Author Topic: Ten Key Left 2021 (full size 104 key custom keyboard)  (Read 15587 times)

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Offline cest73

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Ten Key Left 2021 (full size 104 key custom keyboard)
« on: Sun, 03 January 2021, 12:36:02 »
Okay we're getting serious slowly...
The intended layout:
258959-0
The front side of the PCB
258961-1
The back side of the PCB
258963-2
Intended goal: maximize mouse playground while avoiding to sacrifice any key of the 104




Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #1 on: Sun, 03 January 2021, 12:36:59 »
https://geekhack.org/index.php?topic=110450.0 <- initial thread with design considerations

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #2 on: Sun, 03 January 2021, 12:53:24 »
My two suggestions for the moment are to split every 2u keys for a universal compatibility. Someone could be interested in your board but with a different layout. A ISO enter key would also be appropriate.
Also, you can manage a fullsize keyboard with a Atmega32u4 as well. There are enough pins for a 11x11 or even a 12x12 matrix.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #3 on: Sun, 03 January 2021, 13:40:38 »
My two suggestions for the moment are to split every 2u keys for a universal compatibility. Someone could be interested in your board but with a different layout. A ISO enter key would also be appropriate.
I agree there, i was rushing the initial publish so we can delve into the particularities and things like that!

The ISO being a fairly common i totally should keep that as an option.

Then, again i doubt i need to split much more than backspace and the two shifts to get a "spare" 1u aside of each?


The hard question is the "Big Ass enter" as i just so happen to have one win key less "big foot" with black alps that might donate the switches (black ALPS) and the key caps, alongside there are quite few XM stem options there too...

Quote
Also, you can manage a fullsize keyboard with a Atmega32u4 as well. There are enough pins for a 11x11 or even a 12x12 matrix.
While i might agree there too, I prefer the much cleaner layout and free pins should i actually choose to ever revise this project pursuing the elusive per switch backlight.it

IIRC the 32u4 is exactly enough for my 104 w/o that one backlight pin? I have 6 rows and 20 columns here and 13 free pins (plus AREF) i guess i could squeeze it by making certain each column is packed with 6 keys and get that number down somewhat?

I was even lazy enough to opt for the larger package of the A90USB1286 over the more compact one.

I doubt it would impact the price too hard, or am I missing something?

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #4 on: Sun, 03 January 2021, 14:13:46 »
I just got rid of the LED diodes but kept the holes
(actually replaced the damn footprint  :'( )

258965-0
258967-1

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #5 on: Sun, 03 January 2021, 14:45:22 »
the two shifts to get a "spare" 1u aside of each?
1.25u and 1u actually. I'd also split the numpad's 2u. But that's just me.

The hard question is the "Big Ass enter"
BAE is a mere combination of ISO and ANSI enter. Once you have the ISO footprint and the stabilizer holes for both variants, you're done.

IIRC the 32u4 is exactly enough for my 104 w/o that one backlight pin?
More than enough. I made a fullsize keyboard out of it with three dedicated LED indicators with a 32u4. It's opensource too if you wanna take a look at it.

I doubt it would impact the price too hard, or am I missing something?
The AT90USB1286 costs twice as much as the 32u4 if I recall but certainly the highest price is on the PCB.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #6 on: Sun, 03 January 2021, 15:01:25 »
[snip]
IIRC the 32u4 is exactly enough for my 104 w/o that one backlight pin?
More than enough. I made a fullsize keyboard out of it with three dedicated LED indicators with a 32u4. It's opensource too if you wanna take a look at it.
What was your design goal? There seems to be more than one G80-3000 on github out there?

Offline Suavity

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #7 on: Sun, 03 January 2021, 17:34:16 »
From a quick glance of the PCB Render, it looks like your traces are really close to the edges of the PCB. Perhaps the placement of the MCU can be repositioned to the spacing between the PrtSc, Esc, Num Lock, and Tilde Keys.  Just food for thought.  :thumb:

Offline Applet

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #8 on: Mon, 04 January 2021, 03:38:34 »
I'd recommend to rotate the switches 180 degrees. There is some issues with that rotation and cherry-profile keycaps.

