pwm.c

通过对单片机的编程

					#include<reg51.h>
#include<stdio.h>
#include<stdlib.h>
#include<absacc.h>
#include<string.h>
#include <ctype.h> 

#define unchar unsigned char
#define unint unsigned int
#define unlong unsigned long

sbit pwm_out=P0^0;//pwm波形输出
unchar ton=90; //高电平宽度为9ms
unchar toff=10;//低电平宽度为1ms
unchar counter=0;
unchar period=100;//一个方波的周期为10ms

void timer(){		  //初始化定时器，每0.1ms产生一次中断
TMOD=0X22;	 //定时器0,1均为方式2
EA=1;		 //开放所有的中断
ET0=1;		 //打开定时器0的中断
TL0=TH0=156;  //经过（256-TH0）个振荡周期后溢出，每个振荡周期为1uS,针对12M的晶振 
TR0=1;		 //打开定时器0
}

void t0(void) interrupt 1 using 0{
	counter++;
	if(counter<=period){
	if(counter<=ton) pwm_out=1;
	else pwm_out=0;
	}
	else  counter=0; 
}
void main(){
timer();
while(1) {}
}