Author Topic: WS2812B or SK6812 Help  (Read 3412 times)

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Offline BlindAssassin111

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WS2812B or SK6812 Help
« on: Wed, 29 November 2017, 13:42:36 »
    So I am trying to design a full size(108 key) board with per key rgb but I have a few issues I am running into in regards to what LEDs to use and how to mount them under a matias switch via a cutout and soldering them inside the slot. As well I was thinking of maybe doing some under glow as well, yes I know it may be a lot but I want to at least have one in the collection and will just use this at home anyways.

    Also I was planning on using the Teensy++ 2.0 as it gives me a little more freedom on the pinout, could actually use the Teensy 2.0 as I was able to make a matrix that only needed 24 pins for a full size but I prefer not to be limited in case I want to add on before I finish the design phase.

I have done quite a bit of searching over the past couple days to no avail, so here are the questions I have:
    1) What are the big differences between them? Pros and cons?
    2) There are two main versions of the SK6812, RGB and RGBW, is it possible to use the RGBW or is that not supported? I would prefer to use those as the white would be way more accurate.
    3) What needs to be changed, if anything, in QMK to use the SK6812? And any info on how to do it myself without the need of kbfirmware.com would be nice so I can do some custom bits.
    4) How do most people power this many LEDs? A power brick plugged in to the board? I want to be able to run all at full brightness, even if I may not always have it set that way.
    5) I read in another thread that the is a 10 μf limit for capacitors on the LEDs, not sure why this is or how to work around it if I have 108+ leds...

    I recently found a 3535 package SK6812 RGB and would love to be able to use that as it would use a smaller cutout in the board and make life a bit easier for routing.

Offline TalkingTree

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Re: WS2812B or SK6812 Help
« Reply #1 on: Wed, 29 November 2017, 14:39:34 »
I was able to make a matrix that only needed 24 pins for a full size
You can actually do that with 21 pins in a 10 * 11 matrix, so a Teensy 2.0 will be enough.

What are the big differences between them? Pros and cons?
The SK6812 has voltage-independent color and brightness over a wide voltage range, which means that the colors of the LEDs should not be affected by a drop in the supply voltage as much as they are on the WS2812B. (source)

Have a look at IBNobody's Matias RGB TKL.

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Offline BlindAssassin111

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Re: WS2812B or SK6812 Help
« Reply #2 on: Wed, 29 November 2017, 15:03:49 »
I was able to make a matrix that only needed 24 pins for a full size
You can actually do that with 21 pins in a 10 * 11 matrix, so a Teensy 2.0 will be enough.

What are the big differences between them? Pros and cons?
The SK6812 has voltage-independent color and brightness over a wide voltage range, which means that the colors of the LEDs should not be affected by a drop in the supply voltage as much as they are on the WS2812B. (source)

Have a look at IBNobody's Matias RGB TKL.

I didn't think to layout a matrix like that for some reason...just did it using the kbfirmware wiring tab and made it take as few as possible, as the visual aid makes it easier to remember where I put the damn keys, lol.

I read IBNobody's diagram but thought it was for the older WS2812 (6 pad) didn't notice it was for the SK6812. But is it possible to use the RGBW ones or just the RGB ones?

And still how would I do the caps? I need another 21 caps over what he did, and his setup only added up to 8.7 μF when I would have 10.8 μF total using 0.1 μF caps. Where does the 10 μF limit come from and how strict is that?
« Last Edit: Wed, 29 November 2017, 15:15:38 by BlindAssassin111 »

Offline TalkingTree

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Re: WS2812B or SK6812 Help
« Reply #3 on: Wed, 29 November 2017, 15:15:21 »
I read IBNobody's diagram but thought it was for the older WS2812 (6 pad) didn't notice it was for the SK6812.
There are six pads because two are Col and Row, he basically made a combined module for switch and LED together.

But is it possible to use the RGBW ones or just the RGB ones?
I'm not entirely sure, but I believe the main difference is in the firmware. Last I read, RGBW are not widely supported. You should ask Jack Humbert.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline BlindAssassin111

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Re: WS2812B or SK6812 Help
« Reply #4 on: Wed, 29 November 2017, 15:20:33 »
There are six pads because two are Col and Row, he basically made a combined module for switch and LED together.

Yeah noticed that now, but at a quick glance during my original search, I saw 6 and thought WS2812 and moved on, should have been more careful...

Offline BlindAssassin111

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Re: WS2812B or SK6812 Help
« Reply #5 on: Wed, 29 November 2017, 15:49:45 »
Also would it be helpful to run the underglow and the backlight on seperate pins or just code it in a way that they act seperate?

Offline TalkingTree

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Re: WS2812B or SK6812 Help
« Reply #6 on: Wed, 29 November 2017, 16:06:32 »
Also would it be helpful to run the underglow and the backlight on seperate pins or just code it in a way that they act seperate?
There is no need, those LEDs are individually addressable.
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Offline BlindAssassin111

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Re: WS2812B or SK6812 Help
« Reply #7 on: Wed, 29 November 2017, 16:39:46 »
There is no need, those LEDs are individually addressable.

Was more just asking if it would be better to just "talk" to the sets seperately. I knew they were addressable. :D

Also what do you think about the whole caps issue? Have any advice on that?

Offline TalkingTree

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Re: WS2812B or SK6812 Help
« Reply #8 on: Wed, 29 November 2017, 17:16:15 »
Was more just asking if it would be better to just "talk" to the sets seperately.
I would guess  the code for two separate series of LEDs would be more complicated or, at least, more redundant, but I have a very limited coding knowledge.

Also what do you think about the whole caps issue? Have any advice on that?
10uF is the USB limit, not the LEDs alone, so you need to take into account the capacitors used by the Teensy 2.0 as well.
Sparkfun recommends a 0.1uF for each LED.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline BlindAssassin111

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Re: WS2812B or SK6812 Help
« Reply #9 on: Wed, 29 November 2017, 21:46:58 »
10uF is the USB limit, not the LEDs alone, so you need to take into account the capacitors used by the Teensy 2.0 as well.
Sparkfun recommends a 0.1uF for each LED.

That was what I was getting at, couldn't remember how they worded it, so wasn't sure how to saw it in my post. The issue is I am going to use 108 leds for the keys and another 12 or so for the underglow, in total between 120 and 130 leds to be safe. If I were to use 0.1 μF caps, that would be 12-13 μF total, therein my issue lies. I don't know if I can use a lower cap or if my dreams are crushed.

Also I got an answer from Jack Humbert and he said the RGBW SK6812 should be supported from what he remembers.

Offline TalkingTree

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Re: WS2812B or SK6812 Help
« Reply #10 on: Thu, 30 November 2017, 04:35:53 »
If I were to use 0.1 μF caps, that would be 12-13 μF total
That could damage your computer's USB ports. Perhaps you could use an external power source then.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff