Li-Fi based Text Communication between Two Arduino

The Li-Fi based text communication system operates by converting digital text input into visible light pulses and then decoding those optical signals back into readable characters. On the transmitting side, an Arduino Nano or UNO interfaces with a 4*4 keypad to capture user input. When keys are pressed, the microcontroller processes the characters and modulates a 5 mm LED using a 220Ω current-limiting resistor. Instead of traditional radio waves, the light from this LED carries the data through free space. On the receiving end, an LDR (Light Dependent Resistor) sensor paired with a 10kΩ resistor acts as a photodetector, measuring the fluctuations in light intensity produced by the transmitter's LED. A second Arduino, such as the Arduino Mega 2560, reads these analog changes across the LDR circuit and translates the varying light pulses back into discrete data packets. Finally, the received message is output to a 16*2 alphanumeric LCD connected via an I2C interface module, which minimizes wiring and efficiently displays the decoded text to the user.