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  #46  
Old 10-15-2014, 07:56 PM
CalcProgrammer1 CalcProgrammer1 is offline
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Quote:
Originally Posted by TellarHK View Post
I actually saw a review a few days ago that had a teardown for one of these keyboards, and gave the part number for the ARM processor inside. It's an ARM CORTEX-M0 based chip running at up to 50MHz. The speed of the CPU on the keyboard was not listed, but it did show a 12MHz oscillator which matched one in a development board for the same CPU.
Have a link? I'm not so interested in the procesor, but I am very interested in the LED driver. If what I posted is correct I think it pretty much proves 8-bit per LED color is out of the question.
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  #47  
Old 10-15-2014, 08:07 PM
emiljensen2 emiljensen2 is offline
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Quote:
Originally Posted by CalcProgrammer1 View Post
Have a link? I'm not so interested in the procesor, but I am very interested in the LED driver. If what I posted is correct I think it pretty much proves 8-bit per LED color is out of the question.
After looking a bit around and going through a decent amount of google pages, I'm pretty sure I found what he was referring to.
http://www.weistang.com/article-1992-1.html
Disassembly starts at page 6
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  #48  
Old 10-15-2014, 08:12 PM
CalcProgrammer1 CalcProgrammer1 is offline
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Quote:
Originally Posted by emiljensen2 View Post
After looking a bit around and going through a decent amount of google pages, I'm pretty sure I found what he was referring to.
http://www.weistang.com/article-1992-1.html
Disassembly starts at page 6
I think he may be referring to the Anandtech review, which does have a picture of the CPU. I just sent an email to the author of that article asking if he/she could possibly confirm the part number or take a photo of the LED controller. I'll look at your article as well.

EDIT:

AHA! I was right :P

3x Panasonic A32181 LED matrix ICs

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  #49  
Old 10-15-2014, 09:30 PM
TellarHK TellarHK is offline
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Sorry I didn't have a link there, but that Anandtech link looks like it. I had to run out the door too quickly to find it.
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  #50  
Old 10-15-2014, 10:41 PM
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the Processor is an NXP LPC11U37F-501.

Source: http://www.anandtech.com/show/8556/c...board-review/2

Also knowing corsair i think LUA will bring out 16mill colors or damn close, because this could ruin the companies rep for reliable products. and the reason for such small response might be the fact that they are trying to get the issues with teh actual hard ware worked out and getting them in to everyones hands before focusing on LUA as there are a lot of people having issues with hardware opr trying to get one
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  #51  
Old 10-15-2014, 10:45 PM
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Well this is going to be intresting. So now im wondering if Razer's or logitech keyboards will have 16.8 mill colors
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  #52  
Old 10-15-2014, 10:52 PM
CalcProgrammer1 CalcProgrammer1 is offline
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Quote:
Originally Posted by zheren159 View Post
the Processor is an NXP LPC11U37F-501.

Source: http://www.anandtech.com/show/8556/c...board-review/2

Also knowing corsair i think LUA will bring out 16mill colors or damn close, because this could ruin the companies rep for reliable products. and the reason for such small response might be the fact that they are trying to get the issues with teh actual hard ware worked out and getting them in to everyones hands before focusing on LUA as there are a lot of people having issues with hardware opr trying to get one
Well looking at the datasheet for the chip they used it seems 16.8 million independent colors is actually impossible. The chip only provides 8 possible brightness levels at once. The only way you could get all the colors it seems is to have all the LEDs the same color (or pick 8 static colors and vary their brightnesses).

Also, Panasonic advertises the chip as supporting 256 levels of brightness, which while actually true in the case of all LEDs being the same color, is very misleading because it does not mean all the LEDs can have 256 levels of independent brightness. Corsair may have been misled by this. Look for the product page for the AN3x chips and it clearly advertises 256 levels of brightness.

