/****************************************************
 * This program will send commands to the uC         *
 * programmed with the atmega168-thermo program and  *
 * echo characters from the microcontroller terminal *
 * device to stdout until the process is terminated  *
 * by a signal. The default terminal is "/dev/ttyS0  *
 * This program is similar to the serial.c program   *
 * except this program will interpret the messages   *
 * received by the device, namely the temperature    *
 * conversion results                                *
 ****************************************************/

#define _GNU_SOURCE 1 /* use GNU extensions (usleep) */

#include <fcntl.h>
#include <inttypes.h>
#include <unistd.h>
#include <termios.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <features.h>
        
#define BAUDRATE B9600
#define MODEMDEVICE "/dev/ttyUSB0"

     
int main( int argc, char** argv ) {
  int device_fd;
  int16_t int_temp;
  float float_temp;
  struct termios device_oldtio, device_newtio;
  uint8_t c[11];
  time_t raw_time;
  struct tm * str_time;
  char chr_time[80];

  device_fd = open( argc>1?argv[1]:MODEMDEVICE, O_RDWR | O_NOCTTY ); 
  if (device_fd <0) { perror(argc>1?argv[1]:MODEMDEVICE); exit(1); }

  tcgetattr(device_fd, &device_oldtio);

  memset(&device_newtio, '\0', sizeof(device_newtio));

  device_newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD;
  device_newtio.c_iflag = IGNPAR;
  device_newtio.c_oflag = 0;
        
  /* set input mode (non-canonical, no echo,...) */
  device_newtio.c_lflag     = 0;         
  device_newtio.c_cc[VTIME] = 0;    /* inter-character timer * 0.1s */
  device_newtio.c_cc[VMIN]  = 11;   /* blocking read until 1 chars received */
  tcsetattr(device_fd,TCSANOW, &device_newtio);
 
  while (1) { 
    tcflush(device_fd, TCIFLUSH);
    write(device_fd, "T", 1);
    read(device_fd, c, 11);  
    int_temp  = 0;
    int_temp |= ((unsigned int) c[1]);
    int_temp |= ((unsigned int) c[2]) << 8;
    
    float_temp = int_temp * 0.0625;
    time(&raw_time);
    str_time = localtime(&raw_time);
    strftime(chr_time, 80, "%c", str_time);
    printf("Time: %s C: %f F: %f\n", chr_time, float_temp, (float_temp*9.0/5.0)+32);
    sleep(1);
  }

  tcsetattr(device_fd,TCSANOW,&device_oldtio);
  close(device_fd);
  return(0);
}