Just a tip: Duplex matrix is a good way to keep the pin count lower, without adding too much complexity: https://wiki.ai03.com/books/pcb-design/page/matrices-and-duplex-matrix . Doing symmetrical matrices can be a bit of a pain (11x11, 12x12 etc) if you don't think it through thoroughly.
« Last Edit: Mon, 04 January 2021, 03:44:12 by Applet »

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #9 on: Mon, 04 January 2021, 03:49:47 »
From a quick glance of the PCB Render, it looks like your traces are really close to the edges of the PCB. Perhaps the placement of the MCU can be repositioned to the spacing between the PrtSc, Esc, Num Lock, and Tilde Keys.  Just food for thought.  :thumb:
Damn!
At first i thought "he's right!", then i reconsidered it...

"How bad can it be to have few traces closer to the edge, and anyhow the ample empty area beneath the space bar is where many other DIYers put the MCU anyway"

Then i looked up some guide lines on the internet, found nothing particular to the placement to the edge, and ground traces are the outer most anyway...


Then i thought of it some more, and damn he's right!


Back to the drawing board program we go...
 ;D

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #10 on: Mon, 04 January 2021, 04:07:46 »
I'd recommend to rotate the switches 180 degrees. There is some issues with that rotation and cherry-profile keycaps.

Kindly no, i have chosen this layout on purpose:
1 - when the backlight is used the switch occludes the light so only the amount coming thru the key cap goes to the eyes
2 - Who is in for the bling can choose a transparent top
3 - who is in for MX might opt for some other profile
4 - who is for the Cherry profile (which i happen to like quite a lot) might pick a recent Kalih made switch as those are "agnostic" to the led orientation and are just as good if not better then their Cherry counterpart.
5 - this is a Matias too PCB and i haven't got to address the illumination of those switches yet  ;D


So, kind and sincere thanks for the heads-up, the illumination LEDs stay "south" NORTH (note to self: no more Hobbit books for you mister, now go under the stairwell to sleep!)

Quote

Just a tip: Duplex matrix is a good way to keep the pin count lower, without adding too much complexity: https://wiki.ai03.com/books/pcb-design/page/matrices-and-duplex-matrix . Doing symmetrical matrices can be a bit of a pain (11x11, 12x12 etc) if you don't think it through thoroughly.

Now that is a good point!
Damn, double back to the drawing board program!
 :eek:
In effect that means I'd be able to go from 6 x 20 --> 12x10 and that is 4 pins more efficient (26 pins vs 22 pins) that way i still could get the 32U4 and have it all?

Edit:missorientation of where the LEDs are
« Last Edit: Mon, 04 January 2021, 06:20:20 by cest73 »

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #11 on: Mon, 04 January 2021, 14:47:01 »
Okay, here goes
* blueprintTKL2021_R02.pdf (732.63 kB - downloaded 49 times.)

259017-1
259019-2


I've fit the tiny atmega (because why not) and got all the keys (104) plus backlight plus 3 status led!


The schematic is posted for brevity too (no license yet, fair use please)


Fingers crossed and expecting comments.

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #12 on: Mon, 04 January 2021, 15:17:54 »
TODO (didn't bother yet):
1- screw holes
2. programmer header
3. alternate status LED solder points

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #13 on: Tue, 05 January 2021, 02:48:47 »
I think I am "there"...
259047-0
259049-1
It's beyond me why the Thru hole LED is connected inversely (had to correct that by had)?

Now i might try to add the optional switches and mounts...

After that, the mount plate is due

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #14 on: Tue, 05 January 2021, 15:39:19 »
Okay,
* blueprintTKL2021_R04.pdf (218.46 kB - downloaded 59 times.)
259075-1
259077-2
Added key names to the silkscreen
Added key names to switches in the schematic (posted the PDF)


1. I checked the mapping and found there is ample space for additional keys in the matrix (the PDF is the annotated schematic)
2. I am very uncertain how will the program perform when i add the double/triple cutouts?


