ESP32 - Door Lock System using Password

In this tutorial, we learn how to make door lock system with password. The tutorial include two main parts:

LCD is optional. It just makes the system a little more convenient.

When the door is unlocked by a correct password, It keeps the door unlocked for 20 seconds, and then automatically lock the door again. The ESP32 code supports multiple passwords.

※ NOTE THAT:

We also made the door lock system using RFID/NFC tutorial.

Hardware Required

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×Keypad 4x4
1×Relay
1×12V Power Adapter
1×Electromagnetic Lock
n×Jumper Wires
1×LCD I2C (optional)
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About Keypad and Electromagnetic Lock and LCD

If you do not have knowledge of electromagnetic lock and button (pinout, how they work, how to connect them to ESP32, how to program for them...), learn about them in the following tutorials:

Wiring Diagram

ESP32 door lock system wiring diagram

Image is developed using Fritzing. Click to enlarge image

ESP32 Code - Door lock system with password using keypad, electromagnetic lock

/* * Created by esp32io.com * * This example code is in the public domain * * Tutorial page: https://esp32io.com/tutorials/esp32-door-lock-system-using-password */ #include <Keypad.h> const int RELAY_PIN = 14; // ESP32 pin GIOP14 connected to the IN pin of relay const int ROW_NUM = 4; //four rows const int COLUMN_NUM = 4; //four columns char keys[ROW_NUM][COLUMN_NUM] = { {'1','2','3', 'A'}, {'4','5','6', 'B'}, {'7','8','9', 'C'}, {'*','0','#', 'D'} }; byte pin_rows[ROW_NUM] = {19, 18, 5, 17}; // GIOP19, GIOP18, GIOP5, GIOP17 connect to the row pins byte pin_column[COLUMN_NUM] = {16, 4, 0, 2}; // GIOP16, GIOP4, GIOP0, GIOP2 connect to the column pins Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM ); const String password_1 = "1234ABC"; // change your password here const String password_2 = "5642CD"; // change your password here const String password_3 = "4545B"; // change your password here String input_password; void setup(){ Serial.begin(9600); input_password.reserve(32); // maximum input characters is 33, change if needed pinMode(RELAY_PIN, OUTPUT); // initialize pin as an output. digitalWrite(RELAY_PIN, HIGH); // lock the door } void loop(){ char key = keypad.getKey(); if (key){ Serial.println(key); if(key == '*') { input_password = ""; // reset the input password } else if(key == '#') { if(input_password == password_1 || input_password == password_2 || input_password == password_3) { Serial.println("password is correct"); digitalWrite(RELAY_PIN, LOW); // unlock the door for 20 seconds delay(20000); digitalWrite(RELAY_PIN, HIGH); // lock the door } else { Serial.println("password is incorrect, try again"); } input_password = ""; // reset the input password } else { input_password += key; // append new character to input password string } } }

Quick Steps

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE
  • Connect the ESP32 board to your PC via a micro USB cable
  • Open Arduino IDE, select the right ESP32 board and COM port
  • On Arduino IDE, Go to Tools Manage Libraries
  • ESP32 add library
  • Search “keypad”, then find the keypad library by Mark Stanley, Alexander Brevig
  • Click Install button to install keypad library.
  • ESP32 keypad library
  • Copy the above code and paste it to Arduino IDE
  • Click Upload button on Arduino IDE to compile and upload code to ESP32 board
  • Put the armature plate close to electromagnet.
  • In put a wrong password, and then input a correct password
  • See the attraction between armature plate and electromagnet during 20 seconds.

ESP32 Code - Door lock system with password using keypad, electromagnetic lock and LCD

The below code added LCD I2C to display the access status. For wiring with LCD, you can see in this tutorial Esp32 - LCD I2C tutorial

/* * Created by esp32io.com * * This example code is in the public domain * * Tutorial page: https://esp32io.com/tutorials/esp32-door-lock-system-using-password */ #include <Keypad.h> #include <LiquidCrystal_I2C.h> const int RELAY_PIN = 14; // ESP32 pin GIOP14 connected to the IN pin of relay const int ROW_NUM = 4; //four rows const int COLUMN_NUM = 4; //four columns char keys[ROW_NUM][COLUMN_NUM] = { {'1','2','3', 'A'}, {'4','5','6', 'B'}, {'7','8','9', 'C'}, {'*','0','#', 'D'} }; byte pin_rows[ROW_NUM] = {19, 18, 5, 17}; // GIOP19, GIOP18, GIOP5, GIOP17 connected to the row pins byte pin_column[COLUMN_NUM] = {16, 4, 0, 2}; // GIOP16, GIOP4, GIOP0, GIOP2 connected to the column pins Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM ); LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows const String password_1 = "1234ABC"; // change your password here const String password_2 = "5642CD"; // change your password here const String password_3 = "4545B"; // change your password here String input_password; void setup(){ Serial.begin(9600); input_password.reserve(32); // maximum input characters is 33, change if needed pinMode(RELAY_PIN, OUTPUT); // initialize pin as an output. digitalWrite(RELAY_PIN, HIGH); // lock the door lcd.init(); // initialize the lcd lcd.backlight(); } void loop(){ char key = keypad.getKey(); if (key){ Serial.println(key); if(key == '*') { input_password = ""; // reset the input password lcd.clear(); } else if(key == '#') { lcd.clear(); if(input_password == password_1 || input_password == password_2 || input_password == password_3) { Serial.println("password is correct"); lcd.setCursor(0, 0); lcd.print("CORRECT!"); lcd.setCursor(0, 1); lcd.print("DOOR UNLOCKED!"); digitalWrite(RELAY_PIN, LOW); // unlock the door for 20 seconds delay(20000); digitalWrite(RELAY_PIN, HIGH); // lock the door } else { Serial.println("password is incorrect, try again"); lcd.setCursor(0, 0); lcd.print("INCORRECT!"); lcd.setCursor(0, 1); lcd.print("ACCESS DENIED!"); } input_password = ""; // reset the input password } else { if(input_password.length() == 0) { lcd.clear(); } input_password += key; // append new character to input password string lcd.setCursor(input_password.length(), 0); // move cursor to new position lcd.print('*'); // print * key as hiden character } } }

Quick Steps

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE
  • On Arduino IDE, Go to Tools Manage Libraries
  • ESP32 add library
  • Search “LiquidCrystal I2C”, then find the LiquidCrystal_I2C library by Frank de Brabander
  • Click Install button to install LiquidCrystal_I2C library.
  • ESP32 LiquidCrystal I2C library
  • Copy the above code and paste it to Arduino IDE
  • Click Upload button on Arduino IDE to compile and upload code to ESP32 board
  • Put the armature plate close to electromagnet.
  • In put a wrong password, and then input a correct password
  • See the attraction between armature plate and electromagnet during 20 seconds.
  • See text on LCD

※ NOTE THAT:

  • In the above codes, To make it simple, we used the delay function. It is better to use millis() instead of delay(). See How to use millis() instead of delay()
  • You can add a piezo buzzer to make the beep sound each time keypad is pressed.
  • In the above codes, the door is locked again after 20 seconds. You can replace it by a door sensor. The door is locked when the door sensor detect the door is closed by user.
  • The commercial door lock system is much more complicated than this tutorial. It may be composed of electromagnetic lock, keypad, RFID/NFC reader, buzzer... If you want to build a commercial-like project, please contact us

Video Tutorial

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※ NOTE THAT:

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