Solution to 51 microcontroller clock accuracy error

A few days ago, I made an electronic clock using STC89C52 microcontroller. After a period of experiments, I found that there is an error in the time accuracy, and one minute is about 4 seconds slower.

This is amazing. Ten minutes will be 40 seconds slower. In one day, it will be no less than half 96 minutes! ! !

The crystal oscillator frequency of this microcontroller is 11.0592mhz, which is the same as the crystal oscillator frequency of most clocks, so there should be no problem.

Consider the source code the day after tomorrow:

In the timer interrupt function:

void t0(void) interrupt 1 using 0 

  {

  tcount++;

    if(tcount==4000)

  {tcount=0;

    second++;

if(second==60)

  {second=0;

   minute++;

    if(minute==60)

{minute=0;

  hour++;

  if(hour==24)

   {hour=0;

   }

}

  }

P1=~P1;

  }

}

The number after interrupt is simply the code name of the interrupt service function.

0 represents external interrupt 0

1 represents the timer counter 0 interrupt

2 represents external interrupt 1

3 represents the timer counter 1 interrupt

4 represents serial port interrupt

So interrupt 1 means that after the timer counter generates an interrupt, it will be executed in this function.

The code is actually quite simple, every 4000 interrupts will occur for 1 second.

etc...

The interruption every 4000 times is 1 second, so the reason is probably here.

Try comparing tcount==3600 with the stopwatch and find that every minute is about 1 second faster.

Bingo! The problem does lie in the value of tcount. Change the value of tcount to 3700. Comparing it with the stopwatch, we find that there is no error in seconds, and the error should be in milliseconds.

void t0(void) interrupt 1 using 0 

  {

  tcount++;

    if(tcount==3700)

  {tcount=0;

    second++;

if(second==60)

  {second=0;

   minute++;

    if(minute==60)

{minute=0;

  hour++;

  if(hour==24)

   {hour=0;

   }

}

  }

P1=~P1;

  }

}

This solves the problem of clock accuracy.