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For technically capable makers, workshop owners, and Home Assistant users, Aura offers a repairable and customizable way to monitor indoor conditions locally. The trade-off is that it still requires careful component selection, wiring, setup, and interpretation of sensor data.
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Quick verdict
Project Aura is a strong fit if you want a polished, touchscreen-based monitor that can operate locally and feed data into Home Assistant. Its main strengths are the ESP32-S3 platform, Sensirion SEN66 sensor, local web interface, OTA updates, MQTT discovery, and optional 0–10 V ventilation control.
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#1 Best Overall
- Know your air – An Alexa air quality monitor that makes it easy to understand what’s in your indoor air.
- Track and measure – Our indoor air quality monitor keeps tabs on 5 key factors: particulate matter (PM 2.5), volatile organic compounds (VOCs), carbon monoxide (CO), humidity, and temperature.
- Stay informed – Get an indication of current indoor air quality from the color-coded LED, and detailed information and an easy-to-understand air quality score in the Alexa app.
- Real-time alerts - Get notifications on your phone or announcements on Echo devices when Alexa detects poor indoor air quality.
- Automate climate control - Enable Routines to turn on or off your compatible Alexa devices, such as air purifiers, dehumidifiers, and fans, when the indoor air quality sensors detect changes.
What Project Aura is
Project Aura AQ combines an ESP32-S3 controller with a 4.3-inch or 7-inch touchscreen, a Sensirion SEN66 air-quality sensor, optional gas sensors, and a 3D-printed enclosure. The software provides a touchscreen interface, locally served web dashboard, charts, events, settings, OTA firmware updates, MQTT, and Home Assistant support.
The design is aimed at detailed environmental monitoring and automation rather than a disposable sensor node. It can also drive an optional GP8403-based 0–10 V output for compatible ventilation equipment. That output is a control interface—not evidence that the complete installation is industrially certified or fail-safe.
The project is maintained by 21cncstudio. Its official resources include the public GitHub repository, community discussions, project page, and browser installer.
How open source is it?
The phrase “open source” needs a qualification. The software stack is public under GPL-3.0-or-later, but not every physical-build resource is contained in the GitHub repository.
| Asset | Availability | Qualification |
|---|---|---|
| Firmware | Public | GPL-3.0-or-later |
| Web dashboard assets | Public | Included in the repository |
| Home Assistant examples | Public | Included in the repository |
| Tests and developer configuration | Public | Available in the repository |
| Enclosure files | Distributed separately | Associated with MakerWorld backer resources |
| Detailed build and wiring guide | Distributed separately | Not entirely in the repository |
In practical terms, the firmware and software platform are open source; some mechanical and assembly resources are distributed through the project’s support and crowdfunding ecosystem. Readers expecting every file to be freely downloadable from one repository should review the MakerWorld project page before committing to a build.
What does it measure?
The base SEN66 configuration is intended to provide:
- Particulate matter
- Carbon dioxide
- Temperature
- Relative humidity
- VOC-related data
- NOx-related data
Those are not the same as having every gas sensor listed in the project documentation. Additional hardware is required for:
- Carbon monoxide, using the supported DFRobot SEN0466
- Formaldehyde, using Sensirion SFA30 or SFA40 options
- Oxygen, using the DFRobot SEN0465
- Other electrochemical gases such as ammonia, sulfur dioxide, nitrogen dioxide, hydrogen sulfide, ozone, and oxygen, where supported modules and wiring are used
Therefore, installing one SEN66 does not automatically provide carbon monoxide, formaldehyde, oxygen, or every other gas in the project’s sensor list. Optional sensors increase both cost and integration complexity.
The SEN66’s VOC and NOx values should also be understood as sensor indices or interpreted air-quality outputs, not automatically as direct laboratory concentration measurements. Aura is most useful for observing trends, changes, and events—not for making unsupported medical, legal, or regulatory conclusions.
Hardware requirements
The minimum useful build requires:
- A supported Waveshare ESP32-S3-Touch-LCD-4.3 or supported 7-inch board
- The 16 MB flash version of the board
- A Sensirion SEN66
- A stable 5 V/2 A USB power supply
- The Aura Sensor Hub PCB or a supported modular wiring arrangement
The 8 MB Waveshare variants are not supported because of the project’s firmware and filesystem requirements. Check the exact flash specification before ordering; a similar-looking board is not necessarily compatible.
