This document contains code for a microcontroller program that interfaces with a 4x4 keypad and LCD display. The main function initializes the LCD and enters a loop that checks each column of the keypad. If a key is pressed, a corresponding function is called to determine the key and display the matching number on the LCD. Several functions are defined to initialize and send data to the LCD, check each keypad column, and display the appropriate number message.

1. #include<reg51.h>
#define port P1;
#define dataport P2;
#define key P0 ;
void lcd_data_str(unsigned char *str);
void lcd(unsigned char str[10]);
void lcd_data(unsigned char item1);
void display(int a);
void lcd_cmd(unsigned char item);
void chek_col1();
void chek_col2();
void chek_col3();
void chek_col4();
void delay(unsigned int m);
sbit rs=port^1;
sbit rw=port^2;
sbit en=port^3;
sbit row1=key^0;
sbit row2=key^1;
sbit row3=key^2;
sbit row4=key^3;
sbit col1=key^4;
sbit col2=key^5;
sbit col3=key^6;
sbit col4=key^7;
//Main program
void main()
{
lcd_cmd(0x01);
lcd_data_str("welcome");
col1=col2=col3=col4=1;
while(1)
{
row1=row2=row3=row4=0;
if(col1==0)
chek_col1();
else if (col2==0)
chek_col2();
else if(col3==0)
chek_col3();
else
chek_col4();
}
}
//Function to decide the key pressed in col1
void chek_col1()
{
row1=row2=row3=row4=1;
row1=0;
if(col1==0)
display(1);
row1=1;
row2=0;
if(col1==0)
display(5);
row2=1;
row3=0;
if(col1==0)
display(9);
row3=1;
row4=0;
if(col1==0)

2. display(13);
row4=1;
}
//Function to decide the key pressed in col2
void chek_col2()
{
row1=row2=row3=row4=1;
row1=0;
if(col2==0)
display(2);
row1=1;
row2=0;
if(col2==0)
display(6);
row2=1;
row3=0;
if(col2==0)
display(10);
row3=1;
row4=0;
if(col2==0)
display(14);
row4=1;
}
//Function to decide the key pressed in col3
void chek_col3()
{
row1=row2=row3=row4=1;
row1=0;
if(col3==0)
display(3);
row1=1;
row2=0;
if(col3==0)
display(7);
row2=1;
row3=0;
if(col3==0)
display(11);
row3=1;
row4=0;
if(col3==0)
display(15);
row4=1;
}
//Function to decide the key pressed in col4
void chek_col4()
{
row1=row2=row3=row4=1;
row1=0;
if(col4==0)
display(4);
row1=1;
row2=0;
if(col4==0)
display(8);

3. row2=1;
row3=0;
if(col4==0)
display(12);
row3=1;
row4=0;
if(col4==0)
display(16);
row4=1;
}
//Function to send Command to LCD
void lcd_cmd(unsigned char item)
{
dataport=item;
rs=0;
rw=0;
en=1;
delay(1);
en=0;
return;
}
//Function to send Data to LCD
void lcd_data(unsigned char item1)
{
dataport=item1;
rs=1;
rw=0;
en=1;
delay(1);
en=0;
return;
}
// Function to send string to lcd_data
void lcd_data_str(unsigned char *str)
{
int i=0;
while(str[i]!='0')
{
lcd_data(str[i]);
i++;
delay(10);
}
return;
}
//Function to initialize the LCD
void lcd(unsigned char str[10])
{
lcd_cmd(0x38);
lcd_cmd(0x0E);
lcd_cmd(0x01);
lcd_cmd(0x82);
lcd_data_str(str);
}
//Function to send the string to be displayed
void display(int a)
{
switch(a)

4. {
case 1:lcd("One :1");
break;
case 2:lcd("Two :2");
break;
case 3:lcd("Three :3");
break;
case 4:lcd("Four :4");
break;
case 5:lcd("Five :5");
break;
case 6:lcd("Six :6");
break;
case 7:lcd("Seven :7");
break;
case 8:lcd("Eight :8");
break;
case 9:lcd("Nine :9");
break;
case 10:lcd("Ten :10");
break;
case 11:lcd("Eleven :11");
break;
case 12:lcd("Twelve :12");
break;
case 13:lcd("Thirteen :13");
break;
case 14:lcd("Fourteen :14");
break;
case 15:lcd("Fifteen :15");
break;
case 16:lcd("sixteen :16");
break;
default:lcd("others");
break;
}
}
//Delay Function
void delay(unsigned int m )
{
int i,j;
for(i=0;i<m;i++)
for(j=0;j<1275;j++);
}
Result: