8051 Timer Operation

8051 Timer Example : To generate a 2sec ON and 1sec OFF PWM pulse by using Timer 0 Mode 1 16-bit operation.

#include <reg51.h>

#include <stdio.h>

sbit pwm = P1^0;

void Timer0_delay(unsigned char);

void main()

{

  while(1)

  {

  pwm = 0;                     //port  1 pin 1 is  low

  Timer0_delay(100);  // 1sec time delay by using  timer

  pwm = 1;                    //port  1 pi1 1 is high

  Timer0_delay(200);  //2sec  time delay by using  timer

  }  ;

  }

void Timer0_delay(unsigned char x)

  {

  for (;x>0;x--)                         // loop rotates up to above given value.

  {

  TMOD = 1;                          //Timer  0  mode 1 16-bit operation

  TH0 = 0xD8;   //load register value by calculating 65536-10000=55536

  TL0 = 0xF0;    //55536 hex value is 0xD8F0 load this value to register.

  TR0 = 1;         //  command is used to start timer  and  increment  the

  while(TF0!=1);  //TH TL register values up to  over  flow  will occur.

  TF0=0;               // timer  0  over  flag we need to reset again use.

  };

  }