err = libusb_interrupt_transfer(usbdev->usb_devh, EP_OUT, send_data, len, &cnt, USB_TIMEOUT);
if (err) {
fprintf(stderr, "Can't send data: %s\n", usb_strerror(err));
err = libusb_interrupt_transfer(usbdev->usb_devh, EP_OUT, send_data, len, &cnt, USB_TIMEOUT);
if (err) {
fprintf(stderr, "Can't send data: %s\n", usb_strerror(err));