The project is one where I want to monitor and log

  • Soil pH
  • Soil moisture
  • Room Temp
  • Room Humidity

Shown in the diagram are:

Capacitive soil moisture detector 3.3-5.5V link

ADC1115 to convert soil moisture sensor data link

DHT11 Temp/Humidity Sensor 3.3V link

Elegoo 8ch relay link

2 Peristaltic Pumps 12V link

My wiring attempt:

Gardening project

Thanks for your help, very new to this, but am enjoying the learning process!

  • 1
    Thanks @tlfong01 I’ve revised things a bit, just looking for a once over of the circuit diagram to ensure there are no mistakes or oversights.
    – Saeven
    Commented Apr 18, 2020 at 5:22
  • 1
    Hi @Saeven, your project plan looks good overall. As you might have read from my other answer to a similar micro-green project, yours is big project, so take your time and go slowly. Happy learning. Cheers.
    – tlfong01
    Commented Apr 18, 2020 at 6:18
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    @Milliways the relay does seem to work on its own. A cursory test to verify on/off is posted here youtu.be/KBXcvMfPYqU. Why do you say they are unsuitable?
    – Saeven
    Commented Apr 18, 2020 at 16:17
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    @jsotola Do they still need to share a ground, if it is grounded by the separate power supply used to power the relay?
    – Saeven
    Commented Apr 18, 2020 at 16:18
  • 1
    @Saeven, no direct ground connection is like connecting a lightbulb to one terminal of a battery only ... your relay board works because of some unknown ground loop ... maybe through the power supply, or maybe through the data pins ... does the relay board work if you activate both of the relays?
    – jsotola
    Commented Apr 18, 2020 at 17:21

1 Answer 1


I think you've gotten some good feedback in the comments, but your question about the correct connection or wiring isn't likely to get an answer - at least not a complete one. I say this for two reasons:

  1. It seems unlikely that anyone will have experience with each of the sensors you've selected

  2. If they did, the answer would be tedious

In other words, your question is very broad.

I'd suggest that you approach this on an incremental basis: Connect one sensor, write some code, test & verify correct operation. If you have problems, than ask a specific question re that one sensor (wiring or code or even both).

So - this isn't an answer at all - it's only a suggestion. Also, I've up-voted your question... not because it's a good question (I do feel it's too broad), but because I'm contemplating a similar project, and I appreciated the links to the different sensors.

Just one other suggestion, and I'll leave you to something more productive :) You can answer your own question here at SE. As you work through this project, you could even post multiple answers covering different aspects. Just a thought...

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