IoT·Jan 1, 2022

Smart Door Lock

Electronic door-lock prototype using keypad / RFID authentication and a servo or solenoid actuator.

Overview

A door lock is the smallest possible access-control system, which is exactly why it is such a good way to learn. Read input, validate it, act on it, give feedback. I built this to play with the whole loop end-to-end.

Specifications

RolePrototype designer and firmware developer

MicrocontrollerArduino / ESP-class controller

SensorsRFID readerKeypad

ModulesServo or solenoid lockBuzzer / status LED

ProtocolsGPIOSPI / UART depending on RFID module

Tech tagsSmart LockRFIDKeypadAccess ControlServo

Architecture

Credential input is processed by the controller. Valid access commands the actuator to unlock for a timed interval and then return to locked state.

Videos

Implementation details

Firmware

Firmware reads keypad/RFID input, checks access credentials, actuates the lock, and gives visual or audio feedback.

Power

Prototype uses low-voltage actuator control; a final door installation would need backup power and mechanical fail-safe design.

Components / BOM

Microcontroller board, Keypad or RFID reader, Servo/solenoid lock, Status LED/buzzer

Engineering challenges

Reliable actuator movement, sane handling of bad input, and giving the user enough feedback that they trust the lock.

Solutions

Kept the control flow simple and predictable: input → check → actuate → feedback. Avoided fancy features in v1 so the basic flow stayed bulletproof.

Results & metrics

Demo video shows the door lock unlocking on a valid input and re-locking on a timer.

Future improvements

Encrypted credential storage, a mobile unlock option, an audit log, a battery backup and a beefier lock mechanism for a real door.