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Hitchhiking with the Airlink interface of CMX

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HansR
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Hitchhiking with the Airlink interface of CMX

Post by HansR »

In August I wrote about some sensor work I was doing and shortly after (roughly 12 hrs) ConligWX wrote about the AirLink. Apparently the AirLink was to be added to CMX as a sensor.

So version 3.9.0 of CMX did get the AirLink interface. I had been thinking this over and it became clear that interfacing to CMX to get the particle concentration data of any particle sensor would not have to be too difficult. So after a short exchange with Mark, I decided to build an interface to CMX (which polls the AirLink) and create a FakeAirLink. After a proof of concept I made a simple but workable application.

If you like working with hardware, have a Raspberry and want to spend some 35 euro on sensors, than I have the software to make it work.
And of course, CumulusUtils will soon support the AirLink (both the real and the fake) as well.

I published the code and you can find the release there as well under the tag (take the most recent).
The Readme should get you started. Other sensors are possible, ask for it (and send me one) and I'll implement if possible.

Git repository here, with code and release and info.
For general info on AirQuality, sensors and AQI interpretation I wrote a separate post.

NB: Although this is slightly a home built device (why I wrote the first message in the Homebuilt forum), the project turned towards CMX as the AirLink became available and a supported device for the Cumulus World. I had already planned to make an AirQuality module for CumulusUtils so combining all this, I decided to make this message in the CumulusUtils part of the forum. It fits. Homebuilt is too separate.
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Phil23
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Re: Hitchhiking with the Airlink interface of CMX

Post by Phil23 »

Interesting Han's,

I've actually got a pair of Sensiron SPS30 Sensors here. Have had various thoughts on what to do with them but never proceeded.

Have two rPi's on hand, a couple of Arduino's & dozens of Micromites.

It was Micromite where I was originally planning to go, in particular adding it into an existing VOC Air Quality monitor I built.

VOC I found to be very interesting after building the unit, in particular the degrading of the air quality of a closed bedroom at night with poor ventilation.
VOC's increased during the night & found the peak to correspond with when my sleep was disrupted.
Also it proved a point that the VOC's pooled from the floor up as they increased in the room.

That could be another interesting sensor to add, cheap as chips, only catch is it requires a warm up period & a bit of a calibration routine occasionally.

Cheers

Phil.

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Re: Hitchhiking with the Airlink interface of CMX

Post by HansR »

@Phil:
Yes, the sensirion is a very well known sensor, I may add it some time. A bit more complex interface but otherwise principally pretty much the same as the PMS1003 I did implement. The Micromites system is interesting, a microcosmos in itself. Never seen it before, might be useful for using analogue sensors such as indeed the VOC or other gas sensors. It adds another layer of coding and complexity but still. I'll look at it in more detail.

Thanks for the reply and the suggestions.
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Phil23
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Re: Hitchhiking with the Airlink interface of CMX

Post by Phil23 »

HansR wrote:
Sun 15 Nov 2020 6:39 am
The Micromites system is interesting, a microcosmos in itself.
There is good support for most interfaces. I actually run 17 temp sensors here over 3 devices which integrate in the end.
There is also a version that runs on rPi, but it would need an additional A/D interface module to read analogue sensors.

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Re: Hitchhiking with the Airlink interface of CMX

Post by ExperiMentor »

Hans, Can you reccomend a cost-effective sensor?

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Re: Hitchhiking with the Airlink interface of CMX

Post by HansR »

Not really. It also depends on what you want to sense ;)

For PM sensor I am very happy with my PMSxyyy sensors. Cheap and workable. Lots of literature.
The SPS30 is very well known, proven but a bit more expensive
For temp/hum the SHT sensors (used by Davis) are very well proven and not too expensive)
If you want pressure as well you might want to go for the BME280
If you want to add VOC you might want to have the BME680.

And so on... not to talk about inside or outside and temp/hum correction.
It is not all that straight forward and requires some study and especially: what do you want to measure?
So many sensors.... I can't even start to have preference. And then I am not even talking about gas sensors (NO2, SO2 etc...)

Choices need to be your own.
Important is you know HOW to read the sensor, to store the data and how to present it.
Cost of the sensor is not the issue these days.
https://meteo-wagenborgen.nl / Cumulus 3.9.1 (build: 3096)
Davis Vantage Pro 2+ / Raspberry Pi 3 Model B Plus Rev 1.3
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Re: Hitchhiking with the Airlink interface of CMX

Post by ExperiMentor »

Thanks for the great introduction - I need to get more into this, had no idea there was so much easily available and cheaply! I had thought the discussion was mainly about PM but guess it would be good to put together a full array for wide-ranging air quaity measurement. I can feel a project coming on!

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