1.1.Read_data.c

// create file data.txt in the folder with the script 

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "spi.h"
#include "gpio.h"
#include <unistd.h>

int main(void) 
{      
    gpio_t *gpio_in;
    gpio_in = gpio_new();
    gpio_open (gpio_in, "/dev/gpiochip0", 26, GPIO_DIR_IN);

    spi_t *spi;
    spi = spi_new();
    int spi_open = spi_open_advanced(spi, "/dev/spidev0.0", 0x01, 1000000, MSB_FIRST, 8, 1);
        if (spi_open == 0)
        {
             printf("spi_open_error"); 
        }
        
        
    void write_reg(uint8_t reg_address, uint8_t val_hex)
           {
           uint8_t zero3[3] = {0x00, 0x00,0x00}; 
           uint8_t reg_address_shift = 0x40 | reg_address;
           uint8_t write [3] = {reg_address_shift, 0x00,val_hex};
           int spi_reg = spi_transfer (spi, write, zero3, 3);
             if (spi_reg == 1)
             {
             printf("spi_reg_error"); 
             }
             
           }
    void send_command(uint8_t command)
           {
           uint8_t zero1[1] = {0x00};
           uint8_t write_command [1] = {command};
           int spi_com = spi_transfer (spi, write_command, zero1, 1);
            if (spi_com == 1)
             {
             printf("spi_com_error"); 
             }
           }        
          write_reg (0x14,0x80);//led
          write_reg (0x05,0x00);//ch1
          write_reg (0x06,0x01);//ch2
          write_reg (0x07,0x01);//ch3
          write_reg (0x08,0x01);//ch4
          write_reg (0x09,0x01);//ch5
          write_reg (0x0A,0x01);//ch6
          write_reg (0x0B,0x01);//ch7
          write_reg (0x0C,0x01);//ch8
          write_reg (0x15,0x20);// mics
          write_reg (0x01,0x96);// reg1
          write_reg (0x02,0xD4);// reg2
          write_reg (0x03,0xE0);// reg3
          send_command (0x10);//sdatc
          send_command (0x08);//start

uint8_t buf[27] = {0}; 
float package [8]={0};   
uint32_t data_test = 0x7FFFFF;
uint32_t data_check = 0xFFFFFF;
uint8_t zero27[27] = {0x00}; 
// int count = 0;

int gpio_edge = gpio_set_edge (gpio_in, GPIO_EDGE_FALLING);  
        if (gpio_edge == 0)
        {
             printf(" GPIO_EDGE_FALLING_error"); 
        }
int timeout_ms = 1000;
FILE *file = fopen("data.txt", "w");
fprintf(file,"ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch8\n");
while (1)  
 {      usleep(100); 
        int gpio_res = gpio_poll (gpio_in, timeout_ms);  
      
        if (gpio_res == 1)
        {   //usleep(100); 
            gpio_edge_t edge = GPIO_EDGE_NONE;
            gpio_res = gpio_read_event (gpio_in, &edge, NULL);
            
            int spi_send = spi_transfer (spi, zero27, buf, 27);
             if (spi_send == 1)
             {
             printf("spi_send_error"); 
             }
                 // count=count+1;
                 // fprintf(file, "%d", count);
      
                 for (int i = 1; i<9; i++)  
                {
                                
                int offset = 3*i;
                uint32_t voltage = (buf[offset] << 8) | buf[offset+1];
                voltage = (voltage << 8) | buf[offset+2];
                uint32_t voltage_test = voltage | data_test;

                    if (voltage_test == data_check)
                    {
                    voltage = 16777214 - voltage;                   
                    }

                  package[i-1]=0.27*voltage;   // (4.5*1000000/16777214)=0.27 
                 // fprintf(file,"data");
                //   fprintf(file," ");
                  fprintf(file, "%.1f", package[i-1]);
                  fprintf(file," ");
                } 
                  fprintf(file,"  \n");
             
            printf("%.1f\n", package[0]); // 0 - first chanel
      }
      else
      { 
          printf("ADS1299 dont send data");
      }  
      
 }
  spi_close(spi);
  spi_free(spi);
  gpio_close(gpio_in);
  gpio_free(gpio_in);
  fclose(file);
return 0;
}