/*#include <Keypad.h>
#include <LCD_I2C.h>

LCD_I2C lcd(0x27, 16, 2);

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

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

void setup() {
  lcd.begin(); 
                 
    lcd.backlight();
  
}

void loop() {
  char key = keypad.getKey();

  if (key != NO_KEY) {
    lcd.println(key);
  }
}*/


// *************** LCD screen  start

#include <LiquidCrystal_I2C.h>

 

#define I2C_ADDR    0x27

#define LCD_COLUMNS 20

#define LCD_LINES   4

 

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

// **************** LCD  end

 

const int numRows = 4; // number of rows in the keypad

const int numCols = 4; // number of columns

const int debounceTime = 20; // number of milliseconds for switch to be stable

// keymap defines the character returned when the corresponding key is pressed

const char keymap[numRows][numCols] = {

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

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

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

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

};

// this array determines the pins used for rows and columns

const int rowPins[numRows] = {9,8, 7, 6}; // Rows 0 through 3

const int colPins[numCols] = {5,4, 3, 2}; // Columns 0 through 2

void setup()

{

 

 // Init LCD screen

  lcd.init();

  lcd.backlight();

 

  lcd.setCursor(3, 0);

  lcd.print("Using LCD");

 

 for (int row = 0; row < numRows; row++)

 {

 pinMode(rowPins[row],INPUT_PULLUP); // Set row pins as input with pullups

 }

 for (int column = 0; column < numCols; column++)

 {

 pinMode(colPins[column],OUTPUT); // Set column pins as outputs

 digitalWrite(colPins[column],HIGH); // Make all columns inactive

 }

}

void loop()

{

 char key = getKey();

 if( key != 0) { // if the character is not 0 then it's a valid key press

 

 lcd.setCursor(3, 1);

 lcd.print("Got key ");

 lcd.print(key);

 

 }

}

// returns the key pressed, or zero if no key is pressed

char getKey()

{

 char key = 0; // 0 indicates no key pressed

 for(int column = 0; column < numCols; column++)

 {

 digitalWrite(colPins[column],LOW); // Activate the current column.

 for(int row = 0; row < numRows; row++) // Scan all rows for key press

 {

 if(digitalRead(rowPins[row]) == LOW) // Is a key pressed?

 {

 delay(debounceTime); // debounce

 while(digitalRead(rowPins[row]) == LOW)
; // wait for key to be released

 key = keymap[row][column]; // Remember which key

 // was pressed.

 }

 }

 digitalWrite(colPins[column],HIGH); // De-activate the current column.

 }

 return key; // returns the key pressed or 0 if none

}