CO2 on a giant screen for bars, restaurants, classrooms and the like.

There are many people who are looking for a CO2 meter with large display that can be seen from a distance for installation on catering, schools, gymnasiums and the like.

The truth is that the system is so flexible which, as you will see below, not only allows for the creation of huge display panels (from 5″ mobiles to 7″ tablets, 12.9″ iPads up to 100″ Smart TVs), but it is possible to create extremely small screens, like the floating teacher window I show below.

During this time I have carried out various prototypes and experiments with different types of displays. I have used large seven-segment LED displays, matrix panels, addressable panels, etc.

The problem I was facing was, on the one hand, the rigidity (each person has different tastes and needs and it would have been necessary to adapt the system to many different types of hardware) on the other hand the construction difficulty and the cost.

Finally, I said to myselfwhy not take advantage of the fact that the CO2 meter has a complete integrated web server and use it for display on all types of screens??

Said and done, I rolled up my sleeves, I got to work and today I bring you the result...

It's not finished yet, but I want to give you a taste of what's to come.

My knowledge of CSS (I know my way around it, but I haven't mastered it) makes it go slower than I would like, and gives me a lot more work than necessary.

If you have CSS knowledge and want to collaborate, please write me through the Telegram group. With a little help we can achieve something very, very attractive and interesting and many people in need will be able to benefit from it.

CO₂ Meter on monitor or TV

Benefits of CO₂ on the big screen

Being based on HTML, CSS, and JavaScript (the web technologies)There are many benefits to be gained from this large screen display system.

Apart from the obvious benefit, which is possible viewing information remotelywe would have the following:

  • Great flexibility content and design
  • No investment. There is no need to no more than the homemade CO₂ meter on this blog (and the device where you want to display it, of course).
  • Adaptable to all types of devices (Phones, tablets, computers, Smart TV, etc.).
  • Possibility of design responsive (self-adaptation to the display device).
  • Multiple simultaneous clients.
  • Possibility of integrating other sources of information.
  • Complete freedom of choice colours, sizes, fontsetc.
  • System fully autonomous (no internet connection required)
  • No library dependencies such as jQuery or others.
  • Customisable logo (I take everything) easily.
  • Possibility to define several pages with different layouts.

Possibilities of the CO₂ meter on large display

Although, for the time being, it is only a prototype (I will soon publish instructions and the necessary filesOn this page, so that you can do the same), the visualisation system already has the following functionalities:

  • Display of any parameter emissions from the CO₂ meter (such as temperature and humidity, in these examples).
  • Real-time visualisation without reloading the page.
  • Display of historical graphs (from Thingspeak or others).
  • Colour changeaccording to the level of CO₂ (traffic light effect) with user adjustable levels.
  • Possibility of displaying external data.

Of all of them, which will be useful to one person or another, I think that the most interesting and useful for everyone is that the display always shows the current CO₂ value. You don't need to reload the page or press any buttons to get the current data.

Display devices

There are many devices on which CO2 visualisation is possible. Whether you need a small stand-alone system, with a tablet, for example, for medium-sized spaces such as a Large format TV, for large venuesyou always have a choice.


The tablet is the display device par excellence.

There are really cheap Android tablets, even older tablets, that you may not use anymore, that you can use for this, giving them a new youth.

They are ideal to put them on fixed to the wall with some kind of bracketlike this one:

Dockem Koala Mount Tablet Wall Mount: Damage-Free Universal Wall Station for iPads, iPad Airs, Pro, 9.7, Galaxy Tab/Note and Other Tablets (Black Version)
  • DAMAGE-FREE INSTALLATION AND REMOVAL: Installs in less than 2 minutes using damage-free 3M Command Adhesive Strips (included) that are rated to hold up to 2.25 kg each; no screws or holes required; designed for use on flat, smooth surfaces (screw-on versions, Koala Mount with screws and Koala Mount 2.0, sold separately).
  • UNIVERSAL: Uses 2 separate mounts that can be configured to any distance required by your device, allowing full width compatibility. This includes iPads 1, 2, 3, 4 and the new iPad 9.7, Pro, Air, Air 2, most Samsung tablets and many more. The mounts will fit any device 11mm thick or less. Can be used with protective cases as long as they are less than 11mm thick.
  • SIMPLE: Super easy to attach and remove, can be set to portrait or landscape mode. No extra accessories needed; no special cases or additions to your tablet. Full access to ports/buttons on devices larger than 7-8'' can work best with our Koala Mount 2.0. Pre-installed cable clips to help keep your cable tidy.
  • MOUNTING: They come with 3M Regular Command strips that are not designed to work in areas exposed to high temperatures or humidity (such as the bathroom). For this, 3M manufactures special strips that are water and heat resistant. In addition, Command strips do not tend to work well on textured surfaces and some papers. We highly recommend our Resistance Test. Command strips are not reusable after they have been removed.
  • COMPATIBILITY NOTE: While it fits most popular tablets, the mounts can lock ports/buttons on both sides between 3.8cm and 9.5cm from the bottom (7-8'' tablets such as the iPad Mini can have ports locked in landscape mode - if this is the case see our Koala Mount 2.0).

