Calculator

• Aim: To make a calculator using ATmega16 microcontroller, LCD (16x2) and Keypad (4x4).

Note: LCD used in 4 bit mode

• Code:

#define F_CPU 8000000UL
#include<avr/io.h>
#include<util/delay.h>
#include<math.h>
void initialize();
void lcd_cmd(char value);
void lcd_data(char value);
void lcd_string(char *str);
void lcd_num(long int number);
void keypad();
void operate();
void check();
void special();
long int z=0,i=0,j=0,ar[10],arr[10],far[10],farr[10],op[10],inc=0;
void initialize()
{
lcd_cmd(0x01); //clear LCD
lcd_cmd(0x02);    //home position
lcd_cmd(0x06);    //L-R
//lcd_cmd(0x04);
lcd_cmd(0x28); //4 bit mode
lcd_cmd(0x0C);    //character generation
}
void lcd_cmd(char value)
{
int un,ln; // pc7-pc4 = un ; pc3-pc4 =ln
un=value&0xF0; // & is anding function
PORTC=0x04|un;
_delay_ms(2);
PORTC=0x00|un;
_delay_ms(2);
ln=(value<<4)&0xF0; //<<=left shif by 4 bits
_delay_ms(2);
PORTC=0x04|ln;
_delay_ms(2);
PORTC=0x00|ln;
}
void lcd_data(char value)
{
int un,ln; // pc7-pc4 = un ; pc3-pc4 =ln
un=value&0xF0; // & is anding function
PORTC=0x05|un;
_delay_ms(2);
PORTC=0x01|un;
_delay_ms(2);
ln=(value<<4)&0xF0; //<<=left shif by 4 bits
_delay_ms(2);
PORTC=0x05|ln;
_delay_ms(2);
PORTC=0x01|ln;
}
void lcd_string(char *str)
{
int i=0;
while(str[i]!='\0')
{
lcd_data(str[i]);
i++;
}
}
void lcd_num(long int number)
{
lcd_cmd(0x04);
long int d=0;
while(number!=0)
{
d=number%10;
lcd_data(d+48);
number=number/10;
}
}
int power(int x){
int i=0;
long int t=1;
for(i=0;i<x;i++){
t=t*10;
}
return t;
}
void operate(){
if(i>j){
i=i-j-1;
}
else if(i<j){
i=j-i-1;
}
long int u=i,v=j,d=0,k=0,e=0,l=0,q=0,w=0,f=0,g=0;
int m=0,n=0;
k=u;
l=v;
while(u>=0){
q=q+power(u)*ar[u];
  u--;
}
while(q!=0){
d=q%10;
e=e+power(k-1)*d;
q=q/10;
k--;
_delay_ms(80);
}
far[m]=e;
                              // final number1
while(v>=0){
w=w+power(v)*arr[v];
v--;
}
while(w!=0){
f=w%10;
g=g+power(l-1)*f;
w=w/10;
l--;
_delay_ms(80);
}
farr[n]=g;
m++;
n++;
check();
}
void special(){
lcd_data(0x00);
lcd_data(0x00);
lcd_data(0x00);
lcd_data(0x0A);
lcd_data(0x15);
lcd_data(0x15);
lcd_data(0x0A);
lcd_data(0x00);
}
void check(){
long int sum=0,sub=0,mul=1;
float div=1.00;
if(z==1){
div=far[0]/farr[0];
if(div==0){
lcd_cmd(0xCF);
lcd_string("0");
}
else if(farr[0]==0){
while(1){
lcd_cmd(0x40);
special();
lcd_cmd(0xCE);
lcd_data(0);
}
}
else{
lcd_cmd(0xCF);
lcd_num(div);
}
}
else if(z==2){
mul=far[0]*farr[0];
if(mul==0){
lcd_cmd(0xCF);
lcd_string("0");
}
else{
lcd_cmd(0xCF);
lcd_num(mul);
}
}
else if(z==3){
sub=far[0]-farr[0];
if(sub==0){
lcd_cmd(0xCF);
lcd_string("0");
}
else if(sub<0){
lcd_cmd(0x8F);
lcd_string("-");
lcd_cmd(0xCF);
lcd_num(farr[0]-far[0]);
}
else {
lcd_cmd(0xCF);
lcd_num(sub);
}
}
else if(z==4){
sum=far[0]+farr[0];
if(sum==0){
lcd_cmd(0xCF);
lcd_string("0");
}
else{
lcd_cmd(0xCF);
lcd_num(sum);
}}
else {
lcd_cmd(0xC3);
lcd_string("NA");
}
}
void keypad(){
PORTD=0x0F;
PORTB=0x0E;
if(PIND==0x0E)
{
lcd_cmd(0x80+i);
lcd_string("7");
_delay_ms(250);
ar[i]=7;
if(z!=0){
arr[j]=7;
j++;
}
i++;
}
else if(PIND==0x0D){
lcd_cmd(0x80+i);
lcd_string("4");
_delay_ms(250);
ar[i]=4;
if(z!=0){
arr[j]=4;
j++;
}
i++;
}
else if(PIND==0x0B){
lcd_cmd(0x80+i);
lcd_string("1");
_delay_ms(250);
ar[i]=1;
if(z!=0){
arr[j]=1;
j++;
}
i++;
}
else if(PIND==0x07 ){
lcd_cmd(0x01);
_delay_ms(100);
i=0;
z=0;
j=0;
inc=0;
}
PORTD=0x0F;
PORTB=0x0D;
if(PIND==0x0E ){
lcd_cmd(0x80+i);
lcd_string("8");
_delay_ms(250);
ar[i]=8;
if(z!=0){
arr[j]=8;
j++;
}
i++;
}
else if(PIND==0x0D){
lcd_cmd(0x80+i);
lcd_string("5");
_delay_ms(250);
ar[i]=5;
if(z!=0){
arr[j]=5;
j++;
}
i++;
}
else if(PIND==0x0B){
lcd_cmd(0x80+i);
lcd_string("2");
_delay_ms(250);
ar[i]=2;
if(z!=0){
arr[j]=2;
j++;
}
i++;
}
else if(PIND==0x07){
lcd_cmd(0x80+i);
lcd_string("0");
_delay_ms(250);
ar[i]=0;
if(z!=0){
arr[j]=0;
j++;
}
i++;
}
PORTD=0x0F;
PORTB=0x0B;
if(PIND==0x0E ){
lcd_cmd(0x80+i);
lcd_string("9");
_delay_ms(250);
ar[i]=9;
if(z!=0){
arr[j]=9;
j++;
}
i++;
}
else if(PIND==0x0D ){
lcd_cmd(0x80+i);
lcd_string("6");
_delay_ms(200);
ar[i]=6;
if(z!=0){
arr[j]=6;
j++;
}
i++;
}
else if(PIND==0x0B){
lcd_cmd(0x80+i);
lcd_string("3");
_delay_ms(250);
ar[i]=3;
if(z!=0){
arr[j]=3;
j++;
}
i++;
}
else if(PIND==0x07){
lcd_cmd(0xC1);
lcd_string("=");
operate();
}
PORTD=0x0F;
PORTB=0x07;
if(PIND==0x0E){
lcd_cmd(0x80+i);
lcd_string("/");
_delay_ms(250);
z=1;
op[inc]=1;
inc++;
i++;