Rank #2
- 【16-in-1 Air Quality Monitor Indoor】Experience the ultimate indoor air quality monitoring with our 16-in-1 Air Quality Monitor, offering real-time detection of 9 key parameters including CO2, PM2.5, PM1.0, PM10, HCHO, TVOC, Temperature, Humidity, AQI, and Time. With 7 distinct AQI alert buzzers, this air quality tester ensures your family breathes with ease.(*Note: "16-in-1" refers to the combination of 9 key detectable parameters and 7 types of AQI alert buzzers.)
- 【Crystal Clear 7-inch Large Display】Enjoy a 7-inch LED display for sharp, clear air quality readings. Provides an instant, comprehensive view of your indoor air without navigating through menus, with three brightness settings for any lighting condition
- 【External High-Precision Sensors with 0.001 Accuracy】Equipped with advanced external high-precision sensors, this device delivers unmatched accuracy (0.001 units) by directly sampling the air. Its innovative multi-sensor array and enhanced airflow design detect even the slightest environmental changes, allowing for instant response and optimal safety. (*Note: Avoid touching the sensors or exposing them to perfumes/strong odors to maintain accuracy.)
- 【Real-Time AQI Alert Buzzers】Our air quality monitor provides real-time monitoring and alerts for pollutants like CO2, PM2.5, PM1.0, PM10, HCHO, TVOC, Temperature, Humidity, and AQI, with 7 distinct alert functions. Stay informed with clear alerts and rest easy with a mute button to silence alarms. Your health and comfort are our priority. Toggle between Fahrenheit and Celsius instantly with a double-press of the "Power" button on this air quality detector.
- 【Up to 8 Hours of Runtime & Flexible USB-C Charging】 Enjoy up to 8 hours of continuous air quality monitoring on a full charge. The USB-C charging interface offers flexible power options and is compatible with widely available USB-C cables, while the included AC adapter provides convenient charging at home. Designed for effortless monitoring wherever you need it—from bedrooms and living spaces to your car and beyond.
The 4.3-inch display has an 800 × 480 resolution. The project also supports a 7-inch display for readers who want a larger interface. The documented I2C pins are GPIO 8 for SDA and GPIO 9 for SCL.
Recommended Free Tools
Common expansion hardware
| Function | Example component |
|---|---|
| Main air-quality sensor | Sensirion SEN66 |
| Pressure | BMP580/BMP581/BMP585, BMP388/BMP390, or DPS310 |
| Real-time clock | PCF8523 or DS3231 |
| Carbon monoxide | DFRobot SEN0466 |
| Formaldehyde | Sensirion SFA30 or SFA40 |
| Ventilation output | DFRobot GP8403/DFR0971 0–10 V DAC |
Custom PCB or modular wiring?
The custom Aura Sensor Hub PCB v1.1 is the cleaner option for a new build. It consolidates connectors and support for the SEN66, pressure sensor, RTC, and related wiring, reducing the number of loose modules inside the enclosure.
A modular Adafruit, STEMMA QT, or Qwiic-style build remains useful if you already own compatible parts or need to source components incrementally. It is more flexible, but it introduces additional cables, pin-order risks, connector-orientation mistakes, and the need to include the specified electrolytic capacitor.
| Route | Advantages | Disadvantages |
|---|---|---|
| Custom Aura PCB | Cleaner assembly and fewer loose modules | Availability and regional pricing may vary |
| Modular build | Flexible sourcing and useful for existing parts | More wiring and more opportunities for mistakes |
| Improvised ESP32 build | Maximum flexibility | Requires adapting firmware, display, enclosure, pin mapping, and sensor support |
Verify every pinout before applying power. A connector that physically fits is not proof that its pin order is correct.
Installing the firmware
For most builders, the browser installer is the simplest route:
- Use the supported Waveshare board and its data-capable USB-C port.
- Connect it with a data-capable USB cable.
- Open the Aura Web Installer in Chrome, Edge, or Opera.
- Follow the project’s flashing instructions.
- Configure Wi-Fi after the first boot.
A charge-only cable or the wrong USB-C connector can make a working board appear undetectable.
