Question

我想使用libusb库为USB编写一些测试应用程序。请问任何人可以建议如何使用usb_control_msg调用设置控制传输？

运行以下代码时出现错误的描述符错误。

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "usb.h"
static int vendor_id;
static int product_id;

typedef struct{
    int requesttype; 
    int request;
    int value;
    int index; 
    char *bytes;
    int size;
    int timeout;
}ctrlmsg_param;

void print_endpoint(struct usb_endpoint_descriptor *endpoint)
{
    printf("=====End point Information====\n");
    printf("bEndpointAddress: %x\n", endpoint->bEndpointAddress);
    printf("bmAttributes:     %x\n", endpoint->bmAttributes);
    printf("wMaxPacketSize:   %d\n", endpoint->wMaxPacketSize);
    printf("bInterval:        %d\n", endpoint->bInterval);
    printf("bRefresh:         %d\n", endpoint->bRefresh);
    printf("bSynchAddress:    %d\n", endpoint->bSynchAddress);
}

void print_altsetting(struct usb_interface_descriptor *interface)
{
    int i;

    printf("\n=====Alternate Setting Information====\n");
    printf("bInterfaceNumber:   %d\n", interface->bInterfaceNumber);
    printf("bAlternateSetting:  %d\n", interface->bAlternateSetting);
    printf("bNumEndpoints:      %d\n", interface->bNumEndpoints);
    printf("bInterfaceClass:    %d\n", interface->bInterfaceClass);
    printf("bInterfaceSubClass: %d\n", interface->bInterfaceSubClass);
    printf("bInterfaceProtocol: %d\n", interface->bInterfaceProtocol);
    printf("iInterface:         %d\n", interface->iInterface);

    for (i = 0; i < interface->bNumEndpoints; i++)
        print_endpoint(&interface->endpoint[i]);
}

void print_interface(struct usb_interface *interface)
{
    int i;

    for (i = 0; i < interface->num_altsetting; i++)
        print_altsetting(&interface->altsetting[i]);
}

void print_configuration(struct usb_config_descriptor *config)
{
    int i;

    printf("=====Configuration Information====\n");
    printf("wTotalLength:         %d\n", config->wTotalLength);
    printf("bNumInterfaces:       %d\n", config->bNumInterfaces);
    printf("bConfigurationValue:  %d\n", config->bConfigurationValue);
    printf("iConfiguration:       %d\n", config->iConfiguration);
    printf("bmAttributes:         %x\n", config->bmAttributes);
    printf("MaxPower:             %d\n", config->MaxPower);

    for (i = 0; i < config->bNumInterfaces; i++)
        print_interface(&config->interface[i]);
}

int print_device(struct usb_device *dev)
{
    usb_dev_handle *udev;
    char str[100];
    int ret, i;
    udev = usb_open(dev);
    if (udev) {
        if (dev->descriptor.iManufacturer) {
            ret = usb_get_string_simple(udev, dev->descriptor.iManufacturer, str, sizeof(str));
            if (ret > 0)
            {
                printf("Manufacturer is %s\n",str);
            }
        }
        if (dev->descriptor.iProduct) {
            ret = usb_get_string_simple(udev, dev->descriptor.iProduct, str, sizeof(str));
            if (ret > 0)
            {
                printf("Product is %s\n",str);
            }
        } 

    }

    if (udev)
        usb_close(udev);
    printf("Possible configurations are %x\n",dev->descriptor.bNumConfigurations);
    sleep(2);
    for (i = 0; i < dev->descriptor.bNumConfigurations; i++)
        print_configuration(&dev->config[i]);

    return 0;
}
int htod( const char* str )
{
    int decimal;
    sscanf( str, "%x", &decimal);
    return decimal;
}
void set_data(struct usb_device *dev)
{

ctrlmsg_param  param;
param.requesttype= 0;
param.request=0;
param.value=0;
param.index=0;
param.bytes=10;
param.size=0;
param.timeout=5000;
usb_control_msg(dev, param.requesttype, param.request, param.value, param.index, param.bytes, param.size, param.timeout);
printf("error is %s\n",strerror(errno));
return;

}
int main(int argc, char *argv[])
{
    struct usb_bus *bus;
    struct usb_device *dev;

    if(argc != 3)
    {
        printf("Error in number of arguments\n");
        printf("Usage:./usb_info <vendor id> <product id>\n");
        exit(0);
    }

    vendor_id=htod(argv[1]);
    product_id=htod(argv[2]);

    printf("initializing USB library\n");
    usb_init();

    printf("Finding Buses and Devices\n");
    usb_find_busses();
    usb_find_devices();

    for (bus = usb_get_busses(); bus; bus = bus->next) {
        for (dev = bus->devices; dev; dev = dev->next) {
            if ((dev->descriptor.idProduct == product_id) && (dev->descriptor.idVendor == vendor_id)){           
                printf("Found device with produxt id %x and vendor id %x\n",product_id,vendor_id);
                print_device(dev);
                set_data(dev);
                print_device(dev);
            }
        }
    }
    return 0;
}

此致和Sandeep

Answer 1

我认为你的意思是usb_control_msg()返回错误代码＆＃34;错误描述符＆＃34;。请澄清这是否不正确。

USB控制传输具有一些非常特定的格式规则，如果您正在形成的数据包被发送到任何兼容设备，它将在总线上返回请求错误/停止。

您正在发送控制转移：

bmRequestType = 0x00
bRequest      = 0x00
wValue        = 0x0000
wIndex        = 0x0000
wSize         = 0x0000

这应该被USB设备解释为GET_STATUS请求，因此wLength需要为2，并且bmRequestType需要设置最高位，表明这是一个IN方向请求（来自主机的点）观点）。这些都来自www.usb.org上的USB规范1.1 / 2.0 / 3.1的第9章。

参数char *bytes（您的param.bytes）也需要是您正在进行的通话中的地址/指针。

用于测试的良好标准控制转移将是：

bmRequestType = 0x80
bRequest      = 0x06
wValue        = 0x0001
wIndex        = 0x0000
wSize         = 0x0008

此请求将返回设备描述符的前8个字节，它对所有状态下的每个USB设备都有效。

其他传输类型（批量，中断）没有这些严格的格式规则，可以更容易开始。我想你已经过了这个问题，因为问题已经发布了很长一段时间，但也许这个回复仍然可以帮助其他人。

使用libusb库的USB应用程序

1 个答案: