Air Quality Sensor

[epierre]

About initial calibration, just a warning from this graph:

chart.png

you can see high levels around july 21 then dropping in august... the sensor has been restarted... that is what the call clean air...

this automatic reading at the start should be stored in the sketch and not reclaculated at each reboot or you would loose all reference on your data...

[epierre]

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[epierre]

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[Yveaux]

@epierre did you just post the same reply 3 times or is the forum software showing yet another bug?

[epierre]

@Yveaux don't know, I did post once...

[korttoma]

I wanted to get acquainted with the MQ2 AirQuality Sensor so I took a look at the sketch from github.
One thing I noticed was that there is some sleep-time defined, is this just to make the sensor report the value every 30 seconds?
I guess it is not for saving power so you can run it on batteries because my understanding is that it needs to be hot in order to function correctly and that will drain the battery fast.

Does not look like the calibration during setup takes in account the preheating time either, maybe it is a good idea to add a delay before the calibration so the sensor gets hot enough.

Please correct me if I'm wrong.

[epierre]

@hek Here is a first list from the most commons:

• Carbon Monoxide – CO
• Carbon Dioxide – CO2
• Oxygen – O2
• Methane – CH4
• Hydrogen – H2
• Ammonia – NH3
• Isobutane – C4H10
• Ethanol – CH3CH2OH (aka C2H5OH or C2H60)
• Toluene – C6H5CH3
• Hydrogen Sulfide – H2S
• Nitrogen Dioxide – NO2
• Ozone – O3
• Hydrocarbons – VOC
• Chlorine CL2
• Ammonium NH4
• Ethanol CO2H50H
• Methyl CH3
• Acetone CH3_2CO
• LPG (both C3H8 C4H10)

[epierre]

@korttoma said:

Does not look like the calibration during setup takes in account the preheating time either, maybe it is a good idea to add a delay before the calibration so the sensor gets hot enough.

Please correct me if I'm wrong.

I see your point, but from experience I don't see a difference on heating... I should have a closer look. This one does not need a special pre-heating as some other (MQ-7).

Clearly this cannot run on battery on MQ/TGS/MICS series, so surely removing the sleep and adding a wait would do the trick the same way.

If you want to play and see something, the MQ135 is much better for it reacts to CO2, so having someone in a room or not you could see it easily changing.

A current weakness on the sketches is to take into accound humidity and temperature to correct the value, that will come too.

[epierre]

I was looking for some other gas sensor, but these have no shield ready to connect to arduino :

Sensor	     Operating Voltage  	Heater Power
MiCS-2710 (NO2)	  2.5 V	           43 mW
MiCS-5525 (CO)	   5.0 V	           76 mW

do I need a dedicated 2.5 V linear regulator such as Microchip TC1071VCT713 ?

[epierre]

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[epierre]

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[epierre]

@hek about initial calibration, how would I do check if there is a value in the eeprom or not, and if not run an initial calibration ?

[hek]

@epierre

Unwritten eeprom has the value 0xff.

[Omemanti]

Hi,
First of al I'm a novice in all of this. I can read some code but the whole arduino thing is new to me.

I tried to get the MQ135 working on my uno with tearing apart the : https://github.com/empierre/arduino/blob/master/1.3/MQ135dgi.ino.
I tried to pull out the bits and parts to get a accurate reading on my serial monitor.

It sometimes read 1 or 2, but most of the time it is 0.
Can it have something to do with it being mounted on its own PCB? (I ordered the one suggested in the store..)
Can someone help me out?

Groetjes Mark

[epierre]

@Omemanti hello have you plugged it on the right pins, this is an analogic sensor to be plugged on A0, with 5V and GND pins. Don't wire the digital one, useless...

My minimal value is 53.. so not 0 or 1 hwich looks more like the digital output ;-)

[Omemanti]

should be alright right?

[epierre]

@Omemanti cabling is correct

[korttoma]

Hi,
Where can I find AirQuality1.xml?? (or all files related to this device if there are others then the .xml)

01 09/03/14 13:46:53.685 ctrl_chr[31;1mDevice_LuaUPnP::LoadDeviceDoc can't load /etc/cmh-lu//D_AirQuality1.xmlctrl_chr[0m <0x2acc9000>
02 09/03/14 13:46:53.686 ctrl_chr[33;1mJobHandler_LuaUPnP::m_sMissingFile_set /etc/cmh-lu//D_AirQuality1.xmlctrl_chr[0m <0x2acc9000>

Seems like if this file is missing it brakes the whole MySensors plugin.
All devices related to MySensors plugin are blank and nothing seems to update.
Deleting the device that use AirQuality.xml will make the rest work again.

Help!!

[hek]

@korttoma

Unfortunately no one has created it :(

[korttoma]

@hek
ahh, that's why I cant find it... no pressure from my side to get one done but maybe we should mention this little detail on the MySensors building page just as a heads up for others since there is a sketch published and all...