jianpan.c

键盘的驱动。3X3的键盘。调试成功。 at89s51 .

#include<reg51.h>
#define P_keyborad P0
// 06.10.9 高4位列，低四为行（行接上拉电阻（高电平））
//----------------
void Delay(unsigned int i);//延间函数
unsigned char Getkey(void);//取key值函数

//---------------
void main()
{
	unsigned char m;
	while(1)
	{
	 	m=Getkey();
	}
}
//-------------------
void Delay( unsigned int i )
{
	while(i--);
}
unsigned char Getkey(void)
//0x11,0z21,0x41,0x81
//0x12,0z22,0x42,0x82
//0x14,0z24,0x44,0x84
//0x18,0z28,0x48,0x88
{
	unsigned char scancode,tempcode;
	P_keyborad=0xf0;
	if(P_keyborad & 0xf0 !=0xf0)//判断是否有键按下
	Delay(20) ;//延时
	else return 0;
	if(P_keyborad & 0xf0 !=0xf0)//判断是否有键按下
	   ;
	else return 0;
	scancode=0xfe;//11111110
	while( scancode != 0xEF)//11101111
	{
		P_keyborad = scancode;
		if (P_keyborad & 0xf0 !=0xf0)//判断按键是否在此列
		{
			tempcode= (P_keyborad & 0xf0) | 0x0f;
			return( (~tempcode) + (~scancode) );
		}
		else scancode= (scancode <<1) | 0x01;//继续扫描
	}
}