APP_UART_COMMUNICATION_ERROR on handle

[diocorreia]

I'm having troubles parsing the received data stream form an UART device. If i just print whatever i received from the datastream, everything works just fine.

    if (p_event->evt_type == APP_UART_DATA_READY){
        app_uart_get(&rx);
        NRF_LOG_RAW_INFO("%c", rx);
        NRF_LOG_FLUSH();
    }

Howeve, if i try to store it in an external string and then print it , it returns APP_UART_COMMUNICATION_ERROR during reception.

    if (p_event->evt_type == APP_UART_DATA_READY){
        app_uart_get(&rx);
        if(rx == 0xD){
            buff[i] = (uint8_t)'\0';
            i = 0;
            NRF_LOG_RAW_INFO("%s", NRF_LOG_PUSH((char *)buff));
            NRF_LOG_FLUSH();
        }else{
            buff[i++] = rx;
        }
    }

[awneil]

What transport are you using for NRF_LOG ?

If it's UART, then NRF_LOG_FLUSH(); could take some time - and cause overrun in your data reception ... ?

diocorreia said:

it returns APP_UART_COMMUNICATION_ERROR

What is "it" ?

[diocorreia]

The project is based on the uart example (on peripheral) and uses RTT as NRF_LOG backend. The event handled by the function is from that type (APP_UART_COMMUNICATION_ERROR).

void uart_handle(app_uart_evt_t * p_event)
{
    uint8_t rx;
    if (p_event->evt_type == APP_UART_COMMUNICATION_ERROR)
    {
        //APP_ERROR_HANDLER(p_event->data.error_communication);
        NRF_LOG_RAW_INFO("APP_UART_COMMUNICATION_ERROR\n");
        NRF_LOG_FLUSH();
    }
    else if (p_event->evt_type == APP_UART_FIFO_ERROR)
    {
        //APP_ERROR_HANDLER(p_event->data.error_code);        
        NRF_LOG_RAW_INFO("APP_UART_FIFO_ERROR\n");
        NRF_LOG_FLUSH();
    } else if (p_event->evt_type == APP_UART_DATA_READY){
        app_uart_get(&rx);
        NRF_LOG_RAW_INFO("%c", rx);
        NRF_LOG_FLUSH();
        nrf_delay_ms(1000);
    }
}

[Karl Ylvisaker]

Hi,

Could you tell me what the value of the event's error_communication is?
It contains the value of the ERRORSRC register, which will give us a clearer picture of what is going on.

As Awneil suggests it might very well be that your RX buffer overflows, such as if app_uart_get() is not called often enough.

Best regards,
Karl

[diocorreia]

It is an overrun problem (communication_error = 1), how could i deal with these problem? Increase the size of UART buffer will solve the problem?

[Karl Ylvisaker]

The overrun error is commonly caused by overflowing the RX buffer.

Increasing the UART buffer might solve this, but not necessarily. It is likely that you will still be receiving at a faster frequency than you are processing the bytes, and therefore a larger buffer will only postpone the inevitable overrun error.
Most likely, you will need to either ensure that you call app_uart_get() more often or clear out/provide a new buffer every so often to prevent it from building up and exceeding its limit.
As Awneil suggested, you call to NRF_LOG_FLUSH might be the culprit here(if there is not more to the application than the code you shared earlier).

Best regards,
Karl