part3.2.3.c

来自「新概念51单片机C语言教程.入门、提高、开发」· C语言 代码 · 共 171 行

#include <reg52.h>    		//52系列单片机头文件
#define uchar unsigned char
#define uint unsigned int 
void delayms(uint xms)				
{
	uint i,j;
	for(i=xms;i>0;i--)		      //i=xms即延时约xms毫秒
		for(j=110;j>0;j--);
}
void send(uchar key_num)
{
	SBUF=key_num;
	while(!TI);
	TI=0;
}
void matrixkeyscan()
{
	uchar temp,key;
    P3=0xfe;
    temp=P3;
    temp=temp&0xf0;
    if(temp!=0xf0)
    {
      delayms(10);
	  temp=P3;
	  temp=temp&0xf0;
      if(temp!=0xf0)
      {
        temp=P3;
        switch(temp)
        {
          case 0xee:
               key=0;
               break;
          case 0xde:
               key=1;
               break;
          case 0xbe:
               key=2;
               break;
          case 0x7e:
               key=3;
               break;
         }
         while(temp!=0xf0)
         {
           temp=P3;
           temp=temp&0xf0;
         }
		 send(key);
      }
    }
    P3=0xfd;
    temp=P3;
    temp=temp&0xf0;
    if(temp!=0xf0)
    {
      delayms(10);
      temp=P3;
      temp=temp&0xf0;
      if(temp!=0xf0)
      {
        temp=P3;
        switch(temp)
        {
          case 0xed:
               key=4;
               break;
          case 0xdd:
               key=5;
               break;
          case 0xbd:
               key=6;
               break;
          case 0x7d:
               key=7;
               break;
         }
         while(temp!=0xf0)
         {
           temp=P3;
           temp=temp&0xf0;
         }
		 send(key);
      }
    }
    P3=0xfb;
    temp=P3;
    temp=temp&0xf0;
    if(temp!=0xf0)
    {
      delayms(10);
   	  temp=P3;
      temp=temp&0xf0;
      if(temp!=0xf0)
      {
        temp=P3;
        switch(temp)
        {
          case 0xeb:
               key=8;
               break;
          case 0xdb:
               key=9;
               break;
          case 0xbb:
               key=10;
               break;
          case 0x7b:
               key=11;
               break;
         }
         while(temp!=0xf0)
         {
           temp=P3;
           temp=temp&0xf0;
         }
		 send(key);
      }
    }
    P3=0xf7;
    temp=P3;
    temp=temp&0xf0;
    if(temp!=0xf0)
    {
      delayms(10);
      temp=P3;
      temp=temp&0xf0;
      if(temp!=0xf0)
      {
        temp=P3;
        switch(temp)
        {
          case 0xe7:
               key=12;
               break;
          case 0xd7:
               key=13;
               break;
          case 0xb7:
               key=14;
               break;
          case 0x77:
               key=15;
               break;
         }
         while(temp!=0xf0)
         {
           temp=P3;
           temp=temp&0xf0;
         }
		send(key);
      }
    }
}
void main()
{
	TMOD=0x20;
	TH1=0xfd;
	TL1=0xfd;
	TR1=1;
	SM0=0;
	SM1=1;	
	EA=1;
	ES=1;
	while(1)
	{
		matrixkeyscan();//不停调用键盘扫描程序
	}
}