#include <stdio.h>
#include <libusb-1.0/libusb.h>

#define TIMEOUT 500

int main( int argc, char **argv)
{
    int i=0,
        rv=0,
        bTransfer=0;

    unsigned short VID = 0xXXXX; //vendor id
    unsigned short PID = 0xXXXX; //product id
    unsigned char EP_out = 0x82; // write into usb  end point
    unsigned char EP_in  = 0x01; // read from usb end point

    unsigned char TX[] = {0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX}; //reqwest
    unsigned char RX[521]; //answer

    struct libusb_device_descriptor desc; //description of device structure

    libusb_device_handle *dev_handle = NULL;   //a device handle
    libusb_context       *ctx = NULL;           //a libusb session
    libusb_device        *dev = NULL;          //pointer to device
    libusb_device        **devs = NULL;        //pointer to pointer of device


    //init libusb
    libusb_init(ctx);

    // get device list
    rv = libusb_get_device_list( ctx, &devs); //get the list of devices
    printf("Number of devices: %d\n",rv);

    //get need device descriptor and number
    while ((dev = devs[i++]) != NULL) //take all connected device one by one
    {
        rv = libusb_get_device_descriptor(dev, &desc); // look in deckritption of current device
        if(rv == 0)
            printf("\tGet descriptor of device\n");

        //test device vendor and product identify
        if( desc.idVendor == VID && desc.idProduct == PID ) // if VID & PID is positive
        {
            // open device
            rv = libusb_open(dev, &dev_handle);
            if(rv == 0)
            printf("Open my device\n");
            break;
        }
    }

    // free device list
    libusb_free_device_list(devs, 1);

    // test to enable device
    if ( dev_handle == NULL )
    {
        printf("Not device found\n");

        //exit work with usb
        libusb_exit(ctx);
            printf("Exit libusb\n");

        return 0;
    }

    // test to device to grubed by kernel
    if(libusb_kernel_driver_active(dev_handle, 0) == 1)
        if(libusb_detach_kernel_driver(dev_handle, 0) == 0) //detach it
            printf("Detach device\n");

    // config  device
        rv = libusb_set_configuration(dev_handle, 1);
        if(rv == 0)
            printf("Set configuration\n");

    // claim interface
        rv = libusb_claim_interface(dev_handle, 0);
        if( rv == 0 )
            printf("Claim 0 interface\n");

    // send data block to device
    rv = libusb_bulk_transfer(dev_handle, EP_in, TX, sizeof(TX), &bTransfer, TIMEOUT);
    printf("Write to device.\n\tReturn value = %d\n\tSend bytes = %d\n",rv,bTransfer);

    // read answer
    rv = libusb_bulk_transfer(dev_handle, EP_out, RX, sizeof(RX), &bTransfer, TIMEOUT);
    printf("Read from device.\n\tReturn value = %d\n\tAccept bytes = %d\n",rv,bTransfer);

    //release the claimed interface
    rv = libusb_release_interface(dev_handle, 0);
    if( rv == 0 )
        printf("Release 0 interface\n");

    // close usb device
    libusb_close(dev_handle);
        printf("Close device\n");

    //exit work with usb
    libusb_exit(ctx);
        printf("Exit libusb\n");

    //erase dev_handle
    dev_handle = NULL;

    return 0;
}

Number of devices: 7
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
Open my device
Detach device
Set configuration
Claim 0 interface
Write to device.
    Return value = 0
    Send bytes = 8
Read from device.
    Return value = 0
    Accept bytes = 521
Release 0 interface
Close device
Exit libusb

Number of devices: 7
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
    Get descriptor of device
Open my device
Set configuration
Claim 0 interface
Write to device.
    Return value = 0
    Send bytes = 8
Read from device.
    Return value = -7
    Accept bytes = 0
Release 0 interface
Close device
Exit libusb