Li-Fi Data Transfer System Project

 Design and Implementation of Li-Fi (Light Fidelity) Data Transfer System

Li-Fi (Light Fidelity) is a wireless communication technology that uses visible light instead of radio waves for data transmission. This project demonstrates a basic Li-Fi data transfer system using an LED as a transmitter and a photodiode as a receiver. Data is transmitted by rapidly switching the LED ON and OFF, and the receiver decodes this light signal back into digital data. This system is secure, fast, and suitable for RF-restricted environments.

🔷 Objectives

• To understand Visible Light Communication (VLC)

• To transmit digital data using LED light

• To receive data using a photodiode/light sensor

• To demonstrate an alternative to Wi-Fi

• To build a low-cost, educational Li-Fi prototype

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🔷 Block Diagram (Text Representation)

Data Source → Arduino (TX) → LED → Light Channel → Photodiode → Arduino (RX) → Output (PC/LCD)

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🔷 Components Required

🔹 Hardware

Component	Quantity
Arduino UNO (TX)	1
Arduino UNO (RX)	1
High Bright LED	1
Photodiode / LDR	1
10kΩ Resistor	2
220Ω Resistor	1
Breadboard	2
Connecting Wires	As required
USB Cable	2

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🔷 Working Principle

• The transmitter Arduino converts data into binary.

• LED blinks at very high speed according to binary data.

• Photodiode detects light variations.

• Receiver Arduino converts received signal back into data.

• Output is displayed on Serial Monitor or LCD.

Light ON = 1
Light OFF = 0

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🔷 Circuit Connections

🔹 Transmitter Side

• LED Anode → Arduino Pin 9

• LED Cathode → 220Ω → GND

🔹 Receiver Side

• Photodiode +ve → 5V

• Photodiode −ve → A0 (Arduino)

• 10kΩ resistor → A0 to GND

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🔷 Arduino Code

✅ Transmitter Code

char data = 'A';

void setup() {
  pinMode(9, OUTPUT);
}

void loop() {
  for (int i = 0; i < 8; i++) {
    if (data & (1 << i)) {
      digitalWrite(9, HIGH);
    } else {
      digitalWrite(9, LOW);
    }
    delay(5);
  }
  digitalWrite(9, LOW);
  delay(100);
}

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✅ Receiver Code

void setup() {
  Serial.begin(9600);
}

void loop() {
  int value = analogRead(A0);
  if (value > 500) {
    Serial.print("1");
  } else {
    Serial.print("0");
  }
  delay(5);
}

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🔷 Output

• Binary data visible on Serial Monitor

• Text can be decoded using software logic

• LED blinks rapidly (invisible to human eye)

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🔷 Advantages

✔ Very high data speed
✔ High security (light doesn’t pass walls)
✔ No RF interference
✔ Safe for hospitals & aircraft
✔ Low power consumption