A CO2 meter with high quality colour TFT display with colour screenconnection with your mobile phone via BluetoothThe new, Wifi communication, ESP-NOW and MQTT, which you can take with you everywhere thanks to its rechargeable battery (optional) and know how, discreetly and at all timesthe quality of the air you breathe.
Here I bring you the meter TUTORIAL FOR THE CONSTRUCTION OF THE CO2 GADGET HARDWARE. The most advanced CO2 meter in existence (that I know of, at least).
Contents
This tutorial is accompanied by a video, which you can find below, with everything explained step by step and in detail so that you can build the CO2 meter with TFT colour display., CO2 Gadget, easily.
You are going to see, in a very easy way, how to prepare the hardware for the CO2 Gadget and how connect the SCD30 sensor to the TTGO T-Display Board
Below you'll find something I'm sure you'll love: My own extended and improved version of the CO2 Gadget firmware with new interesting features:
- Multiple communication modes: Bluetooth, WIFI, and ESP-Now
- More sensors supported, including CO2, temperature, humidity and pressure sensors.
- Support for more screens
- Sending data via MQTT
- Works with many different sensors and displays
This tutorial contains my own improved version, with colour display and rechargeable batteryfrom another previously published project: Mobile CO2 meter with ESP32 and Sensirion SCD30 sensor. If you haven't seen it yet, I suggest you watch it now, because it contains basic information:
Material required
To complete this tutorial, and build your own CO2 meter with TFT colour display, CO2 Gadgetyou will need:
- A TTGO T-Display Board with TFT colour display
- A Sensirion SCD30 Sensor
- A few wires to make the connections
- One rechargeable li-ion battery (optional)
- USB-C cable to connect the TTGO T-Display Board to your computer
Below, in the "Shopping basket" section, I will give you some examples of what you can buy. advice on equipment to buyas well as some useful links to places where you can buy them. at a good price and with guarantees.
Preparing the Hardware
The preparation of the CO2 Gadget hardware is very simple.
I give you two options for mounting: a version in which the sensor and the board are connected by means of small cables and a version in which the sensor and the board are connected by means of small cables and a version in which the sensor and the board are connected by means of small cables. super compact in which sensor and board are bonded together as a single compact block.
Normal" version
For the first version, carefully plug in the TTGO T-Display Board at Sensirion SCD30 Sensor as explained below. Pay attention to each wire so that it goes from the correct pin on the sensor to the correct pin on the board..
You have to connect by means of some wires:
- The VIN pin of the SCD30 to the pin marked 3V on the TTGO board.
- The GND pin of the SCD30 to the pin marked G on the TTGO board.
- SCL pin from SCD30 to pin marked 22 on the TTGO board
- The SDA pin of the SCD30 to the pin marked 21 on the TTGO board.
Sandwich version
The aim of this assembly is to achieve a CO2 meter with a TFT colour display. as compact as possible.
The sandwich version of the meter is connected by means of a pins or hard wires. In this way the TTGO T-Display Board and the Sensirion SCD30 Sensor form a single block.
- The VIN pin of the SCD30 to the pin marked 3V on the TTGO board.
- The GND pin of the SCD30 to the pin marked G on the TTGO board.
- SCD30 SCL pin to the marked pin 21 of the TTGO plate
- The SDA pin of the SCD30 to the marked pin 22 of the TTGO plate
Note that the difference with the normal version is that pins 21 and 22 are reversed.
Below is the video with all the assembly details of this version.
Note that this version is very compact and that the heat generated will affect the temperature sensor and will not be very accurate (in the advanced firmware version, you can enable a temperature offset and disable the temperature display, if you want).
The shopping basket
Here are a few tips and links to websites where you can find buy the materials.
Buying the components from these links will ensure that you get exactly the same components as in the tutorial and that everything matches (not all boards, for example, even if they look almost the same and have the same name, have all the pins in the same place or are labelled in the same way) and you will avoid possible fraud or counterfeiting.
Buy the Sensirion SCD30 sensor
This is the same AliExpress shop where I bought it and it arrived at home in 7 days..
Almost all eMariete users have purchased the sensor from this link and received it quickly.
I recommend you buy it here: Sensirion SCD30 Sensor
You also have the option to buy the sensor on Amazon. It is more expensive, but you will have it at home quickly.
