正在通过 USB 从 Windows PC 与 android 设备通信

Question

我有 android 个设备和 windows 个驱动程序。我必须在附件模式下使用我自己的二进制协议进行通信。是否可以在不编写自定义 USB 驱动程序的情况下向此设备发送数据？

Answer 1

USB 是一个复杂的协议，因为它是 'universal' 并且可以处理多种设备（大容量存储、相机等）。所以在你的 android 设备上必须实现一个基本的 USB 结构来使用像 libusb 之类的标准库。您可以假设是这种情况，因为 android 在大多数情况下用于带有 USB 端口的处理器。

参见http://www.beyondlogic.org/usbnutshell/usb1.shtml。

您可以通过使用 libusb -v

获取有关 USB 设备 classes、接口、配置、端点和 android 设备实现的更多信息

然后，如果您知道 android 设备上的 USB 结构是什么样的，您可以使用 libusb 或其他库将数据写入 usb 结构中的特定端点通过例如libusb_bulk_transfer()、libusb_control_transfer()

http://libusb.sourceforge.net/api-1.0/io.html

如果你想在 java 中编程，你可以使用 usb4java 但是这有点不稳定 http://usb4java.org/quickstart/libusb.html

一般的USB结构是device -> (configuration) -> interface -> endpoint

所以将数据写入端点的方式是：

libusb_init(NULL); 
libusb_open_device_with_vid_pid(NULL, vendor_id, product_id);
libusb_claim_interface(devh, 0);
libusb_bulk_transfer(dev_handle, (2 | LIBUSB_ENDPOINT), data, 
        4, &p, 0); //example
... release interface...
...
libusb_close(devh);
libusb_exit(NULL);

这是从 http://www.dreamincode.net/forums/topic/148707-introduction-to-using-libusb-10/

复制的 C++ 示例

#include <iostream>
#include <libusb.h>

using namespace std;

int main() {
    libusb_device **devs; //pointer to pointer of device, used to      
                            retrieve a list of devices
    libusb_device_handle *dev_handle; //a device handle
    libusb_context *ctx = NULL; //a libusb session

    int r; //for return values
    ssize_t cnt; //holding number of devices in list
    r = libusb_init(&ctx); //initialize the library for the session we 
                             just declared
    if(r < 0) {
        cout<<"Init Error "<<r<<endl; //there was an error
        return 1;
    }
    libusb_set_debug(ctx, 3); //set verbosity level to 3, as suggested in 
                                the documentation

    cnt = libusb_get_device_list(ctx, &devs); //get the list of devices
    if(cnt < 0) {
        cout<<"Get Device Error"<<endl; //there was an error
        return 1;
    }
    cout<<cnt<<" Devices in list."<<endl;

    dev_handle = libusb_open_device_with_vid_pid(ctx, 5118, 7424);  
              //these are vendorID and productID I found for my usb device

    if(dev_handle == NULL)
        cout<<"Cannot open device"<<endl;
    else
        cout<<"Device Opened"<<endl;
    libusb_free_device_list(devs, 1); //free the list, unref the devices 
                                         in it

    unsigned char *data = new unsigned char[4]; //data to write

    data[0]='a';data[1]='b';data[2]='c';data[3]='d'; //some dummy values

    int actual; //used to find out how many bytes were written
    if(libusb_kernel_driver_active(dev_handle, 0) == 1) { //find out if 
                                               kernel driver is attached
        cout<<"Kernel Driver Active"<<endl;
        if(libusb_detach_kernel_driver(dev_handle, 0) == 0) //detach it
            cout<<"Kernel Driver Detached!"<<endl;
    }
    r = libusb_claim_interface(dev_handle, 0); //claim interface 0 (the   
    first) of device (mine had jsut 1)
    if(r < 0) {
        cout<<"Cannot Claim Interface"<<endl;
        return 1;
    }
    cout<<"Claimed Interface"<<endl;

    cout<<"Data->"<<data<<"<-"<<endl; //just to see the data we want to 
    write : abcd
    cout<<"Writing Data..."<<endl;
    r = libusb_bulk_transfer(dev_handle, (2 | LIBUSB_ENDPOINT_OUT), data, 
    4, &actual, 0); //my device's out endpoint was 2, found with trial- 
    the device had 2 endpoints: 2 and 129
    if(r == 0 && actual == 4) //we wrote the 4 bytes successfully
        cout<<"Writing Successful!"<<endl;
    else
        cout<<"Write Error"<<endl;

    r = libusb_release_interface(dev_handle, 0); //release the claimed 
                                                    interface
    if(r!=0) {
        cout<<"Cannot Release Interface"<<endl;
        return 1;
    }
    cout<<"Released Interface"<<endl;    

    libusb_close(dev_handle); //close the device we opened
    libusb_exit(ctx); //needs to be called to end the
    delete[] data; //delete the allocated memory for data
    return 0;
}

所以当您的设备运行时 android 它有一个 USB structure/functionality。要调查设备的 USB 功能（设备 class，如 大容量存储、RNDIS、...），请使用 libusb -v 并查看上面的代码来编写自定义数据到设备上的端点之一。

正在通过 USB 从 Windows PC 与 android 设备通信

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