Developers can build and flash with PlatformIO:
git clone https://github.com/21cncstudio/project_aura.git
cd project_aura
pio run -e project_aura
pio run -e project_aura -t upload
pio run -e project_aura -t uploadfs
pio device monitor -b 115200uploadfs is important. The dashboard, fonts, translations, and other assets are stored in the filesystem image. Flashing firmware without the filesystem can leave the device running but missing expected web-interface assets.
The documented development stack uses the project_aura PlatformIO environment, Arduino ESP32 core 3.1.1, and the ESP-IDF 5.3.x family.
Wi-Fi setup and local access
On first boot, Aura creates a setup access point with a name such as:
Aura-XXXXXX-APThe documentation also lists:
ProjectAura-SetupWhile connected to that setup network, open:
http://192.168.4.1Save the normal Wi-Fi credentials and allow roughly 15 seconds for the device to leave access-point mode and join the regular network. Then use the device’s local hostname, typically:
Rank #3
- 4-in-1 Environmental Monitoring: Simultaneously measures temperature (-40°C to +85°C), humidity (±3% RH), barometric pressure, and VOC gases (IAQ index output).
- Multi-Protocol Interface: 5V compatible with I2C (3.4MHz max) and SPI (10MHz 3/4-wire) for Arduino/Raspberry Pi/ESP32 integration.
- Ultra-Low Power Operation: Current as low as 2.1μA (1Hz temp/humidity) to 3.7μA (triple-sensor mode) with selectable sensor activation.
- Industrial-Grade Precision: VOC response time <1s (new sensor), ±1.5% RH humidity hysteresis, and IAQ air quality indexing capability.
- Ready-to-Use Module: Includes pre-soldered BME680 chip with labeled VCC/GND/SCL/SDA/SDO/CS pins (2x module per order).
http://aura-XXXXXX.local/You can also use its assigned IP address. Do not keep trying 192.168.4.1 after setup; that address belongs to the temporary access point, not ordinary station-mode operation. mDNS uses UDP port 5353, so networks that block multicast discovery may require direct IP access.
Core operation is local and does not require a cloud account. Home Assistant, however, still needs a working local network and MQTT broker.
Dashboard, MQTT, and Home Assistant
The locally served interfaces include the setup portal, sensors page, charts, events, settings, system information, DAC controls, and OTA updates. Documented API routes include:
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GET /api/charts?group=core|gases|pm&window=1h|3h|24h
GET /api/events
GET /api/diag
POST /api/settings
POST /api/ota/api/diag is documented for AP setup mode and can expose Wi-Fi state, IP address, hostname, heap status, OTA state, and recent warnings or errors.
MQTT discovery is enabled by default. With a correctly configured MQTT broker, a compatible Home Assistant installation should discover the device, and the repository includes a dashboard YAML example.
MQTT discovery is not identical to consumer plug-and-play. You may still need to configure broker credentials and permissions, allow traffic across VLANs, and resolve either mDNS or IP connectivity. The Aura dashboard remains available independently of Home Assistant.
Optional 0–10 V ventilation control
With the supported GP8403 module, Aura can provide manual output, timed output, or automatic demand mode. Automatic behavior can use editable thresholds for carbon dioxide, formaldehyde, carbon monoxide, VOC, and NOx; particulate-matter zones remain fixed according to the project documentation.
Use this feature only with equipment that is electrically compatible and validated for the signal. A hobby monitor should not be the sole control or protection mechanism in a hazardous environment. Proper installations need fail-safe behavior, independent interlocks, and equipment-specific commissioning.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Warm-up, placement, and accuracy
The project states that SEN66 VOC and NOx readings require approximately five minutes of warm-up, during which the interface displays WARMUP. Initial readings should not be treated as stable simply because numbers appear on screen.
Placement also matters. Keep the air inlet away from heat-producing electronics, power regulators, and restricted airflow. Internal heat, condensation, cooking aerosols, cleaning products, dust, and proximity to a person’s breath can all affect readings. These are general engineering considerations, not independent Project Aura performance tests.
Rank #4
- High Accuracy & Fast Refresh Data: With this smart sensor, the PM2.5 accuracy is ±15 µg/m³ while temperature and humidity accuracies are ±0.54°F and ±3%RH.The two-second correction data feature shows the latest changes in PM2.5, temperature, and humidity.Keep sensor clear for accurate detection.
- Multifunctional Air Quality Detector: The GoveeLife Air Quality Monitor conveniently measures 3 important indexes for indoor air quality, including PM2.5, temperature, and humidity.
