Cherry G80-3xxx FNKRO mod

xbb · 20 Apr 2011, 21:24

as subject, do you know if it is possible?
It's just about diodes?

Findecanor · 20 Apr 2011, 22:04

Sadly, no. Adding diodes will not change anything.

What is known as "blocking" -- to prevent "phantom key presses" -- is done either with diodes or as part of the programming of the keyboard's controller circuitry. The controller is basically a tiny tiny computer that does only three things: read the keys, detect and block phantom key presses and talk USB and/or PS/2 with the host. The blocking feature is part of the controller's programming -- it's "firmware". The firmware is burned in PROM at the factory. I have never heard of any keyboard that has any upgradeable firmware -- if there were any, the controller ought to be expensive.

Spharx · 20 Apr 2011, 23:51

Findecanor wrote:Sadly, no. Adding diodes will not change anything.

What is known as "blocking" -- to prevent "phantom key presses" -- is done either with diodes ...

Ehhm i see a contradiction in your text.
If I understand this website right it should be possible to make every keyboard full NKRO if you can ( physically ) and know how to put the diodes in. (Correct me if not

) But thats a hell of a lot work.

This guy at geekhack had dealed with diode soldering ... maybe you can ask him for advice once you found out how exactly to arrange the diodes.

xbb · 21 Apr 2011, 00:31

looks like so from that article.
Under the cherry switch you can clearly see which side you have to put the diode.
I've some 1N4148PH diodes I could try...

intealls · 21 Apr 2011, 00:59

It's like Findecanor says. You can't turn a non NKRO board NKRO just by inserting diodes.

Blocking is done by either adding diodes to each switch (and allowing all key combos in firmware) or by simply limiting combinations in firmware.

So even if you add diodes to each switch, the controller will still block keys from registering, since it still thinks the matrix generates ghost keys.

xbb · 21 Apr 2011, 01:13

Ok than I think I will need to find something else to do

Thanks for the infos!

ripster · 21 Apr 2011, 01:36

Spharx wrote:
Findecanor wrote:Sadly, no. Adding diodes will not change anything.

What is known as "blocking" -- to prevent "phantom key presses" -- is done either with diodes ...
Ehhm i see a contradiction in your text.
If I understand this website right it should be possible to make every keyboard full NKRO if you can ( physically ) and know how to put the diodes in. (Correct me if not ) But thats a hell of a lot work.

This guy at geekhack had dealed with diode soldering ... maybe you can ask him for advice once you found out how exactly to arrange the diodes.

Those were Light Emitting Diodes.

Different diodes.

They emit Light.

xbb · 21 Apr 2011, 01:41

Anyway I have asked more information and this is really not easily possible. It requires to either reprogram or change the controller and plus mod the pcb matrix.

ripster · 21 Apr 2011, 02:28

Yeah but now I'm curious whats up with diodes on a Backlit keyboard. I assume there are some SMT diodes peeking out in that pic next to the switch mount.

The OTHER fallacy is you can NOT just put LEDs in-line with the switch. That won't work either. Not enough voltage to do anything.

Peter · 21 Apr 2011, 14:09

Findecanor wrote: I have never heard of any keyboard that has any upgradeable firmware -- if there were any, the controller ought to be expensive.

I think you are wrong about that, I have this keyboard

and I can program it more or less as I please . (Once I receive the appropriate cable

)

I think the reason we can't programme any keyboard as we please is that the required software isn't generally available .
I mean, I can re-program the controller of my USB flash-drive pretty much as I please, within the capabilities of the hardware, with the appropriate Mass-Production Tool, why shouldn't the same be possible for a keyboard-controller ?
((To re-programme your USB Flash-Drive : See flashboot.ru (via Google-translate, it's Russian-only) )

Peter · 21 Apr 2011, 14:12

Yes, there IS such a thing as a one-time programmable Controller, but it requires that you 'blow' a fuse
and renders the controller 'irreparable' if 'something' should go wrong ..

xbb · 21 Apr 2011, 14:20

can't see the picture Peter

Peter · 21 Apr 2011, 14:56

http://deskthority.net/download/file.php?id=452

ripster · 21 Apr 2011, 15:40

RealForce 87U. DIP SWITCH 4.

Firmware Upgrade.

Never had to flip it but I sleep soundly knowing it's there.

Findecanor · 21 Apr 2011, 17:17

Spharx wrote:Ehhm i see a contradiction in your text.

Yeah, I was tired when I wrote that. I should have written "ghost key presses are prevented either by blocking or by using diodes". I'm sorry for the confusion.