8-bit digital tube display electronic clock c51 program

/*
The 8-digit digital tube displays the time in the format of 05-50-00, indicating 05:50:00
S1 is used for hour plus 1 operation
S2 is used for hour minus 1 operation
S3 is used for minute plus 1 operation
S4 is used for minute minus 1 operation
*/

#include
sbit KEY1=P3^0; //Define port parameters
sbit KEY2=P3^1;
sbit KEY3=P3^2;
sbit KEY4=P3^3;
sbit LED=P1^2; //Define indicator light parameters


code unsigned char tab[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f}; //Common cathode digital tube 0-9
unsigned char StrTab[8]; //define buffer
unsigned char minute=19,hour=23,second; //define and initialize to 12:30:00


void delay(unsigned int cnt)
{
        while(--cnt);
}

/******************************************************************/
/* Display processing function */
/******************************************************************/
void Displaypro(void)
{

        StrTab[0]=tab[hour/10]; //Display hour
        StrTab[1]=tab[hour%10];
        StrTab[2]=0x40; //display "-"
        StrTab[3]=tab[minute/10]; //Display minutes

        StrTab[4]=tab[minute%10];
        StrTab[5]=0x40; //display "-"
        StrTab[6]=tab[second/10]; //Display seconds

        StrTab[7]=tab[second%10];
}

main()
{
        TMOD |= 0x01; //Timer 0 10ms inM crystal for timing
        TH0=0xd8; //initial value
        TL0=0xf0;
        ET0=1;
        TR0=1;

        TMOD |= 0x10; //Timer 1 is used for dynamic scanning
        TH1=0xF8; //initial value
        TL1=0xf0;
        ET1=1;
        TR1=1;
        EA = 1;
        Displaypro(); //Call display processing function

        while(1)
        {
                if(!KEY1) //key 1 debounce and action
                {
                        delay(10000);
                        if(!KEY1)
                        {          
                                hour++;

                                if(hour==24)

                                        hour=0; //normal time hour plus 1
                                Displaypro();
                        }
                }

                if(!KEY2) //Key 2 debounce and action
                {
                        delay(10000);
                        if(!KEY2)
                        {
                                hour--;

                                if(hour==255)

                                        hour=23; //Normal time hour minus 1
                                Displaypro();
                        }
                }
                if(!KEY3) //key debounce and action
                {
                        delay(10000);
                        if(!KEY3)
                        {
                                minute++;

                                if(minute==60)

                                        minute=0; //minute plus 1
                                Displaypro();
                        }
                }       
                if(!KEY4) //key debounce and action
                {
                        delay(10000);
                        if(!KEY4)
                        {
                                minute--;

                                if(minute==255)

                                        minute=59; //minus 1
                                Displaypro();
                        }
                }
        }
}


/******************************************************************/
/* Timer 1 interrupt */
/******************************************************************/
void time1_isr(void) interrupt 3 using 0 //Timer 1 is used for dynamic scanning
{
        static unsigned char num;
        TH1=0xF8; //Re-enter initial value
        TL1=0xf0;

        switch (num)

        {
                case 0:P2=0;P0=StrTab[num];break; //Call the buffer values ​​for scanning
                case 1:P2=1;P0=StrTab[num];break;
                case 2:P2=2;P0=StrTab[num];break;
                case 3:P2=3;P0=StrTab[num];break;
                case 4:P2=4;P0=StrTab[num];break;
                case 5:P2=5;P0=StrTab[num];break;
                case 6:P2=6;P0=StrTab[num];break;
                case 7:P2=7;P0=StrTab[num];break;
                default:break;
        }
        num++; //Scan 8 times, using 8 digital tubes
        if(num==8)
                num=0;
}


/******************************************************************/
/* Timer 0 interrupt */
/******************************************************************/
void tim(void) interrupt 1 using 1
{
        static unsigned char count; //define internal local variables

        TH0=0xd8; //Reassign value
        TL0=0xf0;
        count++;
        switch (count)
        {
                case 0:
                case 20:
                case 40:
                case 60:
                case 80:Displaypro();break; //Call display processing at regular intervals
                case 50:P1=~P1;break; //LED flashes for half a second
                default:break;
        }

        if (count==100)
        {
                count=0;
                second++; //second plus 1
                if(second==60)
                {
                        second=0;
                        minute++; // add 1 to the minute
                        if(minute==60)
                        {
                                minute=0;
                                hour++; // add 1 to the hour
                                if(hour==24)
                                        hour=0;
                        }  
                }
        } 
}