独立按键输入检测：

#include<reg52.h>sbit LED1=P1^0;
sbit KEY1=P3^4;void main()
{KEY1=1;while(1){if(KEY1==0)	 //KEY1按下{LED1=0;	 //LED1被点亮}else{LED1=1;}}
}

按键

#include<reg52.h>#define uchar unsigned char
#define uint unsigned intsbit LED1=P1^0;
sbit KEY1=P3^4;sbit dula=P2^6;
sbit wela=P2^7;uchar disnum;uchar code table_duan[]={
0x3f,0x06,0x5b,0x4f,0x66,0x6d,
0x7d,0x07,0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};void main()
{P0=0xfe;wela=1;wela=0;KEY1=1;while(1){if(KEY1==0)	 //KEY1按下{LED1=0;	 //LED1被点亮disnum++;if(disnum==10){disnum=0;}while(!KEY1);  //重要}else{LED1=1;P0=table_duan[disnum];dula=1;dula=0;}}
}

按键在闭合和断开的时候，触电会存在抖动的现象：

 

按键抖动时间是由按键的机械特性决定：

一般为5ms到10ms之间。

按键前沿抖动消除和按键后延抖动的消除：

#include<reg52.h>#define uchar unsigned char
#define uint unsigned intsbit LED1=P1^0;
sbit KEY1=P3^4;sbit dula=P2^6;
sbit wela=P2^7;uchar disnum;uchar code table_duan[]={
0x3f,0x06,0x5b,0x4f,0x66,0x6d,
0x7d,0x07,0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};void delay(uchar);void main()
{P0=0xfe;wela=1;wela=0;KEY1=1;while(1){if(KEY1==0)	 //KEY1按下{delay(10);    //按键前沿抖动的消除if(KEY1==0)   //按键前沿抖动的消除{LED1=0;	 //LED1被点亮disnum++;if(disnum==10){disnum=0;}while(!KEY1);  //重要delay(10);	   //按键后延抖动的消除while(!KEY1);  //按键后延抖动的消除}		 	}else{LED1=1;P0=table_duan[disnum];dula=1;dula=0;}}
}void delay(uchar x)
{uchar a, b;for(a=x;a>0;a--){for(b=200;b>0;b--);}	
}

在代码中增加了延时和判断的代码来消除按键抖动的问题。

然后测试，可以看到数码管的数字显示非常稳定。