Overview

This DIY air quality monitoring system integrates precision sensors with a connected processing platform and a low-power e paper display.

it monitors :

• temperature
• pressure
• humidity
• CO2 level
• air quality (particules/dust)

System Architecture

Processing Unit (Core): The ESP32 S2 Lolin mini manages the sensors.

It offers native Wi-Fi connectivity, ideal for sending data to dashboards (Home Assistant, InfluxDB, or MQTT). Its architecture enables efficient management of peripherals via SPI and I2C interfaces.

But for this project I prefered a simple e-paper display without any connection to Wifi !

Display:

3.7-inch E-Paper (240x416): Electronic ink technology allowing for static data display with zero power consumption between refreshes, ensuring a clear and readable interface.

Air Quality Sensors:

SCD40: Photoacoustic sensor for CO2 concentration, temperature, and relative humidity.

Plantower PMS5003: Laser scattering sensor for measuring fine particulate matter (PM1.0, PM2.5, PM10).

Complementary Environmental Sensors:

BME280: Precision measurement of barometric pressure, humidity, and temperature.

DS18B20: Digital temperature sensor using a 1-Wire interface, ideal for remote measurement or isolated thermal reference.

Schematics

it couldn't be simpler: only one resistor + sensors + ESP32 !

Implementation Considerations

Power Management: The PMS5003 consumes significant current during startup (approx. 100mA). The USB power source and the ESP32’s onboard voltage regulator can handle this peak load.

Bus Sharing:

The BME280 and SCD40 typically use the I2C bus. (they don't have the same addresses so do not conflict)

The E-Paper uses an SPI interface, allowing it to function simultaneously with the I2C sensors without pin communication interference.

Airflow: The PMS5003 requires constant airflow to function accurately. When designing the enclosure, the inlet and outlet are unobstructed and air circulates freely around the temperature and CO2 sensors.

PCB

The PCB can be bought at PCBWay directly from this project page.

The PCB was kindly sponsored by PCBWay and is as usual of excellent quality.

and if you are new to PCBWay please use this affiliated link : https://pcbway.com/g/o35z4O

As you can see corners are "rounded" in order to fit into the 3d printed enclosure.

Enclosure

You can print the enclosure, the PCB will fit inside

Work in progress : please stay tuned