DIY PCB with SMD RGB key lighting

[DonnyD]

I want to build my own ErgoDox keyboard replica (PCB, plate, case). Starting with PCB, i want individually lit SMD RGB keys. Problem is wiring them. I understand that i need to use addressable LEDs (GND, VCC, Dat pins), not with 4 pins because i have limited pins on teensy. So i can daisy chain them to get one long 76 led strip. I understand how these LEDs with data pin work, but how qmk understands which led is assigned to which key ? I want to use qmkconfigurator for firmware.

[Applet]

You can use a LED-controller for individually lit SMD RGB keys. Then you use regular leds that is connected in a matrix. You can find QMK-supported controllers here: https://beta.docs.qmk.fm/features/feature_rgb_matrix

They are connected on I2C on the teensy, so use only 2 GPIO's.

I'd recommend to start out with something a bit simpler if this is your first PCB.

[DonnyD]

Okay, forget about individualy controlled key lighting. If i just use smd rgb addressable leds as one long strip i will only need 3 pins (GND, VCC Data) right ? I think that way is much easier to wire them and program using online configurators. And if i want to make effects with individualy lit keys i can write the code myself in the future. Its like underglow strip, but its longer and goes in each key. Correct me if i wrong, but i think only problem is powering them.

[Applet]

Am I right that you would like to use something like a WS2812, but for in/under switch leds? I have not seen any addressable leds that is suitable as in/under switch leds. But someone else here might know one. I guess you could make holes for them in the PCB, then wire everything up underneath the PCB?

But yes, If you use something like the WS2812, you only need to use TX/data, VCC and GND on the teensy.

[DonnyD]

I would use SMD RGB compatible switch and maybe try smaller, lesspower hungry led.
Hipothetically speaking, if i reverse engineer ergodox and wire my keyboard exactly the same,i should be able to use ergodox online configurator ?

[Durburz]

WS2812 are supported by QMK and should work.
It's better to use WS2812C as they are the same except they are less bright and consume less energy.

I have cutouts and WS2812C 5050 on my current prototype PCB. It's a pita to solder and I'll have to change some things but for a single keyboard I'd say it works.

[plut0nium]

Am I right that you would like to use something like a WS2812, but for in/under switch leds? I have not seen any addressable leds that is suitable as in/under switch leds. But someone else here might know one. I guess you could make holes for them in the PCB, then wire everything up underneath the PCB?

But yes, If you use something like the WS2812, you only need to use TX/data, VCC and GND on the teensy.

WS2811 is basically the driver chip of the WS2812 without the LED...
You can place it under the board and have a regular RGB LED on the other side, under the key.
This doubles the number of components though, and WS2811 is not as easy to source...