Adding KRO to Cherry G80 with diodes?

[IvanIvanovich]

Not sure if I am just being retarded here, and I should probably know this from being around awhile but...
Suppose you have a G80 which is only 2KRO, and the switches of course have no diode but the pcb does have the holes and traces for them per switch, if I soldered in diodes would it have the desired effect or just be a big waste of time?

[alaricljs]

What's presently in place of the diodes?

[IvanIvanovich]

Nothing. It just has plain switch only 2 solder points on switch to pcb for the main terminals but solder points for diodes on the pcb. So I was thinking in theory I could maybe go from 2KRO to nKRO if I added the missing diodes. But I am not sure if that theory is valid or not as there may be other factors like the controller or something that wouldn't make a difference if I did add them.

[alaricljs]

Hmmm.. so you'd have to do some fairly serious surgery to get the diode in-line between one of the switch leads and it's trace.

[IvanIvanovich]

Well yes, but I have a bunch of with diode switches and have been debating changing the switch flavor on that board anyway... if it would work I think it would be worth it. Just don't want to do all of that soldering for nothing. Nothing tricky needs done, with diode switch it has 4 solder points on pcb, just on this they didn't use 2 of them on pcb which were left empty. The PCB is ready for them, just the switches didn't have them for whatever reason Cherry needed to save that $.15 by leaving out the diode and crippling it to only 2kro.

[keyboardlover]

I recall that it's not possible but can't remember why

[alaricljs]

If the switches work without diodes and there's no jumper in place of the diodes, then adding diodes to the board will do nothing.   

[IvanIvanovich]

:sadface:, so then I will go to option 2 on another board, which does have the wire placeholder. So if it have those it will work for sure? Also somewhat related, I have yet another board that DOES already have diodes in place, but it ALSO has holes and traces for led. So since you can't have both the led and diode as far as I can tell, if I replace some diode switch with led switch will that break the nkro?

[alaricljs]

If there are diodes in place then removing the diodes will break the matrix, you'll need a jumper or you can try routing the diode around the LED leads.  Technically it's not the NKRO but ghosting that will happen.  More or less key presses will end up showing than are really happening depending on the combination pressed.  If there are jumpers in place where diodes should be then adding diodes could fix ghosting.  NKRO is entirely up to the firmware.  If the firmware isn't designed to deal with more than N key presses, then you are stuck with N or less.  If you're getting 2, sometimes more kro and ghosting, then you may improve the situation with diodes.  If all you ever get out is 2 kro (plus mods) then it's likely diodes won't help you.

[IvanIvanovich]

I see, so if I can bend the diode enough, or the legs of the led enough I should be able to jam an led in there too in theory. I was planning on adding the led  to 1234qwerasdfg so ghosting there would be the absolute worst to have for sure.

[Soarer]

If there are jumpers in place where diodes should be then adding diodes could fix ghosting.

Probably not! In practice, boards I've seen with jumpers fitted to the switches just use them to avoid having separate jumpers on the (single-layer) PCB, and the way they are used would not support fitting diodes.

[alaricljs]

If there's a jumper in every switch?  That would be.... interesting.

[IvanIvanovich]

I've had a few boards that have it that way, just a plain wire instead of a diode inside every switch on G80 which is more usual than the one I wanted to mod that dosen't.

[Soarer]

Yeah, recent G80-3000 are built with a jumper in each switch. Easier to assemble, I guess. Still has 20 or so other jumpers on the PCB though.

Back on topic... It's pretty odd to have PCB holes but not use them! Maybe they were just added for mechanical reasons - that would help in modding it because you wouldn't have to cut any tracks going to the diode pins. But you'd still need to cut at least one track per switch, add a link to the diode, and a link from the diode back to the matrix.

[IvanIvanovich]

Some of the things that Cherry did are just mysteriously illogical. I was hoping for some easy way to improve an otherwise great board by making it better than 2kro with stuff I already had. So given it's oddity would a controller replacement be of any benefit to increase the KRO?

*off-topic - why the hell does it say 'honk!' and how can we make it go away?

