#include <Keypad.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,16,2); 


const byte rows=4;
const byte cols=4;
// các phím 
char key[rows][cols]={
{'1','2','3', 'A'},
{'4','5','6', 'B'},
{'7','8','9', 'C'},
{'*','0','#', 'D'}
};
// cac chan arrduino
byte colPins[cols]={5,4,3,2};
byte rowPins[rows]={9,8,7,6};
Keypad keypad= Keypad(makeKeymap(key),rowPins ,colPins ,rows,cols);
const String password = "1234"; // có thể thay đổi password

String input_password;
int count = 1; 
void setup() {
  lcd.init();
  lcd.clear();
  lcd.backlight();    

  lcd.setCursor(0,0); 
  lcd.print("Nhap mat khau: ");
  pinMode(10, OUTPUT);
}
void loop(){
  char key = keypad.getKey();
  if (key){
    if(key == '*') {
      lcd.clear();
      lcd.setCursor(0,0); 
      lcd.print("Nhap mat khau: ");
      input_password = "";
      count =1;
    } else if(key == '#') {
      count = 1;
      if(password == input_password) {
        lcd.setCursor(2,1); 
        lcd.print("  dung");
        digitalWrite(10, HIGH);
        delay(100);
        digitalWrite(10,LOW);  
      } else {
        lcd.setCursor(2,1); 
        lcd.print("  sai");
        digitalWrite(10, HIGH);
        delay(100);
        digitalWrite(10,LOW); 
        delay(100);
        digitalWrite(10, HIGH);
        delay(100);
        digitalWrite(10,LOW); 
        delay(2000);
        lcd.clear();
        lcd.setCursor(0,0); 
        lcd.print("Nhap mat khau: ");
      }
      input_password = "";
    } else {
      input_password += key;
      count++;
      lcd.setCursor(count,1); 
      lcd.print("*"); 
    }
  }
}