Introduction

The NFC Access Control System is a student project developed for the NFC Technology course at RWU (Ravensburg-Weingarten University). Starting with two fundamental course tasks—reading and writing NFC tags—this project evolved into a complete access control solution built on Arduino technology with the PN532 NFC module.

Project Evolution

This project demonstrates a structured learning approach:

Course Task 1: Tag Reading: Introduction to NFC communication by reading card UIDs and identifying different card types. See Examples for the basic read implementation.
Course Task 2: Tag Writing: Building on Task 1 to write data to NFC cards, understanding memory structures, and handling different card types. See Examples for the write implementation.
Extended Project: Full Access Control System: Integrate reading and writing capabilities into a complete access control solution with card management, persistent storage, LCD interface, and physical access control.

The result is a robust, feature-rich platform suitable for both educational purposes and real-world access control applications.

What is NFC?

Near Field Communication (NFC) is a set of communication protocols that enable two electronic devices to communicate over a distance of 4 cm or less. NFC operates at 13.56 MHz and is commonly used for:

Contactless payment systems - Credit cards, mobile payments
Access control and security - Building entry, time tracking
Data exchange between devices - File sharing, pairing
Smart posters and advertising - Interactive marketing, product information
Public transportation - Ticket validation, fare collection

NFC builds on RFID (Radio-Frequency Identification) technology and supports multiple communication modes, making it versatile for various applications.

System Architecture

The system consists of several key components working together:

System Architecture Overview

Hardware Layer

Arduino Nano: The main microcontroller (ATmega328P) running the access control logic
PN532 NFC Module: Handles NFC communication with cards at 13.56 MHz
LCD Display: 16x2 character display providing visual feedback to users
Button Interface: Four push buttons for menu navigation (Up, Down, Select, Back)
Relay Module: Controls physical door locks or access gates

Software Layer

Access Control System: Main application logic coordinating all components
NFC Reader Interface: Abstraction layer for PN532 communication (read/write operations)
Card Database: EEPROM-based persistent storage for authorized cards
Menu System: User interface for system management and card operations

Design Philosophy

The system is designed with several key principles in mind:

Security First

All card verification happens locally without network dependency
Authorized cards are stored securely in non-volatile EEPROM
Physical relay control prevents unauthorized access
Custom sector technology for advanced card management

User Friendly

Clear LCD feedback for all operations
Intuitive button-based navigation
Visual status indicators
Minimal learning curve for end users

Educational Value

Progressive learning from simple read/write to complete system
Well-documented code with extensive comments
Practical examples demonstrating key concepts
Foundation for further NFC exploration

Flexibility

Support for multiple card types (Mifare Classic, NTAG, Ultralight)
Store up to 40 authorized cards
Advanced card cloning for access duplication
Easy card management through menu system
Configurable access duration and system behavior

Reliability

IRQ-based card detection for fast response (<100ms)
Non-blocking operation for smooth user experience
Robust error handling and recovery
Persistent storage survives power cycles

Use Cases

The NFC Access Control System is suitable for:

Educational Applications

Learning NFC fundamentals (Tasks 1 & 2)
Embedded systems course projects
RFID/NFC technology demonstrations
Arduino programming education

Practical Applications

Office and laboratory access control
Residential building security
Storage room and restricted area management
Maker space equipment access
Prototyping commercial access control solutions
Time and attendance tracking

Technical Specifications

Hardware Requirements

Microcontroller: Arduino Nano or compatible (ATmega328P)
NFC Module: PN532 (SPI or I2C mode)
Display: HD44780-compatible 16x2 LCD
Input: 4 push buttons (active LOW with pull-up)
Output: 5V relay module
Power: 5V DC, ~200mA typical

Software Capabilities

Supported Cards: Mifare Classic 1K/4K, Mifare Ultralight, NTAG213/215/216
Card Capacity: Up to 40 authorized cards in EEPROM
Detection Time: < 100ms with IRQ mode, ~100-200ms polling mode
UID Support: 4-byte and 7-byte UIDs
Communication: SPI or I2C (PN532), 4-bit parallel (LCD)
Memory Usage: ~15KB flash, ~1KB SRAM
EEPROM: Circular buffer for card storage with wear leveling

Performance Metrics

Read Response: < 100ms from card detection to access decision
Write Speed: ~50-100ms per block/page including verification
Menu Response: Immediate button feedback
Relay Activation: Configurable (default 3 seconds)
Power Consumption:
- Idle: ~50mA
- Reading: ~150mA
- Relay active: ~200mA

Getting Started

To begin working with this system:

Start with basics: Complete Task 1 (reading) and Task 2 (writing) using the examples in Examples
Set up hardware: Follow the wiring diagrams in Hardware Setup
Install software: See Installation for PlatformIO setup
Build the full system: Review Usage Guide for complete system operation
Explore advanced features: Learn about card cloning in Card Cloning Technology

Project Structure

The project is organized as follows:

examples/ - Simple examples for Tasks 1 & 2 (read and write)
src/ - Main application code (full access control system)
include/ - Header files and class definitions
lib/ - External libraries
docs/ - This documentation
test/ - Hardware test utilities

Each component is modular and well-documented, making it easy to understand and extend.