}
else if(PIND==0x0D ){
lcd_cmd(0x80+i);
lcd_string("x");
_delay_ms(250);
z=2;
op[inc]=2;
inc++;
i++;

}
else if(PIND==0x0B){
lcd_cmd(0x80+i);
lcd_string("-");
_delay_ms(250);
z=3;
op[inc]=3;
inc++;
i++;

}
else if(PIND==0x07){
lcd_cmd(0x80+i);
lcd_string("+");
_delay_ms(250);
z=4;
op[inc]=4;
inc++;
i++;

}
}
void main()
{

DDRC=0xFF;
initialize();
DDRD=0x00;
DDRB=0xFF;
while(1){
keypad();
}}

• Hardware information: 

PortD= Row of keypad (PD0-A, PD1-B, PD2-C, PD3-D);
portB=Column of keypad (PB0-1, PB1-2, PB2-3, PB3-4);
portC= LCD Display
{
 pc0=RS
pc1=R/W
pc2=E

pc4-pc7 = Data pins (D4-D7)
}  

• Proteus Simulation:

 

 

Simulation of Calculator

 

 

•  Constraints: 

1) Only displays integer

2) Small delay 

3) To correct clear the whole screen

• Conclusion: 

Calculator has been created using C programming in Avr studio software and simulation of the same in proteus software. The simulation picture is shown above and the constraints have been noted.