keyscan.c

一个执行效率不错的键盘扫描程序。附有Proteus仿真

#include<reg51.h>
#include<absacc.h>
#define uchar unsigned char
#define uint unsigned int
unsigned char  code table[]={0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};
//unsigned char  code dispbit1[]={0,1};
//unsigned char  code dispbit2[]={1,0};
unsigned char dispbit[]={0xfe,0xfd};
unsigned char dispbuf[]={0,0};
unsigned char  cnt;
sbit S1=P2^0;
sbit S2=P2^1;
void delays(void);
unsigned char  kbscan(void);
void main(void)
{uchar key;

 TMOD=0x01;
 TH0=(65536-4000)/256;
 TL0=(65536-4000)%256;
 TR0=1;
 ET0=1;
 EA=1;

 while(1)
   {key=kbscan();
    delays();
	dispbuf[0]=key/16;
	dispbuf[1]=key%16;

   }
}

void delays(void)
{
 uchar i;
 for(i=300;i>0;i--);
}

//
uchar kbscan(void)
{
 uchar sccode,recode;
 P3=0xf0;
 if((P3&0xf0)!=0xf0)
 {
  delays();
  if((P3&0xf0)!=0xf0)
  {
     sccode=0xfe;
	 while((sccode&0x10)!=0)
	 {
	    P3=sccode;
		if((P3&0xf0)!=0xf0)
		{
		   recode=(P3&0xf0)|0x0f;
		   return((~sccode)+(~recode));		   
		 }
		 else sccode=(sccode<<1)|0x01;
	  }
	}
 }
 return(0);
}

void Timer0() interrupt 1 using 1
{ 
  TH0=(65536-4000)/256;
  TL0=(65536-4000)%256;

 // S1=dispbit1[cnt];
 // S2=dispbit2[cnt];
  P2=dispbit[cnt];
  P0=table[dispbuf[cnt]];
  cnt++;
  if(cnt==2)cnt=0;
  }