app_uart_init() function error:

Question

Hello, 
 I wanted to add uart in ble_custom_template project. I have added UART and FIFO Libraries in User include Libraries. Also i set the bits for uart in sdk_config.h. Still I get following error. 
 Linking xyz.elf Output/Release/Obj/smart_cap_v1/modbus_handle.o: in function `uart_init': undefined reference to `app_uart_init' Build failed 
 I read other Q and A also as lot of people have this error. But didnt get promisable answer. Please guide me for the same. 
 
 Thank you in advance. 
 Regards.

chinmaydixit · Answer

Hello,

I solved the problem by adding some macro definations from uart example to my project which are not in my project. It solved my error. But right now, I have a problem with app_uart_get function though I can see the data on RX pin. Also it seems NRF_DRV_UART_EVT_RX_DONE is generated.

void data_send_uart(uint8_t slaveaddress,uint8_t fn_code,uint16_t start_address,uint16_t number_of_pts)
{
  char crc_data[2]={0};
  uint8_t data_write[8];
  uint8_t len,Index=0;
  unsigned char CRCLo = 0xff;
  unsigned char CRCHi = 0xff;
  unsigned char *puchMsg;
  uint16_t crc;

  data_write[0]=slaveaddress;
  data_write[1]=fn_code;
  data_write[2]=start_address/256;
  data_write[3]=start_address%256;
  data_write[4]=number_of_pts/256;
  data_write[5]=number_of_pts%256;

  

  len=sizeof(data_write)-2;
  puchMsg= data_write;
  while(len--)
  {
    Index = CRCLo ^ *puchMsg;
    puchMsg++;
    CRCLo = CRCHi ^ auchCRCHi[Index];
    CRCHi = auchCRCLo[Index];
  }

  data_write[6]=CRCLo;
  data_write[7]=CRCHi;

  printf("CRC Low Byte : %x\n",data_write[6]);
  printf("CRC High Byte : %x\n",data_write[7]);

  printf("data sent :\n");
  for(int i=0;i<sizeof(data_write);i++)
  {
    printf("%x\n",data_write[i]);
  }

    uint8_t i;
    for(i = 0; i < sizeof(data_write); i++)
    {
        while (app_uart_put(data_write[i]) != NRF_SUCCESS);
    }
}

static void on_read(ble_cus_t * p_cus, ble_evt_t const * p_ble_evt)
{
    uint32_t time = 0;
    ret_code_t err_code;
    char rx_data[8];
    ble_gatts_evt_rw_authorize_request_t  req = p_ble_evt->evt.gatts_evt.params.authorize_request;

    data_send_uart(21,4,0,1);
    nrf_delay_ms(500);
    
    //while(uart_received_flag==0);
    uart_received_flag=0;
    //err_code=app_uart_get(rx_data[0]);
    
    for(int i=0;i<8;i++)
    {
        err_code=app_uart_get(&rx_data[i]);
        printf("error code %d",err_code);
        APP_ERROR_CHECK(err_code);
    }
    
    

    printf("Rx data :%s",rx_data);
    
    



    if(req.type == BLE_GATTS_AUTHORIZE_TYPE_READ){
        ble_gatts_rw_authorize_reply_params_t response;
        response.params.read.gatt_status = BLE_GATT_STATUS_SUCCESS;
        response.type = BLE_GATTS_AUTHORIZE_TYPE_READ;
        response.params.read.update = 1;
        response.params.read.offset = 0;
        response.params.read.len =strlen(data);
        response.params.read.p_data = (uint8_t *)data;

        err_code=sd_ble_gatts_rw_authorize_reply(p_ble_evt->evt.gatts_evt.conn_handle, &response);
        APP_ERROR_CHECK(err_code);
        //NRF_LOG_INFO("Reply function responded with: %d", err_code);
    }
}


This is my OnRead Function when there is a read Command and on which we respond to that command

sd_ble_gatts_rw_authorize_reply function. In this function I am sending some MODBUS Data to my 
controller (right now i am just shorting TX and RX for testing) and trying to get the data which
will be present in RX_FIFO and for that, i am using app_uart_get. But everytime I get ERROR CODE 5
which is NRF_ERROR_NOT_FOUND. Please guide me.
Thank you so much.

Regards.