- Model: SCD30
- Name: air quality sensor
Buy the LILYGO® TTGO T-Display
This is the official shop of LILYGO®, the manufacturer of the board, so you have the guarantee of seriousness and that the board is original.
I recommend you buy it here: TTGO T-Display Board
You will see that there are several versions. I recommend that you buy the one that says "4MB CH340K Chip".
Versions with 16MB are currently not supported.
You also have the option of buying the plate on Amazon. It is slightly more expensive, but you will have it at home quickly.
- Chipset: ESPRESSIF-ESP32 (Wi-Fi and Bluetooth) LX6 32-bit Xtensa 240MHz single core/dual core microprocessor
- FLASH: QSPI flash 4MB / PSRAM 8MB
- Display: IPS ST7789V 1.14 inch, USB: C-Type
- Working current: approx. 67MA, quiescent current: approx. 350uA
- Modular interface: UART 、 SPI 、 SDIO 、 I2C 、 LED PWM 、 TV PWM 、 I2S 、 IRGPIO 、 ADC capacitor touch sensor pre-amplifier DACLNA preamplifier
Step-by-step video tutorial
In the following video you will find step-by-step instructions for the construction of the CO2 Gadget meter to make it very easy for you to assemble it.
Update from the video
If you want to to achieve an even cleaner assemblyThe power supply cable of the sensor can be positioned in this way:
Note that you will have to remove the plastic from the last pin of the strip in order to solder the positive from the inside (I recommend you do this formerly welding the sandwich, it will be much easier for you).
Making these videos takes a lot of work. If you like the video don't forget to like and subscribe to the channel. That will motivate me to keep making more videos like these.
3D printed box
With the idea of the CO2 Gadget being a small and compact meter, which you can take anywhere, ideally you should use a 3D printed box.
Here you have a collection of boxes, specifically designed for CO2 gadgets, to give your project an almost professional result:
Cellular Polypropylene (PP) Boxes
If you don't have access to a 3D printer, you can make a cellular polypropylene (PP) box very easily.
Here is the complete step-by-step tutorial:
Use with battery
The first thing you have to bear in mind, in order to have the right expectations, is that this is not a low power meter, although it can be powered by batteries. so you can easily take it with you wherever you go.
The TTGO T-Display board features built-in battery charger and charge the battery connected to about 300mA (default, but can be changed by replacing a resistor) when connected via USB.
The primary use of this meter is connected to a power supply or charger and the battery is an extra to use it autonomously for a few hours from time to time. Of course, there's nothing to stop you from adding as big a battery as you like and getting much longer battery life.
In the picture below you can see one of the 3D printed case prototypes with an 800mAh battery.
In the following image you can see the consumption profile of the meter for 10 seconds:
As you can see, the meter consumes approximately 97mAwhich can be rounded up to 100mA.
This means that we would theoretically have an autonomy of approximately 10 hours of continuous operation with a 1000mAh batteryThe battery life is about 20 hours with a 2000mAh battery and about 35 hours with a 3500mAh 18650 battery. In practice, the battery life will be shorter because the hardware is not particularly optimised and will not be able to squeeze all the power out of the battery.
Please note that, as with any battery-powered device, you must use a battery that has the appropriate protections. At a minimum the battery should have short circuit, overcharge, over-discharge, and over-current protection.
Many batteries include these protections, but if yours does not, you will need to fit a protection plate like this one:
Battery protection
Battery protection plate on AliExpressAdvanced CO2 Gadget firmware
The CO2 Gadget firmware is one of the most advanced available, both in devices made by makers and in commercial devices, and has many advanced features.
In the following article you can see all about the firmware for CO2 Gadget, as well as the instructions to record it in the meter we have just built, with just a couple of clicks and without the need to install anything on your computer.
Having problems? Meter Frequently Asked Questions
Although the project is very straightforward, there is always the possibility that you may have a question or a problem.
In this list you will find answers to the most common questions and doubts.
Many of the changes applied via the website require a restart of the meter.
On the configuration page itself you have a button that allows you to reboot (remember to save your changes first).
For security reasons, password fields are disabled by default. This is because passwords are transmitted in plain text over the network, which could allow them to be captured by a sniffer or other techniques.
The recommended and most secure method of setting the passcode is via the on-screen menu, the USB menu, or via Bluetooth using the MyAmbiance application.
If you want to enable password editing, you will need to add the relaxedSecurity=true parameter to the URL:
http://ip_del_medidor/preferences.html?relaxedSecurity=true
CO2 Gadget is fully supported by Home Assistant - you don't have to do a thing!
Thanks to MQTT Discovery, Home Assistant will detect CO2 Gadget automatically and you will see it in Home Assistant without having to do anything.
Of course!
As soon as you configure CO2 Gadget to connect to your MQTT broker, Home Assistant will discover the CO2 meter automatically and you will see it in Home Assistant without you having to do anything.
The configuration through the website has limited error checking, so it is very important that you are very careful with the data you enter.
If the changes prevent CO2 Gadget from starting or configuring correctly, you may need to erase the flash memory.
If you need to reset the CO2 Gadget configuration, you will need to erase its flash memory.
The easiest way to do this is via the web recorder, by selecting the "Erase device" option:
This may be because your Windows installation does not have the necessary drivers to communicate with it.
Normally Windows 10 should download it from the internet automatically, but there may be cases where this is not the case.
Depending on the communications chip on your ESP32 board, you will need one or the other.
Choose the option that corresponds to your ESP32 board and your computer's operating system.
Drivers for CP2102 on Windows
Windows 10 - Windows 10 - Windows 10 should download automatically
Windows 7/8/8.1
Drivers for CH341 on Windows
Windows - Windows 10 should download it automatically
Drivers for MacOS
MacOS - NodeMCU with CP2102 chip
MacOS - NodeMCU with CH341 chip
Linux Drivers
You do not need to install the drivers. You can check this with dmesg
Drivers for ch9102x under Windows
Some NodeMCU boards (few, so far) have the ch9102x chip. Here you can download the ch9102x driver for Windows (page in Chinese, I have not found it in English) select the first link):
It seems that for the ch9102x to work properly it is preferable not to exceed 115200 bps.
This is BEFORE The problem with CO2 Gadget loading is usually related to a hardware error (something wrongly connected, power supply problems, USB cable, etc.).
Although CO2 Gadget supports other sensors, and all supported sensors are of good quality, I recommend one of these sensors:
Sensirion SCD30 Sensor (recommended)
Senseair S8 LP (recommended)
This is usually due to a problem with the power supply or wiring.
Make sure you are using a good quality charger. Any mobile phone charger that has an output of more than 500mA should be used. real (I recommend 1 Ampere), will do.
If you have problems with operation or if you get wrong readings, try a charger that says 1000 or 2000 mA. Often the data given by the charger is far from its real capacity.
I recommend that you use a quality power supply or charger. The vast majority of problems are due to power supply problems.
Also be careful with the cables. You can't imagine how many cables there are that give problems because of their poor quality.
If you have problems with USB power, try another USB cable. We have seen many cases here of poor quality USB cables giving problems and replacing the cable with a better one solved all the problems.
With the sandwich version you should have no problems with the connection between the board and the sensor, but if you are making the version with the sensor attached to the board by cables, make sure that the cables are as short as possible and not extremely thin.
If you are powering the sensor with a battery connected directly to the battery terminal on the TTGO T-Display board (not a battery or powerbank connected to the USB port) and you are getting erroneous readings or resets it could be for one of these reasons:
1. You are using a bad (or very low capacity) battery.
The sensor needs a stable 3.3V to function correctly. A battery in poor condition (old, worn or misused) may not be able to provide the required current without dropping in voltage, which could cause the sensor to receive less than 3.3V.
Voltage drops can also occur if too small a battery is used. For example, a 300mAh battery (to say a capacity as it depends on the particular battery) may not be able to maintain the voltage when the meter is consuming 300mA.
2. The battery voltage is below the minimum voltage that the meter needs to operate.
The meter needs to operate through its internal battery connector at a voltage of at least 3.5-3.6V (a little more or less depending on the tolerance of the components on your particular board). Below a certain battery voltage, no 3.3V will come out of the 3V pin and the sensor will give erroneous measurements or behave strangely.
This minimum voltage of 3.5-3.6V is also responsible for the meter not "squeezing" the maximum power from the battery and reducing its autonomy. You can improve this point by using an external step up to power the sensor at 5V (or step down to power the sensor at 3.3V) or a low voltage drop voltage regulator, such as the MCP1700-3.3V, to power the sensor independently directly from the battery without going through the T-Display board. I will expand on this in the tutorial as soon as I have time.
