SENSORS/ACTUATORS

INTERNET OF THING (IoT)

Arduino MKR WiFi 1010 - Water/Liquid Valve

This comprehensive guide explains how to control the flow of liquids like water, beer, or oil using the Arduino MKR WiFi 1010 and a solenoid valve. Whether you're building an automated watering system, a beverage dispenser, or an industrial control project, learning to use a solenoid valve with Arduino MKR WiFi 1010 opens up countless automation possibilities.

What You'll Learn:

Connecting a solenoid valve to Arduino MKR WiFi 1010 through a relay module
Programming Arduino MKR WiFi 1010 to control solenoid valve operations
Understanding how solenoid valves work with Arduino MKR WiFi 1010 control signals
Wiring a relay between Arduino MKR WiFi 1010 and solenoid valve for safe operation
Writing Arduino MKR WiFi 1010 code to open and close solenoid valves automatically
Implementing timed solenoid valve control with Arduino MKR WiFi 1010
Switching the solenoid valve with a MOSFET module instead of a relay: the same ON/OFF idea, but silent and with no contacts to wear out

Real-World Applications:

Home automation: Use Arduino MKR WiFi 1010 with solenoid valve for automatic garden watering
Industrial control: Arduino MKR WiFi 1010 controlling solenoid valves in manufacturing processes
Beverage dispensing: Solenoid valve and Arduino MKR WiFi 1010 for automated drink machines
Aquarium systems: Arduino MKR WiFi 1010 managing solenoid valves for water changes

The same method works for controlling gas flow, making Arduino MKR WiFi 1010 and solenoid valve combinations perfect for various fluid control applications.

The valve can be driven by a relay or by a MOSFET module. Both of them only open and close the valve, because a valve has no "half open" state. So why use a MOSFET module? It makes no click, it switches faster, and it has no metal contacts that wear out over time. You will see both ways in this tutorial.

Hardware Preparation

1	×	Arduino MKR WiFi 1010
1	×	Micro USB Cable
1	×	Relay
1	×	Alternatively, MOSFET Module (AOD4184, LR7843 or FR120N)
1	×	Liquid Solenoid Valve
1	×	12V Power Adapter
1	×	Optionally, DC Power Jack
1	×	Breadboard
1	×	Jumper Wires

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of Water/Liquid Valve

A solenoid valve is an electromechanical device that controls liquid or gas flow using an electromagnetic coil. When powered, the coil creates a magnetic field that moves an internal plunger, opening or closing the valve. These valves are perfect for automated control systems with the Arduino MKR WiFi 1010.

Pinout

A solenoid valve typically has two connection points for power:

Red positive pin (+): Connect this pin to the +12V terminal of your DC power supply.
Black or other colored negative pin (–): Connect this pin to the ground (GND) terminal of your DC power supply.

How Water/Liquid Valve works

The valve is usually shut. When you add 12V of DC power to its two points, the valve opens so water or liquid can flow.

※ NOTE THAT:

Some valves have a rubber ring inside that needs a minimum pressure to open the valve after you apply 12V DC. This pressure is made by the liquid flowing.

Some valves only let the liquid flow in one direction.

How to Control Water/Liquid Solenoid Valve

If the valve gets power from a 12V supply, it will open. To control the valve, you must use a relay between the Arduino MKR WiFi 1010 and the valve. The Arduino MKR WiFi 1010 sends signals to the solenoid valve through the relay. Find out more about the relay in the Arduino MKR WiFi 1010 - Relay tutorial.

You can also put a MOSFET module where the relay is. New to this module? The Arduino MKR WiFi 1010 - MOSFET Module tutorial shows how it works and how to wire it.

