ESP32 - Water/Liquid Valve

This tutorial instructs you how to control a liquid flow such as water, beer, oil by using ESP32 and a solenoid valve. It is the same for controlling gas flow.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	USB Cable Type-C
1	×	Relay
1	×	Liquid Solenoid Valve
1	×	12V Power Adapter
1	×	(Optional) DC Power Jack
1	×	Breadboard
1	×	Jumper Wires
1	×	(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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Introduction to Water/Liquid Valve

Pinout

Solenoid Valve usually has two terminals:

Positive (+) pin (red): needs to be connected to 12V of DC power supply
Negative (-) pin (black or other): needs to be connected to GND of DC power supply

How Water/Liquid Valve works

Normally, the valve is closed. When 12V DC is applied to the two terminals, the valve opens and water/liquid can flow.

※ NOTE THAT:

For some kinds of valve, there is a gasket arrangement inside, so there is a minimum pressure requires to open the valve (after 12V DC is applied). The pressure can be created by liquid flow.
For some kinds of valve, liquid can only flow one direction.

How to Control Water/Liquid Solenoid Valve

If the valve is powered by 12V power supply, it opens. To control the valve, we need to use a relay in between ESP32 and valve. ESP32 can control the solenoid valve via the relay. Learn more about relay in the ESP32 - Relay tutorial

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

ESP32 Code

The below code repeatedly turns the water valve ON in five seconds and OFF in five seconds,

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-water-liquid-valve */ #define RELAY_PIN 16 // ESP32 pin GPIO16, which connects to the water valve via the relay // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin A5 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); }

Quick Instructions

If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
Do the wiring as above image.
Connect the ESP32 board to your PC via a micro USB cable
Open Arduino IDE on your PC.
Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
Copy the above code and paste it to Arduino IDE
Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
Check the water flow

Code Explanation

The above ESP32 code contains line-by-line explanation. Please read the comments in the code!

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