Brief: Visible light communication is a rising high-speed and high-security communication technology, also known as LiFi (LightFidelity). Our team tried to use MCU and computer to implement VLC communication technology. The first stage demo uses 80C51 MCU, blue LED and photodiode for digital signal communication, the bandwidth is small, and the communication protocol is incomplete. In the second stage, the Arduino UNO board and DAC chip are used to transmit and receive analog signals through OFDM (Orthogonal Frequency Division Multiplexing) technology, and the original digital signal protocol is perfected, which greatly improves the communication bandwidth and speed.

Chip 1 get signal from the 4x4 keyboard, convert it to hexadecimal data (1-F, no 0) then send the data to the Chip 2 through the blue LED and photodiode. The Chip 2 display the data immediately on the LED display tube.

In demo 2, I wrote two computer program to handle the data input and output. Choose a file in send program, then the send board would send the file content to the receive board. The receive program would gather these data and combine it into a file. As a result, the file can send from one side to the other side thorough the Li-Fi system.