51

计算机控制系统

#include    <reg51.h>
void delay(void)
  {
   unsigned int i;
   for(i=0;i<100;i++);
  }
void main(void)
  {
   unsigned char num,i=0;
   while(1)
     {
	  P1 = 0xff;
	  num = P1&3;
	  switch (num)
	    {
		 case 0:
		   P1 = 0xff;
		   break;
		 case 1:
		   if(i<100) P1 = 0xf3;
		   else P1 = 0xff;
 		   break;
		 case 2:
		   if(i<100) P1 = 0xcf;
		   else P1 = 0xff;
		   break;
		 case 3:
		   P1 = 0;
		   break;
		}
	  delay();
	  i++;
	  if(i>200)  i = 0;
	 }
  }