CO2 Gadget: High-Quality CO2 Meter with ESP32

Last modified 2 years

I’ve been building CO₂ meters and testing firmware for years, and I can assure you that CO₂ Gadget It’s the best I’ve seen for the ESP32. A web interface with an Apple-style design, full integration with Home Assistant, particulate matter sensors, low power consumption for months of battery life… and it’s all open source.

If you’re looking for a reliable CO₂ monitor, with no restrictions or subscriptions, you’ve come to the right place.

Quick installation

Install CO₂ Gadget on your ESP32 with a single click from your browser.

TasteVersionDateInstall
TTGO_TDISPLAY_SANDWICH v0.014.00609-06-2024
TTGO_TDISPLAY v0.014.00609-06-2024
TDISPLAY_S3 v0.014.00609-06-2024
esp32dev_OLED v0.014.00609-06-2024
esp32dev v0.014.00609-06-2024
esp32dev_ST7789_240x320 v0.014.00609-06-2024
ttgo-t5-EINKBOARDGDEM0213B74 v0.014.00609-06-2024
ttgo-t5-EINKBOARDDEPG0213BN v0.014.00609-06-2024
ttgo-t5-EINKBOARDGDEW0213M21 v0.014.00609-06-2024
ttgo-t7-EINKBOARDGDEM029T94 v0.014.00609-06-2024
ttgo-t7-WEACT_GDEH0154D67 v0.014.00609-06-2024
ttgo-t7-WEACT_DEPG0213BN v0.014.00609-06-2024
ttgo-t7-WEACT_GxEPD2_290_BS v0.014.00609-06-2024

Choose the flavour you want to install and follow the instructions.

  • TTGO_TDISPLAY_SANDWICH: TTGO T-Display board with I2C sensor on alternate pins (SDA on 21 and SCD on 22)
  • TTGO_TDISPLAY: TTGO T-Display board with I2C sensor on normal pins (SDA on 21 and SCD on 22)
  • TDISPLAY_S3: T-Display S3 board with I2C sensor on normal pins (SDA on 42 and SCD on 43). Available soon.
  • esp32dev_OLED: Generic ESP32 board with OLED display (SH1106 128X64)
  • esp32dev: Generic ESP32 board without display
  • esp32dev_ST7789_240×320: Generic board with 240×320 TFT display and ST7789 controller
  • ttgo-t5-EINKBOARDGDEM0213B74: Lilygo TTGO T5 with e-Ink display with panel GDEM0213B74
  • ttgo-t5-EINKBOARDDEPG0213BN: Lilygo TTGO T5 with e-Ink display with DEPG0213BN panel
  • ttgo-t5-EINKBOARDGDEW0213M21: Lilygo TTGO T5 with e-Ink display with panel GDEW0213M21
  • ttgo-t7-EINKBOARDGDEM029T94: Generic ESP32 board with e-Ink display GDEM029T94
  • ttgo-t7-WEACT_GDEH0154D67: Generic ESP32 board with WeAct Studio e-Ink display GDEH0154D67
  • ttgo-t7-WEACT_DEPG0213BN: Generic ESP32 board with WeAct Studio e-Ink display DEPG0213BN
  • ttgo-t7-WEACT_GxEPD2_290_BS: Generic ESP32 board with WeAct Studio e-Ink display GDEM029T94 BS

Optional, clear the memory:

When uploading the firmware you have the option to select "Erase device", which will first erase the ESP32 memory and reset all settings. Recommended when installing CO2 Gadget for the first time.

⚠️ First time? Brand «Erase device». Installation Guide.

Features

  • 20+ sensors — CO₂, PM and environmental factors. Sensors Guide.
  • 5 protocols — Wi-Fi, BLE, MQTT, ESP-NOW.
  • 3 screens — TFT, OLED, E-Ink. Web UI.
  • Low consumption — Up to 3 months. Low Power.
  • Open source — GPLv3. Why?

Support

Telegram · GitHub · FAQ

53 thoughts on “CO2 Gadget: Medidor de CO2 de Alta Calidad con ESP32”

  2. Hi,

    Very impressed by your gadget. I am using MH-z19 CO2 sensor and not sensirion. How could I activate it?
    Thanks

  3. Hi Mariete,

    I am using the T-Display board, one of my buttons is broken. I am using the Serial Monitor to enter information. In the WiFI menu, how do I clear data so I can enter my home SSID/PW?

    SSID: You must enter the SSID, the "name", of the access point you want the CO2 Gadget to connect to.
    I don't see a method to clear the previous entry.

    Thanks for the wonderful Tutorial and your software!

    • Hi Joe.

      You don't need to clear the previous data. Simply type your SSID/PW overwriting the old value. If the old value was longer than the new data you can simply overwrite the rest with spaces (CO2 Gadget will clean the leading spaces on save).

