单片机小白，主页第一篇文章有共通代码详解。

独立按键一：按下数码管显示小时增加（>23变00）
独立按键二：按下数码管显示分钟增加（>59变00）
独立按键三：长按关闭时钟自增后，可使用按键一.二对数码管显示时间进行更改
独立按键四：按下时钟启动

运行效果:

代码：

#include <reg52.h>
#define u8 unsigned char
#define u16 unsigned int

	 sbit button1=P3^1;
	 sbit button2=P3^0;
	 sbit button3=P3^2;
	 sbit button4=P3^3;
	 sbit add_1=P2^2;
	 sbit add_2=P2^3;
	 sbit add_3=P2^4;

     u16 n=0;
     u8 x,y,z;
	 u8 code table[10]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};
  
	 
//DingshiQi YanShi
void delay_ds(u8 ms)
  {
    u8 T=0;
    TMOD=0x01;
    TH0=0xfb;
    TL0=0x80;
    TR0=1;
    while(T<ms)
    {
     if(TF0==1)
	   {
	    TF0=0;
	  	TH0=0xfb;
        TL0=0x80;
	    T++;
	   }
    }
    
  }//1.25*ms
	

//shuaxin
void shuaxin()
 { 
	 add_1=0;
     add_2=0;
     add_3=0;
	 P0=table[z%10];   
	 delay_ds(1);	
	 P0=0x00;    //01
			
	 add_1=1;
	 add_2=0;
	 add_3=0;
     P0=table[z/10%10];
     delay_ds(1);	
	 P0=0x00;    //02
	 
	 add_1=0;
	 add_2=1;
	 add_3=0;
	 P0=0x40;
     delay_ds(1);	
	 P0=0x00;    //03
	 
	 add_1=1;
	 add_2=1;
	 add_3=0;
	 P0=table[y%10];
     delay_ds(1);	
	 P0=0x00;    //04
	 
	 add_1=0;
     add_2=0;
     add_3=1;
	 P0=table[y/10%10];   
	 delay_ds(1);	
	 P0=0x00;    //05
			
	 add_1=1;
	 add_2=0;
	 add_3=1;
     P0=0x40;
     delay_ds(1);	
	 P0=0x00;    //06
	 
	 add_1=0;
	 add_2=1;
	 add_3=1;
	 P0=table[x%10];
     delay_ds(1);	
	 P0=0x00;    //07
	 
	 add_1=1;
	 add_2=1;
	 add_3=1;
	 P0=table[x/10%10];
     delay_ds(1);	
	 P0=0x00;    //08
 }	//11.25ms
	
 
//1 s
void Ding_shi()
  { 
	u8 T=0;
    TMOD=0x01;
    TH0=0xf7;
    TL0=0x00;    //2.5ms
	shuaxin(); 
    TR0=1;
    while(T<80)
    {
     if(TF0==1)
	   {
	      TF0=0;
		  TH0=0xf7;
          TL0=0x00;    //2.5
		  shuaxin();   //10          12.5ms*79=987.5ms
		  T++;
	   }
    }
  }

//
void Ding_shi01()
  { 
	u8 T=0;
    TMOD=0x01;
    TH0=0xf7;
    TL0=0x00;    //1.25ms
    TR0=1;
    while(T<20)
    {
     if(TF0==1)
	   {
	      TF0=0;
		  TH0=0xf7;
          TL0=0x00;    //1.25
		  shuaxin();   //20           12.5ms*79=987.5ms
		  T++;
	   }
    }
  }
	




void main()
{  
   u8 k,j;
   k=j=0;
   button1=0xff;
   button2=0xff; 
   button3=0xff;
   button4=0xff;

	
   while(1)
   {       
       
	  shuaxin(); 	
		 
     if(button1==0)
	    {
	     delay_ds(2);
	     if(button1==0)
	     {
	       while(!button1)
	        { 
                 x++;
                 
			     if(x>23)
			    	x=0;
			    	
				Ding_shi01();
	        }
	        
	     }
	     
	    }
			
			
	   if(button2==0)
	    {
	     delay_ds(2);
	     if(button2==0)
	     {
	       while(!button2)
          {
		
	            y++;
	            
			    if(y>59)
				  y=0;
				  
			    Ding_shi01();			
						
