Interrupt of 1s -Atmel 89C51

[Mike]

How to fix timer0 to have one second interrupt ?
I have idea but dont work..
i tried to put 20 interruptes for 50ms because that is equal to 1s and that didnt work.

I need one second to put some numbers on display every second..

Any other idea?

I mustn use delay(), only counter which i using for counting 20 interruptes !!!!!!!!!!!!!!!!!!

 

[Mike]

So, I need to write only numbers (every second) in string on display (memory mapped on 0x8001 adress)  which are divding with 2 .

I must use counter not delay () for interrupt …

Below is code which i imagine but dont work correctly…

#include <reg51.h>
#include <math.h>
typedef unsigned char byte;
byte a[3]= {2,1,8};

byte counter, frequency,displ;
int i=0;
byte xdata display _at_ 0x8001;

sbit switcher=P0^0;

void Inic(void) {
    EA=1;
    ET0=1;
    TMOD=1;
    TH0=0x3C;
    TL0=0xB0;
    TR0=1;
    counter=1;
    frequency=0;
}

void timer0(void) interrupt 1 using 2 {
    TR0=0;
    TH0=0x3C;
    TL0=0xB0;
    TR0=1;

if(switcher)    {
    if(!(–counter)) {
    counter=frequency;
            
        display=displ;    
        
    
                
        
    
            
    }}     }  
            
        
        
    

void main(void) {
    Inic();
    while(1) {
        
        if(switcher) {    
         for (i=0;i<3;i++)    {
    if(a/2)       {
            displ=a;        
        frequency=20;
    
    }  }      }  }     }
 

 

[Ashutosh Bhatt]

ur logic is perfect. count 20 timer interruts of 50 ms. ur code might be wrong. post ur code

[Mike]

Now I tried like this below but stil dont have 1 second per number which is divided with 3 . .. He put all numbers which are divided with 3 in one second

Code:

#include <reg51.h>
                 
typedef unsigned char byte;

byte a[9]= {7,5,16,3,1,4,11,9,6};
byte counter;
byte frequency;
byte displ;
byte xdata display _at_ 0x8001;
byte started = 0;
int i=0;

sbit switcher=P0^0;
 
void Inic(void)
{
    EA=1;         // enable global interrupt
    TMOD=1;       // configure timer0 to 16 bit timer
    TH0=0x3C;     // set timer0 to 0xC350
    TL0=0xAF;     // 50,000 decimal
    
    counter=1;    // set counter to 1
}

 
void timer0(void) interrupt 1 using 2
{   
    TH0 = 0x3C;           // set timer0 to C350 = 50,000
    TL0 = 0xAF;           // after each interrupt                    
    
    counter–;            // count the interrupt
    if(counter == 0)      // count 20 interrupts for 1 sec delay       
       {
       counter = 20;      // reset counter to 20
       if(started == 1)   // if timer is started
         {   
         while(i < 9)     // go through array "a" to find a multiple of 3  
           {
           if( (a[i] % 3) == 0) // multiple of 3 has remainder = 0                 
              {
              display = (a[i]);  // display a matching number
              i++;          // increment i to the next number in "a"
              break;      // break out of the while loop after displaying a number
              }
           i++;            // increment i to the next number in "a"
           }                 // end while i < 9     
         if(i == 9)       // if 9, all numbers have been tested
           {
           ET0 = 0;       // disable timer 0 interrupt
           TR0 = 0;       // stop timer0 – all of "a" has been checked
           started = 0;   // started = 0, stop until switch pressed again   
           }
         }  // end if started == 1    
       }  // end if counter == 0
}

void main(void)
{
   Inic();        // initialize timer0
   switcher = 1;  // write 1 to switcher to use as an input
                  // it should have a pullup resistor to pull it high
   while(1)       // continuous loop
     {                    // the switch should pull P0^0 low
     if(switcher == 0)    // using switcher as a start switch
       if(started == 0)   // if counter is stopped
          {         
          started = 1;    // started goes 1 when switch pressed
          i = 0;          // set i for first byte in "a" array
          counter = 1;    // counter to 1 to get first number
                          // quicker (or 20 to wait 1 second)
          TH0=0x3C;       // set timer0 to 0xC350
          TL0=0xAF;       // 50,000 decimal
          ET0=1;          // enable timer0 interrupt
          TR0=1;          // start timer0 running         
          }
     }            
}

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