Relay vs MOSFET Module for a Solenoid Valve

	Relay	MOSFET Module
Valve control	open or closed	open or closed (no PWM for a valve)
Noise	the relay clicks (and the valve too)	the module is silent (only the valve itself clicks)
Switching speed	slow, milliseconds	very fast
Wear	contacts wear out with use	no moving contacts
Valve power	AC or DC valves	DC valves only
Supply voltage	any the relay is rated for	6V or more (the gate needs it); a 12V valve is fine
Isolation	yes, through the coil	yes, through a PC817 optocoupler
Choose it for	AC valves, simple ON/OFF	12V DC valves that open and close often

The control is the same in both cases: open or closed. Do not try to use PWM to "half open" a solenoid valve. It does not work and it can make the coil hot. Pick the MOSFET module for a quiet, long-lasting 12V DC setup, and the relay for an AC valve.

Wiring Diagram

Follow this wiring diagram carefully to connect your solenoid valve to the Arduino MKR WiFi 1010 through a relay module:

This image is created using Fritzing. Click to enlarge image

Connection Summary:

Arduino MKR WiFi 1010 control pin → Relay signal input
Relay power terminals → 12V DC power supply and solenoid valve
The relay isolates the Arduino MKR WiFi 1010's low-voltage circuit from the high-power valve circuit

Arduino MKR WiFi 1010 Code

This Arduino MKR WiFi 1010 code demonstrates automatic solenoid valve control. The program repeatedly opens the valve for five seconds to allow liquid flow, then closes it for five seconds. This cycling pattern is useful for timed watering systems, periodic dispensing, or testing your valve setup.

/* * This Arduino MKR WiFi 1010 code was developed by newbiely.com * * This Arduino MKR WiFi 1010 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-mkr/arduino-mkr-wifi-1010-water-liquid-valve */ #define RELAY_PIN 3 // The Arduino UNO R4 pin connected to the IN pin of relay // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin as an output. pinMode(RELAY_PIN, OUTPUT); } // the loop function runs over and over again forever void loop() { digitalWrite(RELAY_PIN, HIGH); // open valve 5 seconds delay(5000); digitalWrite(RELAY_PIN, LOW); // close valve 5 seconds delay(5000); }

Detailed Instructions

New to Arduino MKR WiFi 1010? Complete our Getting Started with Arduino MKR WiFi 1010 tutorial first to set up your development environment.

Carefully connect the components to your Arduino MKR WiFi 1010 board following the wiring diagram shown above - proper connections are essential for safe operation!
Connect your Arduino MKR WiFi 1010 to your computer using a USB cable
Launch the Arduino IDE on your computer
Select the Arduino MKR WiFi 1010 board and its correct COM port
Copy the code above and paste it into the Arduino IDE
Click the Upload button to compile and upload the code to your Arduino MKR WiFi 1010 board
Ensure your 12V power supply is connected to the relay and solenoid valve
Place the valve's output in a container or connect it to your liquid system
Observe the solenoid valve opening and closing in 5-second intervals
You should hear a clicking sound from both the relay and the valve as they operate
Check to see if the water or liquid is flowing during the open periods

Code Explanation

Let's break down how the Arduino MKR WiFi 1010 code controls the solenoid valve:

Setup Phase:

The code defines the relay control pin and initializes it as an OUTPUT
This pin will send HIGH (on) or LOW (off) signals to the relay module

Main Loop:

digitalWrite(relayPin, HIGH) - Activates the relay, which connects 12V power to the solenoid valve, opening it
delay(5000) - Keeps the valve open for 5 seconds (5000 milliseconds)
digitalWrite(relayPin, LOW) - Deactivates the relay, cutting power to the valve and closing it
delay(5000) - Keeps the valve closed for 5 seconds before repeating the cycle

The code comments provide additional details for each line - review them to understand the complete operation.

Troubleshooting Tips

If your solenoid valve isn't working with Arduino MKR WiFi 1010, try these solutions:

Valve Doesn't Open:

Verify the 12V power supply is connected and working - use a multimeter to check voltage
Confirm the relay is clicking when activated - if not, check the Arduino MKR WiFi 1010 signal pin connection
Test if the valve needs minimum pressure - try raising the liquid source higher
Check that liquid flow direction matches the arrow on the valve body
Ensure the relay is rated for the valve's current draw (usually 300-500mA)

Valve Opens But No Flow:

Check for blockages in the valve or connected tubing
Verify sufficient liquid pressure in the supply line
Some valves require 0.02-0.8 MPa minimum pressure to operate properly
Inspect the valve for debris or damage to the internal seal

