Author Topic: New AliExpress find - 12v WS2811 pixel strings  (Read 17528 times)

Offline gadgetsmith

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #45 on: January 19, 2016, 09:59:47 AM »
BTW If you ever get some Minleon strings you will never look at the other nodes the same...  Everything about them is clearly in another league.

Including the price tag!  Just looked them up.  Yikes!   :o

Offline twooly

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #46 on: January 19, 2016, 10:06:50 AM »
DIYLED Express has them a little cheaper and allows you to select the wire color (I hate multi).  Plus if you buy larger quantities it drops lower.  They just don't have the higher 6" spacing option.

http://www.diyledexpress.com/index.php?main_page=product_info&cPath=42_44&products_id=267

Shipping cost reasonable?   

yep standard usps rates.

Offline gadgetsmith

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #47 on: January 19, 2016, 10:25:03 AM »
+1.  I would love if Jon could expound on the chip architecture.  I've not seen a chart or breakdown before.  Curious why certain people like certain chips. 

There are many people better qualified on chip architecture. Somebody like David who actually has had to support the different chipsets in the F16v2.

http://www.doityourselfchristmas.com/wiki/index.php?title=Different_Styles_of_Pixels

This is a nice list.  Most pixels will be 8-bit, and I believe a copy of what World Semi came up with, the WS28XX line of pixel control.  An example would be Titan Micro (TM), they manufacture the TM 1803/4 to drive 3 channels, just like the WS2811, but they also have the TM1809 that drives 9 channels, and the  TM1812 which drives 12 channels... this means less IC's on say pixel strip if using TM1812 vs TM1804.  Regarding bit depth, one notable exception is TLS3001, which uses 12-bit dimming.  I've head people say it's very smooth dimming.

In my experience, I think the GECE's have nice dimming, although only 4-bit, just not they way it gets implemented either through sequencing software, or hardware.  The original controllers seem to demonstrate great dimming, but the hack that allows us to use them with all the great controllers and software don't talk to the pixels like they were originally designed, at least that's what i'd gotten out of all the reading up on them I did last season.

Offline gadgetsmith

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #48 on: January 19, 2016, 10:27:52 AM »
DIYLED Express has them a little cheaper and allows you to select the wire color (I hate multi).  Plus if you buy larger quantities it drops lower.  They just don't have the higher 6" spacing option.

http://www.diyledexpress.com/index.php?main_page=product_info&cPath=42_44&products_id=267

Little cheaper than Holiday Coro, but not cheaper than this AliExpress guy.  Added DIYLED to the list on Post #41 for comparison.

Online JonB256

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #49 on: January 19, 2016, 12:19:12 PM »
In my experience, I think the GECE's have nice dimming, although only 4-bit, just not they way it gets implemented either through sequencing software, or hardware.  The original controllers seem to demonstrate great dimming, but the hack that allows us to use them with all the great controllers and software don't talk to the pixels like they were originally designed, at least that's what i'd gotten out of all the reading up on them I did last season.

The smoothness of the GECE pixels on their original controller is probably similar to the tricks used by LOR on their CCR and CCP lights. They are 4-bit but add some bit shifting in there to make them appear smoother and more colorful than they otherwise would.

Offline L1011

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #50 on: January 19, 2016, 12:28:53 PM »
I may be wrong, but I believe its impossible for a WS2811 to run in 5-bit color mode.

In typical Chinese fashion, the description can not be trusted.  It says they are WS2811 and it says they are 5-bit.  One of those statements is wrong.  Due to the high popularity of ws2811 chips, my gut feeling is that the ws2811 statement is more believable than the 5-bit statement.

I looked it up and the spec for WS2811 is indeed 8-bit.  Further, I emailed the seller to clarify his description.  Hopefully they're 2811's.  This is a good lesson for my fellow n00bs out there: Verify the specs before buying pixels!
Newbie for 2016 using FPP, F16v2r, F4v2, and WS2811 bullet pixels.

Offline gadgetsmith

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #51 on: January 19, 2016, 12:37:10 PM »
In my experience, I think the GECE's have nice dimming, although only 4-bit, just not they way it gets implemented either through sequencing software, or hardware.  The original controllers seem to demonstrate great dimming, but the hack that allows us to use them with all the great controllers and software don't talk to the pixels like they were originally designed, at least that's what i'd gotten out of all the reading up on them I did last season.

The smoothness of the GECE pixels on their original controller is probably similar to the tricks used by LOR on their CCR and CCP lights. They are 4-bit but add some bit shifting in there to make them appear smoother and more colorful than they otherwise would.

Not sure about the bit shifting or LOR stuff, but I seem to recall reading that the 64th bit position is used as a global dimming level for a GECE string.  This gives nice fades, but only of a given color.  You can change color, or you can change intensity, but you can't change both.  So, for the small embedded sequences using the original controller, it works well... but, attach these GECE's to a system that allows cross fades, etc., geared towards 8-bit, and not surprisingly, they just don't work as well.  If we were able to provide a way to sequence GECE lights per the original spec, and hardware to also support, I think people could get them to look better, but honestly, i'm happy with the performance thus far.  I only use them as roof outline, which in my book is not so critical as compared to say; a MegaTree.