          }
	    
			 }
		 }
			
		
		if(button3==0)
	    {
	     delay_ds(3);
	     if(button3==0)
	     {
	       while(!button3)
           {
				shuaxin();
	        }
	      }	
	     }			                                                     
		
		           
		if(button4==0)
	    {
	     delay_ds(2);
	     if(button4==0)
	     {  
		   while(!button4)
		   {
	         while(1)
	         {
					 
					 z++;
					
					 if(z>59)
					 { y++;
					   z=0;}
					   if(y>59)
						 { x++;
						   y=0;}
						   if(x>23)
							   x=0;
							   
					 Ding_shi();
							 
					 if(button3==0)
	                   break;																					
	
			   }
			 }
       }
    } 
  }			
}

视频演示

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Proteus 仿真图

代码：

#include<reg51.h>

typedef unsigned char uchar;
typedef unsigned int uint;

//按键定义
sbit key_stop = P3^0;
sbit key_star = P3^1;
sbit key_fen = P3^2;
sbit key_shi = P3^3;

//0~9的十六进制数码
uchar code num[10] = {0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8, 0x80, 0x90};  // 0~9

//秒、分、时标志
uchar miao = 0, fen = 0, shi = 0;  

//秒、分、时高位低位
uchar miao_L, miao_H, fen_L, fen_H, shi_L, shi_H; 

//计数
uint counter = 0;  


void delay(uint x){  //延时函数
	while(x--)
		;
}//delay

void key_delay(int xms){  //按键延时函数 x ms
	unsigned int i, j;
	for(i=0; i<xms; ++i)
		for(j=0; j<110; ++j)
			;
}//key_delay

void T0_Init(){  //定时器初始化
	
	TMOD = 0x01; 
	TH0 = 0x3c;  
	TL0 = 0xb0;	 
    EA = 1;  //开总中断
	ET0 = 1;     
	TR0 = 1;    
}//T0_Init

void display(){  //显示函数
	
	P2 = 0x20;  
	P0 = 0xbf;	
	delay(50);
		
	P2 = 0x04; 
	P0 = 0xbf;
	delay(50);

	P2 = 0x80;  // 1000 0000
	P0 = num[miao_L];  
	delay(50);

	P2 = 0x40;	// 0100 0000
	P0 = num[miao_H]; 
	delay(50);

	P2 = 0x10;	// 0001 0000
	P0 = num[fen_L];  
	delay(50);

	P2 = 0x08;	// 0000 1000
	P0 = num[fen_H];  
	delay(50);

	P2 = 0x02;	// 0000 0010
	P0 = num[shi_L];  
	delay(50);
	
	P2 = 0x01;	// 0000 0001
	P0 = num[shi_H]; 
	delay(50);

}//display

void keyscan(){  //按键函数

	if(key_stop == 0){
		key_delay(20);
		if(key_stop == 0){
			EA = 0;  //关总中断，即停止
			while(!key_stop);
		}
	}//key_stop
	
	if(key_star == 0){
		key_delay(20);
		if(key_star == 0){
			EA = 1;  //开总中断
			while(!key_star);
		}
	}//key_star	
	
	if(key_fen == 0){
		key_delay(20);
		if(key_fen == 0){
			fen++;
			while(!key_fen);
		}
	}//key_fen++
	
	if(key_shi == 0){
		key_delay(20);
		if(key_shi == 0){
			shi++;
			while(!key_shi);
		}
	}//key_shi++
}

void main(){

	T0_Init(); 
	
	while(1){

		display();
		
        keyscan();		
   }

}//main

void timer0_Init() interrupt 1{  //中断函数 
 	 
	 counter++;

	 if(counter == 20){
	 	counter = 0;  
	 	miao++;	//i = 100 

		if(miao == 60){
			miao = 0;  
			fen++;

			if(fen == 60){
				fen = 0;  
				shi++;

				if(shi == 24){
					shi = 0;
					fen = 0;
					miao = 0;
				}
			}
		}

		miao_L = miao%10;  
		miao_H = miao/10; 

		fen_L = fen%10; 
		fen_H = fen/10;  

		shi_L = shi%10;  
		shi_H = shi/10;

	 }
 }//timer0_Init

完整工程

时钟——两组实验.zip