#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);

const int numRow=4;
const int numCols=4;
const int debounsTime = 20;

const char keymap[numRow][numCols]={

{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'*','0','#','D'}
};

const int RowPins[numRow]={9,8,7,6};
const int ColPins[numCols]={5,4,3,2};


void setup() {

lcd.init();

lcd.backlight();

lcd.setCursor(3,0);

lcd.print("Using LCD");


for(int Row=0;Row<numRow;Row++){

  pinMode(RowPins[Row], INPUT_PULLUP);
}
for (int Column=0;Column<numCols;Column++){

pinMode (ColPins[Column],OUTPUT);
digitalWrite(ColPins[Column], HIGH);

}
  // put your setup code here, to run once:

}

void loop() {

char key=getKey();
if (key!=0){

lcd.setCursor(3,1);

lcd.print("Got key  ");
lcd.print(key);


}



  
  // put your main code here, to run repeatedly:

}
char getKey(){

char Key=0;

for(int column=0;column<numCols;column++){
  digitalWrite(ColPins[column], LOW);
  for(int row=0;row<numRow;row++){

    if (digitalRead(RowPins[row])==LOW){


      delay(debounsTime);
      while(digitalRead(RowPins[row])==LOW);
      Key=keymap[row][column];
    }
  }
  digitalWrite(ColPins[column], HIGH);
}



return Key;
}