Soil Moisture Sensor

A simple soil moisture sensor using an Arduino UNO microcontroller.

Components Used

• Arduino UNO
• Soil Moisture Sensor
• LCD Display (2x16) with I2C Module

Code

This program is written in the C++ programming language.

👉 View Code

Used Libraries

• hd44780
• Wire

Connections

Arduino Pin	Display Pin	Sensor Pin
GND	GND	GND
A4	SDA	❌
A5	SCL	❌
A0	❌	AOUT
5V	VCC	❌
3.3V	❌	VCC

Calibration

Sensor Calibration Code

The sensor data pin is connected to pin A0.

void setup() {
  Serial.begin(9600);
}
void loop() {
  int value;
  value = analogRead(A0);
  Serial.println(value);
  delay(100);
}

Steps

First, record the highest value the sensor obtains when dry. Change the value in the code (default is 603) to the measured value:

const int dryValue = 616; -> const int dryValue = YOUR_VALUE;

Next, measure the value the sensor obtains when wettest. Measure and replace the value in the code:

const int wetValue = 292; -> const int wetValue = YOUR_VALUE;

Now, upload the code to the Arduino and everything should work!