范的理解是,所有HID设备都需要具有控制端点(端点0)和中断IN端点.但似乎这里的端点0是中断输入端点,而不是控制端点.

然而,为了使设备枚举,它必须成功地在控制端点上传输其描述符数据.因此,我推断出控制端点必须被找到(并使用),因为主机实际上枚举了设备.

这是我能够继续进行的,如上所述,在应用程序级别呈现给我的唯一接口/端点是从设备到主机的中断类型.我的应用程序没有可用的端点从主机到设备,中断或控制.因此,设备等待被告知该做什么,并且主机等待设备中发生的事情.不是很刺激.

请记住,此设备在连接到Windows时会正确响应,例如,我能够发送包含13个字节数据的报告,这些数据会导致设备点亮LED.所以它似乎符合USB HID规范.作为一种绝望的行为,我尝试将这一个端点用作控制端点和中断OUT端点,使用controltransfer()和UsbRequest()将数据提交给设备,在任何一种情况下都没有响应.

所以我的问题是:"控制传输端点是(？)用于设置设备,为什么我无法找到并使用它？"

感谢您的任何见解,以下是相关代码,如果需要,我可以将其余内容全部包括在内:

private UsbManager mUsbManager;
private UsbDevice mDevice;
private UsbDeviceConnection mConnectionRead;
private UsbDeviceConnection mConnectionWrite;
private UsbEndpoint mEndpointRead;
private UsbEndpoint mEndpointWrite;

    // check for existing devices
    for (UsbDevice device :  mUsbManager.getDeviceList().values())
    {
        //Need to filter for my device when other HIDs are also connected, but for now...           
        String devName = device.getDeviceName();
        if (DEBUG == 1){
        Toast.makeText(UsbHidDeviceTesterActivity.this, "My device got connected: " + devName, Toast.LENGTH_LONG).show();
        }
        //mDevice = device;
        setHIDDevice(device);
    }

private boolean setHIDDevice(UsbDevice device)
{    
    UsbInterface usbInterfaceRead = null;
    UsbInterface usbInterfaceWrite = null;
    UsbEndpoint ep1 = null;
    UsbEndpoint ep2 = null;
    boolean UsingSingleInterface = true;

    mDevice = device;

    //This HID device is using a single interface
    if (UsingSingleInterface)
    {
        //usbInterfaceRead = device.getInterface(0x00);//only 1 EP on this interface
        usbInterfaceRead = findInterface(device);

        //Try getting an interface at next index
        //usbInterfaceWrite = device.getInterface(0x01);//throws exception

        // Try using the same interface for reading and writing
        usbInterfaceWrite = usbInterfaceRead;

        int endPointCount = usbInterfaceWrite.getEndpointCount();
        if (DEBUG == 2)
        {
            Toast.makeText(UsbHidDeviceTesterActivity.this, "Endpoints: " + endPointCount, Toast.LENGTH_LONG).show();
            //Toast.makeText(UsbHidDeviceTesterActivity.this, "Interface: " + usbInterfaceRead, Toast.LENGTH_LONG).show();
        }

        if (endPointCount == 1)//only getting 1 endpoint
        {
            ep1 = usbInterfaceRead.getEndpoint(0);
            //As an act of desperation try equating ep2 to this read EP, so that we can later attempt to write to it anyway
            ep2 = usbInterfaceRead.getEndpoint(0);
        }
        else if (endPointCount == 2)
        {
            ep1 = usbInterfaceRead.getEndpoint(0);
            ep2 = usbInterfaceRead.getEndpoint(1);
        }
    }

    else        // ! UsingSingleInterface
    {
        usbInterfaceRead = device.getInterface(0x00);
        usbInterfaceWrite = device.getInterface(0x01);
        if ((usbInterfaceRead.getEndpointCount() == 1) && (usbInterfaceWrite.getEndpointCount() == 1))
        {
            ep1 = usbInterfaceRead.getEndpoint(0);
            ep2 = usbInterfaceWrite.getEndpoint(0);
        }
        if (DEBUG == 3)
        {
            Toast.makeText(UsbHidDeviceTesterActivity.this, "Using Dual Interface", Toast.LENGTH_LONG).show();
        }
    }

