Sebastian Kopacz

Portable NPK Soil Sensor - Unfinished

  • Aug 20, 2021

Sensor for detecting nitrogen, phosphorus, and potassium in garden soil. Current status: Abandoned in a functional but nonportable state.

Source code

Project Summary

Objective

Make a durable and portable NPK sensor I can use in the garden.

Justification

  • I was getting into gardening at the time and wanted to test my soil.
  • Learning opportunity to program and wire an Arduino project.

Features

  • Displays nitrogen, phosphorus, and potassium values from a NPK sensor to an OLED screen.

Challenges

  • Figuring out a portable power source delayed this project for years.
    • This is the reason why this project is currently unfinished.
    • I have this solved now after finding a small and portable 9v power supply, but my interest in this project has since passed.
  • The Arduino Nano I was using for this project had only a few KBs of memory.
    • Had to slim my code down to only what was absolutely necessary.
  • I discovered that the tutorial I was following made a mistake and only used one byte of data from a two byte value.
    • Meaning, my tests were making absolutely no sense and I had no idea what was happening until I finally managed to make sense of the manual.
    • Since then this seems to have been corrected in several newer tutorials and the manual I found online while writing up this brief report looks a lot less confusing than what I had available at the time of making this project.
  • Feature creeping this project into a tutorial on how to build such a device yourself when I should have just wrapped it up and then written a very brief description like the one you’re currently reading.

Lessons learned

  • Do not finalize enclosures until the entire project is completed.
  • Do not blindly trust tutorials to always be correct.
  • Even for a seemingly simple project it’s always best to be aware of hardware limitations at the start of the project.

Improvements

  • Switching to an E-Ink display.
    • Much lower power consumption than an OLED.
    • Not as pretty, but that doesn’t matter for this project.
  • Finally get around to actually wiring up the portable 9v battery and designing a new enclosure so that this project can be considered finished.

Screenshots

Work in progress pictures

Videos

A simple test video I took for my girlfriend at the time

Credits

Tutorials

Third Party Libraries