Relay Doesn't Click:

Verify the Arduino MKR WiFi 1010 pin is set as OUTPUT in the code
Check connections between Arduino MKR WiFi 1010 and relay signal pin
Test the relay with a different pin to rule out relay failure
Ensure the relay module has proper power supply (VCC and GND)

Inconsistent Operation:

Check all wire connections are secure and not loose
Verify the 12V power supply can provide enough current
Look for voltage drops in long wire runs - use thicker wires if needed

Using a MOSFET Module Instead of the Relay

Want the valve to switch without the relay click? Replace the relay with a MOSFET module. The valve still only opens and closes, but the switching part is now silent and has no contacts that wear out.

Note that the relay and the MOSFET module use different pins on this page. The relay uses pin 3, and the MOSFET module uses pin D6. So each wiring has its own code.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Connection Summary:

Arduino MKR WiFi 1010 pin D6 → module PWM pin
Arduino MKR WiFi 1010 GND → module GND pin
12V adapter + → module + terminal, shared with the valve red wire (+)
Valve black wire (−) → module LOAD terminal
12V adapter − → module − terminal
The valve is a coil, so put a 1N4007 or 1N5819 diode across its two wires. The stripe (cathode) goes to the valve + wire.

Code

The code works the same way as the relay code: HIGH turns the valve ON (open), and LOW turns it OFF (closed). The valve opens for 5 seconds and closes for 5 seconds, again and again.

A solenoid valve must only get full ON or full OFF. Never send it a PWM signal. That is why this page does not use the fade code from the MOSFET module tutorial.

/* * This Arduino MKR WiFi 1010 code was developed by newbiely.com * * This Arduino MKR WiFi 1010 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-mkr/arduino-mkr-wifi-1010-water-liquid-valve */ #define MOSFET_PIN 6 // The Arduino MKR WiFi 1010 pin D6 connected to the PWM pin of the MOSFET module // The setup function runs once on reset or power-up void setup() { pinMode(MOSFET_PIN, OUTPUT); // set the pin as an output } // The loop function repeats indefinitely void loop() { digitalWrite(MOSFET_PIN, HIGH); // open the valve for 5 seconds delay(5000); digitalWrite(MOSFET_PIN, LOW); // close the valve for 5 seconds delay(5000); }

Detailed Instructions

Wire the Arduino MKR WiFi 1010, the MOSFET module and the valve as shown in the diagram above
Connect the Arduino MKR WiFi 1010 to your computer with a USB cable
Open the Arduino IDE and select the board and COM port, as in the relay Quick Steps above
Copy the code above, paste it into the Arduino IDE and click Upload
Watch the valve open for 5 seconds and close for 5 seconds. This time you will hear only the valve, not a relay

Tip: The MOSFET module works only with DC, and its supply must be about 6V or more. If your valve runs on AC, keep using the relay.

Challenge Yourself - Creative Customizations

Once you have the basic solenoid valve control working with Arduino MKR WiFi 1010, try these enhancements:

Sensor-Triggered Valve Control:

// Add soil moisture sensor to trigger valve int moistureLevel = analogRead(A0); if (moistureLevel < 300) { // Soil is dry digitalWrite(relayPin, HIGH); // Open valve delay(10000); // Water for 10 seconds digitalWrite(relayPin, LOW); // Close valve }

Multiple Valve Control:

Connect several solenoid valves to different Arduino MKR WiFi 1010 pins
Create a watering sequence that operates each valve independently
Build a multi-zone irrigation system with scheduled watering

WiFi Control Integration:

Use the Arduino MKR WiFi 1010's built-in WiFi to create a web interface
Control your solenoid valve remotely from your smartphone
Add scheduling features for automatic daily watering
Send notifications when watering begins and ends

Advanced Features:

Add a flow sensor to measure the amount of liquid dispensed
Implement safety timers to prevent valve from staying open too long
Create a rain sensor integration that skips watering when it's raining
Add a water level sensor to prevent empty reservoir operation

Video

Learn More

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