#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display

char key_pressed;

void setup() {
  // put your setup code here, to run once:

  for (int i=2;i<6;i++) pinMode(i, INPUT_PULLUP);
  for (int i=8;i<12;i++) pinMode(i, OUTPUT);
  Serial.begin(9600);
  Serial.println("Started");
  lcd.init();                      // initialize the lcd
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Keypad:");
}

void loop() {
  // put your main code here, to run repeatedly:
  key_pressed=0;

  for (int i=8;i<12;i++) digitalWrite(i, HIGH);
  digitalWrite(8, LOW);
  if (digitalRead(2)==LOW) key_pressed='A';
  else if (digitalRead(3)==LOW) key_pressed='B';
  else if (digitalRead(4)==LOW) key_pressed='C';
  else if (digitalRead(5)==LOW) key_pressed='D';
  digitalWrite(8, HIGH);

    digitalWrite(9, LOW);
  if (digitalRead(2)==LOW) key_pressed='3';
  else if (digitalRead(3)==LOW) key_pressed='6';
  else if (digitalRead(4)==LOW) key_pressed='9';
  else if (digitalRead(5)==LOW) key_pressed='#';
  digitalWrite(9, HIGH);

  digitalWrite(10, LOW);
  if (digitalRead(2)==LOW) key_pressed='2';
  else if (digitalRead(3)==LOW) key_pressed='5';
  else if (digitalRead(4)==LOW) key_pressed='8';
  else if (digitalRead(5)==LOW) key_pressed='0';
  digitalWrite(10, HIGH);

  
    digitalWrite(11, LOW);
  if (digitalRead(2)==LOW) key_pressed='1';
  else if (digitalRead(3)==LOW) key_pressed='4';
  else if (digitalRead(4)==LOW) key_pressed='7';
  else if (digitalRead(5)==LOW) key_pressed='*';
  digitalWrite(11, HIGH);



  if (key_pressed!=0)
  {
    Serial.print("Key= ");
    Serial.println(key_pressed);

    lcd.setCursor(0,2);
    lcd.print("Key: ");
    lcd.setCursor(5, 2);
    lcd.print(key_pressed);
  }

}