[NRF51822QFAC][SDK11] How to recover Uart errors

[Lalit Kumar]

Hi,

I'm trying to interface SIM808 with nrf51822 over uart using nrf_drv_uart. Everything works well for some time, but then uart starts reporting error code 1, NRF_UART_ERROR_PARITY_MASK, for all transactions on uart. Re-initializing the uart doesn't correct it. Also the time after which error starts appearing is also random, varies from 15 minutes to 1 hour. The problem is not with the module as when the error occurs, I can still communicate with the module using external uart to usb. Here is what I think is relevant information:

• Baudrate is 115200
• Tx is blocking
• Listen to rx for 20ms
• Max transaction size for rx is 10 bytes

I can upload the code, if necessary.

Hoping for a positive response and thanks in advance :)

[Susheel Nuguru]

When you get a parity error you will not get the RX complete event for that particular byte. You should do this in your uart event handler.

static void uart_event_handler(nrf_drv_uart_event_t * p_event, void* p_context)
{
   ...
   ...

    else if (p_event->type == NRF_DRV_UART_EVT_ERROR)
    {
        nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_TXDRDY);
        nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_RXTO);
        nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_ERROR);  /* thanks for correction Lalit*/
        nrf_drv_uart_uninit
        nrf_drv_uart_init
 
    }

   ...
   ...
}

[Lalit Kumar]

Works like a charm!!! Events clearing was the main issue. I'm still getting parity error on some commands but re-initializing the uart resolves it. Just a minor correction in your solution, a typo:

nrf_uart_event_clear(NRF_UART0, EVENTS_ERROR);

should be

nrf_uart_event_clear(NRF_UART0, NRF_UART_EVENT_ERROR);

[Susheel Nuguru]

good that it worked, thanks for fixing the typo. I have fixed the answer with your correction.

[Lalit Kumar]

Sorry, forgot to mark as answer. Done. And thanks for help.