404.c

与前面几个都是keyboard程序

#include "reg52.h"

//数码管上显示的0-9的显示代码

//共阴:
//unsigned char code LEDCODE[]=
//{0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};   //共阴

//共阳
unsigned char code LEDCODE[]=
{0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e};     //共阳

void delay(void)  //好像是延时10MS
{
  unsigned char i,j;
  for(i=20;i>0;i--)
  for(j=248;j>0;j--);
}

void main(void)
{
  unsigned char key;
  P2=0X00;      //初始化数码管显示"8"
while(1)
{
P3=0xef; //此举是为了方便在平凡老师提供的仿真附件上使用
P1=0xef;//扫描第一列
      if ((P1 & 0x0f)!=0x0f)     //判断是该列是否有键按下
        {
            delay();             //去抖动
          if ((P1 & 0x0f)!=0x0f) //再判断该列是否有键按下
            {
              switch(P1& 0x0f)   //读取行的代码，分析是哪一行有键按下
                {
                  case 0x0e:
                    key=15;
                    break;
                  case 0x0d:
                    key=14;
                    break;
                  case 0x0b:
                    key=13;
                    break;
                  case 0x07:
                    key=12;
                    break;
                }
              P2=LEDCODE[key];//送出显示
              while((P1&0x0f)!=0x0f);//等待按键释放
            }
        }
P3=0xdf;//扫描第二列     
P1=0xdf;//扫描第二列
      if ((P1 & 0x0f)!=0x0f)
        {
            delay();
          if ((P1 & 0x0f)!=0x0f)
            {
              switch(P1 & 0x0f)
                {
                  case 0x0e:
                    key=11;
                    break;
                  case 0x0d:
                    key=10;
                    break;
                  case 0x0b:
                    key=9;
                    break;
                  case 0x07:
                    key=8;
                    break;
                }
              P2=LEDCODE[key];
              while((P1 & 0x0f)!=0x0f);
            }
        }
P3=0xbf;//扫描第三列
P1=0xbf;//扫描第三列
      if ((P1 & 0x0f)!=0x0f)
        {
            delay();
          if ((P1 & 0x0f)!=0x0f)
            {
              switch(P1 & 0x0f)
                {
                  case 0x0e:
                    key=7;
                    break;
                  case 0x0d:
                    key=6;
                    break;
                  case 0x0b:
                    key=5;
                    break;
                  case 0x07:
                    key=4;
                    break;
                }
              P2=LEDCODE[key];
              while((P1&0x0f)!=0x0f);
            }
        }
P3=0x7f;//扫描第四列
P1=0x7f;//扫描第四列
      if ((P1&0x0f)!=0x0f)
        {
             delay();
          if ((P1&0x0f)!=0x0f)
            {
              switch(P1 & 0x0f)
                {
                  case 0x0e:
                    key=3;
                    break;
                  case 0x0d:
                    key=2;
                    break;
                  case 0x0b:
                    key=1;
                    break;
                  case 0x07:
                    key=0;
                    break;
                } 
              P2=LEDCODE[key];
             while((P1 & 0x0f)!=0x0f);
            }
        }
                   
     }
}