keypad.c

键盘 显示程序

#include<reg51.h>
code char key_code[] = { 0X7E,0X7D,0XBD,0XDD,0X7B,0XBB,0XDB,0X77,0XB7,0XD7,0XBE,0XDE,0XE7,0XEB,0XED,0XEE};
code ksp[4] = {0x7F,0xBF,0xDF,0xEF};
void delay (void)
{
 unsigned char i, j;
 for (i = 0; i < 5; i++)
      for (j = 0; j < 255; j++);
}
char keypad_scan()
{
 char key,i;
 P2 = 0xF0;
 while (P2 != 0xF0);
  do{
     for( i = 0; i <= 3; i++)
     {
	  P2 = ksp[i];
	  if(P2 != ksp[i])
	   {
	     delay();
		 key = P2;
		 if(key != ksp[i])
		 {
		  return (key);
		 }
	   }
	 }
    }while(1);
}
//检查是否有按键被按下
char gotkey()
{
  char temp,i;
  temp = keypad_scan();
  for (i = 0; i <= 15; i++)
  {
   if (temp == key_code[i]) return(i);
  }
  return(16);
}