Wireless 10 Key Layout // First Time Builder

[dustin_b211]

I work as a tech In photography and I’m looking to build a niche wireless keyboard with 10-12 keys. The unit will sit with a remote monitor and all for the viewer of that monitor to tag images as they please.

This is my first time venturing down this road. My intuition is to go to the Nice!Nano v2 as it seems easy to work with. Please advise.

Additionally, in terms of connecting keys, I’m not sure where to start with custom layout.  Any tutorial recommendations?  I’ve designed and built PCB’s, so I just need a bit of a roadmap to get going.

Appreciate any and all help!

[nevin]

there are a couple number pads or macro pads that would fit what you're looking for.
just find one that is made to use a promicro (nice nano), etc. i love the "just add promicro" type pcbs.
here are some:
https://www.etsy.com/listing/891388524/soyuz-numpad-pcb-or-kit (or from another source)
https://keeb.io/collections/bdn9-collection/products/bdn9-3x3-9-key-macropad-rotary-encoder-support (the rev.1 was add promicro, rev.2 controller is built into pcb, so don't get rev.2)
https://keeb.io/products/chocopad-16-key-macropad-for-kailh-choc-low-profile-switches (a low-profile macropad using choc switches)
https://keeb.io/products/the-stick
https://boardsource.xyz/store/5ecc2008eee64242946c98c1

if you want your own layout and a nice nano, the pcb would only be the switch matrix and maybe a reset button. (pretty simple as far as pcb's go). or if you didn't want to do a pcb, you could get the plates cut and hand wire it, will be very easy for a macropad.

Some good handwiring articles: (show you how to do the key matrix)
https://geekhack.org/index.php?topic=87689.0
https://deskthority.net/viewtopic.php?t=1067

other resources (make your layout in keyboard layout editor and have plates cut from that layout)
http://www.keyboard-layout-editor.com/
http://builder.swillkb.com/
https://kbplate.ai03.com/

Pcb guide
https://github.com/ruiqimao/keyboard-pcb-guide

.... you could also use half a split keyboard (though this will be more than 10-12 keys) something like a corne keyboard or one of the other small split ergo kits.

[dustin_b211]

Thank you @Nevin, I'll review this.  I'm sure I'll have questions.  I'm less concerned about the PCB aspect and more figuring out writing the firmware.

In terms of the PCB, I intend to do diodeless keys and basic white backlit keys just so they can be seen in darker environments. The only thing I haven't worked with, in this case, is the MOSFET for the LED's.

[nevin]

yes, but only being 10-12 (or less) leds, you might be ok. just make sure to put them on a PWM pin on the controller.

[dustin_b211]

So I think I've simplified this down to five keys, that could change.  In the mean time, would anyone be willing to review this schematic for me?  Keep in mind I'll be using the Nice!Nano rather than a pro micro.

[nevin]

what switches with leds are those?
unless one of the switches is for the leds, they would always be on, because they are not connected to a pin on the controller to controll them.

- you could use one of the addressable strips, would only use one pin on controller.
- is it supposed to be per key led or underglow?

[dustin_b211]

I’m just looking for backlight, nothing fancy.  The switches are cherry Mx. This unit will live with a stand alone monitor - hence needing wireless.

[nevin]

these are typically what's used for in switch / per key rgb.
https://keeb.io/collections/diy-parts/products/sk-6812-mini-e-rgb-leds-12-pack
here's the data sheet
https://cdn-shop.adafruit.com/product-files/4960/4960_SK6812MINI-E_REV02_EN.pdf
and look like this when cutouts are made in the pcb



if you just want underglow, these are pretty standard for diy
https://keeb.io/collections/diy-parts/products/rgb-led-strips-sk6812-ws2812b-compatible

both are addressable in a string.

so, if you're doing one switch per pin
you'd have one pin to control the leds.

backlight / per key rgb shines out the top of the board through or around the keycaps.
underglow is on the bottom of the board, light bouncing off of whatever the board is sitting on.

another thing to think about..... can't make it too small or the battery will be tiny and have to be recharged more frequently than if it was a larger battery with more room in the case.

[dustin_b211]

So you’re saying if I have 5 switches then the LEDs would occupy an additional 5 pins rather than a single PWM pin making each LED addressable?

[nevin]

no, the 5 switches to 5 individual pins
the leds would be strung together and only need one pin to control them.
look at page 9 of the data sheet to see an example.

[dustin_b211]

Ah got it. Now given these need minimum 3.7v, I'll need a MOSFET, what would you suggest, or does this work?  And with these I'd use clear body key switches I assume?

Any idea where to find an eagle library that contains the footprint for the sk-6812?

[nevin]

no, that fet is CHONKY.
you should be fine with 5 leds. get voltage from Vcc ---> resistor --> LED +
the important part is tying the leds together with the D-in, D-out pins.
controller---[din LED dout]---[din LED dout]---[din LED dout]--- etc.

[dustin_b211]

I thought VCC was only 3.3v?

