overrun error when receiving data from UARTE

Question

Hi, 
 I have problem with using nrf_serial.h, I am receiving data from Ublox GPS, baud rate = 9600, no flow control as we dont have enough IO pins. 
 Device is nrf52840 with SDK 16.0. I am using SERIAL_MODE_DMA, SERIAL_BUFF_RX_SIZE = 128, SERIAL_FIFO_RX_SIZE = 4096. 
 I am constantly getting NRF_SERIAL_EVENT_DRV_ERR events (overrun) even if fifo is empty (see picture below). If i get NRF_SERIAL_EVENT_RX_DATA event I set a flag and call nrf_serial_read in task as i dont want to spend too much time in IRQ.

lukavr · Accepted Answer

Hi, 
 No I print string on USB (similar to USB cdc acm example). Event handler is very simple, I would send received data to queue which is processed by task, but there is same problem if I just print random string. 
 Best regards 
 Luka 
 void uart_event_handler_modem(void * context, nrf_libuarte_async_evt_t * p_evt)
{
 ret_code_t ret;

 switch (p_evt->type)
 {
 case NRF_LIBUARTE_ASYNC_EVT_ERROR:
 {
 
 }

 break;
 case NRF_LIBUARTE_ASYNC_EVT_RX_DATA:
 {

 console("random string
"); 
 nrf_libuarte_async_rx_free(&libuarte2, p_evt->data.rxtx.p_data, p_evt->data.rxtx.length);

 }
 break;
 case NRF_LIBUARTE_ASYNC_EVT_TX_DONE:
 {

 }
 break;
 case NRF_LIBUARTE_ASYNC_EVT_OVERRUN_ERROR:
 {
 
 }
 break;
 default:
 break;
 }
}

ovrebekk · Answer

Hi 
 And how is the console(..) function implemented? 
 Could you try to set a flag in the event handler and call console(..) from the main context instead, and see if this works better? 
 Best regards Torbjørn

lukavr · Answer

Hi, 
 Problem is solved, thank you so much for your help. 
 I was using non thread safe FreeRTOS function inside ISR and that caused a problem. 
 Best regards, 
 Luka

overrun error when receiving data from UARTE

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