Understanding "White handling/CCT" with regards to the Athom GU10 bulbs


I’m new to this community. As I was planing to make my new used home smart, I started with choosing the right bulbs. Via the topics “Tuya” → “Tasmota” → “Athom” I got to the WLED project. :slight_smile:

However, my first goal is to integrate standard bulb features like dimming and the control of the color temperature. For that I need to understand the WLED basics and “White handling/CCT”. Because I already brought Athom GU10 bulbs.

On blakadder you can find some pictures of the internals of the bulb (Link). The bulb implements RGB+CCT and, as far as I understand, has separate LEDs für “White” and RGB. It would be nice, if someone can confirm this to verify my knowledge. Otherwise I don’t understand the warning:

Do not turn on the cool or warm color and RGB channel at the same time, and do not turn on the white mixing mode (SetOption105 1 should not be executed). Otherwise, the bulb will be damaged

from the blakadder page. And does this also mean, that the correct Auto White mode for the Athom bulbs is “Accurate” to avoid damage to the bulbs?

If I set the “Auto White mode” to “Accurate”, does this also mean White Balance correction is not applied, as the RGB LEDs are not used?

The chapter CCT handling also states:

WLED starting with version 0.13.0 also supports bus types with two white channels, one with a warm color temperature (e.g. 2700 Kelvin, reddish white) and one with a cold white color temperature (e.g. 8000 Kelvin, bluish white).

But if I pass values in Kelvin via JSON to the cct parameter (Link), it is not doing anything. It accepts the values, but does not change the color temperature. Only values between 0 and 255.

The knowledge article is also a little bit confusing as there is written:

It is also possible to pass a value in the range of 1900 to 10091 , in which case it is treated as a Kelvin color temperature, where 1900 is mapped to a relative value of 0 and 10091 to a relative value of 255 .

and then later it says:

If your code relies on absolute Kelvin values, a reasonable estimate for the warm white point (relative 0 ) could be 2700K, while cold white (relative 255 ) could commonly be 6500K.

Does 0 represent 1900K or 2700K? :thinking:

I hope, I did not ask to many questions and it helps also other people than me, to understand WLED better. :smiley:


Is there no one who can answer my question? :cry: