Door Intrusion Alarm

About this project

Build an after-hours door intrusion alarm for a library, reading room, or store room using a simple two-wire magnetic reed switch. Hold the arm button for 2 seconds when locking up and the system goes into Armed/Secure mode with a green LED and the LCD confirming 'ARMED'. If the door opens while armed, a 10-second exit-delay countdown appears on the LCD (enough time for the person arming it to step out) — if the door isn't reclosed and the system isn't disarmed before the countdown hits zero, a full alarm triggers: continuous buzzer, flashing red LED, and an on-screen elapsed-alarm timer. Every confirmed intrusion event is permanently counted using the Arduino's built-in EEPROM, so the total survives a power cut and can be checked the next morning. The WOW moment: arm it, open the door after the delay expires, and watch the whole panel go from silent green to full alarm red — then disarm it and see the persistent intrusion counter tick up by one. Build time: 2-3 hours. Fully offline, no WiFi, no app, no cloud.

What you get

• Complete, commented source code
• Full components list with quantities
• Pin-by-pin wiring guide and connection table
• Step-by-step upload and testing guide
• Project report (.docx, IEEE style)
• Presentation slides (.pptx)