key.c

来自「不少单片机C代码」· C语言 代码 · 共 41 行

#include <reg51.h>
#define uchar unsigned char
#define uint  unsigned int
void  dlms(void);
uchar kbscan(void);

void main(void)
{ 
 uchar key; 
 while(1)
  { key=kbscan();
    dlms();
  }
}

void  dlms(void)
{ uchar  i;
  for(i=200;i>0;i--) {}
}

uchar kbscan(void)
{ uchar sccode,recode;
  P1=0xf0;
 if((P1&0xf0)!=0xf0)
   {  dlms();
      if((P1&0xf0)!=0xf0)
       { sccode=0xfe;
	 while((sccode&0x10)!=0)  
	  { P1=sccode;
	    if((P1&0xf0)!=0xf0)
	     {  recode=(P1&0xf0)|0x0f;
		return((~sccode)+(~recode));
	     }
	     else
	      sccode=(sccode<<1)|0x01;
	  }
	}
   }
  return(0);
}