float ds18x20_temp_read( char *id, char family )
{
   FILE *f;
   char path[MAX_PATH_LEN];
   float value;

   sprintf( path, "%s/%02X.%s/temperature", OWFS_PATH, family, id );
   f = fopen( path, "r" );

   if ( f == NULL )
   {
      printf( "Error opening file %s for read!\n", path );
      return -1;
   }

   fscanf( f, "%f", &value );
   fclose( f );

   printf( "t: %f\n", value );
   return value;
}