BME680 gas resistance values

ESPHome
3

So did you guys figure this out? I also have very low readings (8550ohm) and have no clue what this means.

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Still waiting for input of other people… at least I am not alone :wink:

5

Hello,

27899 Ohms lol but i am printing a 13 hours PLA part with my 3D Printer…

I read here https://forums.pimoroni.com/t/bme680-observed-gas-ohms-readings/6608/17

we can have a IAQ value with this formule :
comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh]

How can i integrate this in EspHome with Lambda please?

3 Likes
6

Wow you found it.

I also want to know how to make it IAQ

you great !! thx.

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@minsuke

thanks!

but do you know how integrate this in Lambda please? :wink:

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Your resistance is high (and thus air quality is also good) if you are printing PLA.

Perhaps I should also start printing more 3d parts to have better air quality :smile: :thinking:.

I wonder if we would put both sensors in the same room they would show the same values.

9

LOL…

Hopefully PLA is not bad for health like ABS… :wink:

Is there a way to convert this value in EspHome? my knoledge is not enought good to make the Lambda formule with comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh]

Any idea?

10

Did anyone convert gas resistance to AQI?

11

what are the ranges people are getting in Ohms? I have just set mine up via ESP home and was getting a constant 48633, it was like this for attest 24 hours. I have now moved across to a tasmota device I had lying round and im getting close to 10000.

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I have mine in the basement, typically get values ranging from 12,000-16,000.
Last night I was working on some hydraulics, spraying penetrating oils and such, the value shot down to 5,600 overnight and has been crawling back up.

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Does Tasmota AQI calculation?

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No unfortunately, neither does esp home. I did notice last night though that the home assistant integration does.

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I have the BME680 from Adafruit running, and have the IAQ calculatet this way:

sensor:
  - platform: bme680
    temperature:
      name: "BME680 Temperature"
      oversampling: 16x
    pressure:
      name: "BME680 Pressure"
    humidity:
      name: "BME680 Humidity"
      id: hum
    gas_resistance:
      name: "BME680 Gas Resistance"
      id: g_res
    address: 0x77
    update_interval: 60s  
# comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh]    
  - platform: template
    name: "BME680 IAQ"
    id: IAQ
    unit_of_measurement: IAQ
    lambda: 'return log(id(g_res).state) + 0.04 *  id(hum).state;'

Just use the lambda to do this simpel calculation.

Edit: I run this on a ESP32

11 Likes
16

Which integration?

17
1 Like
18

First off, thanks for posting the lambda for converting to IAQ. I do have a question though. Since setting this up, my IAQ has been a consistent ~10. I’ve tried blowing on the sensor, burning a candle nearby, trying to see if I see it change and…nothing. Anyone else having oddly consistent readings? All my other parameters seem to fluctuate.

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Thanks.
Its working with esphome.

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For anyone coming across this I found this one uses the bosch library which has it all built in now

# Minimal example configuration with common sensors
i2c:

bme680_bsec:

sensor:
  - platform: bme680_bsec
    temperature:
      name: "BME680 Temperature"
    pressure:
      name: "BME680 Pressure"
    humidity:
      name: "BME680 Humidity"
    iaq:
      name: "BME680 IAQ"
    co2_equivalent:
      name: "BME680 CO2 Equivalent"
    breath_voc_equivalent:
      name: "BME680 Breath VOC Equivalent"

text_sensor:
  - platform: bme680_bsec
    iaq_accuracy:
      name: "BME680 IAQ Accuracy"
4 Likes
22

from a room where people smoke
image

1 Like
23

I know, this is a very old discussion, but I am confused:

In the official ESPHome documentation, there is the lambda-example:

  - platform: template
    name: "BME680 Indoor Air Quality"
    id: iaq
    icon: "mdi:gauge"
    # calculation: comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh]
    lambda: |-
      return log(id(gas_resistance).state) + 0.04 *  id(humidity).state;
    state_class: "measurement"

(Source)

Isn’t the comment # calculation: comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh] giving a different formula then actually calculated in the lambda?!

What is best practice: do you go with the BSCE-configuration or the general configuration?

Would be nice, if someone could clarify this.