测宽度.bak

51定时器常用例子包括测频率测脉宽产生波形

	#include"at89x52.h"
	#define uchar unsigned char
	#define uint  unsigned int
	sbit m=P1^0;
        sbit key=P3^4;
	uchar code  tv[]={0xfe,0xfd,0xfb,0xf7};
	uchar code  a[]={0x3f,0x06,0x5b,0x4f,
                     0x66,0x6d,0x7d,0x07,0x7f,
                     0x6f,0x77,0x7c};
	uchar data  led[4];
	uchar data  tvdata;

	
	void delay(void)
       {
	uint i;
	for(i=0;i<100;i++);
       }


      ledxianshi()
        {
          uchar k,i;
     	  led[0]=tvdata/100;
	  led[1]=tvdata%100/10;
	  led[2]=tvdata%10;
	  led[3]=10;
		
		for(k=0;k<4;k++)
		 { 
		   i=led[k];
		   P0=a[i];
		   P2=tv[k];
	           delay();
		 }
	 } 

	void main()
         {  TMOD=0X09;
	    TH0=0; 
            TL0=0;
	    
	     while(1)
	     {while(P3_2==1);
	      TR0=1;
	      while(P3_2==0);
	      while(P3_2==1);
	      TR0=0;
	      tvdata=TL0;
	      TH0=0;
	      TL0=0;
	      ledxianshi();
	     }
	 }