Offline gadgetsmith

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #52 on: January 19, 2016, 12:39:42 PM »

I looked it up and the spec for WS2811 is indeed 8-bit.  Further, I emailed the seller to clarify his description.  Hopefully they're 2811's.  This is a good lesson for my fellow n00bs out there: Verify the specs before buying pixels!

No need to worry, they are 2811's.

Offline zwiller

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #53 on: January 19, 2016, 12:39:58 PM »
Good info!  Nice writeup...  Yes the Minleon strings are pricey but they are pro grade.  I believe they are the 3001/12bit chips.  Not sure how all this plays out but I think our system is 8bit so not sure what happens when the F16v2 runs them.  I will say that if you are interested in colors besides RGB you should take a look at them.  Yellow/orange/purple/indigo are as good as rgb.  Also, the fades are as good as incans but that is with the Minleon controller.  I keep wondering if there will someday be "light curves" or something that will help the 8 bit lights with color and/or fades. 
Sam
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Online JonB256

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #54 on: January 19, 2016, 01:04:21 PM »
I believe they are the 3001/12bit chips. 

Minleon (and a few others) do use the TLS3001 chip. The F16v2 controller (and the F4v2) supports that chip, but Dave Pitts may be the one to tell you if the controller actually uses all 12bits per color.

and, gadgetsmith, your explanation of the GECE workings sound very similar to the way I heard the LOR strings described. That chipset, plus pricing, are the reasons I did not go with LOR pixels when I first saw them. Plus, their ribbons were always 3 LEDs per Pixel, too, and I didn't like that.

and here's an old post from jStJohnz on the AusChristmas site. Has a lot to do with how different Pixel chipsets manage their outputs:

Quote
It is possible to achieve a similar result with 8-bit pixels.  The approach is similar to what LOR does to get 128 dimming levels using 5-bit 6803s.  By slightly varying the pixel intensity on every refresh pass, you can effectively extend the number of intensity bits.  For example, to use the 6803s as 7-bit pixels, you use the 5 high-order bits as the base intensity value, then use the 2 low-order bits to determine when to add an extra bit.
Example:  Desired 7-bit intensity = 0000001, base intensity (5 MS bits) is 0, now use the 1 LS bits (01) to transmit an actual intensity value of 00001 to the pixl every 4th refresh.  A 10 value of the 2 LS bits would mean you send intensity 1 every other time, etc.  If the refresh rate is fast enough the eye sees this as having effectively 128 dimming steps instead of 32.
With 8-bit pixels, you use a similar scheme.  In my case I have a gamma lookup table that returns 12 bit values, originally  for use with the TLS3001.  With 8-bit pixels you do the gamma table lookup, then discard the 2 LS bits keeping a 10-bit result.  The MS 8 bits becomes the base intensity value, and the 2 LS bits are used for the dithering, in other words they determine which refresh passes get bumped up by 1 bit.  The effect is an effective 10-bit pixel, and the improvement in the dimming characteristic is very noticeable on the low end.
This is only workable if the basic refresh rate is high enough to keep the dithering invisible.
« Last Edit: January 19, 2016, 01:10:54 PM by JonB256 »

Offline zwiller

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #55 on: January 19, 2016, 02:30:39 PM »
LOL^  I was going to posted a link to that thread... 

Offline Skunberg

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #56 on: January 19, 2016, 03:15:07 PM »
The gece can be graceful or horrible. Depending on your sequencing. Several times I had to cut out stuff or move to a different prop because it looked choppy on the gece. But you get better at it.

Offline AussiePhil

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #57 on: January 19, 2016, 04:18:33 PM »
5 bit = the cheapish pixels originally available and quickly dropped by most when 2801 8bit became around the same price.

8 bit = nearly every pixel type we use these days except for the rarer 12bit 16 bit pixels

12 bit = as each dmx channel is only 8 bit the magic must happen at the hardware controller level to dither changes, typically you run these at 2x or 4x the incoming data rate and spread the change out over the period.
If you run these at the same refresh rate as the incoming data then you get ZERO benefit due to the 8 bit incoming signal.

16 bit yes there are now 16 bit pixels and they will either dither the 8 bit signal or they require you to use 2 dmx channels (per colour) to get 16 bit resolution.


Offline verynoblecause

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #58 on: January 19, 2016, 05:07:49 PM »
I didnt mean to derail the original topic by asking for a comparison of smoothness, but I am glad I did as this has been very informative.  Just to complete the learning, let me ask what is meant by 8-bit.  I have always assumed there is actually 24 bits, 8 bits or 256 values for each R,G&B.  I never considered intenisty bits, as I assumed that overall intensity would be a product of each colors value.  Is it vastly different than that?  Where can I learn more?  Thanks!

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Offline tbone321

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Re: New AliExpress find - 12v WS2811 pixel strings
« Reply #59 on: January 19, 2016, 06:14:34 PM »
The bits being referred to is the number of bits per channel that the nodes use.  An 8 bit node means that each channel uses 8 bits and yes, these channels control the intensity of each color and the mixing of these primary colors by intensity creates the output color of the node.

 

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