How does the Corsair k65 achieve nkro?

[boogerlad]

If anyone knows for sure, please provide a technical explanation. I've heard many theories like the faster polling rate is responsible, or the keyboard emulates multiple keyboards connected to a hub. I've google online and all the proof is just marketing or silly hypotheses like "it's running on usb 3.0 full speed, hurr durr more bandwidth111111"

I've yet to see a disassembly of this keyboard too. Do certain controllers allow for nkro operation through usb?

[ne0phyte]

The Noppoo Choc Mini and Pro have full NKRO. They do so by acting as usb hub with 3 (if I remember correctly) keyboards connected.

[boogerlad]

While that doesn't answer my question, thank you. The Noppoo Choc Mini seems to be superior to the k65 in all aspects, other than aesthetics which I don't really care for. Does the usb hub introduce any latency? Also, is the nkro implementation os independent?

[ne0phyte]

It works flawless on Windows and Linux and there is a way to get it working on OSX but since it's not a raw usb HID device it may or may not work with other operating systems. I used it for gaming and I never noticed any latency.

[boogerlad]

Thank you for the very prompt responses and guiding me towards a better product!

[ne0phyte]

Oh there is also a Noppoo Choc Mid which is tenkeyless. I guess it features full NKRO as well.
EDIT: Yep. The mid has nkro over usb, too.

[mtl]

The TMK firmware has some information here, though it may be a bit dated (some of the notes come from 2010). Of course this may not apply to the Corsair or Noppoo boards.

[Soarer]

I don't know the k65, but since the page lists Windows as a requirement I'd guess it works in a similar way to the Chocs, which use low-speed USB, and appear as two keyboards.

Appearing as two keyboards isn't via a hub (real or virtual) - each USB device can have multiple interfaces, and a keyboard on each interface. No extra lag there. Also, further interfaces for media and power keys etc might appear as extra keyboards, but this is unrelated to NKRO functionality.

Hasu's notes still apply, but be aware they were mainly written when using full-speed USB 2 (which makes it easier). The bitmap version is the best for full NKRO.

[Muirium]

The bitmap version? Is this the technique you use to achieve NKRO with your converter? It's amazing with my Model F and OS X! Indeed, I seldom use anything else; OS or keyboard!

[Soarer]

It is. Bitmap with full-speed USB is problem free!

IIRC, the chocs use bitmaps as well, but because of low-speed USB they have to split it over two keyboard interfaces, which is where the problem comes with OS-X.

[Muirium]

This could be the problem with using your converter on my 12" PowerBook: its ports are USB 1, not 2!

How does bitmap NKRO work? Got a link?

[Soarer]

I doubt they're USB 1.0... probably USB 1.1, which has full-speed

Hasu's notes describe NKRO vs normal pretty well... describing how HID works is best left to the HID docs!

[Muirium]

One of the few times that 1.1 was necessary to say!

[Soarer]

That's why I always say "full-speed" instead of "USB 2"!

USB 1.0 is so rare that "USB 1" usually means USB 1.1. And TBH, I haven't bothered learning any details about 1.0 because of that

Anyway, when using low- or full-speed, it shouldn't matter whether the host is USB 1.1 or USB 2.0, or whether the device is USB 1.1 or USB 2.0 - any combination should work.

[boogerlad]

Are there any cherry mx red keyboards that follow this "bitmap" method of nkro over usb? Preferably a full sized without any frills. How would I determine what method of nkro a usb keyboard uses?

Would I be able to swap the controller of any nkro under ps/2 keyboard with a teensy2.0 and flash the tmk firmware? How difficult would it be?

[Muirium]

It's possible. But as soon as you're inside a keyboard, things get specific. Many good boards (Poker II for instance) have a soldered controller and are a nightmare to replace.

Simplest solution would be to build Soarer's converter and plug your USB keyboard into it with it's PS/2 adapter! I can vouch for Soarer's USB NKRO from my Model F. It's a joy to behold!

http://deskthority.net/workshop-f7/xt-a ... t2510.html

Soarer's converter is simply a Teensy 2 wired up appropriately, running his firmware. You could build it right inside the keyboard if you liked. I use mne with several keyboards so it stays outside, with multiple sockets for my varied beasts.

Just be sure the keyboard is truly NKRO over PS/2. The converter can't make it any better after the fact.