How to serial read hundreds of sensors ?

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keghn

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Re: How to serial read hundreds of sensors ?
« Reply #15 on: November 28, 2017, 05:41:12 pm »
 The GPIO  pins can read external voltages or output a voltage. These pins are on the out side of the board. Python code can access them:)

Access to GPIO with Python on Your Raspberry Pi 3:   

https://www.arrow.com/en/research-and-events/articles/raspberry-pi-gpio



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ranch vermin

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Re: How to serial read hundreds of sensors ?
« Reply #16 on: November 29, 2017, 01:37:18 pm »
Like Keghn is saying,   u need a giant parallel buss but u can only do that from scratch cause consumer hardware pretty much always just recurses down a single wire (usb type device) cause its 10000 times easier that way - and having busses thicker than your arm is something youd only see in a tardis somewhere in time. :)

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Thierry

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Re: How to serial read hundreds of sensors ?
« Reply #17 on: November 30, 2017, 11:32:04 am »
I took some informations.

It seems that multiplexing in my case would bring :
- a huge number of wires going to the same place
- non accurate signals
- a lot of "noise" due to the distance between sensors and processor.

What some guys suggest is to have a master processor receiving data from slave processors themselves connected to sensors (1 slave per sensor).

In this case :
- 4 short wires only between each sensor (A, B, VCC, GRND)
- Technically easier to add new sensors and manage the global architecture

This is the schematic they attached :

http://www.electro-tech-online.com/attachments/rs485-png.49989/

What do you think of this ?

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Zero

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Re: How to serial read hundreds of sensors ?
« Reply #18 on: November 30, 2017, 12:58:03 pm »
If each sensor emits data at a given frequency (wireless), you can catch'em all at once using Fourier transform. Just use radio waves instead of audio waves!
Quote
An MP3 splits a song into short segments. For each audio segment, Fourier’s trick reduces the audio wave down to its ingredient notes, which are then stored in place of the original wave.
http://nautil.us/blog/the-math-trick-behind-mp3s-jpegs-and-homer-simpsons-face

50%  :uglystupid2:
50%  8)

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Thierry

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Re: How to serial read hundreds of sensors ?
« Reply #19 on: December 01, 2017, 04:37:51 pm »
Hey guys !! I found my Christmas gift !  :D :D :D :D

I don't know what results I will get but at least I must try it ! (yes it is multiplex but I must try to see if it is ok or not)

http://mayhewlabs.com/products/arduino-mux-shield

EDIT : WTF the cost of delivery to France !!!!!!!!!!!!!  :uglystupid2: :tickedoff: it double the price !!!
I will look at China stuff then !
« Last Edit: December 01, 2017, 10:06:20 pm by Thierry »

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keghn

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Re: How to serial read hundreds of sensors ?
« Reply #20 on: December 01, 2017, 05:48:39 pm »
  Another way is to just daisy chained all devices and sensors together. The cpu, or arduino, starts a pulse that activate
the first device. When the device shut down it passes a pulse to the next device int the daisy chain. Odd devices accept
write data, even devices are read data to the cpu. 


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korrelan

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Re: How to serial read hundreds of sensors ?
« Reply #21 on: December 02, 2017, 01:27:02 pm »
For one of my projects I used a matrix of 20X20 LED’s that simply changed intensity/ brightness according to sensory stimulus.

I then just pointed a webcam at the matrix and used software to read the values into a program.

I also once used a bank of simple light detecting resistors (LDR) stuck onto a monitor.  So I could control servos etc just by changing the brightness of the section of screen under the LDR's.  That was on a ZX81... so quite a few years ago lol.

Cheap, quick and easy.

 :)
It thunk... therefore it is!

 


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