The AirGradient ONE Air Quality Sensor (Presoldered-Version, PCB Version 9)


These build instructions cover the pre-soldered version of the AirGradient ONE monitor kit for PCB version 9. It is the successor of the DIY Pro series and combines the best features of the DIY and (formerly closed source) AirGradient ONE series. If you have a different version please find your correct build instructions in this overview. The version number is printed on the PCB.

The AirGradient ONE monitor measures PM, CO2, TVOC, NOx, temperature and relative humidity. These measures can be shown on the display and sent to a server (e.g. the AirGradient platform or any other cloud backend) for data logging.

You can purchase the kit with all components from our Online Store and be sure that everything fits. We ship world-wide.

Fully assembled AirGradient ONE PCB

This new version contains a RGB LED bar on the backside of the PCB that can be used to visualize the air quality with different colors. All 11 LEDs are individually addressable.

New RGB LED bar that shines through the enclosure

Video Tutorial (for previous version)

Skills And Equipment Required

For this project you should be familiar with the following:

Skill Description
Computer A Linux, Mac, or Windows computer with the Arduino IDE installed to flash the software onto the ESP-C3. You can also flash the software directly from the browser.
Screwdriver You need a Torx (T6) screwdriver which is included in the kit.


Below is the list of components that you will receive with the pre-soldered kit:

Component Approx. Price
AirGradient ONE PCB v9 with ESP32-C3-MINI, OLED Display, connectors and pin sockets
Plantower PMS5003 PM Sensor with cable
Senseair S8 CO2 Sensor with pre-soldered pins
SHT4x Temperature and Humidity Sensor Module with pre-soldered pins
SGP41 TVOC / NOx Sensor Module with pre-soldered pins
USB-C Cable 90-degree head
Enclosure UV-resistant injection molded ASA plastic
Screws for Enclosure M1.8x10 (Torx T6)
Screws for PCB M2*4.5 (Torx T6)
Screws for PM Sensor M2*4.5 (Torx t6). Same screws as for PCB.


The schematics (right click and open image in new tab for full screen)


The assembly of the pre-soldered parts is very simple, just make sure you mount the components in the correct direction. The labels on the components should match the labels on the PCB. The PCB might come in blue or black color but are functionally identical.

Location of the Components on the PCB

We recommend you start in the following order:

ESP32-C3 Mini

The board already contains the ESP-C3-MINI microcontroller installed so there is nothing you need to do. Please note that it is connected to the USB connector on the board so that it can be flashed through the USB port.

There are also two buttons below which you might need during the flashing process.


SHT40 Module (Temperature and Humidity Sensor)

Install the SHT4x module as per the picture below. It is put on the pin headers at the bottom left of the board labelled “SHT1”. Note that the SGP4x (TVOC) module looks very similar. So make sure you install the SHT module which is labelled “SHT4x”.

Please make sure that the module faces outwards.

SHT4x Module

Senseair S8 Module (CO2 Sensor)

Put the CO2 Module onto the pin sockets labelled “CO2 Sensor”. Make sure that the orientation is correct and all pins slide into the sockets.

SHT Module

The CO2 sensor uses a 7-day automatic baseline calibration and thus might need some time to become accurate.

PMS5003 (PMS Sensor)

The PMS Sensor is connected with the enclosed cable to the PCBs JST connector labelled “PMS”. Please note that we use a cross-over cable and thus the longer cable that is often shipped with the PMS5003 sensor will not work. You need to press the cables into the PM sensor and connector tightly.

Please ensure that the cable is fully plugged in on both ends.

PMS Location
PMS JST Connector
Screws for PMS Sensor

Then screw the PMS5003 onto the PCB.

SGP41 AirGradient TVOC / NOx Module

The TVOC / NOx module is mounted in the slot in the top left corner labelled “I2C3”.

Please make sure you mount the module in the correct orientation. The sensor needs to face outwards.

Testing And Putting It Into The Enclosure

Now you can power on the device and you should be able to see the display lighting up. If you flashed the Wi-Fi version, you need to connect it to the Wi-Fi. To do this open you Wi-Fi settings on the phone and look for a hot spot called “AirGradient______”. Then connect to it and enter your Wi-Fi network credentials. It will then connect to Wi-Fi and start displaying and sending the air quality data.

In case you have any issue, check this guide or get help from the Open AirGradient Forum.

If everything works, you can screw the PCB into the top cover of the enclosure and close the enclosure.

Screws for PCB

Then screw them on both sides (each 2 screws).

Location for PCB screws

Once the PCB is firmly screwed on the top part of the enclosure, you can close the enclosure with the longer screws.

Screws for enclosure

The enclosure screws are going on the four sides into the ventilation vents:

Location for enclosure screws

Please note that the mini screwdriver enclosed with the kit might not have enough torque to screw these screws in. In that case, please use a larger T6 screwdriver, or you can also put some oil/soap on the screws to make them go in easier.

Soap helps getting the screws into the enclosure in case you use the mini screwdriver

Power Supply

The power supply is not included in the kit. Please get a standard 5v, 2A power supply.

Direct Flashing Through The Browser

In case you have received the new AirGradient 9PSL as a kit version, we strongly recommend you update the firmware because we have recently fixed a few bugs that might affect your device.

You can either manually flash the code through the Arduino software or use the simple button below. Connect the board to your computer through a data-capable cable and press the button below. Make sure you use the Chrome or Edge browsers on your computer for this to work.

Firmware for PCB Version 9 (ESP-C3-MINI) Your browser doesn't support this. Please use Chrome or Edge on Mac or PC. You are not allowed to use this on HTTP!

Once the code is flashed, it will open a hotspot for 180 seconds to which you can connect and then set your Wi-Fi 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.

If you do not connect it to Wi-Fi within the 180 seconds after startup it will go into the offline mode and show the air quality parameters without sending the data.

Manual Flashing With The Arduino Software

The above direct flashing is the easiest way to get the firmware onto the board 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 make any changes you’d like.

Please read the following blog post on how to install the Arduino software, set up the ESP32-C3 and the AirGradient Arduino library.

AirGradient Arduino Software Setup Instructions

Flashing Of The AirGradient Firmware

Once you have the Arduino Software setup for the ESP32-C3, you can flash it with the AirGradient firmware.

Step Description
1 Go to Tools, Manage Libraries, and then search for AirGradient and install the AirGradient library.
2 Once it is installed, go to File, Example, AirGradient and select the ONE_V9.ino code
3 Read the instructions on top of the example code and install the additional libraries
4 Then flash this code the same way you flashed the BLINK example


With the button, you can set the configuration of the display. Press the button on start up and it will enter a menu. Then short press the button until you find the configuration you like. Long press the button to save and reboot.

You can set the unit for PM2.5 (μg/m³ or US AQI) and the temperature unit (°C or °F).

The following configurations are available:

Configuration Number Temperature PM Unit Orientation
1 °C ug/m3 Bottom Right
2 °C US AQI Bottom Right
3 °F ug/m3 Bottom Right
4 °F US AQI Bottom Right

Solutions For Schools

AirGradient offers a sophisticated, powerful and responsive Air Quality Monitoring Solution for Schools. You can connect these DIY monitors to the AirGradient platform, integrate with many existing brands or use our professional AirGradient ONE monitor.

If you are interested in a free trial of the solution for schools, please contact us.

AirGradient Dashboard

Our kits come with several months of free subscription to the AirGradient dashboard. To connect your monitor to the dashboard, please follow these instructions.

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This work is licensed under CC BY-SA 4.0.

This license requires that reusers give credit to the creator. If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.

Copyright AirGradient Co. Ltd.