Capacitive Soil Moisture Sensor – Arduino Simple Tutorial

				
					/*
 * Capacitive Soil Moisture Sensor Reader for Arduino Uno
 * Reads sensor data from analog pin and outputs to serial monitor
 */

// Define the analog pin connected to the sensor output
const int SENSOR_PIN = A0;

void setup() {
  // Initialize serial communication at 9600 baud rate
  Serial.begin(9600);
  
  // Print header information to serial monitor
  Serial.println("================================================");
  Serial.println("Capacitive Soil Moisture Sensor Monitoring");
  Serial.println("================================================");
  Serial.println("Raw Value (0-1023) | Voltage (0-3.3V) | Moisture %");
  Serial.println("------------------------------------------------");
}

void loop() {
  // Read raw analog value from sensor (0-1023)
  int rawValue = analogRead(SENSOR_PIN);
  
  // Convert raw value to voltage (0-3.3V)
  float voltage = rawValue * (3.3 / 1023.0);
  
  /*
   * Convert raw sensor value to moisture percentage
   * Note: These calibration values are examples - adjust based on your specific sensor:
   * - Dry in air: ~620 (0% moisture)
   * - Wet in water: ~320 (100% moisture)
   * Actual values may vary - perform calibration for accurate readings
   */
  int moisturePercent = map(rawValue, 620, 320, 0, 100);
  
  // Constrain moisture percentage to valid range (0-100%)
  moisturePercent = constrain(moisturePercent, 0, 100);

  // Print all values to serial monitor in formatted columns
  Serial.print("      ");
  if (rawValue < 1000) Serial.print(" "); // Alignment spacing
  Serial.print(rawValue);
  Serial.print("       |      ");
  Serial.print(voltage, 2); // Display voltage with 2 decimal places
  Serial.print("V     |     ");
  if (moisturePercent < 100) Serial.print(" "); // Alignment spacing
  if (moisturePercent < 10) Serial.print(" ");  // Additional spacing for single digits
  Serial.print(moisturePercent);
  Serial.println("%");

  // Wait 2 seconds before next reading
  delay(2000);
}