The AirGradient DIY Air Quality Sensor

(BASIC Version)

Introduction

As part of the Open AirGradient, this instruction teaches how to build a compact and powerful PM2.5 fine dust sensor with AirGradient.

The monitor displays PM2.5, CO2, Temperature and Humidity and can optionally send the data to the AirGradient platform or any other cloud backend for data logging.

You will need some basic soldering skills and experiences with microcontrollers are a plus. However, even if you are a beginner, you won’t need to worry because we made the instructions really easy! Also, if you get stuck please get in touch with us. We are more than happy to help!

If you want to build a monitor with a larger display, a better enclosure and more extensability, check out the DIY Pro instructions

Fully assembled kit

Jeff Geerling’s Video Instructions

Jeff featured our DIY sensor on his you tube channel and created a very nice video on how to assemble the sensor.

Skills and Equipment required

For this project you should be familiar with the following:

SkillExplanation
Basic soldering skillsBoth the D1 mini microprocessor and some of the components we use like the OLED display need to get the pins soldered onto it. It is not very difficult and you can learn it easily. Look for example on this tutorial.
Soldering iron & SolderTo solder the component pins and cables.
BreadboardA breadboard is helpful to fix the components during soldering.
Computer(Linux, Mac, or Windows) with the Arduino IDE installed to flash the software onto the D1 mini.
micro USB data cableto connect the D1 Mini to the computer for flashing and later for electricity. IMPORTANT: Many micro USB cables only provide charging but do not allow the data transfer for flashing. So please make sure you have a micro USB DATA cable.

In case you are unfamiliar with soldering or want to build the monitor quickly, we also do have kits available wich are pre-soldered and thus do not need any soldering. These kits can be assembled within a short time.

Components

Below is the list of components that you need to source with a link to AliExpress and normal price ranges.

ComponentApprox. Price
Wemos D1 MiniUSD 2 - 4
Wemos OLED displayUSD 2 - 3
Plantower PMS5003 PM SensorUSD 15 - 20
Senseair S8 CO2 SensorUSD 25 - 30
SHT30 or SHT31 Temperature and Humidity Sensor ModuleUSD 3 - 5
PCBSee below on how to make a PCB
EnclosureSee below on how to 3D print the enclosure

AliExpress might not ship to all countries. In case they do not ship to your country, please try and source the exact same component from elsewhere.

You can also purchase the kit from our online store Online Store.

You do not need to put all sensors on the PCB, you can customize your sensor however you like it by removing or adding different sensors.

Schematics

You can use the following schematics:

Schematics

Make your own PCBs

In case you want to make your own PCBs you can use the Gerber files or open the PCB schematic in the Easyeda editor and order PCBs from there.

You can also build the sensor without the PCB just by soldering the sensor modules with wires directly to the Wemos D1 Mini.

Built without PCB

We strongly recommend you assemble the monitor with a PCB as it will be much easier and more robust.

Direct flashing through the browser

You can either manually flash the code through the Arduino software or use the more simple button below.

Connect the Wemos D1 Mini through a data-capable cable with your computer and press the button below. Make sure you use Chrome or Edge on a desktop computer for this to work.

Once the code is flashed, it will open a hotspot for 60 seconds to which you can connect and then set your WiFi credentials. By default it will connect to the AirGradient Dashboard. If you want to use another endpoint you can change the code with the manual flashing method below.

Note that you cannot flash through the USB-C port on the PCB as this one is only for power. For flashing always use the USB port on the D1 mini.

If you do not connect it to WiFi within the 60 seconds after startup it will go into the offline mode and show the air quality parameters without sending the data.

Features
With temperature in Celcius Your browser doesn't support this. Please use Chrome or Edge on Mac or PC. You are not allowed to use this on HTTP!
With temperature in Fahrenheit Your browser doesn't support this. Please use Chrome or Edge on Mac or PC. You are not allowed to use this on HTTP!

If you flash with above method, you can skip the next section and continue at the section “Soldering the Components”.

Manual Flashing with the Arduino Software

Above direct flashing is the easiest way to get the firmware onto the D1 mini but if you want to make changes to the code, you can also flash the code through the Arduino software environment. All software for the AirGradient DIY sensor is open source and thus you can do any changes required.

Please read the following blog post on how to install the Arduino software and also on how to install the D1 Mini board and the AirGradient Arduino library.

AirGradient Arduino Software Setup Instructions

Flashing of the D1 Mini with the AirGradient firmware

Once you have the Arduino Software setup for the D1 Mini, you can flash it with the AirGradient firmware.

