Arduino Calculator Project Using Keypad and LCD | Makers’ Muse

Arduino Calculator Project Using Keypad and LCD | Makers’ Muse

Overview

A calculator is a device used to solve mathematical problems easily and in a fast way. This calculator can add, subtract, multiply, and Divide. 

In this project, we have used a (4*4) keypad to take input and an LCD to show output. A potentiometer is also used to adjust the LCD to show the output. Keys used 

A – Addition

B – Subtract

C – Multiplication

D – Divide

Hardware required 

1. Arduino Uno R3
2. Potentiometer
3. Keypad 4*4
4. Resistor
5. LCD
6. Jumper Wires

Schematic Diagram

Fig 1.  Circuit Diagram

Arduino Code : 

#include <LiquidCrystal.h> 

#include <Keypad.h> 

const byte ROWS = 4; 

const byte COLS = 4; 

char keys[ROWS][COLS] = {

  {‘1′,’2′,’3′,’A’},

  {‘4′,’5′,’6′,’B’},

  {‘7′,’8′,’9′,’C’},

  {‘*’,’0′,’#’,’D’}

};

byte rowPins[ROWS] = { 0, 1, 2, 3 };

byte colPins[COLS] = { 4, 5, 6, 7 }; 

Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS ); 

const int rs = 8, en = 9, d4 = 10, d5 = 11, d6 = 12, d7 = 13; 

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

 long Num1,Num2,Number;

 char key, action;

 boolean result = false;

void setup() {

  lcd.begin(16, 2); 

  lcd.print(“Calculator”); 

  lcd.setCursor(0, 1);  

  lcd.print(“-Raghav”);  

   delay(2000); 

    lcd.clear();

}

void loop() {

key = kpd.getKey(); 

if (key!=NO_KEY)

DetectButtons();

if (result==true)

CalculateResult();

DisplayResult();   

}

void DetectButtons()

{ 

     lcd.clear();

    if (key==’*’) 

    {Serial.println (“Button Cancel”); Number=Num1=Num2=0; result=false;}

     if (key == ‘1’) 

    {Serial.println (“Button 1”); 

    if (Number==0)

    Number=1;

    else

    Number = (Number*10) + 1; 

    }

     if (key == ‘4’) 

    {Serial.println (“Button 4”); 

    if (Number==0)

    Number=4;

    else

    Number = (Number*10) + 4; 

    }

     if (key == ‘7’) 

    {Serial.println (“Button 7”);

    if (Number==0)

    Number=7;

    else

    Number = (Number*10) + 7; 

    } 

    if (key == ‘0’)

    {Serial.println (“Button 0”);

    if (Number==0)

    Number=0;

    else

    Number = (Number*10) + 0; 

    }

     if (key == ‘2’) 

    {Serial.println (“Button 2”); 

     if (Number==0)

    Number=2;

    else

    Number = (Number*10) + 2; 

    }

     if (key == ‘5’)

    {Serial.println (“Button 5”); 

     if (Number==0)

    Number=5;

    else

    Number = (Number*10) + 5; 

    }

     if (key == ‘8’)

    {Serial.println (“Button 8”); 

     if (Number==0)

    Number=8;

    else

    Number = (Number*10) + 8; 

    }   

    if (key == ‘#’)

    {Serial.println (“Button Equal”); 

    Num2=Number;

    result = true;

    }

     if (key == ‘3’)

    {Serial.println (“Button 3”); 

     if (Number==0)

    Number=3;

    else

    Number = (Number*10) + 3; 

    }

     if (key == ‘6’)

    {Serial.println (“Button 6”); 

    if (Number==0)

    Number=6;

    else

    Number = (Number*10) + 6; 

    }

     if (key == ‘9’)

    {Serial.println (“Button 9”);

    if (Number==0)

    Number=9;

    else

    Number = (Number*10) + 9; 

    }  

      if (key == ‘A’ || key == ‘B’ || key == ‘C’ || key == ‘D’) 

  {

    Num1 = Number;    

    Number =0;

    if (key == ‘A’)

    {Serial.println (“Addition”); action = ‘+’;}

     if (key == ‘B’)

    {Serial.println (“Subtraction”); action = ‘-‘; }

     if (key == ‘C’)

    {Serial.println (“Multiplication”); action = ‘*’;}

     if (key == ‘D’)

    {Serial.println (“Division”); action = ‘/’;}  

    delay(100);

  }

}

void CalculateResult()

{

  if (action==’+’)

    Number = Num1+Num2;

  if (action==’-‘)

    Number = Num1-Num2;

  if (action==’*’)

    Number = Num1*Num2;

  if (action==’/’)

    Number = Num1/Num2; 

}

void DisplayResult()

{

  lcd.setCursor(0, 0);  

  lcd.print(Num1); lcd.print(action); lcd.print(Num2); 

  if (result==true)

  {lcd.print(” =”); lcd.print(Number);} 

  lcd.setCursor(0, 1);   

  lcd.print(Number); 

}

Precautions

1. Connections should be done properly.
2. Arduino is case sensitive, so code accordingly.
3. Give different colours to the wires.
4. Adjust the potentiometer to get output on the LCD.

Conclusion:

The Arduino Calculator Project, using a keypad and LCD, is a simple yet powerful way to understand embedded systems and electronics. It teaches how hardware and software work together to perform real-world applications like arithmetic operations. Projects like this spark creativity and problem-solving skills in learners.

At Makers’ Muse, we believe in empowering students through hands-on learning. Explore more innovative ideas and enhance your skills with coding schools to become a future-ready innovator.