#include<reg51.h>
#define  uint  unsigned int

sbit P10=P1^0;

void main(void)
{       uint k=0;
    	TMOD=0x20;
        TR1=1;
		P10=0;
        TH1=0X00;TL1=0X00;
		while(1)
        {
		
                while(!TF1);
                TF1=0;

               
                while(++k==2000)
                {
 						P10=!P10;
                        k=0;
 		}
                
        }
}