Thread: 8051 tacho

I,ve made a "tacho" using an 8051 , a 4511 decoder and 4 digit 7 seg display. its not very accurate where am i going wrong with my code.

Code:

#include <reg66x.h>

#define on 1
#define off 0

void delay();

unsigned int F,number,i,count,overflow,digit1,digit2,digit3,digit4;
 float T;

sbit enable_digit1 = P1^0;
sbit enable_digit2 = P1^1;
sbit enable_digit3 = P1^2;
sbit enable_digit4 = P1^3;

void an_interrupt() interrupt 0 using 1
{
 TR0 =on;
  if (count<3)
  {count++;}
  else
   TR0 = off;
   T = overflow* 65536 ;
   T = T + ( TH0 *256 ) + TL0 ;
   T = T * 0.000000543;
   F = 1/T;
   number = F * 60 ;
   digit1 = (number/1000);
   digit2 = ( (number%1000)/100 );
   digit3 = ( (number%100)/10 );
   digit4 = ( (number%10) );
   count = 0;
   overflow = 0;
   TH0 = 0x00;
  TL0 = 0x00;
    }

void timing ()interrupt 1 using 2
 {
  overflow++;
 }

void main (void)
{
  count = 0; // set count zero
  IT0 =on;  // make interrupt edge triggered
  TMOD = 0x01;   //mode 1
  TH0 = 0x00;
  TL0 = 0x00;
  TR0 = off; //timer0 off
  EA = on;   //global enable all
  ET0 = on;  //enable timer zero
  EX0 = on;    //enable external interrupt
 
  while (on)
    {
   P2 = digit1;         //multiplex digits on and off
   enable_digit1 = on;
   delay();
   enable_digit1 = off;
   P2 = digit2;
   enable_digit2 = on;
   delay();
   enable_digit2 = off;
   P2 = digit3;
   enable_digit3 = on;
   delay();
   enable_digit3 = off;
   P2 = digit4;
   enable_digit4 = on;
   delay();
   enable_digit4 = off;
    }
}


void delay()
   {
     for(i=0; i<255; i++)
    {
    }
   }

Thanks for pointing that out. i'll give it a try as soon as i can.
Any more advice is more than welcome. Thanks again

The value shown on the dislay is too high and is fluctuating

ive changed code a little values on the display are changing by 60 each time, the reading are quite good between 1-5Hz and 56 -165 Hz Between 5 to 56 the reading fluctuates

Code:

#include <reg66x.h>
#define on 1
#define off 0

void delay();

unsigned int number,i,count, digit1,digit2,digit3,digit4;
float T,F,overflow;

sbit enable_digit1 = P1^0;
sbit enable_digit2 = P1^1;
sbit enable_digit3 = P1^2;
sbit enable_digit4 = P1^3;

void an_interrupt() interrupt 0 using 1
  {
  TR0 = on;
  if (count == 0)
    {
     count++;}
  else
  {
  TR0 = off;
   T = overflow* 0x10000 ;
   T = T + ( TH0 *256 ) + TL0 ;
   T = T * 0.000000543;
   F = 1/T;
   number = F * 60* count ;
   digit1 = (number/1000);
   digit2 = ( (number%1000)/100 );
   digit3 = ( (number%100)/10 );
   digit4 = ( (number%10) );
   count = 0;
   overflow = 0;
   TH0 = 0x00;
  TL0 = 0x00;
   
  }
}

void timing ()interrupt 1 using 2
 {
  overflow++;
 }

void main (void)
{
  count = 0; 
  IT0 =on;    
  TMOD = 0x01;   
  TH0 = 0x00;
  TL0 = 0x00;
  TR0 = off; 
  EA = on;   
  ET0 = on;  
  EX0 = on;    
  
  while (on)
    {
  

   P2 = digit1;         
   enable_digit1 = on;
   delay();
   enable_digit1 = off;
   P2 = digit2;
   enable_digit2 = on;
   delay();
   enable_digit2 = off;
   P2 = digit3;
   enable_digit3 = on;
   delay();
   enable_digit3 = off;
   P2 = digit4;
   enable_digit4 = on;
   delay();
   enable_digit4 = off;
    }
}


void delay()
   {
     for(i=0; i<55; i++)
    {
    }
   }

The display is now not jumping up in steps of sixty, but using an input signal of less than 60 Hz, i am still getting the wrong readings on the display.Could this be due to the micro I am using

Well you did multiply by 60 for some reason.