Eliza's Custom Life Support System (ECLSS)

a fast, cheap, and out of control IoT environmental sensor node.

what is it?

ECLSS (the NASA acronym for "Environmental Control and Life Support Systems") is an ESP32-based implementation of a WiFi-enabled environmental & air quality sensor node that reads data from a variety of I²C sensors and exposes data in the prometheus metrics format.

hardware

• microcontroller: ESP32-C3. i'm using the QT Py ESP32-C3 from Adafruit.

  the software could easily be tweaked to work with any ESP32-C3 board with a few source changes (e.g. which pins are I²C). i picked the QT Py board because it's small and cute and has a Stemma QT connector.

• sensors:

  Note note that any given sensor is optional; the software gracefully handles missing sensors and will continue to collect data from other sensors if one isn't present on the I²C bus. of course, if you're missing a particular sensor, you won't be collecting the data it measures :)

  • Sensirion SCD30 NDIR CO₂ sensor (with temperature and relative humidity).
  • Bosch BME680 temperature, barometric pressure, humidity, and VOC (MOX gas sensor). i meant to get the slightly newer BME688 breakout but i clicked the wrong one. a BME688 would also work.
  • Plantower PMSA003I particulate matter sensor, measuring particulate matter concetrations.
  • Sensirion SGP30 tVOC sensor: this sensor measures total volatile organic compounds (tVOC). it also calculates an equivalent CO₂ (eCO₂) measurement based on the tVOC measurement. in my experience, these eCO₂ numbers are wildly different from the "real" CO₂ measurements provided by a sensor like the SCD30. i wouldn't treat them as an authoritative measurement of CO₂ concentration, but they might still be interesting
  • more sensors coming soon! there are several different I²C air quality sensors, and even more different temperature/pressure/humidity sensors, on the market. eventually, i'd like to add drivers for most of the commonly-available sensors, so you can just plug in whichever ones you're able to get easily or already have lying around...
• human interfaces:
  • no display yet! i'm thinking an e-ink display might be cool...
  • i'm using the Neopixel LED on the QT Py board as a wifi status indicator.
• misc:
  • TCA4307 hot-swap I²C buffer (OPTIONAL). this is totally optional; it allows hot-swapping Stemma QT sensors without the risk of the I²C bus getting stuck. in practice, you're probably not going to hot-swap the sensors, but my software supports hot-disconnection and reconnection of sensors so it's a fun litle tech demo...

software

• runs a WiFi access point (SSID: eclss) for configuration. connect to eclss and open http://192.168.71.1 (or eclss.local, if your browser/device resolves mDNS hostnames) to configure the SSID and password of a WiFi access point to connect to.

• exposes an HTTP server on port 80 with a (mobile-friendly, reactive) web UI at / and prometheus metrics at /metrics:

  

• advertises the following mDNS services with the hostname eclss.local:

  • _http._tcp
  • _https._tcp
  • _prometheus-http._tcp
  • _prometheus-https._tcp

• the _prometheus-http/_prometheus-https mDNS services would allow something like msiebuhr/prometheus-mdns-sd to automatically discover ECLSS scrape targets.

• grafana dashboard you can add to a Grafana instance to display ECLSS prometheus metrics:

  

building and running it

see BUILD.md for details.