#include "18F2525.h"

#fuses HS,NOWDT,NOPROTECT,NOLVP,INTRC

#use delay(clock=8000000)

#include "M:\PIC\Photogate timer with LCD\flex_lcd_photogate_final.c"
//==========================

int1 button, timer_en;  //button used for ready button polling, timer_en used for ext interrupt first run, second run
int1 donebit = 0;  //donebit used to end mid-sampling loop
long count, time, rem, divtest;  //count is count of timer overflows, time is ms, rem is us, divtest is for adjustment


#int_timer0
void  timer_isr()
{
   count++;
  // waste = 0;

   set_timer0(108);
}

#int_ext
void ext_isr()
{
       timer_en = !timer_en;

       if(timer_en == 0)
       {
          enable_interrupts(int_timer0);
          ext_int_edge(H_TO_L);

          donebit = 0;
       }
       else if(timer_en == 1)
       {
          disable_interrupts(int_timer0);
          donebit = 1;
       }
}

readyprep()
{
   count = 0;  //reset count
   timer_en = 1;

   lcd_putc("\fReady\b"); // LCD ready indicator

   ext_int_edge(L_TO_H);

   enable_interrupts(int_ext);
   enable_interrupts(global);

   return 0;
}

math()
{
      time = (count / 10); //convert to milliseconds
      rem = count % 10;  //modulus for microseconds
      rem *= 50;  // convert to microseconds
      
 /*      divtest = time % 2;
      
     if(rem == 400, divtest == 1)
         {
             time = time + 1;  //possibly necessary compensation value
             rem = rem - 400;  //possibly necessary compensation value
         }

      if(rem == 50)
         {
            rem = rem - 50;
         }  */
         return 0;
}

countroutine()
{
   readyprep();  //prepares screen and vars

   while(donebit == 0)  //mid-sample waiting area
      {
         delay_us(3);
      }

      disable_interrupts(global);
      disable_interrupts(int_timer0);

      math();  //computes count into ms, us

  /* if(count != 0)
   {
      readybit = 1;
   } */

   donebit = 0;

   printf(LCD_putc,"\f%lu.%03lu ms \b", time, rem);  //%lu for long ints
   delay_ms(100);

   return 0;

}



void main()
{
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1|RTCC_8_BIT);  //setup timer
   disable_interrupts(int_timer0);
   disable_interrupts(global);

   lcd_init();  // Always call this first.

   delay_ms(100);

   lcd_putc("\fFilm Shutter\nSpeed Timer\b"); // Startup message


//**** Main While Loop**********
      while(1)
   {
     button = input(pin_A0);

     if(button == 0)
     {     countroutine();   }  // go to countroutine if ready button was pressed
     if(button == 1)
     {     delay_us(3);    }  //maintains value until ready button pressed
   }
}