{"id":81139,"date":"2024-05-28T23:50:44","date_gmt":"2024-05-29T03:50:44","guid":{"rendered":"https:\/\/www.engineersgarage.com\/?p=81139"},"modified":"2024-05-23T12:42:18","modified_gmt":"2024-05-23T16:42:18","slug":"otp-based-door-lock-system-arduino","status":"publish","type":"post","link":"https:\/\/www.engineersgarage.com\/otp-based-door-lock-system-arduino\/","title":{"rendered":"How to design an OTP-based door lock"},"content":{"rendered":"

Today, mobile-based authentication to verify a person’s identity is common. Online service providers often use it for access to services, approval of transactions, or to change a user’s credentials.\u00a0<\/span><\/p>\n

Imagine using a similar mobile-based authentication to enter your home, office, or any private space. It’s possible. In this project, we’ll design a mobile-based access system for access to a private room. This device controls the room’s door using a relay. The door only opens if the one-time password (OTP) sent via a registered mobile number is confirmed.\u00a0<\/span><\/p>\n

This device is built using Arduino Mega. It uses an IR sensor and a SIM900 modem to send an SMS containing a random OTP. The user can enter the OTP through a keypad. The system also has an OLED screen attached that serves as the user interface and guides users in accessing the room.\u00a0<\/span><\/p>\n

Components required<\/strong><\/p>\n

    \n
  1. Arduino Mega 2560 x1<\/li>\n
  2. SIM900 GSM modem x1<\/li>\n
  3. IR sensors x1<\/li>\n
  4. SSD1306 OLED x1<\/li>\n
  5. Relay\/Electronic lock x1<\/li>\n
  6. Connecting or Dupont wires<\/li>\n<\/ol>\n

    Circuit connections
    \n<\/strong>To build this device<\/span>, the SIM900 modem, SSD1306 OLED, IR sensor, 4×4 keypad, <\/span>and<\/span>\u00a0relay or electronic lock are interfaced with Arduino Mega \u2014 which offers enough GPIOs to work with all these components.\u00a0<\/span><\/p>\n

    To interface the SIM900<\/span>, the modem\u2019s GND, TX, and RX pins are connected to Arduino\u2019s ground, RX1, and TX1 pins. The keypad is connected to Arduino\u2019s GPIO 22, 24, 28, 30, 32, 34, and 36.\u00a0<\/span><\/p>\n

    The seven-pin SSD1306 OLED module is used and connected to the Arduino as follows.<\/span><\/p>\n

    \"\"<\/a><\/p>\n

    The IR sensor is connected to Arduino’s GPIO 8. The relay or electronic lock is interfaced at Arduino’s GPIO 50. The device’s circuit connections are shown below.<\/p>\n

    \"\"<\/a><\/p>\n

    Arduino sketch
    \n<\/strong>After making the circuit connections, upload the following sketch to Arduino Mega. Remember to replace the registered mobile number you want to receive the OTP in the sketch.<\/p>\n