Hardware designer and self-described "electrical engineering witch" Jana Marie Hemsing has designed a neat device for monitoring air quality and other environmental conditions, complete with an attractive Grafana dashboard: the Anotter Sensor Hub.
"[A] smol side project is this indoor environment sensor with Prometheus-exporter," Hemsing writes of the neat device. "Its focus lies in tracking particulate matter (1µm, 2.5µm, 4µm, & 10µm) and providing a NOx [Nitrogen Oxides] and VOC [Volatile Organic Compounds] index. The design is dead simple, just an [Espressif] ESP32 & a Sensirion SEN055 as main sensor. Both are clamped together by four 3D printed feet. The ESP32 provides a simple webpage with Prometheus metrics."
The heart of the system is, as Hemsing explains, the Sensirion SEN055 environmental sensor. In addition to measuring four sizes of particulate matter pollution — with many of its rivals concentrating on just 2.5µm and 10µm, usually written as PM2.5 and PM10 — the sensor tracks volatile organic compound concentration, temperature, and humidity for a generalized look at overall air quality and environmental conditions.
Below the sensor is the hub itself, a custom circuit board which plays host to a Espressf ESP32-WROOM-32U microcontroller module, providing a dual-core 32-bit Tensilica Xtensa processor running at up to 240MHz alongside 4MB of flash storage and both Wi-Fi and Bluetooth connectivity. The Wi-Fi radio is used to connect one or more nodes to a network, where the data gathered by the sensor can be sent to a Prometheus server — and visualized on an attractive Grafana dashboard, complete with instant and historical readings.
"Other I2C, SPI, or PWM [hardware] can be added to the designated connectors," Hemsing adds of the host board's capabilities. "All ESP32 pins are broken out to offer bodging all sensors imaginable to the host board. The PCB and components (w/o SEN055) are about ~5$, with [the] SEN055 it comes up to ~40€/sensor node [around $42]."
Source code, design files, and STL files for 3D-printing the mount legs are available on Hemsing's GitHub repository under an unspecified open source license.