Expose colour temperature to HomeKit

Hey team,

When looking at a LIFX Mini Colour bulb via Home by Matthias Hochgatterer, it seems that the only settings provided to HomeKit are Brightness/Hue/Saturation. When I emailed Matthias to ask, he told me to ask the LIFX development or support team to add a colour temperature characteristic for HomeKit.

So, could you please do that? :slight_smile: Or is there another way to set temperature?,

Thanks!

Edited to specific about the bulb in question, i.e. a LIFX Mini Colour.

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Since that post, I’ve received my LIFX GU10 bulbs and they also don’t have a colour temperature characteristic within HomeKit.

So, I’m assuming this is perhaps something that the colour bulbs don’t expose? If so, is it possible to reproduce white+temperature using Brightness/Hue/Saturation?

G’day Avi,

A few months ago, I implemented Color Temperature in my homebridge plugin for LIFX.

HomeKit’s Color Temperature setting is measured in mireds, but there is a way to convert between mired and kelvin.

Matthias should be able to reverse engineer something from my changes or implement something himself (it pretty straight-forward), hopefully LIFX can do the same for official support.

Cheers,

David

Thanks David.

According to Matthias, he needs LIFX to expose a colour temperature characteristic so that he can manipulate it via HomeKit. I’m assuming his app just shows controls for whatever characteristics are reported by the target device.

To be honest, I’ve been trying to avoid using Homebridge, because I didn’t want to maintain another always-on service.

I’ll wait to see what the lifx team have to say before I try anything else.

I’m wondering if this is actually the official enhancement request mechanism, or should I have opened a support ticket with LIFX?

As an aside, I’ve been running @devbobo’s homebridge-lifx-lan plugin for a while now and it’s awesome. My original Kickstarter bulbs are also HomeKit enabled now. :wink:

Poking this thread because I’m not sure exactly how to submit an official feature request. :slight_smile:

Welcome to the First Annual Bumping of My Thread Ceremony. :smiley:

Ping @delfick-employee: Is this something that LIFX is going to implement?

If this is not on your TODO list, I’ll have to remove all my LIFX bulbs from HomeKit and present them via Homebridge instead, because I really need to be able to set temperature exactly on my colour bulbs.

I’m on holiday at the moment, @egosapien might have a better idea :slight_smile:

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Hey sorry I’ve been holiday as well, Easter is a bit of a quiet period. HomeKit only relatively recently introduced a separate kelvin characteristic, but it’s only intended for white-only lights. If you get a Mini Day Dusk you’ll see it has a kelvin characteristic but then not saturation/hue. We’ve considered adding a custom LIFX characteristic for accessing the LIFX kelvin value, but that probably won’t help you with this third party app. I can say that the iOS app uses saturation/hue for exporting Scenes to HomeKit, but this obviously doesn’t match up perfectly. My recommendation would be to either use hue/saturation or the LIFX API which obviously exposes hue/saturation/kelvin.

From what I know, HomeKit has no kelvin characteristic at all. The colour temperature is done in mireds. And exposing both to HomeKit works just find for software-based devices exposed by Homebridge so it if the actual device did it, it should work fine.

As for the scene export via HSB: that’s just plain awful, to be frank. It turns on colour LEDs when really you just want the white ones.

Basically, we need this characteristic exposed: https://developer.apple.com/documentation/homekit/hmcharacteristictypecolortemperature

Any progress here? I’m about to drop all my bulbs out of HomeKit and publish them via Homebridge instead.

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This issue has been known to LIFX, with a fix supported in the HomeKit framework, for more than a year. Given that the LIFX 1,100 lumen bulb is among the most expensive on the market, it’s incredibly disappointing that this feature hasn’t been implemented. I got these bulbs because they are the brightest available for HomeKit, but true color temperature wins out over brightness. I’ll return the four I just bought for those from another company.

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Can I ask what that fix is exactly?

I found the following in one of Apples docs which leads me to believe there was some limitation in exposing both color and color temperature at the same time (made me think it’s either one or the other):

Color Temperature
This characteristic describes color temperature which is represented in reciprocal megaKelvin (MK-1) or mirek scale. (M = 1,000,000 / K where M is the desired mirek value and K is temperature in Kelvin)

If this characteristic is included in the ”Light Bulb”, ”Hue” and ”9.82 Saturation” must not be included as optional characteristics (emphasis added) in ”Light Bulb”. This characteristic must not be used for lamps which support color.

I downloaded the HomeKit Protocol Specification and you’re right (not that I doubted it). I find this deeply annoying. Is there any way you (as a HomeKit-certified device manufacturer) can provide feedback to Apple that this results in inaccurate representation of white colour on bulbs with 4 LEDs?

In the meantime, I’ve re-engineered my automation so that the adjustment of colour temperature occurs externally to HomeKit.