Some advice would be much appreciated


Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #15 on: Tue, 05 January 2021, 18:00:42 »
This is what i need
259081-0
I think i have to figure out how to make custom footprints next


Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #16 on: Thu, 07 January 2021, 16:49:37 »
Work is under way...
259325-0
* 2021-01-07_12-46-34.jpg (199.09 kB - downloaded 41 times.)
XDA keycaps i just received via snail-mail
I am:
1. making steps towards supporting the few most common layouts and key sets (ANSI ISO & co)
2. I have no intention to support each and every possible exotic layout and rare/odd space row(s)
3. i do plan to make a best effort to make this PCB switch agnostic in the sense of best switch stabilizer choice
4. the backlight polarity is chosen (hopefully correct) for the original linear illuminated ALPS switch + options
5. there will be issues and compromises down the road (my gut feeling)
6. i am seeking for a more bombastic name

« Last Edit: Thu, 07 January 2021, 16:58:20 by cest73 »

Offline suicidal_orange

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #17 on: Sat, 09 January 2021, 01:21:27 »
I think D31 is connected to the wrong row, how I spotted that first thing in the morning on mobile I'll never know!  I have not thoroughly checked the rest

Not sure what your problem is with the LED footprint - if it's 'bckwards' you can rotate the LED as it only has two pins.  One square pad on the same side throughout is all you need so you don't need to think during assembly.  Unless the label's wrong in which case you have a valid complaint...

One improvement would be a USB socket with proper through pins, at least for the shield (no, I don't know of one) as surface mount can be ripped off.  Also you could try and squeeze in some holes on the USB lines so if you do remove the socket you can easily wire it up to a break out board.

Good work :thumb:
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Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #18 on: Sat, 09 January 2021, 02:12:15 »
I think D31 is connected to the wrong row, how I spotted that first thing in the morning on mobile I'll never know!  I have not thoroughly checked the rest
:eek:  if you only knew how many times I went over the schematic and the PCB to change one or another thing and never noticed that glaring error
Excellent find  :thumb:

Quote
Not sure what your problem is with the LED footprint - if it's 'bckwards' you can rotate the LED as it only has two pins.  One square pad on the same side throughout is all you need so you don't need to think during assembly.  Unless the label's wrong in which case you have a valid complaint...
As someone noted this might end up as public project (the files) so I understand it would be quite silly to leave an obvious wrong like that if I can address it in this stage - i will most certainly double check before publishing
Quote
One improvement would be a USB socket with proper through pins, at least for the shield (no, I don't know of one) as surface mount can be ripped off.  Also you could try and squeeze in some holes on the USB lines so if you do remove the socket you can easily wire it up to a break out board.


(roughed thru hole mini jack)

USB sockets are the root of all evils. Perhaps i should intentionally opt for the proper "big ass" USB "B" plug so we can use all the obsolete cables we still have lying around? No?
Other than that, a 4 pole plug/header of any sort is a reasonable option (will include) so one can just snip the end of the offending (and hurt inducing) cable and solder on the receptacle or just directly to the PCB

thru hole "proper" jack


Quote
Good work :thumb:
Kind thanks  :D

Offline suicidal_orange

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #19 on: Sat, 09 January 2021, 02:59:48 »
Not sure about USB B, with a connector that heavy on the cable you might rip it out as easily as the stuck on micro :P

There are micro sockets with 4 through hole shield legs, probably the best option if you don't want to go mini or C.
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Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #20 on: Sat, 09 January 2021, 13:15:56 »
Not sure about USB B, with a connector that heavy on the cable you might rip it out as easily as the stuck on micro :p

There are micro sockets with 4 through hole shield legs, probably the best option if you don't want to go mini or C.
I didn't know there are that many options for the USB plug!

I concur with the through hole as the way to go - where the plug goes the board is sure to go too  :p


However, my personal experience is as following:

Cases of death:
  • Big ass USB receptacles  - none
  • mini USB receptacle - maybe few if any
  • micro USB receptacles - both cables, jacks and carrier boards went into shambles one too many times
  • type C - so far 2nd place by preference - it seats in nicely yet tightly and overall provides a good feeling when plugging in/out comparable perhaps only to the biggest option.
So, I might in fact consider the 6 pin SMD type C with 4 thru hole mounts for the shield  :thumb:


OTOH if we speak of cable congestion - it is the best to use cables too obsolete for the kids' phones and gadgets - just to be on the safe side  :rolleyes:


also here current progress pix
259436-0
259438-1
259440-2


Among other things so far - i traverse the damn thing with ease 3-5 times a day to apply a simple change across the hundred (and more) switching sub circuits ...


