SENSORS/ACTUATORS

ESP32 C3 Super Mini - Rain Sensor

Learn how to use an ESP32 C3 Super Mini with a rain sensor to detect rainfall and measure moisture levels. This beginner-friendly tutorial covers both digital and analog rain detection methods with simple wiring and code examples.

In this tutorial, you'll learn:

What a rain sensor is and how it detects rainfall
How to wire a rain sensor to ESP32 C3 Super Mini
How to program ESP32 C3 Super Mini to detect rain using digital signals
How to measure rain intensity using analog readings
How to extend corrosion-free lifespan with smart power control

After completing this tutorial, you can modify the code to activate alarms, motors, or automated systems when rain is detected.

Hardware Preparation

1	×	ESP32 C3 Super Mini
1	×	USB Cable Type-A to Type-C (for USB-A PC)
1	×	USB Cable Type-C to Type-C (for USB-C PC)
1	×	Rain Sensor
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 Rain Sensor

A rain sensor is an electronic module that detects and measures rainfall or snow levels through moisture detection on a sensing pad.

Key Features:

Dual output modes: digital (rain/no rain) and analog (intensity level)
Adjustable sensitivity via built-in potentiometer
Works with both rain and snow detection
Operating voltage: 3.3V to 5V
Quick response time for real-time detection
Perfect for weather stations and automated systems

Two Main Components:

Sensing Pad: Outdoor detection surface with exposed copper traces
Electronic Module: Signal processor with analog and digital outputs

image source: diyables.io

The Sensing Pad

The sensing pad is designed for outdoor placement where it faces rainfall or snow.

How it works:

Contains exposed copper traces divided into two groups
Power traces and sense traces remain separated when dry
Water or snow bridges the traces, completing the circuit
Either group can serve as power or sense trace
Larger surface area provides better detection accuracy

The Electronic Module

The electronic module processes signals from the sensing pad and converts them to ESP32-compatible outputs.

Pin Configuration:

VCC pin: Power supply connection (3.3V to 5V)
GND pin: Ground connection (0V)
DO pin: Digital output (HIGH when dry, LOW when wet)
AO pin: Analog output (varies with moisture intensity)

LED Indicators:

PWR-LED: Power indicator (always on when powered)
DO-LED: Rain detection indicator (on when rain detected)

Sensitivity Adjustment:

Built-in potentiometer adjusts digital threshold
Turn clockwise to increase sensitivity
Turn counter-clockwise to decrease sensitivity
Only affects DO pin, not AO pin readings

How It Works

Digital Output (DO Pin):

Potentiometer sets the rain detection threshold
When moisture exceeds threshold: DO pin goes LOW, LED turns on
When moisture below threshold: DO pin stays HIGH, LED turns off
Ideal for simple rain/no-rain detection projects

Analog Output (AO Pin):

Provides continuous moisture level readings
More water on pad = lower AO value
Less water on pad = higher AO value
Unaffected by potentiometer settings
Best for measuring rainfall intensity

Important Note: Using an ESP32 GPIO pin to power the sensor (instead of constant 5V/3.3V) significantly extends sensor lifespan by reducing electrochemical corrosion between readings.

Wiring Diagram

The rain sensor module offers flexible wiring options depending on whether you need digital detection, analog measurement, or both.

Power Connection Best Practice:

Connect VCC to an ESP32 GPIO pin (not direct 5V/3.3V)
Power the sensor only during readings
This minimizes electrochemical corrosion and extends sensor life

The wiring diagram between ESP32 C3 Super Mini rain sensor

This image is created using Fritzing. Click to enlarge image

Rain Sensor Pin	ESP32 C3 Super Mini Pin
VCC	GPIO2
GND	GND
DO	GPIO6
AO	A5 (GPIO5 / ADC1_CH5)

ESP32 C3 Super Mini Code - Read value from DO pin

This code demonstrates how to detect rain using the digital output from the rain sensor.