- Switchable Display: Press the top button for the clock & PM2.5 display. Long press for 2 seconds to switch to bright screen mode & night mode. The LED indicator displays 4 levels of ambient air quality. 2.4G Wi-Fi is required to display the time.
- Connect with GoveeHome Appliances: Set your target air quality and link with your other GoveeHome smart appliances. GoveeLife air purifiers, humidifiers, and space heaters will turn on and off automatically when the indoor air quality changes.
- H5106 needs to be connected to a power source and supports GoveeLife devices: Smart Air Purifiers - H7126, H7120, H7124, H712C, H7122, H7123; Humidifiers - H7140; Fans - H7100, H7102
The available project material does not establish an independent accuracy study against reference-grade instruments. The project’s higher-quality sensor positioning should therefore not be confused with whole-device certification, calibration traceability, or “industrial-grade” performance.
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Adding the DFRobot SEN0466 gives the project a supported CO-sensing option, but it does not turn Aura into a certified residential CO alarm. Install code-compliant CO alarms separately wherever required, and follow the sensor manufacturer’s specifications for calibration, operating range, replacement, and cross-sensitivity.
Oxygen
The optional DFRobot SEN0465 is listed for ambient oxygen measurement over a 0–25% volume range. It is not intended for Nitrox analysis or breathing-gas decisions. When used alongside the SEN0466 CO sensor, its I2C address must be changed from 0x74 to 0x75 to avoid a conflict.
Oxygen readings should never be treated as a life-safety guarantee. Certified detectors and appropriate workplace procedures remain necessary for oxygen-deficient or oxygen-enriched environments.
Realistic cost and maintainability
The project’s approximate $170–$180 component estimate is a useful baseline for a quality base build, not the price of a complete retail-ready kit. Budget separately for:
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- The 4.3-inch or 7-inch display/controller
- The SEN66 and any optional gas sensors
- The custom PCB or modular wiring
- Power supply, cables, and connectors
- Enclosure access and 3D-printing material
- Shipping, taxes, regional stock, and replacement parts
- Tools, failed prints, and troubleshooting time
The SEN66 is available through electronics distributors; current price and stock vary. Optional DFRobot modules simplify expansion but make the system progressively more expensive and harder to interpret. The custom PCB can improve maintainability by reducing loose wiring, while modular parts may be easier to replace locally.
Common problems and recovery
- Wrong board: confirm that the Waveshare board has 16 MB flash; 8 MB variants are unsupported.
- Board not detected: try the data USB-C port and a known data-capable cable.
- Missing dashboard assets: run
pio run -e project_aura -t uploadfs, then reboot. - Cannot reopen setup page: after Wi-Fi configuration, use the Aura
.localhostname or assigned IP instead of192.168.4.1. - Missing gas sensor: check wiring, pin order, power, and I2C addresses; the SEN0465/SEN0466 combination requires the oxygen sensor address change.
- Unstable early VOC or NOx values: wait through the documented warm-up period and assess trends rather than the first displayed value.
- OTA transfer failure: keep one active client tab or session during the update.
How Aura compares with alternatives
| Alternative | Best for | Trade-off versus Aura |
|---|---|---|
| Commercial IAQ monitor | Fast setup, warranty, and appliance-like use | Usually less open, repairable, and customizable; may depend on cloud services |
| ESPHome ESP32 node | Low-cost Home Assistant sensing | Often cheaper and smaller, but lacks Aura’s integrated touchscreen and dedicated UI |
| Sensirion evaluation platform | Engineering and sensor evaluation | Better suited to component characterization than finished household monitoring |
| Raspberry Pi or industrial system | Large-scale logging, analytics, or demanding installations | More power, maintenance, complexity, and cost |
Who should build Project Aura?
Choose Aura if you want a local-first monitor, a large touchscreen, MQTT and Home Assistant integration, higher-end sensor options than basic hobby modules, a 3D-printable maker project, and software you can inspect or modify.
Choose something else if you need a certified alarm, workplace-compliance instrument, battery-first portable monitor, factory calibration and service, the lowest possible price, or a fully documented build with every physical file in one public repository.
For construction sites, workshops, and renovation environments in particular, Aura can be useful for observing ventilation, dust events, CO2 trends, humidity, and selected gases. It should complement—not replace—site risk assessments, required alarms, professional instruments, and safe working procedures.
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