Supports for MQ analog sensor for air quality

[francescoadriani]

Description:

It's support the analog sensor for quality air (also for esp-32)
-added on list of assignable pins in module
-with adcparams can choose whic mqx you have with seconds param ex: adcparam 10 4 (you have the mq-04)

Related issue (if applicable): fixes #

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.2.0.2.1
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[erdinguma]

Issuing command: adcparam 10 4 is not changing the sensor from the default MQ2 to MQ4. Any guidance?

[barbudor]

@erdinguma Did you correctly configured your ADC input in the GPIO configuration ?

[erdinguma]

@barbudor Yes. Selected “ADC MQ” and I am reading values. Just need to change it to MQ 4.

[rice103]

The help update has not yet been released but you need to change a & b exponential regression params via adcparams.
Syntax is AdcParam1 <ANALOG_MQ_TYPE> <(ANALOG_MQ_A> <ANALOG_MQ_B> <ANALOG_MQ_RatioMQCleanAir>
Last params is not used for now, could be 0

[rice103]

https://github.com/tasmota/docs/blob/development/docs/ADC.md
https://github.com/tasmota/docs/blob/development/docs/Commands.md#adcparam

[erdinguma]

It worked!
Mq-4 command: AdcParam 10, 4.00, 1012.70, -2.79, 4.40

[rice103]

Yeah!

[erdinguma]

For future enhancement, considering high sensitivity of the sensor to humidity and temperature, I inferred from documentation the following relationship of ratio (rs/r0) to temp and humidity.
(From documentation)

(T & H Interpolation)

Ratio adjustment factor (F) for Temp T and Humdity H:
F = 5.693977721259878 + -0.023280722319645328 * T + -0.24767739454737786 * H + 0.00054602964962393 * T^2 + -0.0001297777486611509 * T * H + 0.004485775052457577 * H^2 + -7.564523748530513e-06 * T^3 + 1.277287227509287e-06 * T^2 * H + 1.2323178573075948e-06 * T * H^2 + -2.5805390257858728e-05 * H^3

[rice103]

Is not simple link two sensor value.. But could be a starting point for future developments

[erdinguma]

Yes. I am thinking to implement something similar to Sensirion SGP40 or SGP41 which reads another sensor, SHT4x to compensate VOC sensing for temp and humidity. (I realize SGP41 itself hasn't even been ported to Tasmota yet)

In the interim, I thought to post my compensation formula because it can be used in post processing of data after received from MQTT and it would make a significant difference in results even if not processed at firmware level in real time.

[Links2004]

Hi,
2 questions to the code.

• from where do the values for ANALOG_MQ_A, ANALOG_MQ_B and ANALOG_MQ_RatioMQCleanAir come from?
  I like to use a MQ-135 and cant find the values needed.

• based on the datasheet of the MQ-7 it needs some voltage changes, is this Implemented in the code and if yes how to configure the PIN for it?

[francescoadriani]

@Links2004 #14581 (comment)
No voltage changes implemented