temperature.c

#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <time.h>


int main(void) {
  DIR *main_dir;
  FILE *temp_file;
  struct dirent *read_dir;
  char devices_folder[20] = "/sys/bus/w1/devices";
  char dev_folder[16];
  char full_path[128];
  char buf[256];
  size_t nread;
  char tmpData[6];

  main_dir = opendir(devices_folder);

  if (main_dir == NULL) {
    printf("Folder %s not found\n", devices_folder);
    return 1;
  }

  while ((read_dir = readdir(main_dir))) {
    // Look for device folders, start with 28-
    if (strstr(read_dir->d_name, "28-")) {
      strcpy(dev_folder, read_dir->d_name);
    }
  }
  closedir(main_dir);

  // Build the full path to the file where the read will be written
  sprintf(full_path, "%s/%s/w1_slave", devices_folder, dev_folder);

  while(1) {
    sleep(1);
    temp_file = fopen(full_path, "r");
    if(temp_file == NULL) {
      printf("Couldn't open the w1 device.\n");
      return 1;
    }
    while((nread = fread(buf, 1, 256, temp_file))) {
      strncpy(tmpData, strstr(buf, "t=") + 2, 5);
      printf("T: %s", tmpData);
      float tempC = strtof(tmpData, NULL);
      printf("Temp: %.3f C  ", tempC / 1000);
      printf("%.3f F\n\n", (tempC / 1000) * 9 / 5 + 32);
    }
    close(temp_file);
  } 

  return 0;
}