1keyscan.c

51单片机的4×4键盘控制数码管显示文件

#include <reg51.h>

#define uchar unsigned char
#define uint unsigned int
sbit P1_3=P1^3;
uchar scanflag=0;
uchar code table[]={0x3f,0x06,0x5b,0x4f,	 //0-3
0x66,0x6d,0x7d,0x07,	  //4-7
0x7f,0x6f,0x77,0x7c,	  //8-B
0x39,0x5e,0x79,0x71,0x40};	 //C-F共阴极段码


void delay(void);
uchar keyscan(void);
void display(uchar k);

void main(void)
{
  uchar key=16,temp=0;
  while(1)
  {
   temp=keyscan();
   if (scanflag==1)
   {
   scanflag=0;
   switch(temp)
   {
    case 0x82:			   //键0
    key=0;
	break;
    case 0x11:			   //键1
    key=1;
	break;
	case 0x12:	           //键2
    key=2;
	break;
	case 0x14:		   //键3
    key=3;
	break;
    case 0x21:			   //键4
    key=4;
    break;
    case 0x22:			   //键5
    key=5;
    break;
    case 0x24:			   //键6
    key=6;
    break;
    case 0x41:			   //键7
    key=7;
    break;
    case 0x42:			   //键8
    key=8;
    break;
    case 0x44:			   //键9
    key=9;
    break;
    case 0x18:			   //键A
    key=10;
    break;
    case 0x28:			   //键B
    key=11;
    break;
    case 0x48:			   //键C
    key=12;
    break;
    case 0x88:			   //键D
    key=13;
	break;
    case 0x81:			   //键*
    key=14;
    break;
    case 0x84:			   //键#
    key=15;
    break; 
   	
   }
   }
   //else   key=16;
   display(key);
   
   }
}



void display(uchar k)
{
  P0=table[k];
  P1_3=0;
}



void delay(void)
{
 uint i;

 for(i=300;i>0;i--);
 
}

uchar keyscan(void)
{
 uchar sccode,recode;
 P2=0xf0;  //发全0行扫描，列线输入
 if((P2&0xf0)!=0xf0)  //有键按下
 { 
   delay();           //延时消抖
   if((P2&0xf0)!=0xf0)	//确实有键按下
   {
     sccode=0xfe;     //行扫描初值
	 while((sccode&0x10)!=0)	 //是否扫描到最后一行
	 {
	   P2=sccode;     //行扫描码
	   if((P2&0xf0)!=0xf0)    //本行有键按下
	   {
	     recode=(P2&0xf0)|0x0f;	  //保留P1口高4位，低4位变为1，作为列值
		 scanflag=1;
		 return((~sccode)+(~recode));			  //键编码＝行扫描值＋列扫描值
	   	 
	   }
	   else sccode=(sccode<<1)|0x01;		//该行无键按下，扫描值左移，扫描下一行
	 }
   }
 }
 return(0);   //无键按下，返回0
}