ESP32-S3 Soil Sensor with Arduino IDE

Introduction

The Soil Moisture Sensor measures the water content in soil by outputting analog values that vary based on moisture levels. When connected to an ESP32-S3, you can read these values to automate irrigation systems or trigger alerts. In this tutorial, we’ll learn how to connect the sensor to the ESP32-S3 and monitor soil moisture effectively.

Required Components

• ESP32-S3 Board
• Soil Sensor
• Jumper Wires
• Breadboard (optional)

Pinout

Circuit Diagram / Wiring

• Soil Sensor VCC → VIN/5V (ESP32-S3)
• Soil Sensor GND → GND (ESP32-S3)
• Soil Sensor Analog → GPIO 14 (ESP32-S3)

Code / Programming

/*****************************************************
 * Project     : Soil_Moisture_Sensor_Monitor.ino
 * Description : Reads analog values from a soil moisture sensor
 *               and converts it to percentage for display.
 * Author      : www.oceanlabz.in
 * Modified    : 1/4/2025
 *****************************************************/
 
#define MoisturePin 14  
 
void setup() {
  Serial.begin(115200);  // ESP32-S3 commonly uses 115200 baud
}
 
void loop() {
  int soilMoistureValue = analogRead(MoisturePin);  // Read raw analog value (0-4095 on ESP32-S3)
 
  // Optional: Convert to percentage (roughly)
  int moisturePercent = map(soilMoistureValue, 4095, 0, 0, 100);  // Adjust based on dry/wet calibration
 
  Serial.print("Soil Moisture Level: ");
  Serial.print(moisturePercent);
  Serial.println("%");
 
  delay(1000);
}

Explanation

• The ESP32-S3 reads soil moisture using an analog-capable pin (e.g., GPIO 14).
• The sensor output is mapped to a percentage to represent moisture levels.
• The moisture value is displayed on the Serial Monitor every second.

Troubleshooting

• Incorrect readings? Make sure you’re using an ADC-capable pin
• Always reading 0 or 4095? Check sensor wiring and power supply (usually 3.3V for ESP32-S3).
• Unstable values? Place the sensor properly in the soil and avoid shorting the probes with water.