Design and Implementation of Building Access Control System Based on Single Chip Microcomputer

1. Introduction

• Objective: To design and implement a secure and efficient building access control system using a single-chip microcomputer (SCM).

• Scope: The system will control access to a building by authenticating users through RFID cards, keypads, or biometric methods, and will log entry/exit events.

2. System Requirements

• Functional Requirements:

  • User authentication via RFID cards, keypad, or fingerprint.

  • Grant or deny access based on authentication.

  • Log entry/exit events with timestamps.

  • Admin interface for adding/removing users and viewing logs.

• Non-Functional Requirements:

  • High reliability and security.

  • Low power consumption.

  • User-friendly interface.

  • Scalability for future expansion.

3. System Design

• Hardware Components:

  • Single Chip Microcomputer (SCM): e.g., AT89C51, STM32(e.g., STM32F103VET6), or ESP32.

  • RFID Reader: For reading RFID cards.

  • Keypad: For PIN entry.

  • Fingerprint Sensor: For biometric authentication.

  • LCD Display: For user interaction and system status.

  • Buzzer: For audio feedback (e.g., access granted/denied).

  • Relay Module: To control the door lock.

  • EEPROM/Flash Memory: For storing user data and logs.

  • Power Supply: 5V/12V DC power supply.

• Software Components:

  • Firmware: Written in C or assembly language for the SCM.

  • Authentication Algorithm: To verify user credentials.

  • Logging System: To record access events.

  • Admin Interface: For system management (can be a simple terminal interface or a connected PC application).

4. System Architecture

• Block Diagram:

   

   

  +-------------------+       +-------------------+       +-------------------+
  |   RFID Reader     |       |   Keypad          |       | Fingerprint Sensor|
  +-------------------+       +-------------------+       +-------------------+
          |                         |                         |
          v                         v                         v
  +---------------------------------------------------------------+
  |                      Single Chip Microcomputer                 |
  |                                                               |
  |  +-------------------+       +-------------------+             |
  |  | Authentication    |       | Logging System    |             |
  |  | Algorithm         |       |                   |             |
  |  +-------------------+       +-------------------+             |
  |                                                               |
  +---------------------------------------------------------------+
          |                         |                         |
          v                         v                         v
  +-------------------+       +-------------------+       +-------------------+
  |   Relay Module    |       |   LCD Display     |       |   Buzzer          |
  +-------------------+       +-------------------+       +-------------------+
          |
          v
  +-------------------+
  |   Door Lock       |
  +-------------------+

5. Implementation

• Hardware Implementation:

  • Connect the RFID reader, keypad, fingerprint sensor, LCD display, buzzer, and relay module to the SCM.

  • Ensure proper power supply and grounding.

  • Use pull-up/pull-down resistors where necessary.

• Software Implementation:

  • Initialization: Initialize all peripherals (RFID, keypad, fingerprint sensor, LCD, etc.).

  • Main Loop:

    • Wait for user input (RFID card, keypad entry, or fingerprint).

    • Authenticate the user.

    • If authenticated, activate the relay to unlock the door and log the event.

    • If not authenticated, deny access and log the event.

  • Admin Interface:

    • Allow admin to add/remove users via keypad or connected PC.

    • Allow admin to view logs.

• Code Snippets:

  c

   

  // Example: RFID Authentication
  void authenticateRFID() {
      char rfid[12];
      readRFID(rfid);
      if (checkDatabase(rfid)) {
          unlockDoor();
          logEvent("Access Granted", rfid);
      } else {
          denyAccess();
          logEvent("Access Denied", rfid);
      }
  }
  
  // Example: Keypad Authentication
  void authenticateKeypad() {
      char pin[4];
      readKeypad(pin);
      if (checkPIN(pin)) {
          unlockDoor();
          logEvent("Access Granted", "Keypad");
      } else {
          denyAccess();
          logEvent("Access Denied", "Keypad");
      }
  }

6. Testing and Validation

• Unit Testing: Test individual components (RFID, keypad, fingerprint sensor, etc.).

• Integration Testing: Test the system as a whole to ensure all components work together.

• Security Testing: Ensure the system is secure against unauthorized access.

• Performance Testing: Test the system's response time and reliability.

7. Conclusion

• The designed access control system is efficient, secure, and scalable.

• Future enhancements could include wireless connectivity (Wi-Fi/Bluetooth), mobile app integration, and cloud-based logging.

8. References

• Datasheets for the SCM, RFID reader, fingerprint sensor, etc.

• Relevant literature on access control systems and embedded systems design.

This outline provides a comprehensive approach to designing and implementing a building access control system using a single-chip microcomputer. The actual implementation details will depend on the specific components and requirements of the project.