Electronic clock that can adjust time-C language

Using stc89c52 microcontroller, the circuit is very simple, using eight-bit common anode digital tube, P0 port is the segment selection of the digital tube, P2 port is the bit selection. Use key1-key3 to adjust the time

Key points:
1. Modularization of functions
2. Interruption

#include
#define uchar unsigned char
#define uint unsigned int
sbit p2_0=P2^0;
sbit p2_1=P2^1;
sbit p2_2=P2^2;
sbit p2_3=P2^3;
sbit p2_4=P2^4;
sbit p2_5=P2^5;
sbit p2_6=P2^6;
sbit p2_7=P2^7;
sbit key0=P3^2;
sbit key1=P3^3;
sbit key2=P3^4;
sbit key3=P3^5;
sbit p17=P1^7;
uint t=0;  
uint key=0;
uchar set=0;
uchar second=00,minter=55,hour=11;
uchar second_1,second_2,minter_1,minter_2,hour_1,hour_2;
const uchar tab[]={ 0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xbf} ; //0~~9 digital table

void delay() //Delay subroutine
  { uint i;
   
      for(i=0;i<240;i++);

  }
 void time_0(void) interrupt 1 using 0 //Internal timer 0 internal timing 50ms
  {
     TH0=0x3c;
  TL0=0xb0;
  t++; // t is the number of times the timer is counted
  }
   
 
  void display(uchar secondd,uchar minterr,uchar hourr) //Subroutine to display the time
  {
    second_1=secondd/10;
 second_2=secondd%10;
 minter_1=minterr/10;
 minter_2=minterr%10;
 hour_1=hourr/10;
 hour_2=hourr%10;
 P0=tab[second_2];
 p2_0=0;
 delay();
 p2_0=1;     
 P0=tab[second_1];
 p2_1=0;
 delay();
 p2_1=1;

 p2_2=0;
 P0=0xbf;
 delay();
 p2_2=1;

 P0=tab[minter_2];
 p2_3=0;
 delay();
 p2_3=1;     
 P0=tab[minter_1];
 p2_4=0;
 delay();
 p2_4=1;

 p2_5=0;
 P0=0xbf;
 delay(); //The delay is to make — “——” appear, otherwise the time is too fast, —
 p2_5=1;

 P0=tab[hour_2];
 p2_6=0;
 delay();
 p2_6=1;     
 P0=tab[hour_1];
 p2_7=0;
 delay();
 p2_7=1;
  }
  void time()
  {
   
          //Has the 1s timing reached?
      if(t==19) //1s is up, add one second
     { t=0;
       second++;
       if(second==60) // Is it 60 seconds? If so, reset the seconds to zero and add one second to the minutes. If not, exit.
    {
              second=0;
      minter++;
      if(minter==60) // Is the minute 60? If yes, clear the minute and add one to the hour; if no, exit
      { minter=0;
          hour++;
       if(hour==24)
        {
   
        hour=0;
        }
      }
     }
     }
   
   display(second,minter,hour); //Call the display function to display the time
  }
    
uint scan_key() //Adjust time button scanning function
    { //Delay
   delay(); //Judge if key3 is pressed, return 1 to call the time adjustment function, if it is not zero, return 0 and do not adjust
   if(key0==0)
     set=1;
    if(key0==1)
      set=0;
    return set;
 }
  
   void set_time() // adjust time function
     { uchar m;
    if(key1==0) delay(); //Adjust the hour, confirm key1 is pressed
    if(key1==0) hour++; // x hours increment
    if(hour==24) hour=0; //Hours count to 24, starting from zero
    for(m=0;m<20;m++) //Loop 20 times
     { time(); //Call the display function to display the time
            
  }
    if(key2==0) delay(); //Adjust minutes
    if(key2==0) minter++;
    if(minter==60) minter=0;
     delay();
       time(); //Call the time function to display the time
     if (key0 == 0)

     time();        
            
  }
  void main() //The main function sets the internal timer
  {
     TMOD=0X01;
      TH0=0X10;
      TL0=0X00;
      EA=1;
      ET0=1;
      TR0=1;
   P2=0xff;
    
      while(1)
    {
      if(key0==0) // p determines whether the time adjustment button is pressed, that is, whether the time needs to be adjusted
    {
       p17=0;
    delay();
    delay();
    
    delay();
    p17=1;
    delay();
     delay();
      key=scan_key();
  
     }
   
   switch(key)
   { //Has the 1s timer expired?
         case 0: time(); break;
   case 1: set_time();break;
   default :break;
   }
    }
      
  }