Question

我正在尝试编写一个应用程序来读取和写入连接的USB设备。我正在使用libusb。在我找到设备之后，配置失败了。我正在http://libusb.sourceforge.net/doc/index.html关注libusb的开发人员指南。其中说明：

usb_set_configuration设置设备的活动配置。配置参数是描述符字段bConfigurationValue中指定的值。成功时返回0或＆lt;错误时为0。

我在我的源代码（下面）中演示了我使用bConfigurationValue作为配置参数，但是我从usb_set_configuration返回的值总是-1。我不明白为什么？

输出：

[user@local workspace]$ ./application 
Device Found @ Address 005 
Vendor ID 0x018d1
Product ID 0x04e12
INFO: bConfigurationValue = 1
config status =-1
claim status =-1
alt status =-22
TX status =-1
RX status =-1 -> RX char = 0
[user@local workspace]$

来源：

int main(int argc, char *argv[])
{
    struct usb_bus *bus;
    struct usb_device *dev;
    struct usb_dev_handle *android_handle;
    int status;
    unsigned char send_data = 0x51;
    unsigned char receive_data = 0;

    usb_init();

    if ((handle = locate_device()) == 0)
    {
        printf("Error: Could not open the device\n");
        return (-1);
    }

    printf("INFO: bConfigurationValue = %d\n", config_val);
    status = usb_set_configuration(handle, config_val);
    printf("config status = %d\n", status);

    status = usb_claim_interface(handle, 0);
    printf("claim status = %d\n", status);

    open_status = usb_set_altinterface(handle, 0);
    printf("alt status = %d\n", status);

    status = usb_bulk_write(handle, 4, &send_data, 1, 500);
    printf("TX status = %d\n", status);

    usb_bulk_read(handle, 3, &receive_data, 1, 500);
    printf("RX status = %d -> RX char = %d\n", status, receive_data);

    usb_close(handle);

    return 0;
}

usb_dev_handle *locate_device(void) 
{ 
    ... 
    config_val = dev->config[myDeviceIndex].bConfigurationValue;
    ...
}

编辑：

以root身份运行应用程序时，将返回以下错误代码：

Device Found @ Address 005 
Vendor ID 0x018d1
Product ID 0x04e12
INFO: bConfigurationValue = 1
config status = -16
claim status = -16
alt status = -22
TX status = -16
RX status = -16 -> RX char = 0

使用libusb的Linux USB应用程序

0 个答案: