Edit: Usecase - I am creating a small model for Vehicle-to-Vehicle Visible Light Communication. I have written the communication protocols and using OOK (on off keying) for the transmitter.
Basically, I want these light to switch ON and OFF really fast (say 20ms) according to the logic I've written in my code.
I am creating a small model for Vehicle-to-Vehicle Visible Light Communication. I have written the communication protocols and using OOK (on off keying) for the transmitter.
Basically, I want these light to switch ON and OFF really fast (say 20ms) according to the logic I've written in my code.
I'm pretty sure it's just a basic power line from the USB connector
so any mosfet/transitor design will do and you need to hack an USB cable to plug Ito the USB on one side and use the + and - wires on the other side that you'll connect to a transistor driving power.
Do you have a sensor and an Arduino program to measure the switching speed of your light? At some point the persistence of the light source will limit the switching speed and you should be able to find that as part of your testing.
That is just an LED light source. Buy an LED light source that doesn't have a USB plug and power it separately, using a transistor to switch it on from a port pin.
Thanks Paul, I will keep that in mind. And you are correct, the switching speed of LED and detecting capabilities of photodiode are the main limitations in Visible light communication.
We can only achieve a low bit-rate (around 50-100 bps) using simple OOK. Will switch to other methods (PWM, etc.) as next phase of the project.
Hi Emily!
Since we're using this to establish Vehicle to Vehicle Communication, the idea is that we'll use the existing infrastructure installed in all cars (headlight and taillight) to establish a communication link.
That is why we're using Visible white light in the prototype.
I like people reinventing the wheel. Will it be triangular this time?
Yoke aside: why don't you simply use IR as virtually all IR remote controls do? You get ready to use receiver, too. And you could add a white led for show.
I see. Wouldn't you want to prototype with actual automotive light sources then? Driving a modern headlight/taillight will be different than driving your LED module.
Exactly. Visible light will suffer far more from ambient light pollution than IR. This is undoubtedly a school project though, so maybe a suitable conclusion is to demonstrate what a bad idea it is.
Look, you may be right. Like I said, the idea was to use the infrastructure already available in cars (visible light of headlight and taillight), hence Visible light communication.
I had the same doubt as you guys when I saw all the beautiful libraries of IR already available on Arduino. But this is a funded college project, so I didn't question much when my professor chose this as our topic
P.S. He is ordering a car's DRL system to do actual testing btw. (Again, not my funds; I do what he tells me :P)
You can probably take advantage of those with visible light just as well maybe just at a different data rate. One big problem to solve will be how to filter a usable signal out of the very large noise level of ambient visible light.
Your professor might be demonstrating to you how throwing money at a problem doesn't always result in a solution, a valuable lesson, or maybe they are just not a very good engineer.
You could post the exact model you will be using. If it is a modern assembly it will probably be CAN bus compatible and that in itself will come with its own unique requirements.
There are literally dozens of different Daylight Running Lights implementations. I want to stress the suggestion to post the exact one you get as any further help will depend on knowing exactly what you are working with. Your requirement to work within the existing automotive infrastructure will have to be kept in mind throughout the design process. It would make little sense to consider older DRL implementations unless this is purely an intellectual exercise. Modern systems will be CAN bus controlled. The lights are dimmed when the system is in certain states and perhaps this can be used to modulate the light for communication. I have no idea at what rate one could do that.