Under normal conditions the sensor measurements are quite stable and there should not be large jumps in the reported concentration unless there is a real sharp difference in the air.
If you find that the CO2 concentration measurements are too unstable (e.g. in an interior room with little movement), it is usually due to one of the following reasons:
1. CO2 sensor power supply problems: CO2 sensors need a very stable voltage to work well. If the voltage is not stable due to, for example, poor quality chargers/feeders and/or cables. Check the previous point "The meter seems to go "crazy" sometimes".
2. Air currents: The CO2 sensors we use are very sensitive to direct air currents (some more, some less) so it is important that they are protected and not directly exposed to air. Ideally, they should be placed in a suitable box.
Even if you are going to calibrate outdoors and there is some wind, you may see instability in the measurements. In this case you can even put the meter in a transparent plastic bag, not completely airtight, and press the calibration button through it. If it is already in its box you should have no problem.
CO2 sensors in a box do not need a lot of air intake to work perfectly. A small opening is enough (even the small slots left in the box for buttons, pushbuttons, display, etc.).
To find out if you are suffering from problem 1 or problem 2 I suggest that you put the meter in a box (transparent if necessary) and observe its measurements. If the measurements stabilise it is probably a problem with the air currents, if the measurements do not stabilise it is probably a problem with the power supply.
The power supply to the CO2 sensor is extremely important to obtain good readings.
Not only must the voltage be within the manufacturer's specifications, but it must also be stable. A CO2 sensor should not be powered directly from the battery, because as the voltage drops as the battery discharges, the measurements will change.
Furthermore, you must calibrate the CO2 sensor with the voltage that will be used later. If you calibrate the CO2 sensor with one voltage and later use the sensor with a different voltage, the measurements will be wrong.
The solution for using 5V CO2 sensors with battery power is to use a step up or "booster module". More on this here: Adding battery charger to ESP8266 and ESP32 (well done).
Note: The tutorial with the TTGO T-Display board and SCD30 CO2 sensor feeds the sensor at 3.3V (within the manufacturer's specifications) via an on-board regulator, so you don't have this problem. You have to pay attention if you replace it with another sensor.
Be aware that the temperature and humidity sensors are affected by the heat generated by the electronics of the meter (especially in very compact enclosures, where the temperature inside the enclosure can get quite high).
If you want accurate measurements, you will have no choice but to isolate these sensors from the rest of the meter's electronics.
You can make the displayed temperature closer to the real temperature by adjusting the "Offset" in the "Temp Config" menu. For example, I have set an Offset of 13.5ºC on the compact meter with TTGO T-Display board because it generates quite a lot of heat (relatively).
The SCD30, SCD40 and SCD41 sensors also automatically adjust the humidity deviations based on the temperature setting (offset) so that the measurements obtained are also quite close to reality.
Relative humidity is temperature dependent.
For the SCD30, SCD40 and SCD41 sensors, which adjust the relative humidity calculation based on temperature, if the temperature reading is not correct, the humidity will not be correct either.
Try to correct the temperature by applying an offset as indicated. here.
If you are using a Sensirion SCD30, SCD40 or SCD41 sensor, the temperature offset is processed by the sensor's own firmware (the program loaded into the sensor by the manufacturer).
The firmware of these sensors is implemented in such a way that the temperature offset is applied over time, so you will not see it applied all at once, but over several minutes.
Simply set the offset you need and wait several minutes and you will see it gradually take effect.
The battery voltage displayed on the screen is merely a guideline. The circuitry does not allow a very accurate battery reading and I do not think it is worth the trouble to improve this point.
If you want to have a more accurate voltage indication you can adjust the voltage reference in the "Battery config" menu.
When the battery charge is too low, the charger kicks in to recharge the battery. This additional charge can cause a drop in battery voltage. The magnitude of this voltage drop varies depending on the specific hardware you are using. It takes some time for the voltage to recover and rise above a certain threshold (currently around 4.45V) that CO2 Gadget uses to determine if it is running on external power.
As a result, it may take some time for the battery icon to reflect the switch to external power.
It is important to note that a similar voltage drop can occur when the CO2 sensor performs a measurement. For example, with an SCD30 sensor, the current can increase from around 70mA to over 270mA during a measurement, which can potentially cause the voltage to drop below the 4.45V threshold, leading CO2 Gadget to erroneously assume that it is operating on battery power.
