Do i need to wary about HW UART buffer when using UART driver library ?

[KoFuKu]

I am using nrf_drv_uart library.

UART communication is set in non-blocing mode, and transfer od data is relised with nrf_drv_uart_rx and nrf_drv_uart_tx functions.

I am using: uint8_t[100] rx_buffer = {0}; for data reception. But, problem is that nrf_drv_uart_rx function returns error: NRF_ERROR_NO_MEM even if rx_buffer is mostly free.

I thouth that i dont need to think of peripheral UART buffer (hardware UART buffer of 6 bytes) when using UART driver library.

And i can not find any documentation how and way to handle this error event, can anyone confirm this and perhaps gives some advice.

Thanks in advance.

//Handler
void uart_co2_bsl_handler(nrf_drv_uart_event_t * p_event, void * p_context)
{
    switch(p_event->type)
    { 
        case NRF_DRV_UART_EVT_TX_DONE:
            flag_co2_tx_done = 1;
        break;

        case NRF_DRV_UART_EVT_RX_DONE: 
            flag_co2_rx_done = 1;
        break;
    
        case NRF_DRV_UART_EVT_ERROR: 
            if(p_event->data.error.error_mask == NRF_ERROR_DATA_SIZE)
            {
                NRF_UART0->ERRORSRC = CLEAR_REGISTAR;
            }
            else if(p_event->data.error.error_mask == NRF_ERROR_INVALID_DATA)
            {
                NRF_UART0->ERRORSRC = CLEAR_REGISTAR;
            }
            else if(p_event->data.error.error_mask == NRF_ERROR_TIMEOUT)
            {
                nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_RXTO);
            }
            else if(p_event->data.error.error_mask == NRF_ERROR_SVC_HANDLER_MISSING)
            {
                nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_ERROR);
            }
            else if(p_event->data.error.error_mask == NRF_ERROR_NO_MEM)
            { 
                nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_ERROR);
            }
            else
            {
                APP_ERROR_HANDLER(p_event->data.error.error_mask);
            }
        break;
    
        default:
        break;
    }
}

//Init.
void uart_co2_bsl_config(void)
{ 
    nrf_drv_uart_config_t config;
    config.pselrxd = UART_RX;
    config.pseltxd = UART_TX;
    config.pselrts = RTS_PIN_NUMBER;
    config.pselcts = CTS_PIN_NUMBER;
    config.baudrate = NRF_UART_BAUDRATE_115200
    config.hwfc = NRF_UART_HWFC_DISABLED;
    config.parity = NRF_UART_PARITY_EXCLUDED;
    config.interrupt_priority = APP_IRQ_PRIORITY_LOWEST;
    config.p_context = NULL;
    
    APP_ERROR_CHECK(nrf_drv_uart_init(&config, uart_handler));
}

[Susheel Nuguru]

Upvoted, 10 points for your calm explanation.

Sorry, as you said, we were going in wrong direction. And thanks for bringing me back : )

here is no direct way to flush the RX hardware fifo. But you can try something I mentioned in this post which helped few.

or

You can manually read the RXD register 6 times to force clear the fifo (irrespective of the how many bytes were received).

[KoFuKu]

Thank you for quick response. This is exactly what i needed to hear.