测周期测频.c

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
	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];
	uint data f;


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


      ledxianshi()
        {
          uchar k,i;
     	  led[0]=f/1000;
          led[1]=f%1000/100;
	  		led[2]=f%100/10;
	  		led[3]=f%10;
	  		
		for(k=0;k<4;k++)
		 { i=led[k];
		   P0=a[i];

		   if(k==1){P0|=0x80;}

		   P2=tv[k];
	           delay();
		 }
	 } 

	void main()
         {   TMOD=0x10;
	         TH1=0; 
             TL1=0;
	     while(1)
	     {while(P3_5==0);
	      while(P3_5==1);
	      TR1=1;
          while(P3_5==0);
	      while(P3_5==1);
	      TR1=0;
	            f=(TH1<<8)+TL1;
	            f=100000000/f;              //f=1000000L/f;
	      while(1)
	      {ledxianshi();}
	     }
	 }