[SOLVED] Aqara Motion Sensor Illuminance via Zigbee Binding

Hi everybody,

I want to use the Aqara Motion Sensor (including illuminance sensor) to control my lights.
Therefore I’m using the Zigbee binding and the CC2531 coordinator.
The general setup is working fine and all motions and the illuminance are reported to openhab and furthermore to my items.

The item “MotionSensor_Illuminance”, represents the current illuminance reported by the motion sensor. This value reported in my setup is usually between 0 and 1, even if it is bright. Only if the sun is very shiny, the value is approx 8.

The sensor which is used in the Aqara Motion Sensor (BH1750) should report values between 1 - 65535.
Please can somebody tell me which values are reported to you or if its somehow possible to adjust the sensitivity.

Maybe @chris or @kubawolanin can help out here?

Thanks in advance :slight_smile:

I have a similar if not the same Aqara “Human” sensor which reports illuminance too. I am using zigbee2mqtt. Right now it’s night time, there is a 9W LED bulb turned on about 2-3m away from the sensor, and it is reporting illuminance value of about 40-50.

When I turned off that 9W LED light, there’s still another source of light further away, but the room is relatively dim by now, the reported illuminance dropped to 13.

When I turned that light off too, and closed the door to the room, so it’s quite dark, it didn’t report the change immediately. I am guessing it doesn’t report it unless it needs to report occupancy status changes. So I went into the room to trigger the occupancy sensor, and it then reported the illuminance down to 6.

I have several of these sensors. Two are used as night light sensors, to turn on some lights dimly at night for several minutes. One is used on my front porch to alert me when someone’s standing there. This has given me some false alerts unfortunately. I’m not sure whether it got triggered by heat, tree branch movements, birds, cat, etc. I did see a cat and a bird sometimes, but at other times, I didn’t see anything that could’ve triggered it.

Thanks for your answer :slight_smile:
As far as I know there are just two versions available of the Aqara Motion Sensor. So I guess you have exactly the same sensor.

  • The first generation without Illuminance measurement
  • The second generation with Illuminance measurement

That means for you the illuminance sensor is working properly. Just for interest - below what value do you turn on the light? I guess something below 100?!

The only difference I see, is that I’m using the Zigbee Binding and you Zigbee2Mqtt.
Honestly I can’t imagine that it makes a difference which of these bindings/system are used. It’s just a way how the illuminance value is transferred to openhab. What do you think?

I also checked the values in different situations. At night with several Hue Lights I had the following values:
100% --> 0,47
90% --> 0,36
80% --> 0,26
50% --> 0,06
20% --> 0,0

On a normal day when it’s not very sunny or cloudy the value is around 0,6-1,2
If its a very sunny day the value is around 8.

Hi Max and Jim,

I also have the same Aqara motion sensor with the illuminance sensor, which I have linked via the Xiaomi gateway v2 and using the Xiaomi Mi Smart Home Binding. In the beginning I found out that the illuminance is being reported in lux, so that’s how I have implemented it in OH. Only comparing it with a separate lux meter some while back I have readings (indoors, facing a wall illuminated by a window) up to and over 1000 on very sunny days, my cut off value for turning the lights on is 5 and at night it goes down to 0. This all nicely fits in with the lux examples on wikipedia for me https://en.wikipedia.org/wiki/Lux

Since you both seem to have very different results I am wondering if the binding being used has an effect, possibly a transformation, on the values being reported. Would be interesting to see what other people see depending on the binding being used.

With Max’ results, for example, I would assume that mulyiplying them with the factor 100 would give a realistic lux reading.

For my purpose of turning on a momentary, dim night light, the threshold that seems to be acceptable is illuminance value of 8 or less as reported by zigbee2mqtt. This still turns on the light during the day when it’s not very dark though but it’s better than not turning it on at all when needed.

I don’t really know what the value means, whether it’s in lux or something else. I didn’t bother finding out, since I just determined the threshold value I want based on trial and error, as it isn’t critical for me. Additionally, I have a check against Sun_Elevation (from the astro binding) so if the sun is up, the night light rule doesn’t activate. Of course this won’t work if the room can be dark during the day.

How are you guys using the illuminance value for?

I use it in a very similar way. If it’s day and the threshold in below 5 the light turns on and a timer is set to turn if off again after there has not been any movement for a certain time. If it’s night the light turns on as well, but once the movement timer kick in a very low night lighting scene is being activated instead of turning the light off completely.

So do you keep the light constantly on but dim until the morning (when the illuminance level goes up?)

Not constantly, only when I’m still up and about in the evenings. I find it more comfortable when the room has a very low night light on already, as it does take a brief moment when entering the room to turn the lights up and there also isn’t a complete change from total darkness to the normal lighting. Once it’s bedtime I activate my bedtime mode which turns off all the lights in the house - apart from the bedroom, which gets turned off when it’s sleep time. Getting up at night the movement sensors activate a night mode, which is a very low eye friendly red lighting, again on timers which turn off the lights completely afterwards.

@Hans_Lree yes I’m with you. It would be interesting if there is some transformation either in the Zigbee2Mqtt or Mi Binding.
Jim’s values and mine are very comparable (just multiplied factor 100).

The problem I have is the sensor isn’t accurate enough in a low-light situation.
Your threshold is 5 or 8 - In my setup that would be 0,05 - 0,08
Often very small values as 0.00 are transmitted. For example currently the value is 0.00 even its not night/dark outside.

I use the illuminance value like you both to decide if the light should be turned on or not.

That’s my impression as well

Have you tried to show the values with even more digits behind the comma? Just to see if there might actually be lower value variations like 0,003 registered.

Yes I’ve tried it already. THere are just 2 values after the comma provided.
The smallest value I ever got, was 0.05. Everything below is just 0.00

So I suppose that would be my 5 lux threshold. If the brightness is similar for you, that from thereon you would want the light to switch on it would just be ok, I assume. Anything lower does register differently for me, but is not really relevant to my lighting setup.

May I ask in which direction your sensor is pointing in the room?

I agree with you. It should be the similar behaviour.

The only bad thing is, that the value often is 0.00 where I expect it should be at least 0,05 (5 lux). But I think this is just how accurate this sensor is.

The sensor sits in the opposite of the window with direction to the window.

I would suggest pointing the sensor towards a larger white/bright area of the room, being illuminated by the window, and not towards the window itself (which generally gives quite a lower reading than the reflected light of large white/bright areas/walls in the room). This should give a more accurate representation of the brightness in the room. Obviously only if it’s still possible to register the motions that way :wink:

Might be worth trying out.

Thank you. I’ll take care of it. I will try different positions over the next few days.

Thanks to @guy-inkognito we know how to calculate correct values.