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Topic: Multiple Analog Inputs? (Read 268 times) previous topic - next topic

TCO2

Hey!

So I'm working on a project where I am planning on having about 30+ analog inputs, the only problem is I can't find a board which has this amount of analog in pins (the most I can find is the mega board at 15 in pins)

Is there a board which has 30+ analog in pins or is there a way around this?

Many thanks

pylon

Use an analog multiplexer (p.e. CD74HC4067), or better two of them.

gilshultz

It is almost impossible to answer your question because of the lack of information.  Try searching the internet, search with this as a start: "analog input board 32 channels". In about 10 minutes I found hundreds of converts available in board and chip format.  What voltage range, what interface, ambient conditions, etc. are a few of the questions that need to be answered.
Good Luck & Have Fun!
Gil

Semtex9

perhaps use multiple nanos and communicate over serial to central?

Wawa

#4
Nov 16, 2019, 02:45 am Last Edit: Nov 16, 2019, 02:46 am by Wawa
perhaps use multiple nanos and communicate over serial to central?
More processors is usually a beginner's mistake.

Port expanders is usually the better solution.
16 analogue channels per analogue pin with this board.
Leo..

Grumpy_Mike

perhaps use multiple nanos and communicate over serial to central?
Just to emphasise Wawa's point
No, never do this.

TomGeorge

#6
Nov 16, 2019, 11:28 am Last Edit: Nov 16, 2019, 11:29 am by TomGeorge
Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .

Can you tell us the application please?
What sort of analog inputs, voltage, current?
What rate do you want to sample the analog inputs?

Thanks.. Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

GoForSmoke

How fast do you need to read these inputs?

There might be a reason to use multiple boards (to read > 1 pin at a time) but at least put them on an SPI bus.

Every time you switch from one analog pin to another there has to be "settle time" before the ADC can make a good read. Would you be happy reading 4 or 5 pins per millisecond?



1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

stargazing

More processors is usually a beginner's mistake.

Port expanders is usually the better solution.
16 analogue channels per analogue pin with this board.
Leo..
Just to emphasise Wawa's point
No, never do this.
Could you please explain why expander is a better solution and multiple processors isn't good idea?

PieterP

Communication and synchronization between multiple processors is hell. Having to maintain two different programs is cumbersome. Microcontrollers are more expensive than multiplexers.

Using a multiplexer requires 10 lines of code, communicating between multiple processors is much harder.

Pieter

stargazing

Communication and synchronization between multiple processors is hell. Having to maintain two different programs is cumbersome. Microcontrollers are more expensive than multiplexers.

Using a multiplexer requires 10 lines of code, communicating between multiple processors is much harder.

Pieter
Fair enough. :)

TomGeorge

I think @TC02 is waiting for the ultra-reliable email notification system of this forum to work... :o :o :o


Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

GoForSmoke

If I use AVR's as dedicated SPI slaves, multiprocessing won't necessarily become difficult.
But I get this feeling that for some folks it would anyway.
1) http://gammon.com.au/blink  <-- tasking Arduino 1-2-3
2) http://gammon.com.au/serial <-- techniques howto
3) http://gammon.com.au/interrupts
Your sketch can sense ongoing process events in time.
Your sketch can make events to control it over time.

Semtex9

#13
Nov 18, 2019, 01:59 pm Last Edit: Nov 18, 2019, 03:36 pm by Semtex9
More processors is usually a beginner's mistake.

Port expanders is usually the better solution.
16 analogue channels per analogue pin with this board.
Leo..
Just to emphasise Wawa's point
No, never do this.
OK, I respect that, for one big process, but since he didn't mention the function much, I thought if he maybe has remote processes since 30+ inputs?!, he can manage them on site with small arduinos, and give commands/feedback by the central board over SPI or even lan, that way its not very time sensitive and usually that's how industry works, I may be a noob, but not a stupid one

if the layout was a smart home project, where say you need to control some temperatures and brightneses and what not, why not decentralize the task by rooms even with the troubles of communication, leaving the central board to interface with say an app?
if its a robot or a scanner of some sort and it dosen't have to pid or something for every input I totally agree with you guys, but never say never since multiprocessoring can also be the only way if you need one part of the system to run really fast, and stop just to take tunings or something.
Altho OP is probably well below the hard stuff

Grumpy_Mike

Quote
Altho OP is probably well below the hard stuff
That is the call I made when I wrote my answer.

Often beginners say to me that too much information is given in a reply and it only confuses them. While we are all engineers and love an exception to any rule, beginners often don't know enough to be able to cope with this and it just acts as a fog of confusion or, as I have seen recently, accusations that they were given wrong information.

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