This fluctuation may cause the battery icon to alternate between battery and external power modes.
Similarly, if the display is set to be on when connected to external power and off when on battery, the voltage drop when switching to battery mode may cause the display to turn off. This lower power consumption may cause the voltage to rise again, resulting in an on/off/on/off cycle, with the battery icon reflecting this behaviour.
It is worth noting that these problems can occur depending on the hardware used. While we cannot control the hardware on the board, the use of quality cables, a reliable power adapter and a good quality battery can help mitigate these problems.
Play around with the buttons and familiarise yourself with their behaviour. Test to get the feel of what is a long press and what is a short press.
Experiment with how text data (such as SSID and WiFi password) is entered.
At first it may seem a bit erratic and confusing but you will soon get used to it. You will see that the system is not difficult at all and allows us to do everything with just two buttons (otherwise we would have to put additional buttons).
The sensor is a delicate measuring instrument. You should take the following precautions when mounting it:
– Weld it fast, don't dawdle. The sensor is very sensitive to extreme heat.
- The sensor is sensitive to static electricity. Avoid touching the pins and components with your fingers as much as possible.
- Before touching the sensor, touch something with your hand, which is grounded, to discharge static electricity (e.g. a water or heating pipe).
- The sensor housing is not just a box, it is an active part of the sensor. Be careful not to put any force on it.
Normally everything will work the first time if you follow the tutorial step by step.
If you find yourself in the situation where you have already recorded the meter's firmware and don't know what it is doing, you can find out what is going on through the serial (USB) port on the board.
When you turn on CO2 Gadget and it starts to boot, it starts to pull information about its boot and what it is doing through the USB port.
You can view this information by installing a serial terminal program (Arduino IDE, Putty or other) to the USB port on your computer or simply by selecting the "LOGS & CONSOLE" option in the web firmware upload tool.
CO2 Gadget supports the following CO2 sensors:
Sensirion SCD30 Sensor (recommended)
Senseair S8 LP (recommended)
Sensirion SCD40
Sensirion SCD41
MH-Z19
Cubic CM1106
If you are going to use a 5V powered CO2 sensor it is very important that you read the point "How important is the power supply to the CO2 sensor?"
Yes. CO2 Gadget supports, and has been tested with, the following sensors connected via serial port:
- Senseair S8 LP
- MH-Z19 (A/B/C/D)
- Cubic CM1106 (and possibly the CM1107 although I have no reports from people who have tried it).
The pins to connect the sensor depend on the board you are using.
At the moment, there is support for generic ESP32 boards (almost any board) and the TTGO T-Display specifically.
CO2 Gadget supports many different boards and displays.
You can use a normal ESP32 development board, e.g. the ESP32 DevKitC-32D boardand how to display using, for example, a I2C OLED display with 128*64 pixel SSH1106 driver
Ask the Telegram group if you need help.
Yes, you can measure the voltage by connecting the battery positive to a pin on your board. In the table Pins used by CO2 Gadget you have the one used by default on your board.
Note that on most boards the maximum allowable value on this pin is 3.3V, while a fully charged li-ion battery can give 4.2V, so you will need to put a resistive divider on the input like this one, which divides the input voltage by 2:
You can use any 3.7v nominal Li-ion or Li-Po battery. It will depend mainly on the dimensions of the case.
The TTGO T-Display board uses a TP4056 charger chip without additional protections (overcharge only), so the battery must have, at a minimum, short-circuit, over-discharge, and over-current protection.
If the battery does not have internal protections, it would be advisable to install a protection plate like this or similar.
You can use a 128×64 pixel OLED SSH1106 display.
The OLED display has a high display qualityeven outdoors, with a fairly low power consumption (around 20mA).
Its connection could not be simpler. It is connected via I2C bus, just like the SCD30 or SCD4x sensor, just connect it in parallel with the sensor. as shown in the diagram below. 
You can use the two CO2 Gadget outputs to connect relays or contactors to activate and deactivate extractors, fans, air cleaners, etc. when CO2 levels reach certain levels.
The concentrations at which these outputs are activated are customisable and match those you have configured in the options menu "...".CO2 Sensor"as orange and red colours.
In this example, when CO2 reaches 700 ppm, CO2 Gadget will activate the orange output and when it reaches 1000 ppm it will activate the red output (the orange output will also remain active).
