#define KEY P1 //鍵盤所連接的I/O接口組定義

/*********************************************************************************************
函數名：16個陣列式鍵盤驅動程序
調  用：? = Key ();
參  數：無
返回值：unsigned char 鍵值0~16
結  果：有鍵按下時返回值為鍵值1~16，無鍵按下時返回值為0
備  注：在主函數中不斷調用
/**********************************************************************************************/
unsigned char Key (void){ //4*4陣列鍵盤處理程序
unsigned char a,b,c;
KEY = 0x0f; //設定鍵盤初始電平狀態
if (KEY != 0x0f){ //讀取鍵盤狀態是否改變
   Delay (20); //延時20ms去抖動
   if (KEY != 0x0f){ //重新讀取
	  a = KEY; //寄存狀態值到a
	}
	KEY = 0xf0; //設定鍵盤反向電平狀態
	c = KEY; //讀取反向電平狀態值到c
	a = a|c; //a與c相或
	switch(a){ //鍵盤狀態查表
	   case 0xee: b = 1; break;
	   case 0xed: b = 2; break;
	   case 0xeb: b = 3; break;
	   case 0xe7: b = 4; break;
	   case 0xde: b = 5; break;
	   case 0xdd: b = 6; break;
	   case 0xdb: b = 7; break;
	   case 0xd7: b = 8; break;
	   case 0xbe: b = 9; break;
	   case 0xbd: b = 10; break;
	   case 0xbb: b = 11; break;
	   case 0xb7: b = 12; break;
	   case 0x7e: b = 13; break;
	   case 0x7d: b = 14; break;
	   case 0x7b: b = 15; break;
	   case 0x77: b = 16; break;
	   default:   b = 0 ; break;
	   }
	}
return (b); //將b中的鍵值代號送入函數返回值
}
/**********************************************************************************************/