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Topic: 20 analog Output pins (Read 500 times) previous topic - next topic

Okaghana

Hello.

I need to controll a dimmer with 20 channels with a 0-10V analog signal. For this I need 20 analog output pins on my arduino.
Can I use the UNO for this? It has only 14 I/O pins, but topics say, that you can transform the analog input pins into output pins. Or do I have to use a bigger board (And if yes: which?)?

Also... Do I need to use a "filtering circuit" on the PWM pins as shown in this forum?


Grumpy_Mike

The Arduino has no analogue outputs. It has some PWM outputs but these are not analogue.

It is unusual for a controller to need an analogue input, are you sure this is what it needs and not a PWM input?
The answer to this question decides which of two solutions you need.

Please provide a link to your controller.

Robin2

Maybe what the controller needs is 20 potentiometers?  If so you could operate 20 digital potentiometers with an Arduino.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MarkT

Post the datasheet/product page for the dimmer in question please...
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Okaghana

It is unusual for a controller to need an analogue input, are you sure this is what it needs and not a PWM input?
The answer to this question decides which of two solutions you need.
The dimmer Uses a Analog 0-10V signal. https://en.wikipedia.org/wiki/0-10_V_lighting_control

Its a simple DC current which has a voltage between 0 and 10V, which is use to controll exacly one type of light. Our system has 4 areass which each 5 types of light (white,red,green,blue,yellow), so we need 20 outputs


Post the datasheet/product page for the dimmer in question please...
Well... There is non. Its a ,in a workshop, selfbuild dimmer. An Vrey Old one.

wvmarle

You will have to look for an external DAC. This one may not be too useful (just one DAC), but there will be with more outputs available.
As it's I2C you can add as many DACs on just two pins as they have unique addresses available. You'll be addressing them digitally (by writing a value to a register), and get an analog voltage out.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Okaghana

You will have to look for an external DAC. This one may not be too useful (just one DAC), but there will be with more outputs available.
As it's I2C you can add as many DACs on just two pins as they have unique addresses available. You'll be addressing them digitally (by writing a value to a register), and get an analog voltage out.
A thing might be interesting: At the moment wo have the analog Dimmers and an old system, but in a few years, we might get a new dimmer which uses DMX.
Im primaly focused on controlling the old system, but also I want to take care of the newer Version.

Back to the toppic: So with this thing I could basically controll only 1 channel. I looked for versions with more channels, but couldnt find anything except this one. Also it would be good if the DAC would be small,  no huge device. Are there maby shield. I searched, but couldnt find any good ones (I found one which 4 channel, which means i would have needed 5 of them.)


I found this huge list of DAC's, but dont know if they are that what I need

wvmarle

I found this huge list of DAC's, but dont know if they are that what I need
It's quite easy to narrow it down. You want voltage output, not current, and lots of outputs.
Specs of LTC2668-16 seem to fit:: 16-bit resolution, 16 output channels (almost at your 20! Add a 4-channel one and you're at the 20 you want), 0V-10V output range, small (6x6 mm resp. 5x5 mm). May need some external components.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Okaghana

#8
Aug 13, 2017, 06:30 pm Last Edit: Aug 13, 2017, 06:36 pm by Okaghana
Is it important which bit version i order. (12 or 16)
Also: Do you have a photo of a thing like this. How big is it? Maybe an guide how you use these things?

Edit: Also there are different version in the shopping window.. whats the difference: 

wvmarle

Is it important which bit version i order. (12 or 16)
Also: Do you have a photo of a thing like this. How big is it? Maybe an guide how you use these things?

Edit: Also there are different version in the shopping window.. whats the difference: 
I hope you realise all I know is what's in that web site, I never used these chips.

For how to use them: read the spec sheet carefully.

For photo: you can quickly find some images of the package type in Google Images. It's a 6x6 mm QFNL package, maybe 0.5 mm thick - it's tiny. You put half a dozen of those on your finger nail. You may want to look for a breakout board for a QFNL package, or you'll likely have to design your own PCB.


Of course it matters which version you buy! Get the one you need. There may be a price difference, and as you can see in the specs the 12-bit version settles faster at the cost of having a lower resolution. Up to you what you want.

I bet there are more manufacturers that have similar devices around.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

GoForSmoke

#10
Aug 14, 2017, 03:30 am Last Edit: Aug 14, 2017, 03:42 am by GoForSmoke
This is for a light dimmer? What kind of lights? Incandescent and led work fine with PWM and soft-PWM that a Nano should cover 20 lines without touching RX, TX, Led13 (Uno has 18 unused and RX, TX, LED13). Eyes are not so fast nor do filaments cool as quick as PWM at 500Hz to 1000Hz.

Some lights don't take to any kind of dimmer, not sure about CFL's or tubes or halogen bulbs.

Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

GoForSmoke

Is it important which bit version i order. (12 or 16)
Also: Do you have a photo of a thing like this. How big is it? Maybe an guide how you use these things?

Edit: Also there are different version in the shopping window.. whats the difference: 
You need 20 lines then how about 2 of the 12's?

Unless you can solder such small surface mount chips, you will need them mounted on breakout boards. Try eBay.
Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

wvmarle

You need 20 lines then how about 2 of the 12's?
He was asking about the 12-bit vs. 16-bit modules. They come in 1, 2, 4, 8 and 16 channel DAC. Not 12-channel. Hence my suggestion to look at 16+4 channels.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

GoForSmoke

OP won't need any if the lights work on PWM.
Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

Okaghana


I bet there are more manufacturers that have similar devices around
[/quote]

Well... I found this one

OK: Here's what im going to do: Ill order an Arduino and test out if it will work without an dac as "GoForSmoke" has suggested. So far, im happy with the answeres i got.

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