keypad

/*This program is created by Shubham */
/*This program is for appin project */

#include <stdio.h>
#include <reg51.h>

sbit col1 = P0^0;
sbit col2 = P0^1;
sbit col3 = P0^2;
sbit row1 = P0^3;
sbit row2 = P0^4;
sbit row3 = P0^5;
sbit row4 = P0^6;

void delay(unsigned int msec)  // Function to provide time delay in msec.
{
int i,j ;
for(i=0;i<msec;i++)
for(j=0;j<1275;j++);
}

void check_col1() //Function for checking column one
{
row1=row2=row3=row4=1;
row1=0;
if(col1==0)
{
P1 = 0xf9;
delay(100);
}
row1=1;
row2=0;
if(col1==0)
{P1 = 0x99;
delay(100);}
row2=1;
row3=0;
if(col1==0)
{
P1 = 0xf8;
delay(100);
}
row3=1;
row4=0;
if(col1==0)
{
P1 = 0x00;
delay(100);
}
row4=1;
}

void main()
{
col1=col2=col3=1;  //Input Port
while(1)
{
  row1=row2=row3=row4=0;
  if(col1==0)
  check_col1();

}
}