  5. Hi,

    First of all thank you for the nice work and effort you put into this project!

    I can confirm that it works with the CO2 Sensor" MH-Z19. (esp32dev_OLED) I'm using you're latest version 5.0.41.

    I have some questions about the Neopixel led, I can't get it to work on pin26. The individual (green P25, yellow P32, red P33) leds are not a problem.
    Also the 2 push buttons on pin 35/34, I can't get to work. Pin 34 is also used for the battery?
    (tried with pin0 but also nothing). Controlling the menu with serial commands for the moment. Can you please tell me what I can try next?

    One final question, if I understand correctly only co2 sensors are supported for the moment? Because on your github page there are some pm and environmental sensors supported. If needed I'm willing to try some.

    • Hi Bart.

      The support for Neopixel is not in the latest release yet, it's still in a private beta (I was just documenting it yesterday). Will be released over the weekend.

      Let me fix the buttons issue, please. I hope it will be fixed today.

      Support for PM 2.5 is coming. I'm waiting for a fix in a third-party library. I guess it will be ready soon.

      Best regards.

  6. Hi Mariete,

    Thank you again, also for the very fast response.
    I tried the Neopixel part. It's working but I have the wrong type of pixels because the colours are wrong 🙂 Green is red and vice versa.
    I cannot conform button p36 because my esp32-wroom version doesn't have a pin 36.
    I'm also testing the TTGO_TDISPLAY version with Sensirion SCD30.
    If you need more testing I can help you with that but I'm not a guru like you.

    • Hi Bart.

      I had no time to test the Neopixel LED myself. Maybe, it's a bug. I'll try to test it as soon as possible with some original WS2812B (hope today, tomorrow at most).

      Please, try again the updated version with buttons on pins 35 and 0. I realized it makes no sense to have buttons on different pins than those of TTGO T-Display for the "generic ESP32 flavor".

      Please, check (on display or serial terminal) that the loaded version shows, at least, "v0.5.047-feature-neopixel" as there are situations where server or browser cache can serve an outdated version.

      Any testing with new versions is very welcome as I have no time to test each version with different hardwares.

      Thank you for your kind words. No, I'm not a guru! 😀

      • actually there are a lot of flavors of ws2812b led chips/strips, so controllers usually have settings to switch rgb/gbr/brg and other combinations...

        • Thanks, Jakub.

          The only addressable LED introduced right now in this precompiled beta is the original WS2812B. In future versions there will be more addressable LED supported but, before introducing the needed code to select and including it in the menu, I prefer to have some feedback with the original WS2812B, as it's the most widely used and the only one I have.

          Internally CO2 Gadget supports many different addressable LEDs (all the Adafruit library supports). So, you can compile your own version supporting any other with just one line change in code.

          Right now, the issue Bart is having can be a bug where I drive the wrong colour, as I didn't have the time to test it myself.

          • Here I'm back with an update. I hope that you like the feedback.
            It's tested with the latest beta version v0.5.047 as stated in the menu.
            I tried the buttons, button P0 is working perfect but P35 doesn't.
            I will try another esp32 to rule this out.
            As jakub said my Neopixel "problem" will probably be the flavour rgb/gbr/brg.
            Is it possible there is a bug in the menu for the display?
            menu (4) configuration - (7) Display Config - (2) Time to off.
            If I change this other then 0.
            I get error unfunctional, TO DO Main turning off display to save power.

            I also tested the TTGO T- normal version with the Sensirion SCD30.
            I like the colour tft. Can I ask what offset you use for the temperatur?
            Tested the app (not in detail yet), wifi all looks fine.
            The MQTT part is next. I try to test as much as possible for you.

            I have esp-easy firmware with a Sensair S8 next to it but the value of the co2 is roughly 100ppm different than the SCD30.
            Going to put a MH-Z19 with CO2 Gadget side by side to compare all three.

          • Hi Bart.

            Thank you very much. This feedback help me a lot to improve CO2 Gadget and fix things.

            I will build a rig with OLED to test the buttons and some other things (I don't have one built right now for testing). Have you checked (on display or serial terminal) that the loaded version shows "v0.5.047-feature-neopixel"?

            I plan to add over the weekend the LED configuration to the menu so it's possible to select RGB, GBR, NEO_RGBW, etc (there is a place where you can see the "status": https://github.com/melkati/CO2-Gadget/issues/72)

            The issue regarding the "(4) configuration - (7) Display Config - (2) Time to off" problem is because the OLED support, right now, is very limited. Here you can see whats pending to do: https://github.com/melkati/CO2-Gadget/issues/51

            The temperature offset depends a lot on enclosure, TFT brightness, etc. with the compact enclosure in a sandwich configuration I have an offset of 13ºC.

