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how to use different Dotstar strips ?
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how to use different Dotstar strips ?

by mouha on Mon Jun 14, 2021 2:36 pm

Hi,

I'd like to control 12 Dotstar strips independantly: like a matrix of Dostars.
The purpose is to use them to display image and the best would be animated images.
The Processing¨project could be perfect for this but FadeCandy doesn't manage SPI.

So my question is divided as 2 parts :
- The Raspberry can't be used as there is only 2 SPI on it = which board could provide 12 SPI ports ?
- I've been taking a long time to search for already made libraries (see below) but they don't allow to "project" image or animation = how to have an image or animation.
This could be from something to adapt or eventually to program as a python code.

From all I've been searching :
- https://learn.adafruit.com/circuitpython-led-animations/pixel-mapping
- https://learn.adafruit.com/circuitpython-essentials/circuitpython-libraries
- https://www.digikey.com/en/maker/projects/circuitpython-led-animations/d15c769c6f6d411297657c35f0166958

mouha
 
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Re: how to use different Dotstar strips ?

by adafruit_support_carter on Tue Jun 15, 2021 12:49 pm

Do the 12 strips comprise a single matrix? If so, it's best to just chain them as a single strip and then do math to deal with addressing things as a matrix. That's what the PixelMap helper does. That is part of the Animation library, but the general approach would be the same.

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Re: how to use different Dotstar strips ?

by mouha on Thu Jun 17, 2021 12:43 pm

Thank you for your answer.

Actually, all of these strips are this matrix right.
However, the Pixelmap helper seems only to display some kind of animations like :
  • rainbow_v,
  • comet_h,
  • rainbow_comet_v,
  • chase_h,
  • rainbow_chase_v,
  • comet_v,
  • rainbow_chase,
which is not I need. Instead, I'd like to display my own animations sequences.

mouha
 
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Joined: Tue May 20, 2014 6:50 pm

Re: how to use different Dotstar strips ?

by adafruit_support_carter on Thu Jun 17, 2021 12:45 pm

Yep, it doesn't have exactly what you want. But it's the same general idea, in terms of using a single SPI port vs. one for each row.

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Re: how to use different Dotstar strips ?

by mouha on Thu Jun 17, 2021 2:29 pm

I see.
I'd like to know however how it's possible to connect many SPI slaves from a board like PI, Oodo,BeagleBone, etc
All my searches in Adafruit didn't gave any result: like SPI exander nor multiplexer, etc

mouha
 
Posts: 25
Joined: Tue May 20, 2014 6:50 pm

Re: how to use different Dotstar strips ?

by adafruit_support_carter on Thu Jun 17, 2021 4:09 pm

You can have more than one device on a SPI bus. They share SCLK/MOSI/MISO pins. Each one needs a dedicated chip select (CS) pin, which is just any available GPIO pin.

DotStar is not truly a SPI device. It's communication protocol is SPI-like, and it can be driven with a SPI bus. But it doesn't have a CS pin, so won't play nice with other devices on a SPI bus.

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Re: how to use different Dotstar strips ?

by mouha on Thu Jun 17, 2021 4:49 pm

Oh no ... I've bought 12 of them already .
So it means I can't control them via FadeCandy nor as SPI slaves ?
Controlling them through Processing neither (like with the FadeCandy) ?

mouha
 
Posts: 25
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Re: how to use different Dotstar strips ?

by adafruit_support_carter on Thu Jun 17, 2021 5:54 pm

Fadecandy is for use with NeoPixels, which are a little different than DotStars. NeoPixels do not have a dedicated clock line.

There's a brief DotStar vs. NeoPixel comparison here:
https://learn.adafruit.com/adafruit-dot ... s/overview

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Re: how to use different Dotstar strips ?

by mouha on Thu Jun 17, 2021 6:00 pm

thanks.

In conclusion : no hope to use 12 dotstars strips as a matrix to display my personal images as animation ?

mouha
 
Posts: 25
Joined: Tue May 20, 2014 6:50 pm

Re: how to use different Dotstar strips ?

by adafruit_support_carter on Fri Jun 18, 2021 2:31 pm

It's totally possible. Same general suggestion as above - have a single strip and do the matrix-ification in software. Similar to this Arduino library:
https://github.com/adafruit/Adafruit_DotStarMatrix
Then just need something that would go from image/animation to actual DotStar data buffer.

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Re: how to use different Dotstar strips ?

by mouha on Sat Jun 19, 2021 11:12 am

thanks adafruit_support_carter.

I

mouha
 
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Please be positive and constructive with your questions and comments.