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LiFi-Based Data Transfer System

This project demonstrates a simple light-based data communication system using Raspberry Pi Pico boards. Data is transmitted through visible light using a laser diode as the transmitter and an LDR sensor as the receiver. The system supports text message transfer between two computers through a light channel.

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Overview

LiFi (Light Fidelity) uses visible light instead of radio waves for wireless communication. This project shows a basic LiFi prototype capable of sending and receiving text messages. Each character is converted into binary data, transmitted as light pulses, and decoded back into readable text.

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System Components

Hardware

• Raspberry Pi Pico (2 units)
• Laser Diode or LED (Transmitter)
• LDR (Light Dependent Resistor) for Receiver
• BC547 Transistor for amplification
• Resistors and breadboard
• USB cables for serial communication

Software

• MicroPython for Pico firmware
• Python (Tkinter, PySerial) for PC interfaces

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Code Files

pi_tx.py   – Transmitter Pico code
pi_rx.py   – Receiver Pico code
tx_ui.py   – Sender PC interface
rx_ui.py   – Receiver PC interface

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Working Principle

1. The transmitter Pico reads a message from the PC.
2. Each character is converted to binary and sent as light pulses (ON/OFF).
3. The receiver Pico reads light intensity values using the LDR.
4. These signals are converted back to binary and decoded to text.
5. The PC displays received messages through a GUI.

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Setup Instructions

1. Flash MicroPython on both Raspberry Pi Pico boards.

2. Upload:

   • pi_tx.py to the transmitter Pico.
   • pi_rx.py to the receiver Pico.

3. Connect:

   • Laser diode/LED to GPIO15 (TX side)
   • LDR to ADC pin 28 (RX side)

4. Edit COM port numbers in tx_ui.py and rx_ui.py.

5. Run both UI scripts:

   python tx_ui.py
   python rx_ui.py

6. Type messages in the transmitter window to send data over light.

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Images and Outputs

Block Diagram of LiFi Based Data Transfer System

Receiver Side Output (In Raspberry Pi Pico)

Receiver Side UI (In PC)

Transmitter Side Output (In Raspberry Pi Pico)

Transmitter Side UI (In PC)

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Results

• Range: 1–2 meters
• Speed: ~30 bps
• Accuracy: 95–98% in stable lighting
• Secure short-range data transfer with low power consumption

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Future Improvements

• Use photodiodes for faster response
• Add error correction
• Improve data rate with better modulation
• Enable multi-node LiFi networking

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Contributors

• Tholkappiyan B – 23BCE20158
• Pranav P S – 23BCE7250
• Muhammad Sajid Y – 23BCE7802
• Ganesh M – 23BCE8887
• V K Rohith – 23BCE8997
• Hari Prasath M – 23BCE8999

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References

• Li-Fi - Wikipedia
• MicroPython
• Raspberry Pi Pico
• Python.org

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