#include <mega32.h>
#include <delay.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
unsigned char keyscan()
{ 
unsigned char row,col=1,data=16;
while(data==16)
{
PORTB=col;
delay_ms(55);//in delay baray jologiry az larzesh dast ast
row=PINB&0b11110000;
if(row==0b00010000)
{
switch(col)
{
case 1:
data='7';
break;
case 2:
data='8';
break;
case 4:
data='9';
break;
case 8:
data='/';
break;
}
}
if(row==0b00100000)
{
switch(col)
{
case 1:
data='4';
break;
case 2:
data='5';
break;
case 4:
data='6';
break;
case 8:
data='*';
break;
}
}
if(row==0b01000000)
{
switch(col)
{
case 1:
data='1'; 
break;
case 2:
data='2';
break;
case 4:
data='3';
break;
case 8:
data='-';
break;
}
}
if(row==0b10000000)
{
switch(col)
{
case 1:
data='C';
break;
case 2:
data='0';
break;
case 4:
data='=';
break;
case 8:
data='+';
break;
}
}
col=col<<1;
if(col==16)
col=1;
}//payan halghe while
return data;
}//payan tabe

#asm
   .equ __lcd_port=0x1B ;PORTA
#endasm
#include <lcd.h>

void main(void)
{
unsigned char k;
PORTA=0x00;
DDRA=0x00; 
PORTB=0x00;
DDRB=0x0F;
PORTC=0x00;
DDRC=0x00;
PORTD=0x00;
DDRD=0x00;
TCCR0=0x00;
TCNT0=0x00;
OCR0=0x00;
TCCR1A=0x00;
TCCR1B=0x00;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0x00;
OCR1BH=0x00;
OCR1BL=0x00;
ASSR=0x00;
TCCR2=0x00;
TCNT2=0x00;
OCR2=0x00;
MCUCR=0x00;
MCUCSR=0x00;
TIMSK=0x00;
ACSR=0x80;
SFIOR=0x00;
lcd_init(16);

while (1)
      {
      k=keyscan();
      lcd_putchar(k);
      }     
            
}