Automatic License Plate Recognition and Access Control with Micro:bit

Overview

This project demonstrates an integrated system for automatic license plate recognition using Python (OCR with EasyOCR + OpenCV) and hardware control via a BBC Micro:bit.
The goal is to simulate an automated access control system where recognized license plates trigger physical actions such as LEDs, a servo motor, and sound alarms.

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Components

Python (OCR + Control)

• Uses EasyOCR and OpenCV to detect and read license plates from a camera.
• Corrects common OCR mistakes (O→0, I→1, S→5, etc.).
• Validates plate format: AA9999AA (2 letters + 4 digits + 2 letters).
• Compares against a database of valid plates and owners (valid_db.py).
• Sends commands to Micro:bit via USB serial:
  • VALID:<plate>:<owner>\n
  • INVALID\n

Micro:bit (Hardware Control)

• Receives commands from Python over serial.
• Controls two LEDs:
  • Green LED → lights up when a valid plate is detected (while servo is active).
  • Red LED → lights up by default, after servo returns, or immediately on invalid plate.
• Controls a servo motor:
  • Rotates to 90° on valid plate, returns to 0° after 5 seconds.
• Plays sound signals:
  • Short tone for valid plate.
  • Alarm sequence for invalid plate (15 seconds).
• Displays information on the LED matrix:
  • "VALID" + plate number + owner name.
  • "INVALID" for unrecognized plates.
• Manual override:
  • Button A → triggers VALID logic.
  • Button B → triggers INVALID logic.

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Workflow

1. Camera captures a license plate.
2. Python OCR script processes the image and validates the plate.
3. If plate is valid:
   • Sends VALID:<plate>:<owner> to Micro:bit.
   • Micro:bit shows "VALID", plate, and owner.
   • Green LED lights up, servo rotates, then returns after 5s.
   • Red LED lights up again after reset.
4. If plate is invalid:
   • Sends INVALID to Micro:bit.
   • Micro:bit shows "INVALID".
   • Red LED lights up immediately.
   • Alarm sounds for 15s.
5. Buttons A/B allow manual triggering of the same logic.

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Demonstration

• Valid plate → Green LED, servo rotates, owner name displayed, then returns to red LED.
• Invalid plate → Red LED + alarm for 15 seconds.
• Manual override → Buttons A/B simulate the same behavior without Python.

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Requirements

• Python 3.9+
• Libraries: easyocr, opencv-python, torch, numpy, pyserial
• BBC Micro:bit with USB connection
• Servo motor + LEDs connected to Micro:bit pins

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Purpose

This project is designed as a practical demonstration of combining:

• Computer vision (OCR)
• Hardware control (Micro:bit)
• Database integration
• Real-time feedback with LEDs, servo, and sound

It can be used for educational purposes, IoT prototypes, or as a foundation for access control systems.

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Author

Developed by Boris Evtimov
Focused on scalable, practical solutions combining Python, electronics, and cloud-ready architectures.