The red output will be deactivated when the concentration drops below 900 ppm (1000 ppm minus 100 hysteresis) and the orange output will be deactivated when the concentration drops below 600 ppm (700 ppm minus 100 hysteresis).
The 100 ppm hysteresis prevents the outputs from being switched on and off continuously if the concentration keeps fluctuating around the corresponding concentration.
mDNS (Multicast-DNS) support is not available on all computers, it depends on your operating system and its version. If you are using Windows and your version does not support mDNS, the quickest and easiest way to get it supported is to install the Apple Bonjour Print Services for Windows.
CO2 Gadget is constantly being improved and expanded and many new features are being added.
You have available a CO2 Gadget Roadmap where you can see what is planned and what stage of development it is at.
You can ask for the inclusion of a new CO2 Gadget functionality here. If there is something you don't find in CO2 Gadget and you would like it to be implemented, go ahead and ask for it. All requests are studied with great interest.
Not only can it be as accurate as a commercially available meter, but it can also is likely to be more accurate than a commercial meter.
For example, the SCD30 sensor, used in CO2 Gadget, is a better quality sensor than those used in the vast majority of commercial meters under €500 that you can find on the market.
The result will depend on how well you mount it and calibrate it correctly.
Read the article Are home CO₂ meters as reliable, accurate and precise as commercial ones? if you want to know more.
If you encounter any difficulties and need help or have any queries, you have two options:
1. Join the eMariete Telegram group . A group where we talk about cacharreo, where several users, and myself, will be able to help you. This group is mainly in Spanish.
2. Write your question, problem or request in the section CO2 Gadget Issues on GitHub (recommended for questions in English).
This article is intended for users of the CO2 Gadget firmware. For any issue related to your developmentIf you have any questions, problems or requests, please contact us at CO2 Gadget repository in project on GitHub.
For any issue related to developmentIf you have any questions, problems or requests, please contact us at CO2 Gadget repository in project on GitHub.
This article is intended for users of the CO2 Gadget firmware.
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Thank you very much for collaborating with the most difficult thing: SHARING IT AND MAKING IT KNOWN. It's no use how hard I can work on these tutorials if people don't get to know them. THANK YOU TO EVERYONE WHO SHARES!
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Good.
I am a first timer and I have made this setup. With the sandwich firmware the screen kept showing the Sensirion logo. In the app it always shows -45 degrees Celsius, 0 RH and 0 ppm C02.
I have tried the advanced version. Now the emariete logo is displayed and then the screen shows 0ppm in green. The app also shows the same as before.
I don't know if there's something I might have done wrong... Ah, I struggled to find the right drivers, I think the ones that worked fine were the ones from the link on the Chinese page.
Thank you and congratulations on your work.
P.
Hello P.
It is very likely to be due to a wiring error. It would be a good idea to see detailed photos of the assembly, where the connections are clearly visible, to make sure. It is also very important to load the correct version of the firmware (normal or sandwich version), depending on the installation you have done.
Otherwise, the best thing to do is to connect the meter to the computer via the USB port and use a serial monitor to view the messages that the meter outputs via the USB port, which are numerous and indicate step by step what is happening.
I recommend you to go to the Telegram chat group where it will be much easier to see it: https://t.me/emariete_chat
I'm sure we'll find the problem in no time!
Best regards.
Thank you very much!
I'll drop by and ask there. I anticipate that as a newbie anything is possible 🙂
Best regards,
P.
I just dropped by again to say that everything is working perfectly and to thank you for your help and your work to make it possible for any handyman like me to be able to assemble and make this work.
Best regards.
P.
Great! I'm so glad it worked out perfectly for you! 😀
Visit the Telegram group from time to time so you don't miss CO2 Gadget firmware updates - there will be interesting news soon!
Good morning. I have the same problem, how did you solve it in the end?
In the end it was a problem with the wiring (the soldering).
I recommend that you check your connections and if you continue to have problems, please go to the Telegram group so that we can take a closer look.
Thank you. I'll check it out more calmly and if not I'll drop by the group.
Thanks for everything!
Hi, I like this idea, I did read your other articles. Great work. It is possible to use MH-Z19B or Senseair S8 LP sensor, with this TTGO as they are cheaper?
Hi.
Yes. New firmware version (in the works) has full support for Winsen MH-Z19B, Senseair S8 LP, Sensirion sensors SCD30, SCD40 and SCD41 and Cubic CM1106.