I already had errors that i only remedied by editing text files "by hand" (praise Geany!).


I have made a custom library of parts that i couldn't find among whats available on the internet - maybe i should share that once i'm over with the editing.


The darn thing is starting to look scary  :eek:

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #21 on: Sat, 09 January 2021, 13:37:31 »
I might in fact consider the 6 pin SMD type C
That's for charging only.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #22 on: Sat, 09 January 2021, 15:10:26 »
I might in fact consider the 6 pin SMD type C
That's for charging only.
And out of the window it is  :))

So mini or micro remains for the time

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #23 on: Sat, 09 January 2021, 16:42:09 »
So mini or micro remains for the time
Soldering the 16 pin USB-C is not that hard.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #24 on: Sun, 10 January 2021, 14:08:51 »
So mini or micro remains for the time
Soldering the 16 pin USB-C is not that hard.
I watched a YT video of building exactly that - an USB-C compact keyboard...


Perhaps i could live with that - also i liked the many protection options added to that build (polifuse, overvolt arrestor, inductors...)



Right now I'm considering to add option with USB-C or USB mini on the board - no harm to have it as an option i guess?

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #25 on: Sun, 10 January 2021, 14:32:47 »
The mentioned YT series I've been watching

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #26 on: Sun, 10 January 2021, 14:49:33 »
Right now I'm considering to add option with USB-C or USB mini on the board - no harm to have it as an option i guess?
Indeed, go with whatever you feel most confortable with.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #27 on: Sun, 10 January 2021, 15:00:33 »
I still am curious to how You come about to make the G80-3000 keyboard PCB?

Was it a reliability issue with the original boards, the PS/2 going out of favor or the many favors of a cheap donor case fitting a sane and useful 104 key layout?

I ask because i am addressing a life long aggravation of space allocation on the desktop with this very project.

And yes, comfortable - as in general comfort is something that is very important in objects for daily usage like an keyboard, for instance.


So i regard this highly important - to the level i might even consider making it so both of the jacks could be present at once for the ultimate maximum convenience.

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #28 on: Sun, 10 January 2021, 15:12:29 »
I still am curious to how You come about to make the G80-3000 keyboard PCB?
Because Leeku's boards were nowhere to be found and I wanted to experiment. I generally prefer smaller boards infact all the GH80-3000 I made were given to friends.

So i regard this highly important - to the level i might even consider making it so both of the jacks could be present at once for the ultimate maximum convenience.
You could also consider an interchangable breakout board screwed in your case.
I made a type-C for your convenience (link). You can make a mini-B out of the same layout so to swap them around.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #29 on: Sun, 10 January 2021, 22:41:37 »
I still am curious to how You come about to make the G80-3000 keyboard PCB?
Because Leeku's boards were nowhere to be found and I wanted to experiment. I generally prefer smaller boards infact all the GH80-3000 I made were given to friends.

fair, You have even more of my respect now
:thumb:
Quote
So i regard this highly important - to the level i might even consider making it so both of the jacks could be present at once for the ultimate maximum convenience.
You could also consider an interchangable breakout board screwed in your case.
I made a type-C for your convenience (link). You can make a mini-B out of the same layout so to swap them around.
259516-0
 :-\

OTOH i already made changes to the project, while i greatly appreciate the mini PCB and the offered design I'd rather have a single PCB overall so the option is present at all times -- even with both headers soldered on at once  on the extreme end

Offline TalkingTree

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Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #31 on: Mon, 11 January 2021, 09:10:46 »
Damn!
259550-0
It is so cuute my inner nerd wants to keep it but my inner engineer says complexity kills roughedness and reliability  :'( :'(

259552-1
will certainly look up to it if you permit (fair use, credit where credit is due et cetera)

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #32 on: Mon, 11 January 2021, 09:25:53 »
will certainly look up to it if you permit (fair use, credit where credit is due et cetera)
License is CC-BY-SA 3.0. You can even sell it for profit.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #33 on: Mon, 11 January 2021, 15:59:41 »
Profit You say  :thumb:


259606-0
259608-1
259610-2
* blueprintTKL2021_R06.pdf (843.65 kB - downloaded 46 times.)
NEW:
  • added the 5k1 resistors to USB-C
  • both connectors can be resent at once
  • only one can be used at any time
  • both are picked as the most robust option with the least SMD and the most through hole connections

