/* TODO -----> Step #4b */
        if (isrFlag)
        {
            /* pdFALSE because USB task does not have an higher priority 
             * than the other tasks which can call this function */
            errCode = xQueueSendToBackFromISR(USBQueueHandle, &str , pdFALSE);            
        }
        else
        {
            errCode = xQueueSendToBack(USBQueueHandle, &str , APP_QUEUE_DELAY);
        }