error codes for APP_UART_COMMUNICATION_ERROR

[ms360]

I'm seeing a few of these errors in my uart evt handler

I cannot seem to find where these are enumerated in app_uart_fifo.c or nnrf_drv_uart.h or nrfx_uarte.h.

Question 1 - Where can I find these?  

<error> app: APP_UART_COMMUNICATION_ERROR : 1 00
<error> app: APP_UART_COMMUNICATION_ERROR : 5 00
<error> app: APP_UART_COMMUNICATION_ERROR : 4 00

Here is the code generating that log - 

NRF_LOG_ERROR("APP_UART_COMMUNICATION_ERROR : %d %02x", p_event->data.error_code, NRF_UARTE0->ERRORSRC);

When this happens, I try to run

app_uart_flush();

app_uart_close();

APP_UART_FIFO_INIT();

Question 2 - Is there a better way to recover? 

Thanks!

[ms360]

Yup!

Just to note - I am seeing some overruns. Data is definitely getting lost

<error> app: APP_UART_COMMUNICATION_ERROR : 1 01
<error> app: APP_UART_COMMUNICATION_ERROR : 1 00

static void uart_handler(app_uart_evt_t *p_event) {
    switch (p_event->evt_type) {
        case APP_UART_DATA_READY: {
            uint32_t ret;
            do {
                ret = app_uart_get(&(rx_buf[rx_tail]));
                if (NRF_SUCCESS == ret) {
                    rx_tail++;
                    rx_tail %= UART_RX_BUF_SIZE;
                } else {
                    // NRF_LOG_ERROR("ret: %02x", ret);
                }
            } while (ret == NRF_SUCCESS);
        
            app_sched_event_put(NULL, 0, process_data);    
            break;
        }
        case APP_UART_COMMUNICATION_ERROR:
            NRF_LOG_ERROR("APP_UART_COMMUNICATION_ERROR : %d %02x", p_event->data.error_code, NRF_UARTE0->ERRORSRC);
            app_uart_flush();
            Flush_Uart();
            uart_busy = 0;
            break;
        case APP_UART_FIFO_ERROR:
            NRF_LOG_ERROR("APP_UART_FIFO_ERROR");
            break;
        case APP_UART_TX_EMPTY:
            break;
        case APP_UART_DATA:
            NRF_LOG_ERROR("APP_UART_DATA");
            break;
        default:
            NRF_LOG_ERROR("default");
    } 
}

[Vidar Berg]

Thank you. I see the problem now. So ERRORSRC register is being cleared from the nrfx_uarte.c->uarte_irq_handler() handler before it calls your uart_handler():

So the UART and the app are basically not able to keep up with the reception speed. Is using HW flow control an option?

[ms360]

unfortunately there is no HW flow control. 

[ms360]

Just to expand, I'm running at 115200 baud, and I'm sending 8 bytes every 100ms, and about 21ms later, I receive 66 bytes. This does not seem like a lot to cause an overrun. 

[Vidar Berg]

I would recommend considering the Libuarte - advanced UARTE driver in that case. It allows you to work with larger DMA buffers in addition to supporting double buffering. The /examples/peripheral/libuarte example demonstrates how the driver can be integrated.