C51产生特定占空比的PWM波控制直流电机

• 代码如下：

#include<reg52.h>
#define uint unsigned int
#define uchar unsigned char
sbit PWM=P0^2;//  P2.0??pwm
uchar time;  // ????????
void main()
{
    TMOD=0x01;//
    TH0=0xff;//
    TL0=0xf7;//
    EA=1;//????
    ET0=1;//????0??
    TR0=1;//?????0 
    while(1)
    {           
    }           
}
void tim0() interrupt 1
{
    TR0=0;//????,?????
    TH0=0xff;//(65536-10)/256;//?????
    TL0=0xf7;//(65536-10)%256;//0.01ms
    TR0=1;//?????
    time++;
    if(time>=100)  //1khz
      time=0;   
    if(time<=30)   //占空比为30%
      PWM=1;  
    else PWM=0;
}