TODO:
  • route the reset switch actually
  • cam through the BOM and make certain all components can be reasonably easy sourced by an PCB manufacturer outlet
  • sanity check the many vias and adjust accordingly
  • hand optimize the spaghetti traces as much as possible
  • check if the firmware supports PWM and spice-test the picked MOSFET if it does work at all for the LEDs in parallel
  • commit to producing 5 (10?) boards if the price can be around $20 per piece w/o any LEDs

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #34 on: Thu, 14 January 2021, 16:33:43 »
Progress:
259817-0
259819-1
259821-2
  • routed the switch and made the dual USB standard
  • added protections (OC & OV)
More subtle work to be done...
Stay tuned...


Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #35 on: Thu, 14 January 2021, 16:48:04 »
North side in switch LEDs? What keyset are you using?
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline hanya

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #36 on: Thu, 14 January 2021, 18:15:20 »
SMD parts on both side? It cost much more than single sideded PCB.
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Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #37 on: Thu, 14 January 2021, 22:36:16 »
North side in switch LEDs? What keyset are you using?
Well ideally that would be south from the switch, but, alas, at one point i had such a mess beneath the 2 option CAPS that i moved it north, and i think i might get back to try to revisit the idea of south side LED.


In the worst case, it will still under-light the surrounding of the key and make it stand out, but ideally it would light up a keycap window and most if not all of them are on the south side (closest to the user)


Then, again, should it fail, i have them on the "standard" place right above the numpad.

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #38 on: Thu, 14 January 2021, 22:43:05 »
SMD parts on both side? It cost much more than single sideded PCB.
  • There is absolutely no way to avoid having parts on the bottom side, so only the top side parts could be moved down
  • I will try one more pass to see how many parts i can move from the top around the main chip
  • I can opt for placing only one side at the factory - SMD by hand ain't all that hard after all - if the cost is that much higher

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #39 on: Fri, 15 January 2021, 01:57:21 »
it will still under-light the surrounding of the key and make it stand out
No, it won't. I know from experience.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #40 on: Fri, 15 January 2021, 12:55:31 »
it will still under-light the surrounding of the key and make it stand out
No, it won't. I know from experience.
Aww  :confused:


Made me rethink it and You seem to have a good point there - anything outside the illumination hole/area/aperture will simply be obscured by the plate - only (and that is too perhaps) a PCB mount switch could be optionally lit that way...


Where i only a step away from the drawing board that would be a hard back


I have to rethink the switch-illuminated option and if i can't figure it thru i will most likely abandon it  :( .



« Last Edit: Fri, 15 January 2021, 15:32:11 by cest73 »

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #41 on: Fri, 15 January 2021, 16:02:26 »
I feel so validated


Just found out (it's two years old so no big deal)


  • Addressing exact same issue
  • doing it pretty much the same way
  • different enough for my layout not to be a copycat
Regarding the per switch status LEDs:
I will drive the same single switch illumination LED with both signals:
  • the backlight being the weaker
  • the status being the stronger one (about twice the miliamps) - and more pronounced one
this way it will both stand out clearly in both the dark and in the day light




Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #42 on: Sat, 16 January 2021, 07:03:51 »
Albeit slowly, we have reached the point of electrical engineerig considerations:
  • How will the 104+ LEDs fare while driven by the (unknown to me) DMG2301 MOSFET ?
  • what stresses and where will it incur?
  • how much will the tiny yet powerful 3201 impose on the Atmega pins? Can i drive it directly off an output pin or do i need a dedicated driver?
  • current surges? where will they occur? will they impact the operation of the "brains"?
  • how bright the LEDs will shine? how much current will be drawn?
Here comes LTSpice to rescue  :thumb:
259930-0
Attached find the approximate circuit that I used to decide if i need decoupling elements for the LED switch and which ones and where...

