I'm actually quite new with usage of Arduino so forgive me for asking this.I'm currently trying to create a simple FSO(laser) connection between two PCs using two Arduino Uno and Processing software. The main goal for the project is to be able to send and receive text or file from one Arduino to the other. I need to modulate the numeric data with pwm on the receiver. In the transmitter, I want to get the original numerical data that will be decoded with the demodulator. This has to be a fso project, so I need to transmit this digital data with a led diode or laser diode. But I don't know where to start and how to do it. Can anyone who knows about this help? Do you have any resource suggestions? Are there any other components I should use other than laser diode, arduino and photodiode?
You can work out the method of data transmission over short range using an ordinary LED and photodiode. The only additional components required are a current limiting resistor for the LED (220 Ohms) and a load resistor for the photodiode (typically around 100K).
Add the laser when all else is working.
Optical data transmission has been done many times in many different ways, so a little research on the internet will reveal various approaches for how the data can be encoded.
With some thought, even the standard Arduino IR remote control libraries could be used for this purpose, without modification.
Wiserr
This may help
https://www.pjrc.com/teensy/td_libs_IRremote.html
Have you considered using the UART? All the hardware and software is there you just need a driver for your LED/Laser.
Actually, you need to modulate on the transmitter side and demodulate on the receiver side. So far laser frequency modulation is a non-starter. So on-off keying is done, exactly like is done with IR LEDs. Lasers do not like PWM as that makes then always on and producing heat.
Actually, I need to do a project for school. I found a library about manchester modulation on the internet and took a look. Technically it does what I want it to. But I need to explain modulation and demodulation step by step on code. I'm having trouble understanding the library. Can someone enlighten me on this? I am also sharing the link of the library I mentioned.
It sends binary data, as does any other method of binary data transmission.
Why choose Manchester encoding? Pulse width modulation is much easier to understand and code.
Pulse width modulation can also be used. I have no restrictions on this. Do you know of a method where I can explain modulation and demodulation step by step using pwm?
Simply describe how a "1" and a "0" are uniquely produced and identified in terms of on/off times.
If you do not yet understand this, search terms could include "ir encoding".
Here is a very simple IR project just using a standard serial protocol: http://www.zolalab.com.br/eletronica_projetos/serial2ir
EDIT
This is effectively the same solution which @JohnRob mentioned in post #4
and a project using a laser: https://www.instructables.com/Arduino-Encoded-and-Modulated-Laser-and-Infrared-S/
Is UART not a consideration? It would be simple to sent a number to the UART Tx and receive that number or the UART Rx.
Not even slightly difficult.
Data transmission over short range using photodiode is the way that i choosen, working well. Beside I needed to check how does a photodiode works in general and very wide aspect to applicate that well.
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