Water irrigation system - control three valves from one pin, how?

If the relay contacts can handle the current required by all three valves, just switch them in parallel. Check the relay specifications, or post links to the specs for the relay and the valves.

Is there some way that one could control the three valves from one pin on the arduino?

sure, if you want all three valves to do the same thing.

Does there exist some kind of relay/transistor that can take let's say three different signals from the controller (for instance low, medium and high), and then relay the full 12v signal to the valve that correspond with that particular input signal?

I can't even imagine how that would work. But no, there's no such relay. You could build one with three relays and a microcontroller, but then why not just do it with the microcontroller you have.

https://www.ebay.com/itm/1-2-Gravity-Feed-Electric-Solenoid-Valve-12-volt-DDT-CD-12VDC-Plastic-Body-N-C/290763981675?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20160323102634%26meid%3D4c1cef4b600540e7b1f85c985e7159d0%26pid%3D100623%26rk%3D4%26rkt%3D6%26mehot%3Dpp%26sd%3D300653378588%26itm%3D290763981675&_trksid=p2047675.c100623.m-1

The valve in question.

Haven’t chosen relays yet.

Not quite sure what you mean, Jremington!

*i should have specified that I want the different valves to open and close at different times.

Not quite sure what you mean, Jremington!

He is talking about if you want all three valves to come on together, then you just power them in parallel off the same relay. But that doesn't sound like what you want. It sounds like you want the valves to be individually controllable, in which case you're going to need three pins.

What is the point of this exercise? Are you out of pins or something? That is a much easier problem to solve.

Hi, Welcome to the Forum.

Why do you want to use one pin to control 3 valves independently.

You need to do a list of your input and output devices and set out what pins they will use to check your I/O numbers. Do not forget that the analog input pins can be configured as digital I/O.

Thanks... Tom.... :)

Forget about valves.

Use 3 bilge pumps like these. 6.7 x 5.0 x 1.3 in. more like 6.7 x 1.5x 1.3 in.

https://www.princessauto.com/en/detail/12v-200-gph-bilge-pump/A-p4270013e

You could definitely do that. Try Google to see if someone else has done it and if there is a module you can buy. That kind of multi-level control is very common in the steering-wheel controls on any car that has buttons in the wheel.

But it is highly likely that you won't find a module and the easiest way to build it is to use another Arduino. I suggest the Micro is easier to work with.

Thanks Tom!

So something like this does not exist? https://imgur.com/a/BKlaibP

Haha, for no other reason than to see if it was possible. I’m really a beginner and I though that the less pins I use the more pins I could use for later add’ons to this system. And it’s fun to learn!

So the reason I could not find something like this is because it doesn’t exist. Hmm I will have to live with using three pins and three relays then^^

I see Morgan! Will have to google some steering wheels.

Larry’s, using this one: https://m.banggood.com/DC-12V-Solar-Powered-Water-Pump-700LH-Brushless-Magnetic-Submersible-Water-Pumps-p-1275049.html?utm_design=41&utm_source=emarsys&utm_medium=Shipoutinform171129&utm_campaign=trigger-emarsys&utm_content=Winna&sc_src=email_2671705&sc_eh=3767757c547288891&sc_llid=9773714&sc_lid=104858042&sc_uid=LqFr0QT0QQ

The reason for the tank #2 and the valves to gravity fed tube was is because I thought that this pump would pump water too strongly and damage the plants in doing so. But perhaps it can just be used at a lower voltage and hence simplifying the whole thing.

Hmm but would still need valves to direct the water to different places as I want control over the exact amount going into each plant box (overenthusiastic gardener).

Thanks for the replies.

Hi,

If you had 4 or more outputs to control then there are multiplexer ICs to expand your I/O. The condition is that they use 2 or 3 pins themselves.

Tom... :) PS keep learning mate.

An I2C port expander will use only 2 precious pins.

Delta_G:

Is there some way that one could control the three valves from one pin on the arduino?

sure, if you want all three valves to do the same thing.

Actually, there are several ways to control multiple things with a single wire but it takes more circuitry and potentially some clever s/w.

There is the standardized Modbus interface, but those devices are expensive.

It could be something custom like using analog voltages created from PWM signals, frequencies that are filtered using notch filters, or a simple serial (not async) interface that can be decoded using an RC network and a shift register. I have used the latter to control a hd44780 LCD from an ATTiny part.

But all those are much more complex than just using multiple Arduino pins.

--- bill

MorganS: An I2C port expander will use only 2 precious pins.

And if using something like the PCF8574 i/o expander chip then each chip has 8 i/o pins and you can control up to 16 of those chips on the same bus.

You can even re-purpose the cheap ($1 USD) LCD backpacks that use the PCF8574 chip for this.

--- bill

Those may work, not sure of the dimensions.

I have used the ones I linked. You can easily adjust the pressure either by lowering the voltage or adding a Y connector tube. One leg of the Y tube has an adjustable clamp to regulate that legs flow. The other leg just returns it’s water to the same reservoir the submersible pump sits in. You can also feed the pump output into a trough that acts like manifold the length of the area to be watered thus reducing water pressure.

I’d stay away from valves and just use several inexpense simple pumps.

That actually sounded really interesting bperrybap! I’ll take notice, might come in handy some day, although perhaps a bit complicated for this one. Especially since it was so easy to expand the pin count on the arduino, didn’t know that.

Larryd I think you might be right. As the distance from the small tank (#2) to the small balcony box furtherest away from it will be about 4-5 meters I’m not sure if gravity alone will be able to push the water all the way. Three small pumps would probably cost the same as one valve, thanks for the input.

bperrybap: sure, if you want all three valves to do the same thing.

Actually, there are several ways to control multiple things with a single wire but it takes more circuitry and potentially some clever s/w.

There is the standardized Modbus interface, but those devices are expensive.

It could be something custom like using analog voltages created from PWM signals, frequencies that are filtered using notch filters, or a simple serial (not async) interface that can be decoded using an RC network and a shift register. I have used the latter to control a hd44780 LCD from an ATTiny part.

But all those are much more complex than just using multiple Arduino pins.

--- bill

Actually...

I went on to say in that post that you could conceivably create this with three relays, a uc, and some way to communicate from your first Arduino to the one with the relays. But at that point, why not just run them from the first Arduino.

And it becomes a question of why do you want to do this. If there is a real problem then there may be a real solution. But this is an example of the x-y problem as it is.

Delta_G: Actually...

I went on to say in that post that you could conceivably create this with three relays, a uc, and some way to communicate from your first Arduino to the one with the relays.

And I did see that, but I was talking about solutions that didn't need another microcontroller on the other end.

--- bill

bperrybap: And I did see that, but I was talking about solutions that didn't need another microcontroller on the other end.

--- bill

How would you use modbus to control a valve without some controller to receive the modbus signal and physically switch the valve?

Delta_G: How would you use modbus to control a valve without some controller to receive the modbus signal and physically switch the valve?

You can't, I guess I was a bit unclear. I actually meant having to use another Arduino type micro-controller requiring programming on the receiver end since I was assuming using an off the shelf modbus relay/pump/device which has a microcontroller built into the device - which is why they are so expensive.

--- bill

bperrybap: You can't, I guess I was a bit unclear. I actually meant having to use another Arduino type micro-controller requiring programming on the receiver end since I was assuming using an off the shelf modbus relay/pump/device which has a microcontroller built into the device - which is why they are so expensive.

--- bill

Right. That's what I said. You'd have to have a controller on the other end to control the valves. Or some seriously genius circuitry.

Once you involve the second controller this becomes a trivial matter of choosing a communication protocol.