Smart TV

Most Smart TVs in recent years support HTML, CSS and JavaScript (internet technologies) so it will be very easy to use them as a CO₂ display device.

This is a perfect solution for really big rooms where we need information to be seen from all points.

We can put a SmartTV from 4K and 58″for relatively little money than will be seen from far away.

No products found.

regular TVs (with the help of, for example, an Amazon Fire TV Stick)

If you have a slightly older television, or any monitor with HDMI inputYou can use it to display CO₂ levels using, for example, a Fire TV Stick:

Fire TV Stick Lite with Alexa Voice Command Lite (no TV controls), HD streaming
  • Our most affordable Fire TV Stick: fast streaming playback in Full HD quality. Comes with Alexa Voice Remote Lite.
  • Press the button and ask Alexa: use your voice to search for content and start playback in multiple apps.
  • Thousands of apps, Alexa Skills and channels, including Netflix, YouTube, Prime Video, Disney+, DAZN, Atresplayer, Mitele and more. Subscription charges may apply.
  • Amazon Prime members have unlimited access to thousands of movies and series episodes.
  • Live TV: watch live TV shows, news and sports with subscriptions to DAZN, Atresplayer, Movistar+ and more.

Teams of teacher, monitor, supervisor, etc.

It's not all giant screens. Sometimes the essence comes in a small bottle.

Sometimes it is important that the teacher, monitor, supervisor, etc. have the possibility to see permanently the level of CO₂ in the environment.

In this image (bottom right) you can see how a small window "floats" on the teacher's computer over and above what he or she is doingallowing you to view the CO₂ level at all times. The teacher can drag the window to relocate it, resize it and, of course, hide it.


As with everything else, this system also has its limitations.

These are the ones I know of so far (if you discover another one let me know so I can include it).

  • Low security: Not valid if you want to show "sensitive" data. It is intended for public data, so you don't care if someone, in whatever way, connects and gets it.
  • Concurrent users: The microcontroller used in the CO₂ meter (ESP8266) is not a real web server, so it won't support many connections at once. I have tested it with four simultaneous connections and it works, but I don't know how many it would support. This is intended for connecting a few display devices, not for a bunch of people connecting to the CO₂ meter directly.

Examples of visualisation

I will leave you here some examples of what I am doingto give you an idea:

Recommended Tablets

Almost any tablet should do as a display device. Of course, there are so many models that it is difficult to know a priori whether any of them will not work for some reason.

Most importantly, when used as a display device is the tablet is capable of being on and charging simultaneously. Almost all of them do, but not all, I, for example, have one that, even if it is plugged inThe battery consumes more than it charges, so after a few hours it shuts down.

I recommend that you buy your tablet from Amazon, where you will be able to return it and exchange it for another one if it does not work, without any problem.

Here are some of Amazon's best-selling tablets:

Bestseller No. 1
PIXPEAK Tablet 10 Inch Android 13 with 5G WiFi Tablet, 19GB RAM+128GB ROM(1TB Expandable), Octa Core 2.0 GHz Tablet, 8000mAh, 5MP+8MP, FHD, WLAN, Bluetooth, GPS, Tablet with Keyboard ect (Or)
  • 🔥【Android 13 & Maximize your privacy】🔥The tablet is equipped with Android 13.0, New Material You design language makes your tablet more personalized; new privacy information management function, maximize your user experience and privacy protection, making it more convenient and enjoyable to use.
  • 🚀【19GB RAM+128GB ROM & Octa Core Processor】 🚀The tablet is equipped with 19GB (8+11) RAM, which provides enough power for your apps to run smoothly even with multiple apps, and you can download thousands of photos and many videos. It also comes with a high-performance octa-core up to 2.0GHz for a more comfortable experience.
  • 🌐【5G WiFi & 8000 mAh Battery】🔋By connecting to WiFi or mobile hotspot, you can have video conversations with friends or family at any time, and the 8000 mAh battery capacity gives you longer battery life, providing an amazing user experience.
  • 💻【Metal Body & 10.1 inch FHD Display】💻The tablet is equipped with metal body, looks more premium, and the 10.1 inch FHD display offers excellent viewing of different environments. In addition, the tablet features an eye protection mode and a dark mode that automatically adjusts and optimizes the backlight to protect our eyes.
  • 💖【Package Contents & After-sale Quality】🎁Platet Package Contents: PIXPEAK Tablet*1, Protective Case*1, Bluetooth Keyboard*1, Mouse*1, Earphone*1, Charger*1, Charging Cable*1, OTG Cable*1, User Instructions. The tablet supports 2 years warranty time for long term use (no man-made damage). If you have any questions, we will reply you within 24 hours.
SalesBestseller No. 3
FACETEL Tablet 10 Inch Android 13 Tablet Octa-Core 2.0 GHz, 12GB RAM 128GB ROM (1TB TF), 5G WiFi, 5MP+8MP Camera, Bluetooth 5.0, 6000mAh, HD 1280 * 800, Facciale ID, Tablet with Case - Rose Gold
  • 【 Android 13 & Octa-Core 】Tablet uses the most advanced Android 13 operating system and 2.0 GHz Octa-Core MTK processor to ensure it downloads required apps faster and provides super smooth video playback speed and gaming experience. The latest operating system can also automatically clean and filter junk and unwanted ads.
  • 【 5G Wi-Fi and 12GB(6+6)RAM+128GB ROM / TF 1TB 】Tablet 10 Inch supports 5G and 2.4G Wi-Fi frequency band connection. 5G WiFi is suitable for all home networks and can connect to all networks at will. 12GB RAM (6GB RAM + 6GB RAM expansion) and 128GB ROM, the memory can be expanded to 4-1TB, large capacity to meet the daily needs of work and learning, such as YouTube, Netflix, Whatsapp, Facebook, Tiktok, Instagram, Glovo, Fever, Etc.
  • 【 6000mAh & HD Display 】Tablets have a built-in 6000 mAh battery. Once the tablet is fully charged, the battery life can reach 6-8 hours. It supports 5G Wi-Fi, Bluetooth file transfer. The tablet uses a 2.5D HD IPS display with a resolution of 1280 × 800. The 5 MP front and 8 MP rear HD cameras make it easy to record wonderful moments. Note: The Q6 Tablet does not support SIM card.
  • 【 Tablet Accessories & Best Gift 】Android 13 tablet comes with 1 leather case, 1 protective film, 1 charging head and 1 Type-C cable. The net weight of the tablet is 430g and the thickness of 0.9cm makes the whole tablet looks light and flexible, so you can easily carry the tablet in your backpack for some fun outdoor activities or short trips.
  • 【 Lifetime Product Warranty 】FACETEL Q6 Tablet is a great Christmas gift for your family or friends! With a professional support team with 10 years of experience, if you have any problems with your purchase, please contact us as soon as possible via Amazon mail. Upon receipt of an email from Amazon, we will respond quickly and provide technical support and answers to questions, as well as a lifetime warranty.
Bestseller No. 4
DMOAO Tablet 10 Inch Android 12 with 5G Wi-Fi, HD Tablets with 8GB RAM + 64GB ROM (TF 1TB), GPS, 8 Cores 2.0 GHz, Bluetooth 5.0, USB-C, 6000 mAh, 1280*800, Tablet with Keyboard + Mouse + Case, Blue
  • Enhanced 5G+2.4G WiFi : The D3 tablet uses an enhanced dual-band network acceleration engine. Compared to other tablets in its class, the D3 tablet improves data forwarding speed by 80% from hardware quickly. It improves network performance, reduces interference, but also provides a wider reception range for faster, more stable and reliable networks. It gives you a smooth experience in web browsing, video playback and video calls.
  • Android 12 OS: The D3 tablet runs on Android 12, with more comprehensive features and APIs. The Android tablet is Google GMS certified and pre-installed with Google Play Store, so users don't worry about downloaded apps with vulnerabilities or malicious advertising behaviour. D3 offers a greater sense of control, such as intelligent analysis of power-consuming apps or restricting the reading of location information.
  • Expandable 8GB RAM and 1TB ROM: D3 tablet has original 4GB RAM and 64GB ROM. With support for storage expansion up to 1TB, you have more space to store your beloved files, photos and videos. With more freedom to choose to expand the internal storage from 1GB - 4GB RAM to enhance the system running experience, you can also have up to 8GB RAM fully with 4GB (original) + 4GB (expanded) to double the running speed of the tablet.
  • Thin and light 10.1 inch tablet: The D3 tablet is 18% lighter than other tablets on the market, with a bare tablet weight of 430g. The 6mm thickness makes the whole tablet feel light and nimble, so you can easily put the tablet in your backpack to give you some fun for outdoor activities or short trips.
  • After-sales service warranty: D3 tablet PC offers 24 months warranty service. There is a limited time complimentary extended warranty activity. With 7 days after purchase, please contact DMOAO service through Amazon to receive additional 24 months extended warranty service for free. We promise to solve your tablet problems with the best service attitude and fastest speed.
SalesBestseller No. 5
DOOGEE U10 Tablet 10.1 Inch, WiFi 6 Android 13 Tablet, 9GB RAM+128GB ROM, 1280 * 800 IPS Tablet PC, TÜV TÜV Rheinland, 5060mAh, Face ID, OTG, Bluetooth 5.0, 8MP+5MP, Grey
  • 💛【Android 13 +WIFI 6】DOOGEE U10 tablet features advanced Android 13 system, quad-core processor with 2.0 Ghz CPU, ultra-fast app launch and responsive touch control. The DOOGEE U10 tablet features ultra-fast WiFi 6 connectivity for higher capacity, lower latency and more stable network connections. The tablet pc is Google GMS certified and is available to download tens of thousands of stable apps from the Google Play Store.
  • 💜【9 GB RAM + 128 GB ROM+ 1 TB】The 10 inch tablet provides 9 GB memory (expandable 4 GB + 5 GB), allowing you to launch apps quickly, 128 GB storage space, plus 1 TB expandable TF card, this tablet can store more books , programs or movies and easily switch between apps while working or studying. The DOOGEE U10 tablet supports TÜV eye protection mode, making it the most convenient gift choice.
  • 💛【10.1 Inch IPS Display + Facial Recognition】The DOOGEE U10 Android tablet is equipped with a 10.1 inch 1280*800 high resolution IPS display. The 10.1-inch screen offers more space and is perfect for watching movies, videos and browsing websites. As a gaming tablet with front and rear cameras, you can not only video chat with family, friends and colleagues, but also unlock the screen with facial recognition.
  • 💜【WiFi 6 + 5060mAh + OTG】DOOGEE U10 tablet is equipped with Wi-Fi 6 and Bluetooth 5.0, which has higher capacity and faster speed than Wi-Fi 5, and the network connection is more stable. The U10 tablet pc has a 5060 mAh battery that allows you to use the tablet for extended periods of time with power saving mode enabled and also charge other devices. The 8 megapixel rear camera is ideal for selfies.
  • 💛【TÜV Eye Protection + Widevine L1 Certification】The 10 inch tablet has passed TÜV Rheinland Blu-ray certification and you won't feel pain in your eyes after prolonged use. The tablet also supports Widevine L1, which means you can enjoy high quality content on all video sites. U10 tablet is the best gift for your family and friends, birthday and Christmas! Note: The Q6 tablet does not support SIM card!