Edit: Here is the Panasonic product info I think is misleading:

http://www.mouser.com/new/panasonice...x-LED-drivers/

http://www.mouser.com/pdfdocs/Panaso...x_Brochure.pdf

Edit:

The maximum interface clock frequency on this chip is 1MHz. As it is a matrix driver, it must continuously scan through all 144 LED configurations fast enough that it is solid to the eye. Say a 60Hz refresh rate is necessary, that means each LED frame is 1 / (144x60) seconds, or 115 us. Because the chip does not store an 8 bit value for each LED, if it were to actually support 8 bit per LED the CPU would have to update the 8-bit PWM register every 115us. This is likely a 2-byte command at least, as you need to specify the address to write. At 1MHz, a single bit time is 1 us, so a 16-bit command would be at absolute lowest 16us, not accounting for framing and chip select delays. This is assuming they are maxing out the interface speed. That is a VERY tight timing margin. Now they have 3 of these chips to update at this rate. Assuming they are all on one SPI bus, that is 48us minimum needed to update in a window of only 115us. It would need to update before sending any PWM at all, which further complicates things as it could mean up to 48us go by with no command at all. On top of this constant data streaming the CPU is still expected to scan the key matrix at 1ms rates and manage USB interfacing. With a max frequency of 50MHz (per above comments) this sounds like an obscene amount of workload that I honestly do not see being possible. The timing is just too extreme. I also believe the update rate is higher than 60Hz, as 60Hz flicker is quite visible on LEDs. I want to set up a photoresistor circuit and hook it to my oscilloscope tomorrow and actually measure the scan frequency.

Last edited by CalcProgrammer1; 10-16-2014 at 02:00 AM.
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  #53  
Old 10-16-2014, 02:13 AM
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Well damn... but then again seeing how it took over a year to bring out the keyboards its hard to accept that panasonic miss led them and they didnt notice until now. not that i hate the keyboard its quite nice but im assuming some people will want darker colors for me i just like full brightness and have stuff flash.or change colors.
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  #54  
Old 10-16-2014, 03:28 AM
mysticc mysticc is offline
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I see things to go embarassing.
This might explain why it takes so long to get an answer from DEV.
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  #55  
Old 10-16-2014, 06:21 PM
Digital.Zilla Digital.Zilla is offline
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Fantastic detective work Calc. I don't see how Corsair won't be having a suit on their hands for false advertising at this point. I hope I'm wrong though because I want them to fix it... but you can't beat physics.

Quote:
Originally Posted by zheren159
not that i hate the keyboard its quite nice but im assuming some people will want darker colors for me i just like full brightness and have stuff flash.or change colors.
I think you misunderstand. Doing a full brightness rainbow still requires you to fade each channel smoothly from full bright to zero bright which the hardware can't do. Simply set up a rainbow gradient (7 steps (R -> RG -> G -> GB -> B -> RB -> R) and make it play over 10 seconds and you'll see what we're talking about. Is that acceptable to you? It isn't to me, and I suspect to most people. Especially when the keyboard is being advertised as supporting 16.8 million colors.
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  #56  
Old 10-16-2014, 06:32 PM
Digital.Zilla Digital.Zilla is offline
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It's a shame they didn't use the WS2812 5050s. These things are ULTRA bright and have a built in 18mA constant current driver so the brightness remains constant as voltage fluctuates and, more importantly, the PWM is offloaded onto the 'led' itself, letting whatever processor you have running it simply focus on setting color values. They daisy chain and require very strict timing but you can string more than necessary for even a 95, and if chain length were ever an issue, you can just split it into multiple chains. As for the timing, a simple arduino UNO will run them just fine. I'll post a video of what they look like when I get some time.

Edit: Datasheet link

Last edited by Digital.Zilla; 10-16-2014 at 06:34 PM.
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  #57  
Old 10-16-2014, 07:21 PM
CalcProgrammer1 CalcProgrammer1 is offline
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Those look awesome, may have to use them in a project sometime.
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  #58  
Old 10-16-2014, 08:09 PM
uncanny1 uncanny1 is offline
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Amazed at the deduction and persistence on this thread. Very impressive. Going to keep an eye on it for sure. Hoping to see Corsair step-up here.
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  #59  
Old 10-16-2014, 09:16 PM
Digital.Zilla Digital.Zilla is offline
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Speaking of which...

Corsair James... It's been over a week since you said you'd ask your engineers for more details. So I have to conclude one of two things at this point A) you have awful communication at corsair, or B) you guys are scrambling for a way to answer this blatant issue. Based on the details Calc figured out regarding the chip driver, ima' guess it's option B, but I'd like to give you the benefit of the doubt. Care to throw us a bone, please?
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  #60  
Old 10-16-2014, 10:05 PM
Pirateguybrush Pirateguybrush is offline
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I came to the forum looking for answers on why I wasn't able to create slow pulsing effects without the stepped look. This doesn't look good, Corsair.
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