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Lesson 02: Capacitive Soil Moisture Module

In this lesson, you will learn how to use a capacitive soil moisture sensor with an ESP32 Development Board to read the moisture level of soil. We’ll cover connecting the sensor to pin 25, reading its analog value, and interpreting these readings to determine the soil’s moisture level. This project is ideal for beginners as it provides hands-on experience in working with sensors and understanding analog input on the ESP32 platform.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Universal Maker Sensor Kit	94	Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction	Purchase Link
ESP32 & Development Board (ESP32 Board)	BUY
Capacitive Soil Moisture Module	BUY
Breadboard	BUY

Wiring

../_images/Lesson_02_Capacitive_Soil_Moisture_Module_esp32_bb.png

Code

Code Analysis

Defining the sensor pin:

This line of code declares a constant integer sensorPin and assigns it the value of 25, which is the pin the sensor is connected to.
```
const int sensorPin = 25;
```
Setup function:

The setup() function is executed once when the program starts. It initializes serial communication at 9600 baud rate. This setup is necessary for sending data to the serial monitor.
```
void setup() {
  Serial.begin(9600);
}
```
Loop function:

The loop() function runs continuously after setup(). It reads the sensor value from pin A0 using analogRead() and prints this value to the serial monitor. The delay(500) statement pauses the loop for 500 milliseconds before the next reading, thus controlling the rate of data acquisition.
```
void loop() {
  Serial.println(analogRead(sensorPin));
  delay(500);
}
```