[alaricljs]

Honk! is one of the post count titles... it's the last one.  Come up with something better and suggest it in the feedback forum 

[mich]

Keyboards naturally ghost (e.g. pressing q,a,s gets you w from nowhere). Some boards eliminate this problem with diodes, others with precise measurement of resistance or capacitance, the rest simply has special "deghosting" logic in firmware which filters keypresses suspected of being ghosts, even if sometimes they really aren't.

Your keyboard belongs to the last category and adding diodes to it is pointless unless you replace the controller as well.

[dorkvader]

Yeah, I noticed my G80-8113 has jumpers in every switch. To make it NKRO, I'd need 130 diodes and probably some new controller firmware from cherry.

[damorgue]

Sorry to bring this thread up again, but it is relevant to my build.

A) The G80-3000 has, as stated earlier in this thread, jumper wires in every switch.
B) ASDFHUKL kan all be registered at the same time. The controller is thus capable of outputting 8 keys at the same time except of course if any of those block eachother. This is just to show that the controller is fairly capable.

Does these two properties above means that there is a potential that it could be modded to NKRO by replacing the jumper wires with diodes?

[damorgue]

I have been trying to figure out the traces on the G80-3000

- A couple of switches have jumpers that don't lead anywhere.
- It seems like if I replace the jumper wires with diodes, the diodes will affect the next key over much more than the one it is at.

Was my assumption in my previous post correct or false? If both conditions A and B are satisfied, the controller is capable of NKRO?

[Soarer]

Nope. The code in the controller will be actively blocking the combinations that would cause ghosting without the diodes, even if you fit diodes.

[andresteare]

Nope. The code in the controller will be actively blocking the combinations that would cause ghosting without the diodes, even if you fit diodes.

Does this problem applies to teensy conversion too? Yesterday I wired the matrix of my Mx-11800 to a teensy, and had to add #define MATRIX-HAS-GHOST, so if I have to manually instruct the teensy to block ghosted keys, does that mean that I could add diodes, disable blocking and it would work?

[suicidal_orange]

If you've hijacked the matrix you could add diodes and make it work, but the key thing is you would have to cut traces so the signal has to pass through a diode.  There are some places on your pic where there is a main line with branches going to each switch so they wouldn't be too bad but other places the trace runs through the pad so you would need to cut both sides and connect the diodes.  As the PCB is single sided you can see all the traces but it's going to be a lot of work.

If you're interested I'd be happy to colour in a bit to get you started

[andresteare]

If you've hijacked the matrix you could add diodes and make it work, but the key thing is you would have to cut traces so the signal has to pass through a diode.  There are some places on your pic where there is a main line with branches going to each switch so they wouldn't be too bad but other places the trace runs through the pad so you would need to cut both sides and connect the diodes.  As the PCB is single sided you can see all the traces but it's going to be a lot of work.

If you're interested I'd be happy to colour in a bit to get you started

But wouldn't the jumpers in the switches help? the circuit has a jumper inside the switch for every switch, I though that was intended for diodes

[suicidal_orange]

But wouldn't the jumpers in the switches help? the circuit has a jumper inside the switch for every switch, I though that was intended for diodes

The switches are designed so a diode can be installed in them, but you have to design the circuit with that in mind.  On your board the jumpers make all the cyan bits one wire - if you put a diode where the magenta block is the signal from all the switches connected to the left or right would go through it so it wouldn't help the controller know which switch was pressed, and that 'diode' isn't even connected to the switch it would be inside.

[andresteare]

But wouldn't the jumpers in the switches help? the circuit has a jumper inside the switch for every switch, I though that was intended for diodes

The switches are designed so a diode can be installed in them, but you have to design the circuit with that in mind.  On your board the jumpers make all the cyan bits one wire - if you put a diode where the magenta block is the signal from all the switches connected to the left or right would go through it so it wouldn't help the controller know which switch was pressed, and that 'diode' isn't even connected to the switch it would be inside.

(Attachment Link)

Damn, I thought I had an advantage with these jumpers, maybe a put this in a future proyect, but given the difficulty, I'm definitively not in a hurry to do that task, thanks for the help.
And gotta say, your drawing is on point, razor sharp aligned with the traces lol