INTERNATIONAL JOURNAL OF RESEARCH AND INNOVATION IN SOCIAL SCIENCE (IJRISS)
ISSN No. 2454-6186 | DOI: 10.47772/IJRISS | Volume IX Issue XI November 2025
Smart Door Lock System Using Arduino Uno
Ruth Arlene T. Necio., Chenaniah Keziah M. Pastrana., Renz Jio Lazaro., Dr. Ma. Magdalena V. Gatdula
Bulacan State University ‒ Graduate School City of Malolos, Bulacan
Received: 28 November 2025; Accepted: 05 December 2025; Published: 18 December 2025
ABSTRACT
The demand for affordable and customizable security systems continues to grow as embedded microcontrollers
become more accessible. This study explores the development of a Smart Door Lock System using Arduino Uno,
implemented entirely in Tinkercad’s block-based programming environment. The system integrates a
potentiometer acting as an analog password input, a 16×2 LCD for real-time feedback, an LED indicator for
status signaling, and a servo motor as the primary locking mechanism. Results from three test scenarios̶valid
input, invalid input, and user inactivity̶demonstrated consistent and accurate system performance. Findings
highlight the educational value of analog-to-digital processing and conditional logic for early embedded systems
learning, while identifying limitations and opportunities for future enhancement.
Keywords: Arduino Uno; Smart Door Lock System; Tinkercad Simulation; Analog Password Input; Embedded
Systems; Conditional Logic002E
INTRODUCTION
The integration of automation and security in households and small businesses has increased the relevance of
smart lock systems. Microcontroller-based solutions, particularly with Arduino Uno, offer low-cost and flexible
platforms for developing personalized implementations. Simulation tools such as Autodesk Tinkercad enable
students to experiment with circuits and logic flows without requiring physical hardware. This study focuses on
the design and simulation of a Smart Door Lock System utilizing an unconventional input device̶a potentiometer
serving as an analog password source. Despite its impracticality for real-world systems, the potentiometer
provides an excellent foundation for demonstrating analog signal processing, threshold-based authentication,
and actuator control in educational contexts. The purpose of this work is to document the system’s structure,
behavior, and performance, and to evaluate its suitability as a teaching tool for embedded systems principles.
METHODS
The system was composed of an Arduino Uno microcontroller, a 10kΩ potentiometer, a 16×2 LCD display, a
standard LED, and an SG90 servo motor. Using Tinkercad’s block-based coding interface, the potentiometer’s
analog values (0‒1023) were scaled to a simplified range of 0‒255. A password interval (180‒190) was defined
as the “correct” range. When the user adjusted the potentiometer to produce a value within this range, the LCD
displayed “Access Granted,” the LED illuminated, and the servo rotated to 0°, unlocking the simulated door.
Incorrect values triggered “Access Denied,” with the servo remaining locked at 180°. An inactivity timer
displayed an idle message after 10 seconds without adjustment. Three test scenarios̶correct input, incorrect
input, and inactivity̶were conducted to evaluate reliability, stability, and logical accuracy.
The Smart Door Lock System was created using Tinkercad’s virtual electronics environment. The following
components were used:
Arduino Uno – Main controller that processes all inputs and outputs.
Potentiometer – Used as the password input by turning the knob to change the value.
16×2 LCD Display – Shows system messages such as “Access Granted” or “Access Denied.”
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