Good evening,
Has anybody connected the mg811 module in esphome? I was wondering if this sensor is configurable in in esphome or I just need to program it in ide.
Many thanks
J.
You should be good with ADC component.
Anyway there are many different modules around. Do you have A-ref pin?
Ideally the supply voltage would be 6V.
For sure it can work with esphome ADC. The question is; what’s the analog voltage it outputs? There are hundreds of different modules around. Some output 0-2V, some 0-4V, some have selection, some have reference voltage pin… Measure the output, if it gives above 3.3V you need voltage divider or you damage your Esp.
Also be avare that the supply voltage should be 6V +/-0.1V, it might or might not work at 5V supply.
Many thanks for your kind advice. I am going to get voltage converter to have 6v to power it and will certainly measure the AOUT b4 connecting. Thanks again.
Edit: I actually found the module the sensor sits on. It is fc22, which is powered by 5V. I just need to figure out what is the AOut voltage.
Try if it works. It’s not a question of the chip but the sensor itself. MG811 needs 6V for the internal heating element. In sophisticated modules (from Adafruit etc) there are voltage converters onboard.
You are surely right. I am going to give it a try tomorrow or over the weekend, will let you know. Thanks a lot!
Hi again,
the module needs 6V to operate. I however found that it is quite imprecise, do not know - maybe it needs to heat-up longer (some sources say 48 hrs). What wondered me was that the voltage levels were changing when it was just lying on my desk with no particular changes (like I would blow onto it), either it is so sensitive or it is not reliable (again - maybe needs longer warm up)…
I am quite disappointed TBH 
Best, have a great weekend.
J.
Even if the sensor is ok, a lot depends on the other components on that module.
Also Esp32 ADC is not anyhow excellent.
How much?
You can set the update interval to 1s and use esphome sensor filters to average 30 readings for example.
Hi,
I was aware that adc would not be a perfect solution. But probing each 10s gave variations from 1,07v to 0,5v within a minute period. I do not think taking average would have a reasonable meaning if you want your co2 measured level to correspond to reality…
I gave up and will return this sensor and try some other I have found in reasonable price
Many many thanks for your kind help. I do appreciate that a lot.
Go with NDIR sensor. Or acoustic from Sensirion.
CCS811 and SCD41 are arriving today to try.