NOTE: this is WIP, so expect changes in both the layout in LTSpice and on the PCB later on


The last thing one needs is to make a prototype (commit to material) just to find out the product is emitting smoke or, worse yet, failing to emit anything at all  ;D


the big questions:
  • Will the 200% current spike spoil the LED brightness when present in PWM mode?
  • Will the 4mA per (white/amber/blue/<insert random color here>) LED current be enough for the to shine bright enough?
  • will the ~400mA current trigger the USB port protection circutry on the host PC using the keyboard?
  • will there be enough current in the USB port to drive the Atmega alongside the fully shining LEDs?
I leave as an exercise to the readers to master the highly useful LTSpice (aka SwitcherCAD) program i had so many hours to use and learn
(For those using GNU/Linux, just run it thru Wine abstraction layer)




Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #43 on: Sat, 16 January 2021, 09:53:27 »
I be damned  :-\


found another option...
259936-0


The BJT is lacking the intrinsic diode thus blocking current both ways, and those most modern late PNP BJT  are quite on par with those recent MOSFET switches!

enter: 2SAR552P

It can be driven off 30mA pins, can drive up to 3A pulses (way over USB supply) all in all a simpler switch, and if anything odd where to happen i have the fly back diode in place on the base (brought to bear should reverse current ever flow over the device)


Why this exotic PNP/PMOS layout you may wonder?


Earlier I  have decided to have all the backlit LEDs connected to common ground to make the PCB layout simpler, this mandates so called high side switching, and as far as i am aware this is most reliably achieved with BJT.


This is so due to BJT being current controlled devices that only slightly depend to discrete voltage levels - which are a moving target in said high side switching.


Further a note on the dreaded BJT thermal runaway (losing resistance under load and when heating up):
If a single device is used this is totally no issue - it loses resistance as it heats up - thus heating up less - that's about all


It remains only to find out the proper amount of milimaps required per LED to achieve the needed level for a backlit key effect.


This is the more difficult as we actually try make a board for more than just one color of LEDs (white, blue, amber, maybe more)

Am i overthinking this?


Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #44 on: Sun, 17 January 2021, 04:55:50 »
interesting!


it is an FKL design with straight (not mirrored) NP left-swap


i didn't notice all this abundance of the left swap before :^]


Offline whezil

  • Posts: 40
Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #45 on: Sun, 17 January 2021, 13:10:17 »
Is there a specific reason you are not using a daughterboard for the USB connection and are mounting it on the main PCB?
   

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #46 on: Sun, 17 January 2021, 16:19:24 »
Is there a specific reason you are not using a daughterboard for the USB connection and are mounting it on the main PCB?
Yes, the sturdiness of the connector - i like it be stiff and secure  to the keyboard body.


Is that a problem and why?

Offline cest73

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #47 on: Sun, 17 January 2021, 16:28:00 »
The usual progress report:

I went to the Seedstudio PCB service and tested my gerber and drill files - they seem to work and i could pull off the bare PCB as low as sub 15 bucks for 10 - the five althought cheaper is oddly more expensive per piece - for $20 i get whole five more ?
I had everything dialed down except partial metalized holes (the complex LED holes for MX/ALPS SMD illumination)


That's about $150 for a ten batch w/o shipping.


Now i'm moving to make the BOM file acceptable to the service so i can check the SMD placement service too

What are the usual backlit board prices on average?


pix of the KiCAD design thus far:
259989-0
259991-1
259993-2

What is the most usually desired color besides always black?

White? Blue? Red?

Further, should i bother with vias to have the ground islands filled with copper too?
« Last Edit: Sun, 17 January 2021, 16:30:46 by cest73 »

Offline TalkingTree

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Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #48 on: Sun, 17 January 2021, 16:49:06 »
Why are you adding mounting holes at the corners? A Alps PCB requires a plate and that's where your mounting points should be.
Such a large board would flex in the middle if you mount it only by its corners.

Also, get a quote at JLCPBC, you might save a few dollars.
My opensource projects: GH80-3000, TOAD, XMMX. Classified: stuff

Offline cest73

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  • Location: serbia
Re: Ten Key Left 2021 (full size 104 key custom keyboard)
« Reply #49 on: Sun, 17 January 2021, 17:10:13 »
two more services:


https://cart.jlcpcb.com/quote?orderType=1&stencilWidth=410&stencilLength=134&stencilCounts=10

and:

https://www.nextpcb.com/pcb-quote?layer=2&length=410&width=134&count=10&height=1.6

it seems i will only go for placing the 108 switch diodes and 108 LED resistors plus the ATMega and several more most delicate SMD components - the rest will be done "client side"  ;D