Keypad PIN Door Lock

About this project

NumCrypt Matrix Access Vault is a 4-digit PIN authentication system built around a 4×4 matrix membrane keypad and 5V relay module. Enter the correct PIN on 16 physical keys and the relay fires — lighting a green indicator and triggering happy tones to confirm vault access. Three wrong attempts in a row lock the system for 30 seconds with a countdown on the LCD and rhythmic alarm beeps. All status feedback runs through a 16×2 I2C LCD, dual-colour LEDs, and an active buzzer. The system teaches the most important distinction in security engineering: the difference between 'something you have' (RFID card, Project 3) and 'something you know' (PIN code, this project) — the two pillars of multi-factor authentication used in every ATM, bank vault, and smart door lock on earth. Build time: 2.5 hours.

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)