How to recover from nrf_serial driver errors?

RE: How to recover from nrf_serial driver errors?

mzarling — Thu, 12 May 2022 17:01:07 GMT

I had to implement this fix, but found that a delay was necessary between the nrf_serial_uninit(p_serial); and uart_init();

If this delay was not present, then frequently a NRF_SERIAL_EVENT_RX_DATA event would occur with a byte in the receive FIFO after the uart_init();

Has anyone else seen this?

RE: How to recover from nrf_serial driver errors?

droghio — Sat, 27 Oct 2018 17:01:14 GMT

A brief overview is available in the SDK documentation: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk52.v0.9.2%2Fmodules.html

DMA and IRQ functionality is similar, but I believe DMA reduces CPU loading as it can directly dump the results into RAM. Perhaps someone else will be able to offer a better comparison between the two.

RE: How to recover from nrf_serial driver errors?

Glen M — Sat, 27 Oct 2018 14:48:09 GMT

That works - thanks! Also, I didn't realize that DMA was an option for the serial port. How do I know whether I should use DMA mode or IRQ mode? What are the tradeoffs?

RE: How to recover from nrf_serial driver errors?

droghio — Sat, 27 Oct 2018 01:48:22 GMT

The easiest way is to add a listener for the error event and use it to reinitialize the Serial Driver.

Depending on how you have setup the driver it can be as easy as:

// If you already have an event callback you just need to add another case.
// I have omiited the lines where I setup the queue and buffer because it
// doesn't seem applicable to your question.
NRF_SERIAL_CONFIG_DEF(serial_config, NRF_SERIAL_MODE_DMA,
                      &serial_queues, &serial_buffs, &uart_event_handle, NULL);

// Skip a few lines...

void uart_event_handle(struct nrf_serial_s const* p_serial, nrf_serial_event_t event){
    switch (event){
        case NRF_SERIAL_EVENT_DRV_ERR:
            NRF_LOG_INFO("Serial driver error handler");
            uint32_t error;
            if(NRF_UART0->EVENTS_ERROR !=0)
            {
                error = NRF_UART0->ERRORSRC;
                NRF_LOG_INFO("Serial driver err: %d", error);
                NRF_UART0->EVENTS_ERROR = 0;
            }

            nrf_serial_uninit(p_serial);
            
            uart_init(); // <-- The function you use to configure the uart driver.
            break;
    }
}