UART21 can't receive RX data

[Metal01]

I am using the nRF54L10 chip with NSC-V3.0.0, and I encounter an issue when using uart21 (p2.07–p2.08). If RTT is connected, UART transmission and reception both work normally. However, if RTT is not connected, data is often not received, even though I can see the correct RX waveform on an oscilloscope. If the nRF54L10 sends data and the slave device responds immediately, the nRF54L10 can receive the data. But if the nRF54L10 sends data and the slave device responds after a delay of about 10ms, the nRF54L10 cannot receive the data.

[Metal01]

the init function is:

void hal_app_usart_init(uint32_t baud, hal_app_usart_rx_callback callback)

{

  int ret = 0;

  if (!device_is_ready(uart))

  {

    LOG_ERR("UART device not ready");

  }

 

  const struct uart_config uart_cfg =

  {

    .baudrate = baud,

    .parity = UART_CFG_PARITY_NONE,

    .stop_bits = UART_CFG_STOP_BITS_1,

    .data_bits = UART_CFG_DATA_BITS_8,

    .flow_ctrl = UART_CFG_FLOW_CTRL_NONE

  };

  ret = uart_configure(uart, &uart_cfg);  

  if (ret == -ENOSYS)

  {

    LOG_ERR("UART configure failed");

  }

  ret = uart_callback_set(uart, uart_cb, NULL);

  if (ret)

  {

    LOG_ERR("UART callback set failed");

  }

}

the send function is:

void hal_app_usart_data_send(uint8_t const *buf, uint16_t len)

{

    int ret;

    NRF_POWER->TASKS_CONSTLAT = 1;

    ret = uart_tx(uart, buf, len, SYS_FOREVER_MS);

    if (ret)

    {

      LOG_ERR("UART TX failed");

    }

    else

    {

    }

}

the receive function is:

static void uart_cb(const struct device *dev, struct uart_event *evt, void *user_data)

{

  switch (evt->type)

  {  

    case UART_RX_RDY:

    {

      const uint8_t *buf = evt->data.rx.buf + evt->data.rx.offset;

      size_t len = evt->data.rx.len;

      for (size_t i = 0; i < len; i++)

      {

        _usart_rx_callback(buf[i]);

      }

    }

    break;

    case UART_RX_DISABLED:

      uart_rx_enable(dev, _uart_rx_buffer, sizeof(_uart_rx_buffer), RECEIVE_TIMEOUT);

      s_uart_rx_is_enabled = true;

    break;  

    case UART_TX_DONE:

      uart_rx_enable(dev, _uart_rx_buffer, sizeof(_uart_rx_buffer), RECEIVE_TIMEOUT);

    break;

 

    default:

    break;

  }

}