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pic stop working during float division?

 
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adalucio



Joined: 16 Mar 2009
Posts: 29

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pic stop working during float division?
PostPosted: Sat May 14, 2011 9:18 am     Reply with quote
Hi. I have got a pic16f876 (clock 20MHz). I need to count pulses on rb4 and rb5 and do some calculations.

When arrives too many pulses the pic stop working. why?

Thanks

Code:

#include <main.h>
#include "flex_lcd_16x2.c"

unsigned  int16 cicliA = 0;
float portataA = 0;
unsigned int16 cicliB = 0;
float portataB = 0;


#int_RB
void detect_rb_change()
{
   int current;
   static int last = 0;

   set_tris_b(0xF0);
   
   current = input_b();

   if((!bit_test(last,4))&&(bit_test(current,4)))
      cicliA++;
   else if((!bit_test(last,5))&&(bit_test(current,5)))
      cicliB++;

   last = current;
}

void main()
{ 
   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_32);
   
   lcd_init();
   delay_ms(600);
   
   printf(lcd_putc, "\f");
   
   enable_interrupts(INT_RB);
   enable_interrupts(GLOBAL);

   while(1)
   {
      delay_ms(1000);

      portataA = (float) cicliA / (7.5);
      portataB = (float) cicliB / (7.5);

      lcd_gotoxy(1,1);
      printf(lcd_putc, "A: l/min: %lf         ", portataA);
      lcd_gotoxy(1,2);
      printf(lcd_putc, "B: l/min: %lf         ", portataB);

      cicliA = cicliB = 0;
   }
}
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sat May 14, 2011 1:39 pm     Reply with quote
Quote:
When arrives too many pulses the pic stop working. why?

Describe the pulses. What is the repetition rate of the pulses ? What is
the pulse length ? Is it the same pulse length for all pulses ?
What are the voltage levels (high and low) of the pulses ?


Quote:
When arrives too many pulses the pic stop working. why?

What specifically does this mean ? Does it mean the display is not updated ?
adalucio



Joined: 16 Mar 2009
Posts: 29

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PostPosted: Wed May 18, 2011 1:57 am     Reply with quote
Solved with this code. thanks

Code:

#include <main.h>
#include "flex_lcd_16x2.c"

unsigned  int16 cicliA = 0;
float portataA = 0;
unsigned int16 cicliB = 0;
float portataB = 0;


#int_RB
void detect_rb_change()
{
   int current;
   static int last = 0;

   set_tris_b(0xF0);
   
   current = input_b();

   if((!bit_test(last,4))&&(bit_test(current,4)))
      cicliA++;
   else if((!bit_test(last,5))&&(bit_test(current,5)))
      cicliB++;

   last = current;
}

void main()
{ 
   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_32);
   
   lcd_init();
   delay_ms(600);
   
   printf(lcd_putc, "\f");
   
   enable_interrupts(INT_RB);
   enable_interrupts(GLOBAL);

   while(1)
   {
      delay_ms(1000);

      disable_interrupts(INT_RB);
      disable_interrupts(GLOBAL); 

      portataA = (float) cicliA / (7.5);
      portataB = (float) cicliB / (7.5);

      lcd_gotoxy(1,1);
      printf(lcd_putc, "A: l/min: %lf         ", portataA);
      lcd_gotoxy(1,2);
      printf(lcd_putc, "B: l/min: %lf         ", portataB);

      cicliA = cicliB = 0;

      enable_interrupts(INT_RB);
      enable_interrupts(GLOBAL);
   }
}
Ttelmah



Joined: 11 Mar 2010
Posts: 19515

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PostPosted: Wed May 18, 2011 2:58 am     Reply with quote
and the reason is, that the pulses are coming in faster than the arithmetic can be handled (hence PCM programmers questions about rate....).

Best Wishes
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