Advice on building a multi zone watering system

So all things electric and electronic are well outside of my areas of knowledge. So as always, please bear with me... I'm learning.

What I want to do:

Build a multi-zone watering system, with capacitive moisture sensors. I'd even like to be able to individually program the target moisture level, to accommodate different growing media.

How I think it should work:

I would like to build the logic, such that, if any zone needs water, a solenoid to that zone opens. On top of that, if any zone needs watering, the pump comes on (obviously).

I'm not 100% sure what controller I'd need. I think I've found all of the relays and sensors (just any vanilla board and capacitive moisture sensor seems adequate). Solenoid could be tricky.

Just wondering if my idea is properly thought out, and if so, maybe suggestions for the hardware?

Thanks in advance.

If you have no experience, build a prototype that waters one plant. Projects on that are basically "growing on trees" if you don't mind the expression. Google "Arduino plant watering".

Why wouldn't I choose to design something scalable, from the get-go? Knowing that's going to be its logical conclusion?

Why couldn't I simply use a single zone to test?

These questions primarily come revolve around not wanting to buy hardware more than once, if avoidable.

Sure, build something scalable. Sounds good to me.

But I had a reason... it's so you can learn and become more comfortable with the hardware and software. You basically said you know nothing...

Have you done the suggested Google search yet?

Sure, I did. And you're right - there's tons of smaller projects on the subject. But I prefer to be closer to my end goal, and jump right into the deep end.

Most of the projects seem to be missing the "multi' approach. Mind you, I'm just asking for advice on putting together a components list, and a general critique of feasibility.

Then you have to provide more details about the application - how much water, how much area, what is your budget, power availability, etc. etc.

Also describe your "vision" in more detail. How should the pumps/sensors/valves work, generally?

To get some ideas you may take view here:

Most of what I saw were build on nano boards, one plant at a time. I have not been able to find a solenoid operated (think sprinkler system) type system. But I'd be using the same basic components as the plethora of systems that are Google-able. These are small house plants. Most are bonsai.

Well, what do the commercial systems do? Because they are definitely widespread. They may lack sensors, just use a timer or Frank in the basement's judgement. :slight_smile:

I still don't buy the argument that you can't learn anything from building a single unit. Did it occur to you, if you run all the sensors from one board, you would need cables going from there to every sensor? How long? There is a practical limit, especially outdoors.

Let's go back and answer reply #6.

OK, but I'm asking for advice on how to use something like that with Arduino. I don't know if there is going to need to be any special considerations for incorporating a commercially available component, into a hobby board. I'm asking, from a 30,000 foot level, for advice on feasibility and components. I didn't ask for anyone to design my system. Just general guidance. Whether it's a single zone, or 100, I still need to figure out the basic premise of what to use, what's available, etc. I don't know what I don't know.

I didn't argue about building a single unit. I just said, why not figure out the build list, for what's required for a scalable system? Having the capability, does not logically equate to trying to skin the whole cat at once. If I've told you that all the systems I've seen are based off nano boards, what is the fault of asking which board (or other components) would ultimately be required for a more comprehensive system?

I laid out my "vision" in post #1. A relay to switch on the solenoid to the required zone, and power to pump, when any zone requires watering.

I realize I am answering a deleted post, but you asked, so that's it.

Please answer reply #6. Because from 30,000 feet the answer would be, use a pump, valves, sensors and a control system...

Ok, then. Thank you for your time and advice.

You're welcome. Had you provided some details, I might have been able to help.

Given this, I suggest you heed the advice given in reply #2. Writing a whole program from scratch is hard, even if you're just writing code. It goes double or treble if there's electronics and other parts involved. Experienced folks try to get something minimal going and then extend.

Of course, it helps to think about the overall design up front, but it's not uncommon to have to scrap the whole thing and start over so too much time spent on that may be wasted in the end.

Look at arrays if you don't know how to use them - they will be useful here.

I'm not at all worried about the programming. I program 3 languages, on the daily. I'd still need advice on component selection, whether it was one zone or a hundred. I can't say that part enough times... I'm not knowledgable about that aspect of the design. (my area of expertise is mechanical, not electrical, not electro-mechanical, not electronic)

I'm not watering a small town. Just about 8 plants. The only thing that complicates that, is that aspect. Yes, I can do the single zone systems. I've studied them, and have the components for a single watered plant. But LITERALLY the crux of my question, revolves around what hardware is needed to scale up. There are multitudes of fully documented builds for single zones. I WANT TO KNOW WHAT's REQUIRED FOR MULTI-ZONE. I only have an idea, and I've asked for a feasibility assessment.

I mean, it seems so clear to me, but this dialogue is unbelievably frustrating. I just really would like to have my basic questions answered. I'm not even getting technical. It's a design approach. Concepting, Whatever you want to call it.

Is a solenoid the best approach? Or is there a better way? And if so, are we talking plug and play components, or is there some engineering involved? (I'm not going to just be able to intuitively design circuits, if voltages, etc, are mismatched)

This is the closest project that I've been able to find. I'm still not entirely sure if it's a match for what I'm trying to do. Sounds right. But some electro-mechanical expertise would be greatly appreciated.

Oh, I see. I assumed that you were new to coding too. That changes things significantly.

Relays are what you need. That eight way relay board is a useful example. They can switch solenoid valves for water flow and a pump to send water. You will likely need an Arduino with more pins than an Uno so you can read all your sensors. A Mega would have enough but you can also look at port extenders.

Almost every relay board for Arduino use uses Songle relays. A good way to get started, but I would use something more solid for long term use - you may want to look at something with SSRs instead. Make sure that the relay board is optoisolated - it will help avoid voltage spikes that reset your Arduino.

Note too that the relay coils need their own power - the Arduino can control them, but it can't provide enough current to activate them all.

There was an thread here in the last month or two that did pretty much exactly what you're looking for.

The Nano would be perfect for multiple channels, or the WeMOS D1 Mini illustrated above (NodeMCU is just an unnecessarily larger and expensive version) if you need WiFI, a port expander if you need more control lines.

A relay board is obviously needed to switch the 24 VAC solenoids.

ESP32 can handle all the analog sensors.
The ESP8266 cannot do it without additional chips