feat: Add SCD4X

[oscgonfer]

This PR adds support for the SCD4X CO2 sensors by sensirion.
It builds upon on the great work by @Coloradohusky, @hafu and @fifieldt in #4601 and https://github.com/hafu/meshtastic-firmware/tree/add-scd30 (although it doesn't add SCD30 support).

This PR tries to sync that work with the current state master branch, and it's rebased on top of #7190, which is an attempt to decouple AirQualityTelemetry from PMSA0003I sensor (I have just ordered one sensor to test). I also started using the new Sensirion library for this sensor, which has a new release (and a very annoying change in the library name import).

This also goes along with meshtastic/protobufs#719 to support having real temperature and the sensor temperature separately. Testing it, you can see some differences between two sensors that are right next to each other (SHT31 and the one inside the SCD4X).

decoded {
  portnum: TELEMETRY_APP
  payload: "time: 1751450604 air_quality_metrics {   co2: 1602   co2_temperature: 28.4126797   co2_humidity: 55.2819099 }"
}

decoded {
  portnum: TELEMETRY_APP
  payload: "time: 1751450589 environment_metrics {   temperature: 31.69   relative_humidity: 50.19 }"
}

There are some comments that I point in the code directly below. I also tried to make it work with the screen, but I don't think my system allows for testing it ATM.

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Seeed ESP32-S3 Xiao board

[oscgonfer]

An additional comment: these type of sensors generally require a "control" interface to enable or disable features. This is mapped here - and could be a good outcome of the hackathon.

[thebentern]

@oscgonfer protobufs are merged and generated upstream now

[oscgonfer]

rebased onto #7202 - just to keep in mind that the sensirion library needs to be 1.0.0 @thebentern

[fifieldt]

sensirion 1.1.0 was released - updated upstream.

[oscgonfer]

sensirion 1.1.0 was released - updated upstream.

Merged

[hafu]

Thanks for your effort! I can confirm it works with:

• Heltec v3
• RAK11310
• RAK4631 (needs some fixes in Move PMSA003I to separate class and update AQ telemetry #7190

[oscgonfer]

Thanks for your effort! I can confirm it works with:

* Heltec v3

* RAK11310

* RAK4631 (needs [some fixes](https://github.com/meshtastic/firmware/pull/7190#pullrequestreview-2990183787) in

Thank you @hafu ! I fixed and rebased #7190

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[oscgonfer]

Hi @paulwalko @hafu

Do you want to give this a go? I believe it'd be final

[paulwalko]

Hi @paulwalko @hafu

Do you want to give this a go? I believe it'd be final

Looks good to me! Verified with a diy nrf52 node to take measurements (scd41 only) + rak 4631 to upload them.

[oscgonfer]

Cool! I need to fix a minor detail on the Sen5x part, but it'd be done shortly! I'll mark it as ready when it's done!

[hafu]

Hi @paulwalko @hafu

Do you want to give this a go? I believe it'd be final

I'll try to test this next week with at least a Heltec v3

[oscgonfer]

Resolved conflicts on merge. All good on my end, but let's see after tests.

[Tomas-Kuchta-FPV]

Thanks for yor work. It seems to be working.
The high value is me breathing on it.

[hafu]

Can also confirm it works using a Heltec v3.

I also have a MCP9808 temperature sensor connected to the I2C bus. At first it won't work and I got only SCD4X: Data is not ready messages. After connecting only the SCD4X sensor it worked immediately (after reset/reboot). Connected the MCP9809 again and no problems since. I assume it was the wiring on the bread board, which lead to communication issues on the I2C bus.

[oscgonfer]

Thank you both @hafu and @Tomas-Kuchta-FPV for testing. Admin commands are now (WIP) implemented in meshtastic/python#903 in case you want to give it a whirl. The commands are used to modify calibration parameters and other config settings.

[Tomas-Kuchta-FPV]

Thank you both @hafu and @Tomas-Kuchta-FPV for testing. Admin commands are now (WIP) implemented in meshtastic/python#903 in case you want to give it a whirl. The commands are used to modify calibration parameters and other config settings.

I'll test it out.
Just one more thing is that the mobile apps also need to support the CO2 measurement and show it in measurements. I have tried to set up android studio but there seems to be a memory leak with linux, it gobles up ram and crashes. 😅