I'm trying to make a sport timing system.
For this project I need to connect multiple arduino (up to 6) wirelessly.
I was searching for a good compromise between range and speed (data travel) for the antenna/wifi module.
This is a brief explanation of the project:
All the arduinos will be at 50m from each other in a open field.
Each arduino is connected to a photocell.
When the first arduino's photocell beam is interrupted it sends a "start" signal to the next second one.
As soon as the second arduino receives the "start" signal it starts a timer that will be stopped once the 2nd photocell is interrupted.
So the second arduino sends the start signal and the time he calculated to the third and so on.
The sixth arduino will receive a "start" + the 5 times of the previous sections.
Since it has to be as precise as possible for my athletic trainings, I wanted to ask you a good antenna/wifi module.
I saw that the most common is nRF24L01 but I'm afraid that speed connection will be too slow (It may also be a unfounded fear since data exchanged are not many)
And also, do you think the cascade messages will be too much for an arduino nano?
This is my first "big" project, I'm so excited (and also my first post on the forum).
Thank you all in advance.
You would need to run very fast to outpace the speed of connection between 2 consecutive Arduinos in such a system
Where did you get the idea that a connection using nRF24L01 would be too slow for your application ?
Your main problem will probably working at that range
an NRF24L01+ or HC-12 or zigbee wireless network could easily achieve this
with the NRF24L01+ you can have to 6 pipes open for reading at once (but based on what you describe probably only 1 channel is needed). You can use the setDataRate() function to define the transmission datarate. You could try @ 1 Mbps and your message could be pretty short
do you think the cascade messages will be too much for an arduino nano
No. the time calculated will probably fit on 2 or 4 bytes, so it's a small payload
I'm just paranoid. The problem I had in mind was not to outrun but to have a precise time.
I want to check my running improvements, I'm talking about milliseconds or hundredths of a second.
Sorry for the noob question
Thank you very much for your answer
if that works @ 1 Mb/s, this will get you a small message (say a 32 bits payload) pretty quickly to the next base.
I'm talking about milliseconds or hundredths of a second
This will likely impact the 10th of ms but you can possibly fine tune the system and take into account the latency. You'll have to invest also in a great sensor to not add random delay to the measure
Could you please suggest a good photocell?
It will be like a tripwire, always active, it sends a signal when interrupted.
I don't have any specific recommendation - probably indeed a tripwire of some sort - laser if you need a fine line.
what's the moving object? you, a car, a rocket ?
I meant exactly a tripwire with laser.
It will detect my movement, so just a person running.
I was planning to use a KY-008 laser emitter
and maybe as a receiver a KY-022 or VS1838
But I'm afraid those will not work under sunlight
Distance between laser emitter and receiver will be no more than 2 meters.
Those are cheap laser, I doubt you'll be able to get a good detection esp outside or if you send a continuous laser beam.
It would be worth trying by sending an easily identified signal (pulses) and hide the receptor within a tube to protect from daylight
I saw exactly this solution on some threads: make the beam pulse on different frequencies so it is easier to identify instead of having just a beam set to 1 frequency.
In this case the receiver must know the exact frequency (beam's color) and timing, right?
Correct
Beam presence or absence is not just the fact that you get light but light at the right frequency (IR remotes work this way)
In this case I have to find a modulable emitter and a better receiver, do you have suggestions? In case, what key feature should i check on a product, because on Amazon and Aliexpress I'm finding just cheap sensors.
Thank you very much for your time and help.
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