    //because ep1 = ep2 this will now not cause a return unless no ep is found at all
    if ((ep1 == null) || (ep2 == null))
    {
        if (DEBUG == 4)
        {
            Toast.makeText(UsbHidDeviceTesterActivity.this, "One EP is null", Toast.LENGTH_LONG).show();
        }
        return false;
    }

    // Determine which endpoint is the read, and which is the write
    if (ep1.getType() == UsbConstants.USB_ENDPOINT_XFER_INT)//I am getting a return of 3, which is an interrupt transfer
    {
        if (ep1.getDirection() == UsbConstants.USB_DIR_IN)//I am getting a return of 128, which is a device-to-host endpoint
        {
            mEndpointRead = ep1;
            if (DEBUG == 5)
            {
                Toast.makeText(UsbHidDeviceTesterActivity.this, "EP1 type: " + ep1.getType(), Toast.LENGTH_LONG).show();
            }
        }
        if (ep1.getDirection() == UsbConstants.USB_DIR_OUT)//nope
        {
            mEndpointWrite = ep1;
            if (DEBUG == 6)
            {
                Toast.makeText(UsbHidDeviceTesterActivity.this, "EP1 is a write", Toast.LENGTH_LONG).show();
            }
        }
    }

    if (ep2.getType() == UsbConstants.USB_ENDPOINT_XFER_INT)
    {
        if (ep2.getDirection() == UsbConstants.USB_DIR_IN)
        {
            //Try treating it as a write anyway             
            //mEndpointRead = ep2;
            mEndpointWrite = ep2;
        }
        else if (ep2.getDirection() == UsbConstants.USB_DIR_OUT)
        {
            //usbEndpointWrite = ep2;
            mEndpointWrite = ep2;
        }
    }

    //check that we should be able to read and write
    if ((mEndpointRead == null) || (mEndpointWrite == null))
    {
        return false;
    }
    if (device != null)
    {
        UsbDeviceConnection connection = mUsbManager.openDevice(device);
        if (connection != null && connection.claimInterface(usbInterfaceRead, true))
        {
            Log.d(TAG, "open SUCCESS");
            mConnectionRead = connection;
            // Start the read thread
            //Comment out while desperately attempting to write on this connection/interface
            //Thread thread = new Thread(this);
            //thread.start();

        }
        else
        {
            Log.d(TAG, "open FAIL");
            mConnectionRead = null;
        }
     }
    if (UsingSingleInterface)
    {
        mConnectionWrite = mConnectionRead;
    }
    else //! UsingSingleInterface
    {
        mConnectionWrite = mUsbManager.openDevice(device);
        mConnectionWrite.claimInterface(usbInterfaceWrite, true);
    }
    return true;
}

// searches for an interface on the given USB device
 private UsbInterface findInterface(UsbDevice device) {
    Log.d(TAG, "findInterface " + device);
    int count = device.getInterfaceCount();
    if (DEBUG == 7)
    {
        Toast.makeText(UsbHidDeviceTesterActivity.this, "Interface count: " + count, Toast.LENGTH_LONG).show();
    }

    for (int i = 0; i < count; i++) {
        UsbInterface intf = device.getInterface(i);
        String InterfaceInfo = intf.toString();
        Log.d(TAG, "Interface: " + InterfaceInfo);
        //Class below is 3 for USB_HID
        if (intf.getInterfaceClass() == 3 && intf.getInterfaceSubclass() == 0 &&
                intf.getInterfaceProtocol() == 0) {
            return intf;
        }
        //....try just returning the interface regardless of class/subclass
        //return intf;
    }

    return null;
} 
 private boolean sendControlTransfer(byte[] dataToSend)
 {
    synchronized (this)
    { 
    if (mConnectionRead != null)
     { 
        //byte[] message = new byte[13];  // or 14?
        byte[] message = dataToSend;
         if (DEBUG == 9)
         {
             Toast.makeText(UsbHidDeviceTesterActivity.this, "Sending Control Transfer", Toast.LENGTH_LONG).show();
         } 

