Corne with nice!nano v2, underglow only working on one side after setting reset

[lost osprey]

Hi everyone,
I recently bought a Corne Chocolate from 42keebs (https://42keebs.eu/shop/kits/pro-micro-based/corne-chocolate-low-profile-hotswap-split-ergo-40-kit/) with nice!nanos v2 and finished soldering yesterday. Everything seemed to work correctly since I was able to set up keymaps, display and underglow on both halves.

However, I then started to adjust the color of the underglow LEDs to my liking first by using behaviors (https://zmk.dev/docs/behaviors/underglow) and then by configuration (https://zmk.dev/docs/config/underglow). But I never could change the brightness and saturation with CONFIG_ZMK_RGB_UNDERGLOW_SAT_START and CONFIG_ZMK_RGB_UNDERGLOW_BRT_START. Seems like the previous settings applied by the behavior always override those. Due to that I decided to reset both sides by using the instructions found in the documentation (https://zmk.dev/docs/troubleshooting#split-keyboard-halves-unable-to-pair). After flashing both halves I thought everything was working since the lights showed the desired color. However, once I connected both sides ,first with USB-C and TRRS then Bluetooth, only the LEDs on the left side were lighting up. I then got both sides working again after they went idle but if I turn them off and then reconnect the same issue appears again.

I tried using behaviors again and removed all underglow settings except for CONFIG_ZMK_RGB_UNDERGLOW and CONFIG_WS2812_STRIP but that did not change anything.

Does anyone have a clue what went wrong?

[strange yacht]

You may need to clear your bluetooth profiles with a BT_CLR_ALL see the "connected but not working" procedures here

[lost osprey]

Thanks for answering.
Unfortunately those steps did not solve my problem.
However, after I did that and used a new project with no keymaps and only the display and underglow enabled both sides show colors again, but the right side is flickering in different colors.

[strange yacht]

once I connected both sides ,first with USB-C and TRRS then Bluetooth

are you connecting the two sides of the split together with a cable? This currently is currently unsupported in ZMK, need the two to just be connected wirelessly. Flashing lights sounds like a wiring or other hardware issue offhand

[lost osprey]

Ah ok did not know that. Guess I am only using Bluetooth from now on then. But the behavior appears with bluetooth as well.

[strange yacht]

It MAY be possible plugging them together borked something but don't quote me on that, not sure if that makes sense given the wiring

what battery do you have and how many leds?

[lost osprey]

Hopefully not...
I bought Lithium-Polymer Batteries (301230) and 21 SK6812 MINI for each side.

[strange yacht]

I'm guessing the LEDs are browning out, googling 301230's the numbers I'm seeing are like 1C discharge, which if the battery is 75mAh means beyond 75mA discharge you're in flaky territory. Depending on who you ask around here, the SK6812's pull either 12mA, 19mA, or 36mA each (it'll be a range regardless based on how bright they're being asked to go). Going with the conservative estimate, that would be (12mA * 21 LEDs) = 252mA going to the LEDs. So, my guess would be the battery is undersized for that and so the LEDs are getting confused because their supply voltage is dipping. A good way you might be able to check this is plugging that side into a power source, at a low configured brightness the LEDs would behave fine with the battery disconnected. My keeb with the same LEDs I stuck a 10000 mAh battery in to compensate, looking into a more efficient LED solution in my next revision so I could get away with something smaller, like 5000mAh. You may want to check the ZMK power profiler

[lost osprey]

Ok that sounds logical. Thanks for pointing that out.
My plan was to use them at around 5 - 10% of brightness anyway so I guess I can check if lowering the brightness while connected to my PC does get rid of the flickering. If it doesn't I think something might be broken already...
In any case it seems to be better to not use them at all until I have a stronger battery.

[strange yacht]

Good luck! If it helps, this is the battery I'm eyeing. Based on my experience with using 10000mAh batteries and some napkin math you'll probably get 3 days of runtime off of that with the lights relatively low. If you want it in the keeb, you'll need to print another case with space for it under the PCB.

Lmk if it works fine plugged in w the battery disconnected

[lost osprey]

Thank you 🙂
I add another comment when I have some results, but it could take some time.

[lost osprey]

So a few minutes ago I flashed both sides with no changes except for a button on each side that sets the brightness to 10% while keeping the color and saturation at the default values.
While connected to my PC all LEDs were lighting up and I saw no flickering (tested it dor around a minute). Then I pressed the button and still no flickering.
I decided to test it with bluetooth turned on as well and still no flickering with 100% brightness and 10% brightness.
Ok that is not true entirely. I saw it on the left half but only for the last nine keys and I am suspecting that the LED from which on I saw that for a second to be slightly damaged.
Could it be that the first LED on the right side could be damaged and thats why the flickering is happening?