Rancang Bangun Sistem Keamanan Kotak Persembahan Gereja Berbasis Internet of Things (IoT) Menggunakan Metode Research and Development (R&D)

The security of church offering boxes needs to be addressed to prevent unauthorized access and support more effective monitoring of the box condition. This study aims to design and develop an Internet of Things (IoT)-based security system for church offering boxes that can perform user authentication, control access to the lock, detect box opening conditions, and send security information in real time. The Research and Development (R&D) method was applied through the stages of requirements analysis, design, development, implementation, and prototype testing. The system combines a NodeMCU ESP8266, an AS608 fingerprint sensor, a solenoid lock, a magnetic door switch, an OLED display, and Telegram notification. The results showed that all three trials using registered fingerprints successfully granted access, while two trials using unregistered fingerprints were successfully rejected. The system also successfully delivered Telegram notifications in all five notification types, with response times ranging from 0.9 to 1.3 seconds. The lockdown mechanism was activated after five consecutive authentication failures for three minutes, forced opening detection operated successfully, and local security functions remained operational when the Wi-Fi connection was unavailable. The novelty of this study lies in integrating fingerprint authentication, forced-opening detection, a lockdown mechanism, Telegram-based control, and testing of local security functions under Wi-Fi loss in a single prototype for church offering boxes, using non-blocking firmware that prioritizes local processing (hardware-first). The contribution is the prototype design, this firmware architecture, and functional test data that can serve as a reference for developing similar systems.