Code:

#include<reg51.h>
sbit en=P1^0;
void delay();
void delay(unsigned int time)
{
	int i,j;
	for(i=0;i<time;i++)
	for(j=0;j<110;j++);
}
main(){
	while(1){
		delay(1000);  //delay in milliseconds
		en = 0xff;
		delay(1000);
		en = 0x00;
	}
}