toaster.c

Program for polling toaster for temperature and writing to standard output.

/* File:   toaster.c
   Date:   8 October 2004
   Description: Program for polling toaster for temperature
                and writing to standard output.  */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "serial.h"

/* wait_for_prompt: wait for the toaster ready to recceive the
*  common.*/
void wait_for_prompt(FILE *port)
{
    char ch;
    // check until the toaster send '>' to the computer
    do{
        ch = fgetc(port);
    }
    while(ch != '>');
}
/* getTemperature: Get the digital temputer from the toaster.*/
float getTemperature (FILE *port, int channel)
{
    char buffer[10];
    float temperature;
    while(1)
    {
        // Ask for temperature from channel.
        fprintf(port,"T%d\n",channel);
        fflush (port);
        // waitting for the temperature line
        fgets (buffer,10,port);
        fgets (buffer,10,port);
        if (sscanf(buffer,"T%d %f",&channel,&temperature) == 2)
            return temperature;
    }
}

/* store_temp: store the latest temperature sample 'latest' in the
* array 'temp_buffer', which has 'length' elements. All previous
* temperatures are moved to the next higher subscript and the
* oldest is lost. */
void store_temp (float *temp_buffer, unsigned int length, float latest)
{
    int i;
    for (i = 1; i < length; i++)
        temp_buffer[i] = temp_buffer[i - 1];
    temp_buffer[0] = latest;
}
/* Decide the heater heating rate.
   Details described in the report*/
int heaterSet (float *temp_buffer,float setpoint_temperature,float temperature)
{
    int heater_setting;
    float distance = 1;
    float agnle = 1;
    int turbo = 250;
    float temp_rate = (3*temp_buffer[0]-4*temp_buffer[1]+temp_buffer[2])/2;

    distance = (setpoint_temperature - temperature)/(setpoint_temperature -25);
    agnle = (0.35 - temp_rate) / 0.35;
    if (temperature < 25)
        heater_setting = 100;
    else if (distance < -0.06)
        heater_setting = 0;
    else if (distance < 0.15 )
    {
        if (temp_rate > 0)
            heater_setting = 3;
        else if (temp_rate > -0.02)
            heater_setting = distance*((25-12)/0.1) + 12;
        else if (temp_rate < -0.35)
            heater_setting = 100;
        else
            heater_setting = (temp_rate + 0.02)/(-0.03 + 0.02)*(30 - 20);
    }
    else
    {
        if (temp_rate > 0.35 )
            heater_setting = 0;
        else
            heater_setting = turbo * distance * agnle;
    }
    // make sure the heat rate is legal!
    if (heater_setting > 100)
        return 100;
    else if(heater_setting < 0)
        return 0;
    else
        return heater_setting;
}
/* use the heater heating rate to heat the toaster.*/
void heating (FILE *port, int channel,int heater_setting)
{    
    char buffer[10];
    // send the common to the toaster.
    fprintf(port,"H%d %d\n",channel,heater_setting);
    fflush (port);
    // wait for the information send by the toaster.
    fgets (buffer,10,port);
    fgets (buffer,10,port);
}
/* Print out the data to a file.*/
void output (FILE *out_file, int heater_setting, float temperature)
{
    fprintf(out_file,"%d %2.2f\n",heater_setting,temperature);
    fflush (out_file);    
}
/* wait for the delay time (1 second).*/
void delay(int delay)
{
    time_t ref_time = time(NULL);
    while (difftime(time(NULL),ref_time) < delay){}
}

int main (int argc, char **argv)
{
    FILE *serial;
    FILE *out_file;
    float setpoint_temperature = 40;
    float start_temperature = 25;
    int num_temp_sample = 300;
    int channel = 0;
    char *serial_devicename = "/dev/com2";
    char *output_filename = "temp.dat";
    float temperature;
    float temp_buffer[3];
    int heater_setting = 100;
    // check the length of argv.
    if (argc != 7)
    {
        fprintf(stderr, "The arguments are too few OR too more!!!\n");
        return 1;
    }
    //store the argv to the variable
    else
    {
        setpoint_temperature = atof(argv[1]);
        start_temperature = atof(argv[2]);
        num_temp_sample = atoi(argv[3]);
        channel = atoi(argv[4]);
        serial_devicename = argv[5];
        output_filename = argv[6];
    }
    
    if(setpoint_temperature < 25 || setpoint_temperature > 50)
    {
        fprintf(stderr, "The setpoint temperature %2.2f is out of range.\n"
                        ,setpoint_temperature);
        return 2;
    }    
    else if (start_temperature < 25 || start_temperature > 50)
    {
        fprintf(stderr, "The start temperature %2.2f is not correct.\n"
                        ,start_temperature);
        return 3;
    }
    else if (num_temp_sample <= 0 || num_temp_sample >=1000)
    {
        fprintf(stderr,"The number of temperature is out of range");
        return 4;
    }
    else if ( channel < 0 || channel >15)
    {
        fprintf(stderr,"Out of the channel range.");
        return 5;
    }
    
    /* Open stream for reading and appending.  */
    serial = fopen (serial_devicename, "a+");
    if (!serial)
    {
       fprintf (stderr, "Could not open %s\n.", 
          serial_devicename);
       return 6;
    }
    /* Configure serial port for 9600 baud.  */
    if (!serial_configure (serial, 9600))
    {
       fprintf (stderr, "Could not configure %s\n.", 
          serial_devicename);
       return 6;
    }
    
    out_file = fopen(output_filename,"a+");
    if (!serial)
    {
       fprintf (stderr, "Could not open %s\n.", 
          output_filename);
       return 7;
    }
    
    // check if the toaster is ready.
    fprintf(serial,"\n");
    fflush (serial);
    wait_for_prompt(serial);
    while (1)
    {
        // get the temperature.
        temperature = getTemperature (serial, channel);
        // check the prompt, if ready for next time.
        wait_for_prompt(serial);
        // store the last 3 temperatures to buffer.
        store_temp (temp_buffer, 3, temperature);
        // set the heating rate.
        heater_setting = heaterSet (temp_buffer,setpoint_temperature,temperature);
        // print the data to the screen.
        printf("%3d\t%2.2f\n",heater_setting,temperature);
        // heat the toaster.
        heating (serial, channel,heater_setting);

        // record the data to a file after the temperature reach
        // the start_temperature.
        if (temperature >= start_temperature)
        {
            output (out_file, heater_setting, temperature);
            num_temp_sample --;
          }
        // stop the program when record the num_temp_sample.
         if (num_temp_sample == 0)
             break;
         delay(1);
    }
    fclose (out_file);
    fclose (serial);
    return 0;
}