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RGBW vs GRBW
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Please be positive and constructive with your questions and comments.

RGBW vs GRBW

by EugeneR on Sun Jul 07, 2019 8:36 pm

I recently purchased two of the neopixel 60 segments (#2875) from Micro-Center, they only had 2 in stock. I had anticipated buying the other 2 direct from Adafruit. When I connected the 2 segments I had to an Arduino and loaded the library and sample code in the tutorial it worked as expected with the exception that the first color listed in the example , RGBW, was expected to be red but turned out to be green. If I purchase additional segments to complete the ring of 60 from Adafruit, will they be GRBW or RGBW. I am trying to avoid a mixed ring as that would become to complicated to code around! The only mention of this GRBW vs RGBW that I could find is in a blue box warning in your tutorial, https://learn.adafruit.com/adafruit-neopixel-uberguide/arduino-library-use . Thanks for your help

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Re: RGBW vs GRBW

by adafruit2 on Mon Jul 08, 2019 12:26 pm

hiya the 'description' for humans is RGBW, but the actual color order is GRBW. all neopixel "RGBW" strips from adafruit use the same chips so all are going to be identical

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Re: RGBW vs GRBW

by EugeneR on Mon Jul 08, 2019 3:10 pm

Thanks for responding. The sample program lead to some confusion for me. After declaring "Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_RGBW + NEO_KHZ800);" I was expecting the function in the loop "strip.setPixelColor(0, 16, 0, 0, 0);" to set pixel 0 to red with a brightness of 16, but it was green.

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Re: RGBW vs GRBW

by adafruit2 on Mon Jul 08, 2019 3:29 pm

thanks, what's the exact link to t he demo in question? we'll look!

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Re: RGBW vs GRBW

by EugeneR on Mon Jul 08, 2019 6:08 pm

It is located at https://learn.adafruit.com/adafruit-neopixel-uberguide/software. On this page one of the examples does specifically say "strip.setPixelColor(n, red, green, blue, white);" when using RGBW strips so I think that is what lead to my confusion.

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Re: RGBW vs GRBW

by pburgess on Mon Jul 08, 2019 6:17 pm

Try using 'GRBW' in your constructor, like so:
Code: Select all | TOGGLE FULL SIZE
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRBW + NEO_KHZ800);


Then
Code: Select all | TOGGLE FULL SIZE
strip.setPixelColor(n, red, green, blue, white);

should work as expected.

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Re: RGBW vs GRBW

by EugeneR on Mon Jul 08, 2019 8:05 pm

Ok, thanks, I did not realize NEO_GRBW was one of the options. The actual library uses the data in RGBW order. That clears things up.

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Re: RGBW vs GRBW

by keith726 on Fri Jul 19, 2019 12:07 pm

Adafruit, unless I missed it, I don't see anywhere in the description for the 1/4 60 LED rings that they are GRBW not RGB. Worse, your Strandtest sketch does not even list NEO_GRBW as an option.

After tearing my hair out for a couple of hours, I tried setting individual LEDs using SetPixelColor() and realized something was wrong with your Strandtest code. Note that I had to set LED_COUNT to 20 instead of the 15 pixels in order to get the last three pixels to be updated!!??

PLEASE put in your product description for the 1/4 60 LED Ring that it is GRBW, not RGB. and PLEASE add a comment to your Strandtest sketch showing the option for NEO_GRBW is required for these rings.

Now that I set it to NEO_GRBW the Strandtest sketch works beautifully - and the LED_COUNT is correct (I thought it was junk - horrible display with the wrong bitstream setting).

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Re: RGBW vs GRBW

by adafruit2 on Fri Jul 19, 2019 12:27 pm

keith, what product id is this?

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Re: RGBW vs GRBW

by keith726 on Mon Jul 22, 2019 8:46 am

P2874 Neopixel RGBW 60 LED ring (only 1/4 of the full ring - 15 pixels). I bought it a few years ago and just got around to the project.
The label on the bag says "RGBW Natural LED". I realize that "RGB" is a generic term, which means that you get all three colors (plus "W" if there is white also), but if a product is actually GRB, then I think you should flag that to the users. Your Strandtest sketch is intentionally generic: it lists options for entering parameters for the particular LED strings and processors, and I think you should include a listing for the option for GRBW Neopixels, which this one happens to be. By not seeing that there was an option for GRBW in Strandtest, I plugged in RGBW as it says on the product package, and it did not work properly. As I said above, I had to set the number of Neopixels to 20 for a strand that actually has 15 pixels in order for the last three pixels to turn on, and the Strandtest display was not pretty. By changing the declaration for the Neopixel strip object to include "NEO_GRBW" in line 26 of Strandtest, the strip worked fine and I finally saw the beautiful displays that Strandtest produces.
I just wish that you had shown "NEO_GRBW" as an option in the Strandtest listing, and I wish your product pages were more descriptive of this. Also, how about showing maximum amps drawn by each strip so I can design my power supplies?

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Re: RGBW vs GRBW

by adafruit2 on Mon Jul 22, 2019 2:20 pm

theres an example called RGBW strandtest, please use that
https://github.com/adafruit/Adafruit_Ne ... ndtest.ino

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Re: RGBW vs GRBW

by keith726 on Fri Aug 09, 2019 10:30 am

Thank you. That worked well.

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Please be positive and constructive with your questions and comments.