51单片机--键盘扫描

来源：互联网发布：爬虫股票数据编辑：程序博客网时间：2024/04/28 21:30

P3口接16个按键

#include<reg52.h>
#define uint unsigned int
#define uchar unsigned char
sbit dula=P2^6;
sbit wela=P2^7;
sbit key1=P3^4;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71,0};
uchar num,temp,num1;
void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
  for(y=110;y>0;y--);
}
uchar keyscan();
void display(uchar aa);
void main()
{
num=17;
dula=1;
P0=0;
dula=0;
wela=1;
P0=0xc0;
wela=0;

while(1)
  {
   display(keyscan());
  }
}
void display(uchar aa)
{
   dula=1;
   P0=table[aa-1];
   dula=0;
}
uchar keyscan()
{
   P3=0xfe;                  //假设第一行有按键按下
   temp=P3;
   temp=temp&0xf0;
   while(temp!=0xf0)
    {
     delay(5);                //延时判断是否确定按下
     temp=P3;
     temp=temp&0xf0;
     while(temp!=0xf0)
     {
      temp=P3;              //重新把P3赋值给temp 判断temp的值来确定按的键
     switch(temp)
      {
       case 0xee:num=1;
        break;
       case 0xde:num=2;
        break;
       case 0xbe:num=3;
        break;
       case 0x7e:num=4;
        break;
      }
     while(temp!=0xf0)
      {
       temp=P3;
       temp=temp&0xf0;
      }
     }
    }

   P3=0xfd;
   temp=P3;
   temp=temp&0xf0;
   while(temp!=0xf0)
    {
     delay(5);
     temp=P3;
     temp=temp&0xf0;
     while(temp!=0xf0)
     {
      temp=P3;
     switch(temp)
      {
       case 0xed:num=5;
        break;
       case 0xdd:num=6;
        break;
       case 0xbd:num=7;
        break;
       case 0x7d:num=8;
        break;
      }
     while(temp!=0xf0)
      {
       temp=P3;
       temp=temp&0xf0;
      }
     }
    }

   P3=0xfb;
   temp=P3;
   temp=temp&0xf0;
   while(temp!=0xf0)
    {
     delay(5);
     temp=P3;
     temp=temp&0xf0;
     while(temp!=0xf0)
     {
      temp=P3;
     switch(temp)
      {
       case 0xeb:num=9;
        break;
       case 0xdb:num=10;
        break;
       case 0xbb:num=11;
        break;
       case 0x7b:num=12;
        break;
      }
     while(temp!=0xf0)
      {
       temp=P3;
       temp=temp&0xf0;
      }
     }
    }

   P3=0xf7;
   temp=P3;
   temp=temp&0xf0;
   while(temp!=0xf0)
    {
     delay(5);
     temp=P3;
     temp=temp&0xf0;
     while(temp!=0xf0)
     {
      temp=P3;
     switch(temp)
      {
       case 0xe7:num=13;
        break;
       case 0xd7:num=14;
        break;
       case 0xb7:num=15;
        break;
       case 0x77:num=16;
        break;
      }
     while(temp!=0xf0)
      {
       temp=P3;
       temp=temp&0xf0;
      }
     }
    }
return num;

}