If you use any tablet sold on Amazon (whether it is included in this list or not) let me know, with the results obtained, so that I can advise users.

6 thoughts on “El CO2 en pantalla gigante para bares, restaurantes, aulas y similares”

  1. Hello,

    Lately I follow your blog day by day. I am a teacher and I am about to start the CO2 meter project, with students. From what I can see in an image, it seems that you use Thingspeak to publish the sensor readings, I have tried but I have not been able to do it, I have just discovered ESPeasy and I still do not understand the platform well, nor MQTT. However, with Arduinoblocks I haven't had any problems. Could you point me to a tutorial to connect to Thingspeak? I don't think I'll have problems if it's in English.
    I also noticed in the MH-Z19B video that there doesn't seem to be much difference between the results of the original MH-Z19B and the reference Senseair, right?
    Greetings, and thank you very much for all the work you do and show us.
    Thank you

  2. Hi, can you please post at least the basics to be able to view the data on a tablet? Even if it's just the real time value! Thank you very much for the work! Best regards

    • Hello Jordi.

      We are just taking it up again, with the help of our colleague Sey. Let's see if we can give it a good push and publish it soon.

      Best regards.

  3. Hi, how is this project going. I would like to try it out for my premises.
    It seems to me that they are going to make it compulsory.
    I've ordered the parts to start assembling it. I'll keep you posted with my problems 🙂

    Best regards.


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