51单片器用定时器输出PWM控制舵机的问题

只看该作者 · 2014-12-25 20:06

#include <reg52.h>

#define uchar unsigned char
#define uint unsigned int

sbit pwm=P2^0;
uint pwm_val;

void delayms(uint xms);    //Èí¼þÑÓÊ±º¯Êý
void timer_set(uint value);

void main()
{
TMOD=0X01;             //¶¨Ê±Æ÷³õÊ¼»¯
TH0=(65536-1000)/256;
TL0=(65536-1000)%256;
EA=1;
ET0=1;
TR0=1;

while(1)
{
   pwm_val=500;
   delayms(1000);

   pwm_val=1500;
   delayms(1000);
}
}

void timer0() interrupt 1
{
static uchar i=1;
TR0=0;

switch(i)
{
   case 1:
      {
         pwm=1;
         timer_set(pwm_val);
      }break;
   case 2:
      {
         pwm=0;
         timer_set(20000-pwm_val);
         i=0;
      }break;
   default: break;
}
i++;
}

void timer_set(uint value)
{
TH0=(65536-value)/256;
TL0=(65536-value)%256;
TR0=1;
}

void delayms(uint xms)
{
uint i,j;
for(i=xms;i>0;i--)
for(j=125;j>0;j--);
}