README.md

EcoStation

ESP32 based station for urban ecology.

PRE-REQUISITES (WIP)

BUILD INSTRUCTIONS

• Arduino IDE ( add the lines in bold to ~/.arduino15/packages/espxxxx/hardware/espxxxx/{version}/platform.local.txt )

  • A sequential build number is embedded in the code every time a build is made (whether it is successful or not)

  recipe.hooks.prebuild.0.pattern={build.source.path}/../build_seq.sh {build.source.path}

  For the hook to work, you will also need to create a link (or copy the file) to the file "build.sh" from sketch directory to the path of the sketch book. Sorry for the mess ... if you have a better solution, you are most welcome!

STATUS & DEVELOPMENT

This is version 1.0 of the project. It is still work in progress.

The things that might be improved in v1.1 are:

• Software
  • TBD
• Hardware
  • TBD

FEATURES

• Weather parameters:

  • Temperature
  • Pressure
  • Relative humidity
  • Cloud coverage
  • Solar irradiance
  • Sky Quality Meter for light pollution

• Alarms for:

  • Sensor unavailability
  • Low battery

• Operations:

  • External reboot button
  • Debug button (to be pushed when rebooting to activate debug mode)
  • External micro USB socket for debugging (serial console) and firmware updates
  • Configuration mode and runtime configuration updates activable via button

SPECIFICATIONS

This section is being reworked as there are different hardware setups.

• Power consumption:
  • Solar panel version:
    • 12mA in sleep mode
    • ~40mA while active (for ~30s)
• Autonomy: N/A (collecting data)
• Measures (from sensor specs)
  • Illuminance range: 0-88k Lux ( up to ~730 W/m² )
  • Temperature range: -40°C to +85°C
  • Pressure: 300 to 1100 hPa

Runtime configuration interface

Alarms format

The station sends alarm to an HTTPS endpoint as a JSON string:

{ "subject": "reason for the alarm", "message": "what happened" }

Data format

The station sends the data to a web server as a JSON string:

{ "battery_level":92, "timestamp":1675767261, "temp":16.84000015, "pres":941.1413574, "rh":27.296875, "lux":68181, "ambient":21.42998695, "sky":-3.19000864, "sensors":63 }

Where

• battery_level: in % of 4.2V
• timestamp: Unix epoch time
• temp: in °C
• pres: in hPa (QFE)
• rh: relative humidity in %
• lux: solar illuminance
• ambient: IR sensor ambient temperature
• sky: IR sensor sky temperature (substract ambient to get sky temperature, if below -20° --> sky is clear)
• sensors: available sensors (see source code)

REFERENCES

I found inspiration in the following pages / posts:

• No need to push the BOOT button on the ESP32 to upload new sketch
  • https://randomnerdtutorials.com/solved-failed-to-connect-to-esp32-timed-out-waiting-for-packet-header
• Reading battery load level without draining it
  • https://jeelabs.org/2013/05/18/zero-power-measurement-part-2/index.html
• To workaround the 3.3V limitation to trigger the P-FET of the above ( I used an IRF930 to drive the IRF9540 )
  • https://electronics.stackexchange.com/a/562942
• Solar panel tilt
  • https://globalsolaratlas.info/
• TSL2591 response to temperature by Marco Gulino
  • https://github.com/gshau/SQM_TSL2591/commit/9a9ae893cad6f4f078f75384403336409ca85380
• Conversion of lux to W/m²
  • P. Michael, D. Johnston, W. Moreno, 2020. https://pdfs.semanticscholar.org/5d6d/ad2e803382910c8a8b0f2dd0d71e4290051a.pdf, section 5. Conclusions. The bottomline is 120 lx = 1 W/m² is the engineering rule of thumb.