流水灯 外侧<->中间<->外侧

 /*
 //side<-center->side
 //side->center<-side
 //loop
 *//
 #include "reg52.h"

 void delay(unsigned int cnt);

 void main(void)
 {
     //
     unsigned char led_1[] = {0XE7,0XDB,0XBD,0X7E};
     unsigned int x;
     for(x=;x<;x++)
     {
         //
         P1=led_1[x];
         delay();
     }
     for(x=;x>=;x--)
     {
         //
         P1=led_1[x];
         delay();
     }
 }

 void delay(unsigned int cnt)
     {
         //
         while(--cnt);
     }