Homebridge v2 dimming issue

I set up homebridge v2 today. It was a pretty smooth process and is very nice to be able to control my lights from the Home app and via Siri on my iPhone. However, I have a possibly interesting issue. If I ask Siri to dim the lights it seems to work every time. However, if I use the dimmer slider in the Home app on my iPhone then it doesn't work reliably.

Note, I'm dimming a group of lights (set to the Group Bulb Dimmer-2.1). If I open the group in the Hubitat Devices UI then I can see the Hubitat state is updated perfectly (Current States on right of screen shows proper level); it always ends up at the level that I drag the Home app slider to. So, Homebridge seems to be controlling Hubitat just fine but the message is lost on the way to the bulbs.

So, maybe my Zigbee mesh is not strong enough? I did experiment with enabling metering in the group app settings for these bulbs. I tried setting it, went to as high as 250ms, and it seemed to help, maybe, but still not perfect.

Thanks for any other ideas!

You’re best off posting this in the HomeBridge V2 parent thread, where the developers and users of that community integration are most likely to see it.

This strongly suggests to me that this is not a HomeBridge issue. What if you leave HomeBridge/Home out of the picture entirely and just run the "Set Level" command on your group device on Hubitat (from the device detail page, ideally) to see how the real bulbs respond? I suspect you'll find they don't work as expected every once in a while, matching what you see in Home.

If that's the case, there is some troubleshooting that can be done (and additional information that will be needed to do that), but at least this will let you know where to start.

Yes, this is exactly right:

This strongly suggests to me that this is not a HomeBridge issue. What if you leave HomeBridge/Home out of the picture entirely and just run the "Set Level" command on your group device on Hubitat (from the device detail page, ideally) to see how the real bulbs respond? I suspect you'll find they don't work as expected every once in a while, matching what you see in Home.

If I issue the Set Level command from the device detail page as you suggest it usually works, but the group bulbs fail to respond a small percentage of the time. If I do the same experiment while I continuously spam the dimming slider in the home app (targeting a different group of bulbs) then it fails most of the time. Is the Zigbee protocol unreliable (in the sense that UDP is)? It does feel like messages are getting lost.

If that's the case, there is some troubleshooting that can be done (and additional information that will be needed to do that), but at least this will let you know where to start.

If you can point me to this additional troubleshooting I'd greatly appreciate it!

The first question would be what kind of bulbs these are and what the rest of your network looks like (brands and models of the bulbs, and what kinds of other devices you have--brands or models of motion senors, smart plugs, etc.). Some smart bulbs are known not to play well.

Since this is a group, the other question is how the group is configured. For Zigbee, normally Zigbee group broadcasting (this is an option you can enable in that group child app) works well, though for some bulbs it's problematic. I'd suggest starting with it on but see if turning it off makes things better if it's already on. WIthout group broadcasting (I'm not sure most of these really matter if it's on...), you may also want to experiment with the "optimization" settings that won't send commands to bulbs that already say they're in the correct state (this won't work if they are but claim to be), adding some delay with metering (maybe 50-100 ms?), or anything else that may help.

Finally, if you aren't on at least platform 2.3.2.x, I'd recommend that, as there were some changes to how the radios work that are supposed to help both Zigbee and Z-Wave (and theoretically eliminate the need for metering).

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Bulbs are Juno Connect Wafers.
House is two story, a bit under 2000 square feet.
There are 9 of the Juno lights downstairs in the living room.
Upstairs is three bedrooms. Three of these lights in two, five in the third.
Each bedroom also has a Third Reality Zigbee Smart Plug.
And, there is a fourth of these smart plugs in the upstairs hallway, so total of four of these.
Nothing is plugged into the smart plugs, I got them to try and improve the mesh.

My Hubitat is currently on 2.3.2.141, no updates available.

The group is configured with "Zigbee group messaging" enabled. I tried turning that off and that made it worse actually. Sending the set level command resulted in some bulbs being on and some off.

I'm not familiar with those bulbs, but perhaps someone else is and can offer experience. (I've had mixed luck with directly connected Zigbee bulbs personally, and that's one of the reasons I use a Hue Bridge; my experience sounds a lot like yours, but that was before the recent updates. I've just never had a reason to go back when this works so well.)

In any case, I do think you've eliminated HomeBridge as an area for concern. I guess the only other thing that seems like it might help is disabling group broadcasting, and then probably adding metering, to see if that helps? Your mesh is likely solid with at least one repeater in each room, plus likely these bulbs themselves (though I suppose that brings up a related concern of whether these bulbs don't like repeating for the smart plug and some messages might be being eaten instead of passed along, an occasional issue with some brands of bulbs on "mixed" Zigbee networks).

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Thanks for the suggestions. As I have time I'll have to continue experimenting. At least the bulbs are working fairly well now and the issue at hand is fairly easy to work around!