Enviro Grow - replace humidity sensor #3 with a potentiometer for getting the water level

Support
1

Hello,

I am a newbie to Pimoroni but have made the first step by purchasing an Enviro Grow + Accessory kit (means including the pumps).

What I’m trying to achieve is to use the 3rd channel for logging the water level of the water container. Therefore I wanna use a potentiometer, a float and a lever that connects the floating thing with the potentiometer.

So my question is:
Regardless of the effort of customizing the existing code - is it possible to connect a potentiometer to the JST Connector that actually belongs to the 3rd sensor?

And if so, what potentiometer would you recommend in terms of a) battery life and b) accuracy (the expected angle will be approx. 25 deg - less than 1/12 of a full rotation - when not planning to have a gear between the lever and the pot)

Looking forward to hearing som inspirational answers,

SickNature

2

The moisture sensors are capacitive not resistive. A time of flight distance sensor may work though.

Wired up to the qwicc connecter.

3

Hi Kerry,

Thank you so much for this information and pointing me to the fact that a pot wouldn’t work.

Still there are some questions left open:

  1. I am wondering whether this TOF sensor will work for a 15cm high container with - let’s say - max 14cm water depth and the sensor located close to the surface . (I have read that the sensor has an accuracy of +/- 25mm and requires at least 4cm distance.)
    The container has a lid so it will be quite dark inside the box. So I assume there will not be too much distraction but a clear signal instead. Will this increase the accuracy so that I can at least recognize rough water level (let’s say: full - 75% - 50% - 25% - (almost) empty)

  2. Will the proximity sensor be able to deal with a water surface?
    Or do I need any reflector on the surface of the water (kinda float)?

  3. And what about a mirror between the sensor and the water level?
    Because I would prefer installing the sensor outside the box to prevent it from being in such a humid environment.
    That’s why I would love to install the sensor horizontally with a mirror (inside the box under 45°) that reflects the laser beam down towards the water.

Looking forward to hearing from you!

SickNature

4

The answers to those questions, I don’t know? I have never tried to use one of those sensors in this manner. My suggestion was alone the lines of, something to look into, or maybe try. I do wish I could offer more help than that, but my tinkering with one of those breakouts has been very limited.

A potentiometer and float is doable, using an ADC. Getting at an ADC pin on the Pico Enviro Grow looks tricky though. You’d have to solder on some jumpers / wires. Thats why I was leaning towards something that just plugged in to the QWICC connector.

5

Hi Kerry, thanks again for your quick response.
Currently I am quite busy and almost run out of time. But I think I will give it a try later to purchase this TOF sensor and test that approach.
In the meantime let me ask a question to the masses:
Maybe anybody out there in the community has already used the mentioned TOF sensor in that way and can share his/her experience?
Looking forward for any feedback and review.

Best regards,
SickNature

6

It’s too bad the VL53L5CX is out of stock. It looks to a better TOF sensor than the other one. And has Micro Python support.
pimoroni-pico/micropython/examples/breakout_vl53l5cx at main · pimoroni/pimoroni-pico (github.com)

I hadn’t noticed when I posted the link, but the VL53L1X doesn’t appear to have any Micro Python Libraries? I have only ever used mine on a Pi in Python.

7

Ok, then I will replace this in my wishlist. Thanks for pointing this out! 😉