ESP32 C3 Super Mini - Water/Liquid Valve
Learn how to control water flow, beer dispensing, oil flow, or any liquid/gas valve using the ESP32 C3 Super Mini and a solenoid valve. This beginner-friendly tutorial shows you how to automate liquid control for irrigation, dispensing systems, and flow management projects.
In this tutorial, you'll learn:
- What a liquid solenoid valve is and how it controls flow
- How to wire a solenoid valve to ESP32 C3 Super Mini using a relay
- How to program ESP32 C3 Super Mini to open and close the valve
- How to test your automated water valve system
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Overview of Water/Liquid Valve
A solenoid valve is an electromechanical device that controls the flow of liquids or gases using an electric signal.
- Operating Voltage: Typically 12V DC (some models use 5V or 24V)
- Flow Control: Opens when powered, closes when power is removed
- Applications: Water dispensing, irrigation, gas control, beverage systems
- Flow Direction: Some valves are unidirectional (check valve specifications)
- Pressure Requirements: Some models need minimum pressure to fully open
- Perfect for beginners: Simple on/off control makes automation projects easy
Pinout
The solenoid valve has two connection terminals:
- Positive (+) pin (red): Connect to 12V DC power supply positive terminal
- Negative (-) pin (black): Connect to 12V DC power supply ground (via relay control)
How Water/Liquid Valve Works
The valve operates on a simple electromagnetic principle:
- Default State: Valve is normally closed, blocking liquid/gas flow
- Powered State: When 12V DC is applied, electromagnet pulls valve open
- Flow Control: Liquid/gas flows freely when valve is open
- Return to Closed: Removing power closes the valve automatically
※ NOTE THAT:
- Some valves require minimum water pressure to fully open after power is applied - the pressure is created by the liquid flow itself
- Many solenoid valves are directional - liquid can only flow one way (check the arrow marking on valve body)
- Always verify the voltage rating before connecting power to avoid damaging the valve
How to Control Water/Liquid Solenoid Valve
Controlling a solenoid valve with ESP32 C3 Super Mini requires a relay module:
- Why Relay is Needed: ESP32 pins output 3.3V at low current, but valves need 12V at higher current
- Relay Function: Acts as an electronic switch controlled by ESP32 C3 Super Mini
- Control Logic: ESP32 sends signal to relay, relay switches 12V power to valve
- Safety: Relay isolates ESP32 from high-voltage/high-current valve circuit
- Learn More: Check our ESP32 C3 Super Mini - Relay tutorial for detailed relay operation
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Follow the wiring diagram above to connect your ESP32 C3 Super Mini to the relay and solenoid valve.
※ NOTE THAT:
- Safety First: Never connect the 12V power supply directly to ESP32 C3 Super Mini pins
- Double Check Polarity: Verify positive and negative connections on both relay and valve before powering on
- Secure Connections: Ensure all wire connections are tight to prevent intermittent operation
Wiring Connections:
| Component Pin | Arduino Pin | Notes |
|---|---|---|
| Relay Signal Pin | D7 | Control signal from ESP32 |
| Relay VCC | 5V | Power for relay module |
| Relay GND | GND | Common ground |
| Relay COM | 12V Power (+) | 12V input to relay switch |
| Relay NO | Valve (+) | Normally Open to valve positive |
| Valve (-) | 12V Power GND | Valve negative to power ground |
ESP32 C3 Super Mini Code
The code below demonstrates automatic valve control - it opens the solenoid valve for 5 seconds, then closes it for 5 seconds in a continuous cycle.
What the code does:
- Configures D7 as the relay control pin
- Turns the valve ON (opens) for 5 seconds
- Turns the valve OFF (closes) for 5 seconds
- Repeats the cycle continuously for automated flow control
- Provides serial output to monitor valve state
/*
* This ESP32 C3 Super Mini code was developed by newbiely.com
*
* This ESP32 C3 Super Mini code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/esp32-c3/esp32-c3-super-mini-water-liquid-valve
*/
#define RELAY_PIN D7 // The ESP32 C3 SuperMini pin connected to the water valve via the relay
// The setup function runs once on reset or power-up
void setup() {
// initialize digital pin A5 as an output.
pinMode(RELAY_PIN, OUTPUT);
}
// The loop function repeats indefinitely
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 ESP32 C3 Mini? Complete our Getting Started with ESP32 C3 Mini tutorial first to set up your development environment.
- Install Arduino IDE: If you haven't already, follow the ESP32 C3 Super Mini software installation guide
- Wire the components: Connect the relay and solenoid valve to ESP32 C3 Super Mini following the wiring diagram above
- Connect USB cable: Plug your ESP32 C3 Super Mini into your computer using a USB Type-C cable
- Open Arduino IDE: Launch the Arduino IDE application on your computer
- Select your board: Choose ESP32 C3 Super Mini from the board menu
- Select COM port: Pick the correct COM port that your ESP32 is connected to
- Copy the code: Copy the provided code and paste it into a new Arduino IDE sketch
- Upload the code: Click the Upload button to compile and upload code to your ESP32 C3 Super Mini
- Test the valve: Observe the valve opening and closing every 5 seconds, and check water flow if connected
- Pro Tip: Open the Serial Monitor (9600 baud) to see real-time valve status messages and troubleshoot your setup
Code Explanation
The ESP32 C3 Super Mini code includes detailed line-by-line comments explaining each function. Read through the code comments to understand how valve control works!
Key code concepts:
- Pin Configuration: Sets up D7 as an output pin to control the relay
- digitalWrite() Function: Sends HIGH or LOW signals to open/close the valve
- delay() Function: Creates 5-second timing intervals between valve operations
- Serial Monitor: Prints valve status for debugging and monitoring
Serial Monitor Output
Open the Serial Monitor at 9600 baud rate to see the valve operation status:
8
Serial.println("Hello World!");
Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')
New Line
9600 baud
Valve is open
Valve is closed
Valve is open
Valve is closed
Valve is open
Valve is closed
Application and Project Ideas
Use your ESP32 C3 Super Mini water valve control skills to build these practical automation projects:
- Smart Garden Irrigation: Automate watering schedules based on soil moisture or time intervals
- Pet Water Dispenser: Create an automatic water bowl refill system for pets
- Coffee Machine Automation: Control water flow for DIY espresso or drip coffee makers
- Aquarium Auto-Fill System: Maintain constant water levels in fish tanks automatically
- Homebrew Beer Dispenser: Build a controlled beer tap system with precise flow control
- Car Wash System: Automate water spray timing for DIY vehicle cleaning stations
- Hydroponics Nutrient Feeder: Control nutrient solution flow in soilless growing systems
Video Tutorial
Watch the video below for a visual walkthrough of this project.
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...VIDEO
Challenge Yourself
Take your ESP32 C3 Super Mini valve control project to the next level with these challenges:
- Easy: Add a push button to manually open/close the valve instead of automatic timing
- Easy: Change the timing - make the valve open for 10 seconds and close for 3 seconds
- Medium: Add a soil moisture sensor to open the valve only when soil is dry (smart irrigation)
- Medium: Use a potentiometer to adjust how long the valve stays open (variable flow duration)
- Advanced: Build a web server so you can control the valve remotely from your phone browser
- Advanced: Create a scheduled watering system using ESP32 real-time clock (RTC) for specific times each day