            My S8 and SCD30, when in the range 400 to 1000ppm, usually are within 50 ppm one of another:

            If you check on LOGS & CONSOLE

            and then click on RESET DEVICE you can see the first log messages where the version information is:

          • Hi Bart.

            There is a new "Beta-Development Version" (https://emariete.com/en/meter-co2-gadget/#Version_Beta-Desarrollo) that adds a configuration menu ("Neopixel Config"under "Configuration") to choose one of the supported Neopixel types (I'll add more in the future) and brightness.

            Please, after updating make sure it show, at least, "CO2 Gadget Version: 0.5.049-feature-neopixel Flavour: ESP32 OLED".

            Hope it fixes issues with your Neopixel flavor. Please, give me feedback when you have the time to test.

          • Hi Bart.

            The issue with button UP connected to GPIO35 should be fixed now with the new release v0.5.069.

            The issue was, probably, that you didn't have a pull up resistor connected to the UP button. It's fixed now by changing button UP to GPIO15 without needing any resistor. I had to change GPIO as it has a internal pull up (old GPIO35 doesn't have internal pull up).

            Please, if you find any problems, open an issue at CO2 Gadget GitHub repository by pressing green button "New issue".

  7. hello,
    thanks for great work man.
    I made my printed box bigger to fit 18650 cell inside.
    When I try to download history using sensirion app, download state is stuck at 0%, have anyone experienced that?

    • Great! 😀 😀 Great!

      Will you be sharing the box design? I'm preparing a post with some different enclosures so each user can choose the best for him depending on sensor, display used, battery, design preferences, etc. There are already a few of them users sent me, some on Tinkercad.com, so other users can modify to their needs, some others on Thingiverse.com.

      Regarding the download from the App, may be it's a bug introduced in one of the last versions. Could you open an issue for this at GitHub, please?: https://github.com/melkati/CO2-Gadget/issues

        • Great, nice case! Thank you! 😊

          I'll prepare a post on the blog over the next few days with all the available cases for CO2 Gadget and will include these. 👍

          • now I realized that I am using mh-z19b which needs 4,5-5,5V and using the battery it gets only 3,6-4,2V depending on state of charge. I tried powering it using powebank, I measured 4,7V on pins, and values were the same (tested at 500 and 1500ppm level) as from the 4V battery. Do you think it is crucial? I read your article about mh-z19c, which is more picky about the voltage.

          • Hi Jakub.

            The CO2 sensor's power supply is extremely important to have good readings.

            Not only the voltage must be within the specs indicated by the manufacturer but also, the voltage must be stable. You should not power a CO2 sensor directly from the battery because as the voltage drops as the battery discharges the measurements will change.

            Actually, you must calibrate the CO2 sensor at the voltage it will be used later. If you calibrate the CO2 sensor at one voltage and later, you use the sensor with a different voltage the measurements will be wrong.

            The solution to use 5V CO2 sensors on battery is to use a "step up module. More on this here: Adding battery charger to ESP8266 and ESP32 (well done)

            I hope this information is useful to you.

  8. I download the sources, for use with Arduino Ide, and I get a lot of broken includes errors.
    Impossible to compile and upload.

    • Hello Chema.

      No files are missing, everything is in the CO2 Gadget repository on GitHub..

      As explained in the instructions and in the code comments, the code is currently not ready to compile with the Arduino IDE and the instructions are not up to date. If you want to compile with the Arduino IDE, you will have to resolve includes, dependencies and defines yourself.

      When the code is more stable and has less changes I will adapt the code and write the instructions to compile with Arduino IDE (right now it is modified very often with bugfixes and new features and it takes me a lot of time to be aware of maintaining compatibility with Arduino IDE).

      I recommend you to use VS Code with PlatformIO. There are many tutorials on the internet and it is not as difficult as it seems.

  9. Hey Mariete,

    I like your Project really much.
    I want to go on with it on my own, but I am not able to upload the code in arduino IDE, because there is a file missing:
    #include

    Can you tell me, where I can get the file and where to put it? I am trying the last version from GIT.

    I am planning to build more of the devices and to send the data to a database from where I want to go on...

    • Hi Tim.

      There are not files missing, everything is at CO2 Gadget's GitHub repository.

      As explained in the instructions and in the code comments, currently neither the code is ready to compile with the Arduino IDE nor the instructions are up to date. If you want to compile with the Arduino IDE, you will have to solve includes, dependencies and defines yourself.

      When the code is more stable and has fewer changes, I will adapt the code and write the instructions to compile with the Arduino IDE (right now it is modified very often with bugfixes and new functionalities and it takes me a lot of time to be aware of maintaining compatibility with the Arduino IDE).

