pwm变速控制.c

在p1.0上产生一个占空比变化的脉冲信号

/*在p1.0上产生一个占空比变化的脉冲信号，它产生的脉宽调制信号用于电机的变速控制*/   
#include <REG51.H>    
#define uchar unsigned char    
#define uint unsigned int    
   
uchar time,status,percent,period;   
bit one_round;   
uint oldcount,target=500;   
   
void pulse(void) interrupt 1 using 1 /*T/C中断服务程序  1ms--10MHz*/   
{TH0=-833/256;   
 TL0=-83%256;   
  ET0=1;   
   if(++time==percent)P1=0;   
   else if(time==100)   
     {time=0;   
      P1=1;}   
}   
   
void tachmeter(void) interrupt 2 using 2  /*外中断1服务程序*/   
{union{uint word;   
   
       struct {uchar hi;   
               uchar lo;}byte;   
   
       }newcount;   
newcount.byte.hi=TH1;   
newcount.byte.lo=TL1;   
period=newcount.word-oldcount;   /*测得周期*/   
oldcount=newcount.word;   
one_round=1;                    /*每转一圈，引起中断，设置标志*/   
}   
   
   
void main(void)   
{   
  IP=0x04;           /*设置INT1为高位优先级*/   
  TMOD=0x11;         /*T0 T1  16位方式*/   
  TCON=0x54;            //T0 T1 运行，IT1边沿触发/    
  TH1=0;TL1=0;   
  IE=0x86;         //允许中断EX1,ET0/    
  for( ; ; )   
  {if(one_round)   
     {if(period<TARGET) if(percent else *占空比减* ++percent;} *占空比增* {if(percent<100)>0)--percent;   
   one_round=0;}   
   }   
}