A Multi-Mode Smart Door Lock for Classroom Security: Vacancy Detection and IoT based Access

Classrooms often rely on manual or mobile-based door locking mechanisms, which can lead to usability issues and security vulnerabilities, such as unauthorized access or doors inadvertently left open. This paper addresses the challenge of ensuring secure, convenient, and automated classroom access by proposing a multi-mode smart door lock system integrating Internet of Things (IoT) capabilities and occupancy detection. The solution employs an ESP32 microcontroller to control a 12-volt solenoid lock, with access granted either through PIN-based authentication or authorized remote IoT commands. Moreover, the system features real-time vacancy detection: the door remains unlocked while the classroom is occupied and automatically secures itself once the room is vacated, thereby eliminating the risk of doors being left open unintentionally. Experimental validation demonstrates high accuracy in occupancy detection, robust authentication, and reliable IoT communication. Results show marked improvement in both security and user convenience when compared to conventional systems, making this solution well-suited for smart classroom environments where access control and safety are critical.