1.c

#include "p1.h"
#include "flex_lcd.c"

/////////////*FUNCTION DECLARATIONS*///////////////
void init_pic();                                                           
void setTimer();                                                       
int checkTimer();                                                       
void rayCrossed_isr();                           
void clock_isr();                                
int32 convertToCelsius();                        
int convertToASCII(int16 number);                
void lcd_display(int16 number, int x, int y);    
void initialDisplay();                           
int16 read_temperature();                        
void lcd_display_temperature();                  
void phaseControl();                             
///////////////////////////////////////////////////

/////////////////*GLOBAL VARIABLES*/////////////////////////////////////////////////
int16 noOfPeople = 3;    // Number of people inside the room                      
int int_count;         // Number of interrupts left before a second has elapsed   
int unitsPosition, tensPosition, hundredsPosition;                                
                                                                                  
int1 rayOne = 0;       // to record when first beam get crossed                   
int1 rayTwo = 0;       // to record when second beam get crossed                  
int1 pin_changed = 1;                                                             
int1 number_changed = 1;                                                          
                                                                                  
int16 mseconds =0;                                                                
int16 counter_for_temp=0 ;                                                        
                                                                                  
int16 temperature=27;                                                             
                                                                                  
int16 t;           // The A/D conversion of the analog input                      
                   // signal results in a corresponding 10-bit digital number.    
                   // this variable is to store that                              
////////////////////////////////////////////////////////////////////////////////////

void main()
{
   init_pic();

   initialDisplay();

      /* only if the number of people changes the value shown in lcd is changed.
      And temperature is updated when counter_for_temp overflows.*/
       while(1)
       {
         phaseControl();
         if(number_changed)
         {
            lcd_display(noOfPeople,14,1);
            number_changed = 0;
         }

         if(counter_for_temp == 65535)
         {
            lcd_display_temperature();
            counter_for_temp=0;
         }
         counter_for_temp++;
       }
}

/* when timer0 counter overflows(0-255) an interrup occurs. int count which is initially
 * set to INTS_PER_mS, is decremented by 1 inside the isr.
 * When int_count reaches 0, no of miliseconds is incremented by 1
 */
#int_RTCC
void clock_isr() {

    if(--int_count==0)
    {
      ++mseconds;
      int_count=INTS_PER_mS;
    }
}

//Whenever a beam get crossed this isr is invoked.
#int_EXT
void rayCrossed_isr()
{
   if(INPUT(PIN_B2))
   {
      rayTwo = 1;
      if(checkTimer() == 2 && rayOne == 1)
      {
         rayOne = 0;
      }
      if(rayOne == 1)
      {
         if(checkTimer() == 1)
         {
            noOfPeople++ ;
            number_changed = 1;
         }
         rayOne = 0;
         rayTwo = 0;
      }
      setTimer();
   }
  else if(INPUT(PIN_B1))
   {
      rayOne = 1;
      if(checkTimer() == 2 && rayTwo == 1)
      {
         rayTwo = 0;
      }
      if(rayTwo == 1)
      {
         if(checkTimer() == 1 && noOfPeople>0)
         {
            noOfPeople-- ;
            number_changed = 1;
         }
         rayOne = 0;
         rayTwo = 0;
      }
      setTimer();
   }
 }


void setTimer()
{
   int_count=INTS_PER_mS;
   set_timer0(0);
   mseconds=0;
}


/* When both rayOne =1 and rayTwo = 1, this is called */
int checkTimer()
{
   if((mseconds <= MAX_CROSSING_TIME) && (mseconds >= MIN_CROSSING_TIME))
   {
      return 1;
   }

   else if(mseconds > MAX_CROSSING_TIME)
   {
      return 2;
   }
    else
   {
      return 0;
   }
}

int32 convertToCelsius()
{
   return (t*150)/307;
}

void lcd_display_temperature()
{
          temperature =read_temperature();
          lcd_display(temperature,13,2);
}

int convertToASCII(int16 number)
{
   return (number+48);
}

void lcd_display(int16 number, int x, int y)
{
   int unitsPosition, tensPosition, hundredsPosition;

       unitsPosition =number % 10;
       tensPosition = ((number - (number % 10))%100)/10;
       hundredsPosition = ((number - (number%100))%1000)/100;

       lcd_gotoxy(x,y);
       lcd_putc(convertToASCII(hundredsPosition));
       lcd_putc(convertToASCII(tensPosition));
       lcd_putc(convertToASCII(unitsPosition));
}

int16 read_temperature()
{
    delay_us(12);                  //a small delay is required after setting the channel
    t = read_adc();
    return convertToCelsius();
}

void initialDisplay()
{
     delay_ms(25);
     lcd_init();

     lcd_gotoxy(1,1);
     lcd_putc("SYSTEM STARTED..");
     lcd_gotoxy(1,2);
     lcd_putc("================");
     delay_ms(500);
     lcd_gotoxy(1,1);
     lcd_putc("\fNumberInside:");
     lcd_display(noOfPeople,14,1);
     lcd_gotoxy(1,2);
     lcd_putc("Temperature:   C");

}

void init_pic()
{
   setup_adc_ports(AN0);
   setup_adc(ADC_CLOCK_DIV_32);
   setup_psp(PSP_DISABLED);
   setup_spi(FALSE);
   setup_counters( RTCC_INTERNAL, RTCC_DIV_1 | RTCC_8_BIT);
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);
   setup_comparator(NC_NC_NC_NC);
   setup_vref(FALSE);
   enable_interrupts(INT_RTCC);
   enable_interrupts(INT_EXT);
   enable_interrupts(GLOBAL);

   EXT_INT_EDGE(L_TO_H);

   OUTPUT_B(0);
   OUTPUT_C(0);

   SET_TRIS_B(0b01000111);   //pins B0, B1, B2 and B6 are set to give inputs. B0 is the external interuupt pin
                             //B0, B1 & B2 are used for people counting. B6 for zero crossing detection in fan controlling
   SET_TRIS_C(0b00000000);
   SET_TRIS_D(0b00000000);   //D port except D0 pin, is used for lcd panel

   set_adc_channel(0);            //the next read_adc call will read channel 0
}

/*
   the fan is controlled using phase control method.
   Fan is on only if the number of people >0
*/
void phaseControl()
{
   switch(noOfPeople)
   {
      case 0: OUTPUT_HIGH(PIN_B7);
              break;

      default:
       if(INPUT(PIN_B6) && pin_changed == 1)
      {
         if(0<=temperature && temperature<20)
         {
            OUTPUT_HIGH(PIN_B7);
         }
       else if(temperature>=20&& temperature<23)
       {
            delay_us(6000);
            OUTPUT_LOW(PIN_B7);
            delay_us(500);
            OUTPUT_HIGH(PIN_B7);
       }
       else if(temperature>=23 && temperature<25)
       {
            delay_us(5000);
            OUTPUT_LOW(PIN_B7);
            delay_us(500);
            OUTPUT_HIGH(PIN_B7);
       }
       else if(temperature>=25 && temperature<27)
       {
            delay_us(4500);
            OUTPUT_LOW(PIN_B7);
            delay_us(500);
            OUTPUT_HIGH(PIN_B7);
       }
      else if(temperature>=27 && temperature<30)
       {
            delay_us(4000);
            OUTPUT_LOW(PIN_B7);
            delay_us(500);
            OUTPUT_HIGH(PIN_B7);
       }
       else if(temperature>=30)
       {
            OUTPUT_LOW(PIN_B7);
       }
        pin_changed = 0;
      }

   if(!INPUT(PIN_B6))
   {
      pin_changed = 1;
   }
   }
}