What the code does:

Powers the rain sensor through GPIO2 only when reading
Reads digital signal from DO pin to detect rain presence
Displays rain detection status on Serial Monitor
Minimizes sensor corrosion with smart power control
Provides real-time rain/no-rain alerts

/* * 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-rain-sensor */ #define POWER_PIN D2 // The ESP32 C3 SuperMini pin that provides the power to the rain sensor #define DO_PIN D6 // The ESP32 C3 SuperMini pin connected to DO pin of the rain sensor void setup() { // Initialize the Serial to communicate with the Serial Monitor. Serial.begin(9600); // initialize theArduino Nano ESP32 pin as an input pinMode(POWER_PIN, OUTPUT); // Configure the power pin pin as an OUTPUT pinMode(DO_PIN, INPUT); } void loop() { digitalWrite(POWER_PIN, HIGH); // turn the rain sensor's power ON delay(10); // wait 10 milliseconds int rain_state = digitalRead(DO_PIN); digitalWrite(POWER_PIN, LOW); // turn the rain sensor's power OFF if (rain_state == HIGH) Serial.println("The rain is NOT detected"); else Serial.println("The rain is detected"); delay(1000); // pause for 1 sec to avoid reading sensors frequently to prolong the sensor lifetime }

Detailed Instructions

New to ESP32 C3 Mini? Complete our Getting Started with ESP32 C3 Mini tutorial first to set up your development environment.
Upload the Code: Copy the code above and open it in Arduino IDE
Select Your Board: Choose ESP32 C3 Super Mini from the board menu
Connect ESP32: Plug in your ESP32 C3 Super Mini via USB-C cable
Upload: Click the Upload button to transfer code to ESP32
Test the Sensor: Drop water onto the rain sensor pad
Open Serial Monitor: Set baud rate to 9600 to view results
Adjust Sensitivity: If needed, turn the potentiometer to fine-tune detection
Pro Tip: Test sensitivity adjustment with different water amounts to find the perfect threshold for your application

Newbiely | Arduino IDE 2.3.8

──

☐

Newbiely.ino

···

8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')

New Line

9600 baud

[April 15, 2026 10:23:45] The rain is NOT detected [April 15, 2026 10:23:46] The rain is NOT detected [April 15, 2026 10:23:47] The rain is NOT detected [April 15, 2026 10:23:48] The rain is detected [April 15, 2026 10:23:49] The rain is detected [April 15, 2026 10:23:50] The rain is detected [April 15, 2026 10:23:51] The rain is detected [April 15, 2026 10:23:52] The rain is detected [April 15, 2026 10:23:53] The rain is NOT detected [April 15, 2026 10:23:54] The rain is NOT detected

Ln 11, Col 1

ESP32C3 Dev Module on COM15

If the DO-LED stays constantly on or off regardless of water presence, adjust the potentiometer clockwise or counter-clockwise to calibrate the sensitivity threshold for your environment.

ESP32 C3 Super Mini Code - Read value from AO pin

This code shows how to measure rain intensity using the analog output from the rain sensor.

What the code does:

Powers the sensor only during readings via GPIO2
Reads analog values from AO pin to measure moisture levels
Displays numerical rain intensity on Serial Monitor
Lower values indicate more water on the sensor pad
Higher values indicate drier conditions

/* * 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-rain-sensor */ #define POWER_PIN D2 // The ESP32 C3 SuperMini pin that provides the power to the rain sensor #define AO_PIN A5 // The ESP32 C3 SuperMini pin connected to AO pin of the rain sensor void setup() { // Initialize the Serial to communicate with the Serial Monitor. Serial.begin(9600); // set the ADC attenuation to 11 dB (up to ~3.3V input) analogSetAttenuation(ADC_11db); pinMode(POWER_PIN, OUTPUT); // Configure the power pin pin as an OUTPUT } void loop() { digitalWrite(POWER_PIN, HIGH); // turn the rain sensor's power ON delay(10); // wait 10 milliseconds int rain_value = analogRead(AO_PIN); digitalWrite(POWER_PIN, LOW); // turn the rain sensor's power OFF Serial.println(rain_value); // print out the analog value delay(1000); // pause for 1 sec to avoid reading sensors frequently to prolong the sensor lifetime }

