Libuarte and GPS

RE: Libuarte and GPS

Jørgen Holmefjord — Thu, 22 Jul 2021 13:08:13 GMT

The only thing I can think of is to use strchr() to look for the first instance of '\n' character, and copy the string from start og buffer until the pointer where the '\n' character was found using memcpy().

RE: Libuarte and GPS

dariusBotha — Wed, 09 Jun 2021 13:38:33 GMT

Thank you, Jorgen, that worked:)

Is there a way to handle the data up to the "\n" character? so that it keeps filling the uart0_array[] with the data from the GPS until the "/n" character is reached and then break or copy the whole string to another buffer so I can process it?

Because I tried the following (sprintf() and memcpy()) and get the string up to "/n" but after3-4 seconds I get a HardFault_Handler: error.

NRF_LIBUARTE_ASYNC_DEFINE(libuarte, 0, 0, 0, NRF_LIBUARTE_PERIPHERAL_NOT_USED, 255, 5);


typedef struct {
    uint8_t * p_data;
    uint32_t length;
} buffer_t;
//NRF_QUEUE_DEF(buffer_t, m_buf_queue, 10, NRF_QUEUE_MODE_NO_OVERFLOW);
NRF_QUEUE_DEF(buffer_t, m_buf_queue, 10, NRF_QUEUE_MODE_NO_OVERFLOW);


uint8_t uart0_array[500]; //buffer to copy uart data to


void uart_event_handler(void * context, nrf_libuarte_async_evt_t * p_evt)
{
    nrf_libuarte_async_t * p_libuarte = (nrf_libuarte_async_t *)context;
    
    static uint8_t data_array[100];
    static uint16_t index = 0;
    
    switch(p_evt->type)
    { 
      case NRF_LIBUARTE_ASYNC_EVT_RX_DATA:
      {
        strcat(data_array,p_evt->data.rxtx.p_data);
        index++;

      if ((data_array[index] == '\n') ||
          (data_array[index - 1] == '\r'))
      {

          //memcpy(uart0_array,data_array,sizeof(data_array));
          sprintf(uart0_array, "%s", data_array);
          nrf_libuarte_async_rx_free(p_libuarte, p_evt->data.rxtx.p_data, p_evt->data.rxtx.length);
            


          index = 0;
      }


          //sprintf(byte,"%s",p_evt->data.rxtx.p_data);
          //strcat(uart0_array,p_evt->data.rxtx.p_data);
          
          //nrf_libuarte_async_rx_free(p_libuarte, p_evt->data.rxtx.p_data, p_evt->data.rxtx.length);
      }break;
      case NRF_LIBUARTE_ASYNC_EVT_ERROR:
      {
          //printf("\nUART ERROR: %d", p_evt->data.errorsrc);
      }break;
      case NRF_LIBUARTE_ASYNC_EVT_OVERRUN_ERROR:
      {
          //printf("\nUART OVERRUN ERROR");
      }break;
      
    }
}

Thanks for your help so far.

RE: Libuarte and GPS

Jørgen Holmefjord — Wed, 09 Jun 2021 13:28:02 GMT

Hi,

Why do you send the data one and one byte at a time?

You should be able to write the full TX buffer like this:

//Function to send via UART
void send_UART(char *sdata, int len)
{
    ret_code_t ret;
    ret = nrf_libuarte_async_tx(&libuarte, sdata, len);
    
    APP_ERROR_CHECK(ret);
}

Note that you can only start a single transfer at a time, if there is already an ongoing transfer, you will get the NRF_ERROR_BUSY return code.

You can use a do-while to do a blocking wait for the previous transfer to finish:

//Function to send via UART
void send_UART(char *sdata, int len)
{
    ret_code_t ret;
    do {
        ret = nrf_libuarte_async_tx(&libuarte, sdata, len);
    while (ret == NRF_ERROR_BUSY);
    
    APP_ERROR_CHECK(ret);
}

Not sure where you get the NRF_ERROR_NO_MEM return code from, this does not seem to be a valid return code from the nrf_libuarte_drv_tx() function.

To look for a substring in a string, you can use strstr() function. Note that the string function may take long time to process, you should consider doing this outside of the interrupt/event handler, to allow other interrupts to be handled while processing strings.

Best regards,
Jørgen