problem with reading UART data through "libuarte" without event handler...

Question

I used Seggar V5.40 (IDE), SDK version 17.0.2

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 *    such product, must reproduce the above copyright notice, this list of
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 *    Nordic Semiconductor ASA integrated circuit.
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 */
/** @file
 * @defgroup libuarte_example_main main.c
 * @{
 * @ingroup libuarte_example
 * @brief Libuarte Example Application main file.
 *
 * This file contains the source code for a sample application using libuarte.
 *
 */

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include "nrf_libuarte_async.h"
#include "nrf_drv_clock.h"
#include <bsp.h>
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "nrf_queue.h"
#include "nrf_delay.h"

NRF_LIBUARTE_ASYNC_DEFINE(libuarte, 0, 0, 0, NRF_LIBUARTE_PERIPHERAL_NOT_USED, 255, 3);
static uint8_t text[20];
//static uint8_t text[] = "UART example started.\r\n Loopback:\r\n";
static uint8_t text_size = sizeof(text);
//static volatile bool m_loopback_phase;

typedef struct {
    uint8_t * p_data;
    uint32_t length;
} buffer_t;

NRF_QUEUE_DEF(buffer_t, m_buf_queue, 10, NRF_QUEUE_MODE_NO_OVERFLOW);

/*void uart_event_handler( )
{
    
}

*/
char ttt ;
/**
 * @brief Function for main application entry.
 */
int main(void)
{
    bsp_board_init(BSP_INIT_LEDS);
    
    ret_code_t ret = nrf_drv_clock_init();
    APP_ERROR_CHECK(ret);
  
    nrf_drv_clock_lfclk_request(NULL);

    ret_code_t err_code = NRF_LOG_INIT(app_timer_cnt_get);
    APP_ERROR_CHECK(err_code);

   // NRF_LOG_DEFAULT_BACKENDS_INIT();

    nrf_libuarte_async_config_t nrf_libuarte_async_config = {
            .tx_pin     = TX_PIN_NUMBER,
            .rx_pin     = RX_PIN_NUMBER,
            .baudrate   = NRF_UARTE_BAUDRATE_115200,
            .parity     = NRF_UARTE_PARITY_EXCLUDED,
            .hwfc       = NRF_UARTE_HWFC_DISABLED,
            .timeout_us = 100,
            .int_prio   = APP_IRQ_PRIORITY_LOW
    };

    err_code = nrf_libuarte_async_init(&libuarte, &nrf_libuarte_async_config, NULL, (void *)&libuarte);

    APP_ERROR_CHECK(err_code);

    nrf_libuarte_async_enable(&libuarte);
   
   //printf();
  // char test[20];
   // err_code = nrf_libuarte_async_tx(&libuarte, text, text_size);
    //APP_ERROR_CHECK(err_code);

   while (true)
    {
      nrf_libuarte_async_rx_free(&libuarte, &ttt, 1);

      nrf_delay_ms(500);


   




   }
    
}


/** @} */

ret_code_t nrf_libuarte_async_tx(const nrf_libuarte_async_t * const p_libuarte,uint8_t * p_data, size_t length); [this function is for TX data ]

nrf_libuarte_async_rx_free(&libuarte, &ttt, 1); [About this function I am not sure whether receiving the data].

any lead?? and suggestion?