[nevin]

what controller you using? .... wireless, right.
sorry, was still thinking promicro... 5v

nice nano is 3.3v on board. lipo would range 4.2-3.5v-ish (depending on what power circuitry is on the nice nano)
sounds crazy for as little as you want to do (5 keys), but you'd probably need a step up 5v regulator that. the step up part is important because your input voltage will be less than your output. (some regulators only step down). you could probably do it with a simple mosfet as well, just make sure you get the type of fet & the calculations correct.

as for caps...
- translucent, blank. - these are clear or transparent colored caps
- shine through caps - prettymuch only the letter or number should shine though
- pudding caps - similar to shine through, but have the lower half to 3/4 a white-ish plastic that the light will shine through
the latter two will probably only be available in full sets unless you can find just a 10-key set for a numberpad
use these terms to do some google searching and you'll see what i mean.

footprint...
https://github.com/keebio/Keebio-Parts.pretty/blob/master/SK6812-MINI-E.kicad_mod
... of course keeb.io would share the footprint (love these people)

should be able to find in Ki-Cad smd led library
https://kicad.github.io/footprints/LED_SMD

[nevin]

... or save yourself the headaches, and search around for a macropad something like these
https://keeb.io/collections/macropads/products/bdn9-rev-2-3x3-9-key-macropad-rotary-encoder-and-rgb
https://southpawdesign.net/products/spacepad-wireless-wired-macropad?variant=39340766068796
https://www.adafruit.com/product/5128
https://www.etsy.com/market/macropad

[dustin_b211]

Well it takes the fun out of it to buy one...but also, none of them are the form factor I need.

I'm just curious why the first iteration schematic wouldn't work for simple backlit keys (no under glow).  The 5 white LED's can run off the VCC.

Also, in terms of battery, I can run juice to it from the USB port on the monitor.  The battery is more of a backup solution.

[nevin]

yes, but without control they will always be on whatever the default/startup color is and not be able to change them.


unless you use single color leds (which typically operate at a lower voltage as well, depending on the color)


this is what your diagram looks like it's meant to be.

.... taking the fun out of it... just wasn't sure how deep you wanted to get, or were comfortable getting.

[dustin_b211]

Ahh…on the schematic I did a VCC output on Pin5 and then on each LED there is a VCC symbol on the LED+ pin.  So in theory these white LED’s are all connected to pin 5…I did not explain that to you. I don’t need colors I just need backlight so we can see the keys in dark environments. 

[nevin]

then yes, if you're just using simple one color leds, yours should work.
look around for correct voltage/size leds and you may not need to up the voltage. like i said, most of the simple one color leds operate at a lower voltage than the rgb ones. though blue & white are usually on the higher end (voltage) compared to like red or green. because it takes more "light" to make blue or white.

[dustin_b211]

okay, I'm back.  Change of plans, I want to move to a slimmer key switch, I'm thinking maybe the Cherry MX low profiles switches?  Any thoughts on those? 

Second, if I use these I'll probably go with the SK6812 reverse mount LED's as well.  What I need some guidance on though is a good slim mosfet to bump the 3.3v to 5v.  Any suggestions?

[dustin_b211]

Looking for some assistance in programming some SK6812-E LED's with my Nice!Nano. Originally I thought it would be easy, now I'm second guessing myself.  I'm attempting to use this guide, but I have a lot of questions.
This Guide - https://zmk.dev/docs/features/underglow
1. What type of board is the Nice!Nano, nRF52?
2. They keep referencing the LED's in this example as WS2812, what should I reference the LED's I'm using?
3. I'm using pin P0.06, which from the math is pin reference <6>, correct?
4. I've added

Code: [Select]

CONFIG_ZMK_RGB_UNDERGLOW=y
# Use the STRIP config specific to the LEDs you're using
CONFIG_WS2812_STRIP=y to my .conf file, but what is the STRIP config, I presume that's referencing my specific type of LED's?

At this point I'm a bit lost...I appreciate any help.

[nevin]

1. Microcontroller   Nordic nRF52840 (from the nice nano site
2. SK6812 is similar enough to WS2812 you shouldn't need to change anything

ZMK supports all the RGB LEDs supported by Zephyr. Here's the current list supported:
WS2812-ish (WS2812B, WS2813, SK6812, or compatible)

(from your link: https://zmk.dev/docs/features/underglow)

in that little bit of a cinfig it just saying yes to underglow, and yes to the style of underglow (a strip, which i'm guessing you have wired the same way) when they are in a strip or line like this, because the leds are addressable, you can change the color of individual leds.
- there should be a pin notation somewhere as well as a count of the leds somewhere. so it knows how many and on what pin. it needs the number of leds so it knows what led is at what address on the pin, to change the colors of individual leds.

strips like this: https://keeb.io/collections/diy-parts/products/rgb-led-strips-sk6812-ws2812b-compatible

haven't really dug into ZMK yet, but i can probably take a look at some point this week. (if someone doesn't answer sooner)

[dustin_b211]

So I managed to get the LED’s to light up, but I’m unsure how to change anything else at this point.  Hopefully someone can chime in.

Appreciate your help.

[nevin]

you can probably specify a certain color & brightness in the firmware as the default. to change on the fly you'll use keycodes. see below for what QMK uses, hue, saturation, brightness, cycling through designated patters, on/off, etc.
again, i'd have to look up how ZMK does it.

[dustin_b211]

I'm sure I'll eventually figure it out.  I don't need to change it on the fly, since this is a macro-pad, I just want to be able to program the colors to specific keys.

[nevin]

that's a unique use case. not an animation (different colors) and not all one color.

and as far as i know KMK doesn't having a GUI frontend like VIA/Vial (for QMK). which would make this a little easier.

i've specified individual led colors in QMK using them as layer indicators, (when you hold a key to activate another layer, like Fn, certain segments ight a certain color).