keyscan.h

来自「利用51单片机实现4*4的键盘扫描程序 在多个51平台中验证通过」· C头文件 代码 · 共 27 行

#define uchar unsigned char
#define uint unsigned int
#define Keyport P2
//*************延时函数*************//
 void dlms(void)
{uchar i;
for(i=200;i>0;i--){}
} 
//*************键盘扫描**************//
uchar keyscan(void)
{ uchar sccode,recode;
Keyport=0xf0;
     if((Keyport&0xf0)!=0xf0)
       { dlms();
            if((Keyport&0xf0)!=0xf0)
              {sccode=0xfe;
               while((sccode&0x10)!=0)
                    {Keyport=sccode;
                     if((Keyport&0xf0)!=0xf0)
                        {recode=(Keyport&0xf0)|0x0f;
                         return((~sccode)+(~recode));
                         }else
                          sccode=(sccode<<1)|0x01;
                    }
               }
		}
return(0);}