         //first field ox21 is bin 00100001 which splits into 0 01 00001 for direction(1bit)/type(2b)/recipient(5b)
         //To set direction as 'host to Device' we need 0, To set type to HID we need 11 (3), and for recipient we want 00001
         //second field 0x09 is class specific request code, 0x09 is listed as 'reserved for future use'
         //third field 0x200 is value
         //int transfer = mConnectionRead.controlTransfer(0x21, 0x9, 0x200, 0, message, message.length, 0);
         //try with type set to HID
         int transfer = mConnectionRead.controlTransfer(0xC1, 0x9, 0x200, 0, message, message.length, 0);
         if (DEBUG == 10)
         {
             Toast.makeText(UsbHidDeviceTesterActivity.this, "Transfer returned " + transfer, Toast.LENGTH_LONG).show();
         }
     } 
    }
    return true;
 }


private boolean sendInterruptTransfer(byte[] dataToSend)
{ 
    int bufferDataLength = mEndpointWrite.getMaxPacketSize();//The write endpoint is null unless we just copy the read endpoint
    if (DEBUG == 12)
    {
        Toast.makeText(UsbHidDeviceTesterActivity.this, "Max Packet Size: " + bufferDataLength, Toast.LENGTH_LONG).show();
    }

    ByteBuffer buffer = ByteBuffer.allocate(bufferDataLength + 1);
    UsbRequest request = new UsbRequest();
    buffer.put(dataToSend);

    request.initialize(mConnectionWrite, mEndpointWrite);
    request.queue(buffer, bufferDataLength);

    try
    {
        /* only use requestwait on a read
        if (request.equals(mConnectionWrite.requestWait()))
        {
            return true;
        }
        */
    }
    catch (Exception ex)
    {
        // An exception has occurred
        if (DEBUG == 13)
        {
            Toast.makeText(UsbHidDeviceTesterActivity.this, "Caught Write Exception", Toast.LENGTH_LONG).show();
        }
    }

    return true;
}   

Answer 1

您可以使用以下命令获取接口和端点的详细信息的完整列表:

UsbManager mManager = (UsbManager) getSystemService(Context.USB_SERVICE);
HashMap<String, UsbDevice> deviceList = mManager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();

while (deviceIterator.hasNext())
    {
        UsbDevice device = deviceIterator.next();
        Log.i(TAG,"Model: " + device.getDeviceName());
        Log.i(TAG,"ID: " + device.getDeviceId());
        Log.i(TAG,"Class: " + device.getDeviceClass());
        Log.i(TAG,"Protocol: " + device.getDeviceProtocol());
        Log.i(TAG,"Vendor ID " + device.getVendorId());
        Log.i(TAG,"Product ID: " + device.getProductId());
        Log.i(TAG,"Interface count: " + device.getInterfaceCount());
        Log.i(TAG,"---------------------------------------");
   // Get interface details
        for (int index = 0; index < device.getInterfaceCount(); index++)
        {
        UsbInterface mUsbInterface = device.getInterface(index);
        Log.i(TAG,"  *****     *****");
        Log.i(TAG,"  Interface index: " + index);
        Log.i(TAG,"  Interface ID: " + mUsbInterface.getId());
        Log.i(TAG,"  Inteface class: " + mUsbInterface.getInterfaceClass());
        Log.i(TAG,"  Interface protocol: " + mUsbInterface.getInterfaceProtocol());
        Log.i(TAG,"  Endpoint count: " + mUsbInterface.getEndpointCount());
    // Get endpoint details 
            for (int epi = 0; epi < mUsbInterface.getEndpointCount(); epi++)
        {
            UsbEndpoint mEndpoint = mUsbInterface.getEndpoint(epi);
            Log.i(TAG,"    ++++   ++++   ++++");
            Log.i(TAG,"    Endpoint index: " + epi);
            Log.i(TAG,"    Attributes: " + mEndpoint.getAttributes());
            Log.i(TAG,"    Direction: " + mEndpoint.getDirection());
            Log.i(TAG,"    Number: " + mEndpoint.getEndpointNumber());
            Log.i(TAG,"    Interval: " + mEndpoint.getInterval());
            Log.i(TAG,"    Packet size: " + mEndpoint.getMaxPacketSize());
            Log.i(TAG,"    Type: " + mEndpoint.getType());
        }
        }
    }
    Log.i(TAG," No more devices connected.");
}

