#include <LiquidCrystal_I2C.h>
#include<Wire.h>
#include <Keypad.h> //Header file for Keypad from https://github.com/Chris--A/Keypad
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Three columns
char keys[ROWS][COLS] = {
{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'*','0','#','D'}
};
byte rowPins[ROWS] = { 9,8,7,6};
// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte colPins[COLS] = { 5,4,3,2 };
// Connect keypad COL0, COL1 and COL2 to these Arduino pins.
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
// Create the Keypad
LiquidCrystal_I2C lcd(0X27,16,2);
long Num1,Num2,Number;
char key,action;
boolean result = false;
void setup()
{
lcd.init();
lcd.backlight();
lcd.print("Calculator");
lcd.setCursor(0, 1); // set the cursor to column 0, line 1
delay(2000);
lcd.clear();
}
void loop()
{
lcd.setCursor(0,0);
key = kpd.getKey(); //storing pressed key value in a char
if (key=='*') //If cancel Button is pressed
{
lcd.print ("Button Cancel");
delay(1000);
lcd.clear();
}
else if (key == '1') //If Button 1 is pressed
{
lcd.println ("Button 1");
if (Number==0)
Number=1;
else
Number = (Number*10) + 1; //Pressed twice
}
else if (key == '4') //If Button 4 is pressed
{lcd.println ("Button 4");
if (Number==0)
Number=4;
else
Number = (Number*10) + 4; //Pressed twice
}
else if (key == '7') //If Button 7 is pressed
{lcd.println ("Button 7");
if (Number==0)
Number=7;
else
Number = (Number*10) + 7; //Pressed twice
}
else if (key == '0')
{lcd.println ("Button 0"); //Button 0 is Pressed
if (Number==0)
Number=0;
else
Number = (Number*10) + 0; //Pressed twice
}
else if (key == '2') //Button 2 is Pressed
{lcd.println ("Button 2");
if (Number==0)
Number=2;
else
Number = (Number*10) + 2; //Pressed twice
}
else if (key == '5')
{lcd.println ("Button 5");
if (Number==0)
Number=5;
else
Number = (Number*10) + 5; //Pressed twice
}
else if (key == '8')
{lcd.println ("Button 8");
if (Number==0)
Number=8;
else
Number = (Number*10) + 8; //Pressed twice
}
else if (key == '#')
{lcd.println ("Button Equal");
Num2=Number;
result = true;
}
else if (key == '3')
{lcd.println ("Button 3");
if (Number==0)
Number=3;
else
Number = (Number*10) + 3; //Pressed twice
}
else if (key == '6')
{lcd.println ("Button 6");
if (Number==0)
Number=6;
else
Number = (Number*10) + 6; //Pressed twice
}
else if (key == '9')
{lcd.println ("Button 9");
if (Number==0)
Number=9;
else
Number = (Number*10) + 9; //Pressed twice
}
else if (key == 'A' || key == 'B' || key == 'C' || key == 'D') //Detecting Buttons on Column 4
{
Num1 = Number;
Number =0;
if (key == 'A')
{lcd.println ("Addition"); action = '+';}
if (key == 'B')
{lcd.println ("Subtraction"); action = '-'; }
if (key == 'C')
{lcd.println ("Multiplication"); action = '*';}
if (key == 'D')
{lcd.println ("Devesion"); action = '/';}
delay(100);
}
}