pwm.c

pulse width modulation code using servo motor

#include<reg51.h>
sbit PWMPIN=P1^0;
bit F;
unsigned char pwm_width;

void pwm_setup()
{
        TMOD = 0;
        pwm_width =160;
        EA = 1;
        ET0 = 1;
        TR0 = 1;
}

void timer0() interrupt 1
 {
        if(!F)
 		{       //Start of High level
                F=1; //Set flag
                PWMPIN=~PWMPIN;     //Set PWM o/p pin
                TH0=pwm_width;        //Load timer
                TF0=0;                //Clear interrupt flag
                return;         //Return
        }
        else {  //Start of Low level
                F=0; //Clear flag
                PWMPIN = ~PWMPIN;     //Clear PWM o/p pin
                TH0 =255-pwm_width;  //Load timer
                TF0=0;        //Clear Interrupt flag
                return;         //return
        }
}

void main()
{
	pwm_setup();
	while(1);
}