Answer 2

所以,我一直在研究类似的事情.我无法证实,但我认为正在发生的事情是:

1. Android在枚举控制端点的端点时不会列出控制端点.它仅列出其他端点.
2. 与任何端点的连接可以通过controlTransfer方法将控制传输发送到端点0,该方法(从api引用)"在此端点为此设备执行控制事务".
3. 因此,在上面的代码中,我将使用第0个端点作为中断输入端点,但它仍然允许控制传输.
4. 使用HID设备的某个人的示例是Missle Launcher演示,它使用的设备是具有中断端点的HID设备.

Answer 3

控制传输不显示任何接口描述符，其端点号默认为 0，用于传入和传出传输。

如果您有其他接口，这些接口的索引应从 0 开始，即默认控制传输接口不计算在内。

所以你的接口 0 保存了端点 1 描述符。使用 UsbEndpoint 方法查找端点的属性是否为中断类型。如果它是 UsbEndpoint.getType() 的端点类型，则应返回 0x03，而 UsbEndpoint.getEndpointNumber() 的端点编号应返回 0x81，这是端点 1 的通常值。

下面你的代码是错误的：

//first field ox21 is bin 00100001 which splits into 0 01 00001 for direction(1bit)/type(2b)/recipient(5b)
     //To set direction as 'host to Device' we need 0, **To set type to HID we need 11 (3)**, and for recipient we want 00001
     //second field 0x09 is class specific request code, **0x09 is listed as 'reserved for future use'**
     //**third field 0x200 is value**
     //int transfer = mConnectionRead.controlTransfer(0x21, 0x9, 0x200, 0, message, message.length, 0);
     //try with type set to HID
     int transfer = mConnectionRead.controlTransfer(0xC1, 0x9, 0x200, 0, message, message.length, 0);

Type 2 位用于指示类特定请求，即其值为01，0x09 为Hid 类特定请求SET_REPORT，不保留。value 是用作 Hid 类的报告 ID 的 wValue，对于您的情况，如果您的 HID 描述符只有一个报告，则它可能为 0。第 4 个参数是 wIndex，它应该用于指示收件人，对于您的情况，对于作为收件人的接口应该是 0x01。

因此，您的读取或接收数据表单设备的控制传输代码应该是：

int transfer = mConnectionRead.controlTransfer(0xA1, 0x01, 0x00, 0x01, message, message.length, 0);

其中第二个参数中的 0x01 是 GET_REPORT 是隐藏调用特定请求。

您用于写入或发送数据到设备的控制传输代码应该是：

int transfer = mConnectionWrite.controlTransfer(0x21, 0x09, 0x00, 0x01, message, message.length, 0);

由于您只有中断输入端点 1，因此批量或中断传输应如下所示：

int transfer = bulkTransfer (ep1, message, message.length, 0);

要拥有中断 Out 端点，您的设备固件的接口描述符中应该有一个端点描述符。