bomb clock countdown.txt

// Program to make a clock with time setting functionality.

#include<reg51.h>
sbit dig_ctrl_4=P0^0;        //Declare the control pins of the seven segment
sbit dig_ctrl_3=P0^1;
sbit dig_ctrl_2=P0^2;
sbit dig_ctrl_1=P0^3;
sbit reset=P1^4;        // Reset pin to reset the clock.
sbit start=P1^7;        //Start pin to start the clock after the time is set.
sbit incr=P1^6;        //Increment pin to increase the digits during time setting.
sbit set=P1^5;        // Set pin to set the time.
sbit beep=P3^0;
int sel_seg_to_incr=0;
int ret_seg_to_incre=0;
int recnt_incr_seg;
unsigned char dig_disp=0;
int min2=0;
int min1=0;
int sec2=0;
int sec1=0;
char dig_val[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x67};        // to store values corresponding to digits 0 to 9

void delay(int a)        // Function to provide a time delay of approx. 1 second using Timer1.
{
    int i;
    for(i=0;i<a;i++)
    {
        TL1=0xFD;
        TH1=0x4B;
        TR1=1;
        while(TF1==0);
        TR1=0;
        TF1=0;
    }
}

int setfn()        // Function to select minute and seconds digit to be set.
{
    while(set==0)
    {
        switch(recnt_incr_seg)
        {
            case 1:
            if(set==0)        //select the min2 digit
            {
                dig_ctrl_4=1;
                dig_ctrl_3=0;
                dig_ctrl_2=0;
                dig_ctrl_1=0;
                recnt_incr_seg=1;
                ret_seg_to_incre=1;
                P2=dig_val[min2];
                delay(20);
            }
            
            case 2:
            if(set==0)        // Select the min1 digit
            {
                dig_ctrl_4=0;
                dig_ctrl_3=1;
                dig_ctrl_2=0;
                dig_ctrl_1=0;
                recnt_incr_seg=2;
                ret_seg_to_incre=2;
                P2=dig_val[min1];
                delay(20);
            }
            
            case 3:
            if(set==0)        //Select the sec 2 digit
            {
                dig_ctrl_4=0;
                dig_ctrl_3=0;
                dig_ctrl_2=1;
                dig_ctrl_1=0;
                recnt_incr_seg=3;
                ret_seg_to_incre=3;
                P2=dig_val[sec2];
                delay(20);
            }
            
            case 4:
            if(set==0)        //Select the sec1 digit
            {
                recnt_incr_seg=1;
                dig_ctrl_4=0;
                dig_ctrl_3=0;
                dig_ctrl_2=0;
                dig_ctrl_1=1;
                ret_seg_to_incre=4;
                P2=dig_val[sec1];
                delay(20);
                recnt_incr_seg=1;
            }
        }
    }
    return(ret_seg_to_incre);
}

void increase(int a)        //Function to set the minute or seconds digit
{
    while(incr==0)
    {
        switch(a)
        {
            case 1:        // To set the min2 digit.
            P2=dig_val[min2];        //Display the value of min2
            delay(15);
            min2++;
            if(min2==6)
            min2=0;
            P2=dig_val[min2];
            delay(5);
            break;
            
            case 2:        //To set the min1 digit.
            P2=dig_val[min1];
            delay(15);
            min1++;
            if(min1==10)
            min1=0;
            P2=dig_val[min1];
            delay(5);
            break;
            
            case 3:        // To set the sec2 digit.
            P2=dig_val[sec2];
            delay(15);
            sec2++;
            if(sec2==6)
            sec2=0;
            P2=dig_val[sec2];
            delay(5);
            break;
            
            case 4:        //To set the sec1 digit.
            P2=dig_val[sec1];
            delay(15);
            sec1++;
            if(sec1==10)
            sec1=0;
            P2=dig_val[sec1];
            delay(5);
            break;
        }
    }
}

void resetfn()        // This function brings the clock to reset or set mode.
{
    IE=0x80;        //Disable timer0 interrupt to stop the display of the clock
    sel_seg_to_incr=1;
    recnt_incr_seg=1;
    dig_ctrl_4=1;
    dig_ctrl_3=0;
    dig_ctrl_2=0;
    dig_ctrl_1=0;
    P2=dig_val[min2];
    delay(5);
    while(1)
    {
        if(start==0)        //check if start pin is pressed
        {
            TMOD=0x11;        //reset the timer0
            TL0=0xf6;
            TH0=0xFf;
            IE=0x82;        //enabling again the timer0 interrupt to start displaying of the clock
            TR0=1;
            break;        // break loop and return to main program
        }
        
        if(set==0)        //if set pin is pressed call set function
        sel_seg_to_incr=setfn();
        
        if(incr==0)        // if incr pin is pressed call incr function
        increase(sel_seg_to_incr);
    }
}
void display() interrupt 1        // function to display the values on seven segmnet. For more details refer seven segment multiplexing.
{
    TL0=0x36;        //reloading timer0
    TH0=0xf6;
    P2=0xFF;
    dig_ctrl_1 = dig_ctrl_3 = dig_ctrl_2 = dig_ctrl_4 = 0;
    dig_disp++;
    dig_disp=dig_disp%4;
    switch(dig_disp)
    {
        case 0:
        P2=dig_val[sec1];
        dig_ctrl_1 = 1;
        break;
        
        case 1:
        P2=    dig_val[sec2];
        dig_ctrl_2 = 1;
        break;
        
        case 2:
        P2=    dig_val[min1];
        dig_ctrl_3 = 1;
        break;
        
        case 3:
        P2=    dig_val[min2];
        dig_ctrl_4 = 1;
        break;
    }
}

void main()        //main function the programs begins from here
{
    set=1;        //delaring set, reset, start and incr as input pins
    reset=1;
    start=1;
    incr=1;
    TMOD=0x11;        //enabling timer0
    TL0=0xf6;        //loading timer0
    TH0=0xFf;
    IE=0x82;        //initialize timer0 interrupt
    TR0=1;        //triggering timer0
    min2=0;
    min1=0;
    sec2=0;
    sec1=0;
    beep=1;
    while(1)        //forward counting of clock
    {
        while(min2>=0)
        {	if(min2==0 && min1 ==0 && sec2==0 && sec1 == 0)
            {
                break;
            }
            while(min1>=0)
            {
                while(sec2>=0)
                {
                    while(sec1>=0)
                    {
                        if(reset==0)
                        resetfn();
                        if(min2==0 && min1 ==0 && sec2==0 && sec1==0)
                        {
                            beep=0;
							delay(10);
							beep=1;
							delay(10);
							beep=0;
							delay(10);
							beep=1;
							delay(10);
							beep=0;
                            delay(10);
							beep=1;
							delay(10);
							beep=0;
							delay(10);
							beep=1;
                        }
                        delay(20);
                        sec1--;
                    }
                    sec1=9;
                    sec2--;
                }
                sec1=9;
                sec2=5;
                min1--;
            }
            sec1=9;
            sec2=5;
            min1=9;
            min2--;
        }
        min2=0;
        min1=0;
        sec2=0;
        sec1=0;
        beep=1;
		if(reset==0) 
		   resetfn();

    }
}