#include <reg51.h>
#define uint unsigned int
#define uchar unsigned char
void delay(uint z);
void main()
{
    while(1)
     {
        P3=0xde;
        delay(800);
        P3=0xff;
        delay(500);
        P3=0x00;
        delay(800);
        P3=0xff;
        delay(500);
       
      
      }
}
void delay(uint z)
{
   uint x,y;
    for(x=z;x>0;x--)
     for(y=100;y>0;y--);

}
改那就行了