You can find the current development version at https://github.com/melkati/CO2-Gadget
Great work! Thank you very much for your effort.
I have a question about the battery. You said in the article that we must use battery with build in protection (overcharging etc.).
But the ttgo t-display esp32 has a build in battery circuit. Doesn't that take care of the charging? So would it be possible to use a simple cell like the panasonic ncr18650b?
And alternatively, would it be possible to connect 3 x AA NiMh to the board?
Hi Patrick.
The built-in circuit in the TTGO T-Display board is just a charger, that's why you need additional protections.
I don't have any experience with the Panasonic NCR18650B battery, best that you check in the datasheet with the exact reference if it has built-in protection or not.
The charger on board is only good for Li-Ion and Li-po batteries. It can't charge NiMh batteries.
Best regards! 😀
Hi Mariete,
Thank you for your answer.
After some research I found that the the charging circuit in the TTGO protects against overcharging but NOT against over-discharging, which can also ruin the battery. The NCR18650B does not have protection.
I also found this readit- thread where someone tried NIMH, with success, but it was only experimental, but it might work: https://www.reddit.com/r/esp32/comments/hcku6p/ttgo_tdisplay_with_nimh/
For this project I will order a LiPo-pack (with protection), but when I have time I will also try some NiMh AA's, because they are cheap and readily available.
Kind Regards
Great work, thank you for sharing the results of your time and efforts !
I'll take a look to your code, trying to understand how you deal with clockstretching on esp32...
And a question, the sensirion App do not fetch the data, and I do not see any part of your code that could possibly be related to this aspect. Do I miss something or this ability was left alone ?
Hi Mathieu.
The code in this tutorial is not mine. It's from Sensirion. I only wrote the tutorial.
When I tested it, few months ago, fetching the data from the meter to the phone via BLE was working fine. If the problem is with the Sensirion's code you should open an issue at their GitHub repository (link in the post).
My code is at the post "CO2 Gadget: Advanced CO2 Meter". If the problem is with my code and you think it's a bug you should, please, open the issue at CO2 Gadget's GitHub repository.
Good morning. First of all, I'm completely useless when it comes to electronics. I've been reading you guys for a while and I'm sorry I don't understand it as easy as you do. I tried to make the co2 meter and it just stopped trying. It keeps looping giving a 0x10 and 0x13 fault. I have changed the soldering from sandwich to wire and nothing. I don't know if it has a solution or leave it as impossible. I could send you the sensors and you can keep them if I've loaded them or if there is a solution you can tell me. I would be happy to pay for shipping. Thank you for your time.
Hello Arkaitz.
The error you are getting is probably nothing to do with anything having gone wrong, but something else (maybe something silly).
The best way to see it is through the Telegram group. https://t.me/emariete_chat because a bit of research and testing will have to be done to find the problem...
I'm sure we'll have it sorted out in no time.
Best regards.
Good morning. As I am a novice in everything related to electronics, the soldering also leaves much to be desired. Thanks for your time and soon I'll show you the problem and we'll see if it can be solved. Thank you very much for your time.
Hello,
Thank you for the information and your blog.
The reference of the TTGO I have is 19-6-28 V1.1 XY-CP / 16MB CH9102F Chip
[ https://fr.aliexpress.com/item/33050667207.html ]
The pins are different from the TTGO in the tutorial
G - 36
21 – 37
22 – 38
17 – 39
2 – 32
15 – 33
13 – 25
12 – 26
G - 27
G - G
3V - 5V
(connect for USB)
How can I connect it to the SCD 30 captor to make the system work in wired version ?
Is your firmware compatible ?
Thank you for your answer.
As I am not sure you have received my message I am sending it again...
Thank you in advance for your help.
Hello,
Thank you for the information and your blog.
The reference of the TTGO I have is 19-6-28 V1.1 XY-CP / 16MB CH9102F Chip
[ https://fr.aliexpress.com/item/33050667207.html ]
The pins are different from the TTGO in the tutorial
G - 36
21 – 37
22 – 38
17 – 39
2 – 32
15 – 33
13 – 25
12 – 26
G - 27
G - G
3V - 5V
(connect for USB)
How can I connect it to the SCD 30 captor to make the system work in wired version ?
Is your firmware compatible ?
Thank you for your answer.