Project Aura is not just another DIY monitor based on the ESP32. For me, it is an attempt to prove that you can build an industrial-grade device with your own hands that combines simplicity of assembly for a beginner with deep engineering work "under the hood." In this article, I will tell you why I chose this particular hardware platform, how the firmware architecture is structured, why fail-safe algorithms are needed, and how I befriended the device with a smart home.📦 Hardware Platform: No CompromisesWhen designing Aura, I fundamentally refused to use cheap sensor clones. Only components from industry leaders (Sensirion, Bosch, Waveshare). I wanted precision and durability, not a random number generator.Microcontroller and DisplayI chose a powerful combination as the heart of the system:MCU: Waveshare ESP32-S3-Touch-LCD-4.3 (16MB Flash). The huge amount of memory untied my hands: I used the LittleFS file system to store logs, pressure history, and beautiful interface assets.Display: 4.3" RGB LCD with a resolution of 800x480. The image is juicy, the fonts are crisp. The GT911 driver is responsible for the touchscreen — it works responsively, just like on a smartphone.Graphics: I built the entire interface on the LVGL v8.4.0 library with anti-aliasing enabled. By the way, to bypass the known IPC stack overflow problem when initializing a heavy UI, I had to pin the display task (Core 0 Pinning) strictly to the zero core.Sensor ArrayI assembled a "dream team" of sensors in one case:SensorParametersImplementation FeaturesSensirion SEN66T, RH, PM1/2.5/4/10, CO2, VOC, NOxAn industrial "all-in-one" combine. The main plus is the airflow inside the module, optimized by Sensirion engineers.Sensirion SFA30Formaldehyde (HCHO)Optional module. This is the "gold standard" for formaldehyde detection, not a cheap imitation.ℹ️ Note: The SFA30 is fully supported and readily available for purchase. Support for the successor model (SFA40) is already on the project roadmap and will be added upon its release.Bosch BMP580 / DPS310Atmospheric PressureI implemented Dual Pressure Fallback logic: the firmware looks for the BMP580 itself, and if it doesn't find it, it switches to the DPS310.NXP PCF8523RTC (Real Time Clock)Autonomous clock with a CR1220 battery so that the time does not get lost during power outages.  🛒 Bill of Materials (BOM)Below I have gathered the exact list of what is installed in my final prototype. All part numbers are verified personally. You can find them both in local stores and at giants like Adafruit, Digi-Key, or Mouser.Main Board ~$33 Waveshare ESP32-S3-Touch-LCD-4.3 (800x480)Main Sensor ~$60 Sensirion SEN66Adapter for SEN66 ~$6 Adafruit SEN6x Breakout for Sensirion SEN66HCHO Sensor (Optional) ~$55 Seeed Studio Grove - SFA30Barometer ~$8 Adafruit BMP580 (or DPS310 / BMP581)Clock (RTC) ~$7 Adafruit PCF8523I2C Hub ~$6 Adafruit Qwiic / Stemma QT 5 Port HubCapacitor (Power) ~$0.5 Aluminium Electrolytic Capacitor - Radial Leaded 10V 470uF 105CCables (Type 1) ~$4 Grove to STEMMA QT / Qwiic / JST SH Cable - 100mm (4 pcs)Cables (Type 2) ~$4 Qwiic/STEMMA QT-Compatible Cable - JST-SH 4-Pin 50mm (4 pcs)Cable (Type 3) ~$1 JST GH 1.25mm Pitch 6 Pin Cable - 100mm longPower Terminal ~$3 Seeed Grove - Screw TerminalFasteners ~$3 Bolts M2.5x6 BHCS Machine Screw (e.g., Bambu Lab Store) - 20 pcsBattery ~$1 CR1220 3V Lithium Coin Cell (for RTC)The full assembly (together with the cool formaldehyde sensor) comes out to around $170-180.⚡ Important Note on the CapacitorI added this part to stabilize the power supply. The ESP32 at peak consumption (WiFi + screen) can cause voltage drops, and the capacitor smooths them out. No soldering required! Just insert its legs into the terminal block along with the power wires. If you can't find exactly the same one (10V 470uF), feel free to take any electrolytic capacitor with a higher voltage or capacitance (for example, 16V 1000uF).💰 An Honest Talk About PriceI am often asked: "Why should I build a project for $170 if there is a ready-made monitor on for $100?"What are you paying for? This is DIY and crowdfunding. The sum of ~$170-180 is the fair market price of high-end hardware that you buy for yourself. These components remain with you. My contribution. The case design, hundreds of hours of firmware debugging, architecture, and instructions are a separate story. By supporting the campaign, you are paying specifically for the results of my labor, not for a reseller's markup. Compare for yourself. Try to find a ready-made device that simultaneously has a Sensirion SEN66, a separate formaldehyde sensor, a huge IPS touchscreen, and full local integration into Home Assistant without clouds. Professional solutions of this level cost completely different money. 🏗️ Software ArchitectureMy Architectural Principles:Isolation: The network doesn't know about the screen, and the sensors don't know about WiFi. Everyone communicates through managers.Asynchrony: No blocking delays in the main loop. Polling sensors or sending MQTT messages should not "freeze" the interface.System Stability: I added periodic monitoring of available RAM to detect resource usage issues early, ensuring the device runs smoothly for weeks without hanging.🛡️ Reliability (Safety Features)I made Aura as a "set it and forget it" device. It must work 24/7.1. Safe Boot & Last Good Config I implemented a dual configuration system: the current config and the known-good config. If the device crashes on boot 5 times in a row (for example, due to incorrect WiFi settings), Safe Boot will trigger, and the settings will roll back. 2. Task Watchdog A watchdog (180 sec) monitors the main threads. If a task hangs, the Watchdog will hard reset the controller. 3. I2C Recovery The I2C bus can be capricious. I wrote an algorithm: at startup or failures, the controller tries to recover the SDA/SCL lines to revive hung sensors. 4. VOC State Persistence VOC sensors learn for days. To avoid losing progress during a reboot, I save the state of the learning algorithm to internal flash memory. Now, after a restart, the sensor recovers in minutes, not hours.🚀 Functional CapabilitiesThe device collects more than 10 parameters. I added data validation to filter out obvious noise and errors before showing the numbers to you.Smart BarometerHistory: A ring buffer of history for 24 hours is stored internally.Forecast: The system calculates the pressure delta for 3 and 24 hours. This really helps predict weather changes or rain.Time ManagementAccuracy: RTC with battery + NTP synchronization every 6 hours.Time Zones: Support for 37 zones via standard POSIX strings (summer/winter time works correctly).🏠 Integration: Home Assistant and MQTTMQTT Auto-discoveryI use Home Assistant myself and know the hassle of manual configuration. Aura does everything itself. Immediately after connecting to the broker, it sends configs, and the following appear in HA:Sensors (T, RH, PM, CO2, VOC, Nitrogen Oxides, Formaldehyde, Pressure)Statuses (WiFi, RTC Battery)Switches (Night Mode, Backlight)Buttons (Calibration, Restart) Data updates every 30 seconds.Data flies out every 30 seconds.🎨 UI/UX: An Interface Pleasant to Look AtI decided to get away from boring tables with numbers.Themes: 12 color schemes + a web editor for your own themes.Night Mode: Automatically dims the screen so as not to shine in your eyes at night.Personalization: °C/°F, LED control, screen timeouts — customize it for yourself.1. Main Dashboard All vital information on one screen. Large indicators for PM2.5, CO2, temperature, and humidity. Color coding helps instantly assess air quality.2. Settings Screen Device control center. Intuitive access to all configurations without needing to connect to a computer.3. Themes Screen Bored with one color? Choose from 12 preset themes. Want something unique? Create a custom theme in the custom editor via the web page.4. WiFi Screen Scan available networks and connect directly from the device screen. No need to hardcode SSID in the firmware.5. MQTT Screen Full setup for Home Assistant integration: broker address, port, login, and password. Connection status is visible immediately.6. Auto Night Mode A bright screen won't disturb your sleep. Set a schedule, and the device will automatically switch to darker colors at night.7. Auto Screen Timeout Save energy and display life. Set a timeout (30s, 1m, 5m) after which the screen turns off. Wakes up with a touch.8. Time and Date RTC clock management. Select your time zone for internet sync or set the time manually.🎯 Stretch Goals and StatusStretch GoalsUsually in crowdfunding, features are unlocked for money. I decided otherwise: a good device should be complete right away. All functionality (sensors, MQTT, themes) is available to you out of the box. My only stretch goal: If we gather a large community, I will sit down to develop alternative case designs.📢 Project StatusRight now, a fully working, assembled prototype is sitting on my desk. I am taking 1-2 weeks for final "combat" tests and polishing the instructions. Subscribe so you don't miss the release of files and videos.ConclusionProject Aura is an example of how, using accessible hardware (ESP32-S3) and the right approach to software, you can make a thing that surpasses commercial analogs. Open source, modularity, and attention to detail are the base on which you can build your ideal monitor. Let's breathe clean air. Together.