Question

Write a program to display (on 7-segment) continuous up-counting numbers from 00 to 99 (in decimal system) when switch SW2 is pressed and released, and down-counting when switch SW3 is pressed and released.

PLEASE CODE IN C.

PROVIDE ALGORITHM ALSO.

Answer 1

ALGORITHM--

For common cathode 7-seg led Hex code corresponding to digits {0,1,2,3,4,5,6,7,8,9}
will be{0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82, 0xF8,0x80,0x90}

Step 1: Start
Step 2: Declare variables SW2,SW3,LED1,LED2,i,j
Step 3: Initialize hex code array LED_CODE[] 
Step 4: Define a delay function delay() to generate 200ms delay

Step 5: Read SW1 & SW2 from user.
Step 6: If SW2=1
        i=0;
      Repeat the steps until i<10
        j=0;
      6.1 Repeat the steps until j<10 
            LED2 = LED_CODE[j]

            call delay() function
            j=j+1

      6.2 LED1 = LED_CODE[j]

      6.3 i=i+1     

Step 7: If SW3=1
        i=9 
       Repeat the steps until i>=0
        J=9;
      7.1 Repeat the steps until j>=0 
            LED2 = LED_CODE[j]

            call delay() function
            j=j-1

      7.2 LED1 = LED_CODE[j]

      7.3 i=i-1  

Step 8: Stop 

C CODE--(For 8051 microcontroller)

#include <reg51.h> 
#define LED1 P2 //PORT2.0 is connected to segment '1'
#define LED2 P1 //PORT1.0 is connected to segment '2'

void msdelay()  // Function for creating delay of 200 milliseconds.
{
    unsigned i;    
    for(i=0;i<25000;i++);
}

void main()
{
unsigned char i,j;
unsigned int sw2,sw3;
unsigned char seg_code[]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82, 0xF8,0x80,0x90};

if(sw2==1)
{
        for(i=0;i<10;i++)
        {
                LED1=seg_code[i];
                for(j=0;j<10;j++)
                {
                        LED2=seg_code[j];
                        msdelay();
                }
        }
}
        
if(sw3==1)
{
        for(i=9;i>=0;i--)
        {
                LED1=seg_code[i];
                for(j=9;j>=0;j--)
                {
                        LED2=seg_code[j];
                        msdelay();
                }
        }
}
                
}