      I recommend that you use VS Code with PlatformIO. On the internet you have many tutorials, and it is not as difficult at all as it seems.

  10. Hi,

    I have tested the Version: 0.5.049-feature-neopixel Flavour: ESP32 OLED (empty> flash)
    The Bright settings work.
    I can clearly see the setting changing the led from red to green and vice versa but saving the settings and reboot puts the led back to red when it should be green. After checking the settings again after the reboot they are correctly saved. (I have the rgb version). If I toggle them again, it gets the correct colour again.
    I also have the rgb leds connected. I see 700 orange, state in between orange and green. >1000 I have orange and red. But only red I don't have.
    If you want pictures or something, just let me know where to send them.
    The Bright settings work.

    • Hi Bart.

      Thank you for your feedback. It's unbelievably valuable to me.

      So, looks like it's not applying the saved configuration at startup. I'll fix this in the next version.

      Regarding the RGB LED not turning off the orange when turning on the red, it is normal, as these outputs double as relay outputs. If you look in the FAQ at the point "...".Can CO2 Gadget turn ventilation equipment on and off?" the orange output is not turned off when red goes on (to keep ventilation or air cleaning equipment working when CO2 rises). To fix it when working with LED I'll include a new option in menu to select if these outputs should work in "relay mode" (keeping orange on when red goes on) or "LED mode" (turning orange off when red goes on).

  11. Hey Mariete, nice project and got the waffled version running. I had some issues though on flashing from a MacBook where I moved to Windows laptop it was swifltly flashed. The LiPo battery as well: learned that batteries are not all the same size ...
    Question: to try to extend battery life: can you share the BLE message format? That way I could just read the BLE message into my home automation.

    Regards, Wim

  12. Hi Mariete,

    It seems that there is a limit for the length of the wifi password (around 28 caracters). My password is rather long with 37 car and I can't have a wifi connection. Do you confirm this limit. How to overpass it ?
    Anyway, you have done a wonderful job !!!!

    laurent

  13. Hi,

    Is it possible to integrate this CO2 project into Home assistant ?

    I know that it is possible to use SCD30 with ESPHome, but it is not possible to manually calibrate the sensor with ESP Home, whereas it is possible with your project.

    Regards

    • Hi Romain.

      Yes, it's possible.

      The best option is to integrate it via MQTT as its supported by both, Home Assistant and CO2 Gadget, and it's really powerful and simple to setup and use.

  14. I used step-up so voltage is stable 5V, but now I don't know when battery is going to die, TTGO is showing 5V all the time. We could use some analog in pin to show real battery voltage, or maybe, use step up only for powering the CO2 sensor and feed TTGO battery voltage?

  15. Hi,
    I don't understant, I can enable Wifi on my ESP32 with the OLED version firmware. I have this error :

    [WiFi-event] event: 5 - Disconnected from WiFi access point

    I enter my Wifi SSID and the correct password.

    Do you have any ideas ?

    Thanks

    • Hi Romain.

      Don't know what the issue can be here, nobody reported this before. Better open an issue at GitHub as this will need more investigation...

  16. SCD41 running just fine. On the Comm output, I see this:

    ->[SENS] CO2: 1459 CO2humi: 29.81 CO2temp: 32.04 H: 0.00 T: 0.00
    ->[SENS] CO2: 1458 CO2humi: 29.97 CO2temp: 32.08 H: 0.00 T: 0.00

    What is H: 0.00 T: 0.00? I don't know what to look up since I don't know what it could be.

    • Hi Mike.

      CO2 Gadget supports external temperature and humidity sensors (apart from the integrated sensors in the, in you case, SCD41). H: 0.00 T: 0.00 shows data from these external sensors. In your case it's zero because you don't have any connected.

    • Hi jr.

      It's a nice sensor.

      Support for PM sensors in CO2 Gadget is planned. I can't include it now as I don't have one of these sensors. If anyone wants to donate a sensor (or make a pull request to include support for it) I'll be more than happy to include it.

  18. Very nice project, hats off to you!

    Got a couple of questions:
    1. The questions in the FAQ on this page cannot be expanded. Nothing happens when I click them. I tried in Edge and Firefox, both normal and inprivate mode. Is it broken?
    2. Where can I find how to connect a MH-Z19 and a BME280 sensor?

  19. Hello,
    This is an amazing project !
    Sorry If I missed this information, but I was looking for the wiring diagram.
    My plan is to use a MH-Z19C with a TTGO T-display, a BME280 and a WS2812B LED, would this be possible?

    Thanks !

  20. Configuration web page
    In addition to being able to configure CO2 Gadget via its display and serial port, it is possible to change the options via its website.

    Hi,
    I would like to open the configuration webpage, where can I find it?

Comments are closed.