StepDescription
1Go to Tools, Manage Libraries, and then search for AirGradient and install the AirGradient library.
2Once it is installed, go to File, Example, AirGradient and select the PM OLED code
3Read the instructions on top of the example code and install the additional libraries and set the true/false for the sensors you are using
4Then flash this code the same way you flashed the BLINK example
5Once you have successfully uploaded the code you can continue building the hardware

Soldering the Components

Now that you have the firmware flashed, you can solder the components onto the PCB. Please make sure you solder the pins in the correct direction. We recommend you start in the following order:

OLED Display Soldering

If you have a breadboard at hand, we recommend that you fix the pins with the breadboard to ensure that they are straight as shown on this picture.

OLED soldering

Wemos D1 Mini Soldering

Put the long female and male pins through the D1 Mini. Make sure that the female parts are on top of the D1 Mini as shown on this image:

D1 Wemos Mini soldering

Then connect the freshly soldered OLED display into the female pins to better hold them in place. Then turn the D1 Mini with the OLED display attached around and solder the pins onto the D1 Mini

Wemos D1 Mini Soldering onto PCB

The next step is to solder the D1 Mini onto the PCB. Please make sure you solder it the correct way. The micro USB port needs to face outwards. You can also compare the PIN labels on the PCB with the ones on the D1 Mini. You can either solder the D1 Mini directly onto the PCB or use the pin headers as a socket. If you solder it directly, please leave a small gap between the PCB and the D1 Mini to make sure the plug is accessible.

Important: If you use the display or RGB led shield, you need to solder the D1 Mini directly on the PCB without the pin headers as a socket, otherwise it becomes too high and does not fit the enclosure.

D1 Wemos Mini PCB soldering

Now depending on what sensor modules you want to use, please proceed as below.

Soldering the SHT30/31 Module (Temperature and Humidity)

To solder the small pins onto the SHT30/31 module, you can use a breadboard again to fix it into place.

Then put the SHT30/31 module through the corresponding holes on the PCB and solder it onto the board. You only need to solder the four pins. No need to do anything with the two pins on the top of the sensor.

Soldering the Senseair S8 Module (CO2 Sensor)

To solder the small pins onto the S8 module, you can use a breadboard again to fix it into place.

Please make sure that the PINS face downwards as can be seen on this image.

Senseair S8 soldering

Then solder the CO2 sensor onto the PCB. It is important that the bottom side of the CO2 has enough air flow. So make sure the gap is sufficient. It might be a good idea to put it on a female pin socket but you can also solder it directly. You can use the pin that came with the D1 Mini but you need to cut them off to the required length.

Soldering the PMS5003 Module (PMS Sensor)

Normally the PMS5003 comes with a cable. As we will solder one end of the cable directly onto the PCB, you can cut it in half. Then prepare the following four wires as per this image. Please make sure you cut the correct wires.

PMS Cable Wiring

Then solder the cable onto the PCB. Make sure that you solder the correct cable into the correct pin.

PMS Connector

After you have soldered the cable onto the PCB, connect the PMS5003 with the other end of the cable. Then screw the PMS5003 onto the PCB or use double sided tape,.

Done & Enjoy

That’s all and you can now connect the D1 Mini with power and you should be able to see the display lighting up. If you flashed the Wifi version, you need to connect the D1 Mini to the wifi. To do this, open the Wifi Settings on the phone and look for a hot spot called “AirGradient-______”. Then connect to it and enter your Wifi network credentials. It will then connect to your Wifi and start displaying and sending the air quality data.

If there are any issues, you can double check this tutorial and also the images. If you still have problems, please feel free and get in touch with us!

3D Enclosure and Mount

You can also download STL 3D printer files to print an enclosure that exactly fits our PCB. The 3D enclosure consists of a top and bottom part. There are two different top parts depending on if you use the OLED display or not. Please note that if you use the OLED you need to solder the Wemos D1 mini directly on the PCB as it otherwise will become too high.

You can also print a small temperature probe that can be snapped onto the enclosure and thus you can move the temperature sensor outside the main enclosure to avoid the heat from the enclosure impacting the temperature reading.

Download Enclosure STL Files

3D printable enclosure

Solutions for Schools

AirGradient offers a sophisticated Air Quality Monitoring Solution for Schools. You can connect these DIY sensors to our platform, and integrate with many existing brands or use our professional AirGradient sensor.

If you are interested for a free trial, please contact us.

MIT License

The AirGradient DIY sensor’s hardware and software is Open Source and licensed under the MIT license. So feel free to use it any way you like! However we would be happy to hear from you and also appreciate any link back to our page.

Copyright AirGradient Co. Ltd.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.