Detailed Instructions

New to ESP32 C3 Mini? Complete our Getting Started with ESP32 C3 Mini tutorial first to set up your development environment.
Upload the Code: Copy the code above and open it in Arduino IDE
Select Your Board: Choose ESP32 C3 Super Mini from the board menu
Connect ESP32: Plug in your ESP32 C3 Super Mini via USB-C cable
Upload: Click the Upload button to transfer code to ESP32
Test with Water: Gradually add water drops to the sensor pad
Open Serial Monitor: Set baud rate to 9600 to view analog readings
Observe Changes: Watch values decrease as moisture increases
Pro Tip: Record your sensor's dry and wet values to create custom rain intensity ranges (light rain, moderate rain, heavy rain)

Newbiely | Arduino IDE 2.3.8

──

☐

Newbiely.ino

···

8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')

New Line

9600 baud

[April 15, 2026 10:45:12] Analog Value: 3845 [April 15, 2026 10:45:13] Analog Value: 3821 [April 15, 2026 10:45:14] Analog Value: 2456 [April 15, 2026 10:45:15] Analog Value: 1687 [April 15, 2026 10:45:16] Analog Value: 1023 [April 15, 2026 10:45:17] Analog Value: 978 [April 15, 2026 10:45:18] Analog Value: 965 [April 15, 2026 10:45:19] Analog Value: 1134 [April 15, 2026 10:45:20] Analog Value: 2187 [April 15, 2026 10:45:21] Analog Value: 3512

Ln 11, Col 1

ESP32C3 Dev Module on COM15

※ NOTE THAT:

This tutorial uses the analogRead() function to read values from an ADC (Analog-to-Digital Converter) connected to a sensor or component. The ESP32 C3 Super Mini's ADC is suitable for projects that do not require high accuracy. However, for projects needing precise measurements, keep the following in mind:

The ESP32 C3 Super Mini's ADC is not perfectly accurate and might require calibration for correct results. Each ESP32 C3 Super Mini board can vary slightly, so calibration is necessary for each individual board.
Calibration can be challenging, especially for beginners, and might not always yield the exact results you want.

For projects requiring high precision, consider using an external ADC (e.g ADS1115) with the ESP32 C3 Super Mini or using another Arduino, such as the Arduino Uno R4 WiFi, which has a more reliable ADC. If you still want to calibrate the ESP32 C3 Super Mini's ADC, refer to the ESP32 ADC Calibration Driver.

Application and Project Ideas

Here are practical ways to use your ESP32 C3 Super Mini rain sensor in real-world projects:

Smart Home Automation: Automatically close windows and skylights when rain is detected
Garden Watering System: Disable automatic sprinklers during rainfall to save water
Weather Station: Build a complete weather monitoring system with rainfall data logging
Car Alert System: Notify you via smartphone when rain starts and car windows are open
Clothes Drying Monitor: Alert when outdoor laundry needs to be brought inside
Greenhouse Controller: Adjust ventilation and irrigation based on rain detection
Smart Umbrella Reminder: Send reminders to take an umbrella when rain is detected

Video Tutorial

Watch the video below for a visual walkthrough of this ESP32 C3 Super Mini rain sensor project.

Challenge Yourself

Take your ESP32 C3 Super Mini rain sensor skills to the next level with these challenges:

Easy: Add an LED that lights up when rain is detected using the digital output
Easy: Create different alert messages for light rain vs heavy rain using analog thresholds
Medium: Log rainfall data to an SD card with timestamps for long-term weather tracking
Medium: Send email or push notifications when rain is detected using WiFi connectivity
Advanced: Build a complete weather station combining rain sensor with temperature and humidity sensors
Advanced: Create a predictive system that tracks rainfall patterns and forecasts using machine learning

Function References

Learn More

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