Notes

#include <Keypad.h> //Libraries you can download them via Arduino IDE
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>
#define I2C_ADDR 0x3f // LCD i2c Adress and pins
#define BACKLIGHT_PIN 3
#define En_pin 2
#define Rw_pin 1
#define Rs_pin 0
#define D4_pin 4
#define D5_pin 5
#define D6_pin 6
#define D7_pin 7

LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

const byte numRows= 4; //number of rows on the keypad

const byte numCols= 4; //number of columns on the keypad

int rakamsayac = 0;


int code = 1; //The code I used, you can change it
int code1 = 2;
int code2 = 3;
int code3 = 4;
int code4 = 5;
int code5 = 6;
int code6 = 7;
int code7 = 8;
int code8 = 9;

int tot,i1,i2,i3,i4;

char c1,c2,c3,c4;

//keymap defines the key pressed according to the row and columns just as appears on the keypad

char keymap[numRows][numCols]=

{

{'1', '2', '3', 'A'},

{'4', '5', '6', 'B'},

{'7', '8', '9', 'C'},

{'*', '0', '#', 'D'}

};

//Code that shows the the keypad connections to the arduino terminals

byte rowPins[numRows] = {9,8,7,6}; //Rows 0 to 3

byte colPins[numCols]= {5,4,3,2}; //Columns 0 to 3

//initializes an instance of the Keypad class

Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins, colPins, numRows, numCols);

void setup()

{

lcd.begin (16,2);

lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

lcd.setBacklight(HIGH);

lcd.home ();

lcd.print("Kimya Gorevi");

lcd.setCursor(9, 1);

lcd.print("Umutcan");

delay(2000);

}

void loop()

{

char keypressed = myKeypad.getKey(); //The getKey fucntion keeps the program runing, as long you didn't press "*" the whole thing bellow wouldn't be triggered

if (keypressed == '*') // and you can use the rest of you're code simply

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Sayi Giriniz"); //when the "*" key is pressed you can enter the passcode


if (keypressed != NO_KEY && rakamsayac == 0) //Birinci rakama basıldı

{

c1 = keypressed;

lcd.setCursor(0, 1);

lcd.print(c1);

rakamsayac = 1;

}

if((keypressed == "#") && (rakamsayac == 1)){
i1=c1-48;
tot = i1;

}



if (keypressed != NO_KEY && rakamsayac == 1)

{

c2 = keypressed;

lcd.setCursor(1, 1);

lcd.print(c2);

rakamsayac=2;

}

if((keypressed == "#") && (rakamsayac == 2)){
i1=(c1-48)*10;
i2=c2-48;

tot=i1+i2;

}





if (tot == code) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Hidrojen");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 1");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("H");
delay(3000);



}
if (tot == code1) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Helyum");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 2");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("He");
delay(3000);



}
if (tot == code2) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Lityum");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 3");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("Li");
delay(3000);



}
if (tot == code3) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Berilyum");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 4");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("Be");
delay(3000);



}
if (tot == code4) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Bor");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 5");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("B");
delay(3000);



}
if (tot == code5) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Karbon");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 6");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("C");
delay(3000);



}
if (tot == code6) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Azot");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 7");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("N");
delay(3000);



}
if (tot == code7) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Oksijen");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 8");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("O");
delay(3000);



}
if (tot == code8) //if the code is correct you trigger whatever you want here it just print a message on the screen

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Flor");

lcd.setCursor(0, 1);

lcd.print("Atom NumarasI 9");

delay(3000);

lcd.clear();

lcd.print("Sembolu");

lcd.setCursor(9, 1);

lcd.print("F");
delay(3000);



}



else //if the code is wrong you get another thing

{

lcd.clear();

lcd.setCursor(0, 0);

lcd.print("Baska Sayi Seciniz");

delay(2500);

lcd.clear();

lcd.print("YIldIza");

lcd.setCursor(9, 1);

lcd.print("BasInIz");



}



}

}