Li-Fi Data Transfer System using ATmega 32

Abstract

Light Fidelity (Li-Fi) is an emerging wireless communication technology that utilizes the visible light spectrum to enable high-speed data transfer. This research proposes a microcontroller-based Li-Fi system using the ATmega32 to demonstrate low-cost, efficient, and short-range data communication. The transmitter modulates binary data through light-emitting diodes (LEDs), while the receiver employs a photodiode for data detection and demodulation. Experimental results show successful transmission of digital information over a limited distance under controlled conditions, with observations on system limitations and performance factors. This work contributes toward the development of cost-effective, visible light-based wireless networks, suitable for specific low-range applications.

Introduction

1. Introduction

With the exponential growth of wireless data traffic, Li-Fi (Light Fidelity) emerges as a promising alternative to RF communication. It uses visible light for data transmission, offering benefits such as:

• Large unlicensed bandwidth

• Low interference

• Improved security

This project focuses on developing a low-cost, microcontroller-based Li-Fi prototype using ATmega32, an LED, and a photodiode for serial data transfer.

2. Literature Review

• Li-Fi, proposed by Harald Haas, has been studied for modulation techniques (e.g., OOK, CSK), LED efficiency, and ambient noise handling.

• Previous research emphasized factors like LED intensity, receiver sensitivity, and noise mitigation.

• Challenges include limited range, line-of-sight requirement, and ambient light interference.

• This work builds on prior studies to implement a simplified, real-world Li-Fi system using UART and low-complexity modulation.

3. System Architecture

• Transmitter: Keyboard input → ATmega32 encodes via USART → LED transmits light pulses

• Receiver: Photodiode → Signal conditioning (amplifier + comparator) → ATmega32 decodes data → 16x2 LCD displays characters

4. Hardware Components

• ATmega32: Manages UART communication and signal processing

• LED: Transmits data through OOK modulation

• Photodiode: Receives light and converts it to current

• Op-Amp (LM358): Amplifies and sharpens signal

• LCD: Displays received characters

• Power Supply: +5V regulated DC

5. Software Implementation

• Programmed using Embedded C in Atmel Studio

• UART at 9600 baud rate for serial communication

• Uses start/stop bits for synchronization

• Basic error detection with optional parity checking

6. Working Principle

• On-Off Keying (OOK): LED ON = 1, LED OFF = 0

• Transmitted light is detected by a photodiode

• Signal is amplified, digitized, and decoded by the receiving microcontroller

• System works best under direct line-of-sight, achieving short-range data communication

7. Testing & Evaluation

• Distance Testing: Reliable up to 2 meters; signal degradation beyond this

• Ambient Light Testing: Moderate lighting handled well; strong light (e.g., sunlight) causes errors

• Angle of Reception: Precise alignment improves accuracy

• Bit Error Rate: Increased in noisy or high-light environments

• System Robustness: Stable under various indoor conditions

8. Results

• Accurate data transfer under ideal and moderate conditions

• Occasional bit errors with increased distance or light interference

• Comparator effectively mitigated noise

• Demonstrated proof-of-concept for secure, low-power, visible light communication

9. Applications

• Ideal for RF-restricted zones: hospitals, aircraft, data centers

• Smart homes, industrial automation, and underwater communication

• Educational and public transportation systems for RF-free internet access

• Potential for smart city infrastructure using Li-Fi-enabled street lighting

Conclusion

The Li-Fi data transfer system using the ATmega32 microcontroller successfully demonstrates the feasibility of using visible light for data communication. The system proved to be effective in transmitting and receiving data over short distances with minimal error, showcasing the potential of Li-Fi as a high-speed, secure alternative to traditional RF communication. Despite its limitations with distance and ambient light interference, the system\'s performance highlights the effectiveness of low-cost components like LEDs, photodiodes, and microcontrollers in implementing visible light communication.

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Copyright

Copyright © 2025 Neeraja Surati, Shantanu Neve, Aayush Tarjule, Vedaang Chaudhari. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.