ESP32 Soil Moisture Monitor

/*
 * ESP32 Soil Moisture Monitor — Beginner
 * Reads capacitive soil sensor, maps to percentage, lights LEDs.
 *
 * CALIBRATION REQUIRED:
 *   1) Place sensor in dry air → note AIR_VALUE (should be ~2800–3200)
 *   2) Submerge sensor tip in water → note WATER_VALUE (should be ~1200–1500)
 *   Update the defines below with your sensor's actual values.
 */
#define SENSOR_PIN  34
#define LED_GREEN   25   // Moist
#define LED_YELLOW  26   // Moderate
#define LED_RED     27   // Dry
#define BUZZER      32

// ── CALIBRATE THESE for your sensor ─────────────────────────────
#define AIR_VALUE   2800  // ADC reading in dry air (0% moisture)
#define WATER_VALUE 1200  // ADC reading fully in water (100% moisture)
// ────────────────────────────────────────────────────────────────

int readMoisturePercent() {
  // Average 10 readings to reduce ADC noise on ESP32
  long sum = 0;
  for (int i = 0; i < 10; i++) { sum += analogRead(SENSOR_PIN); delay(5); }
  int raw = sum / 10;
  int pct = map(raw, AIR_VALUE, WATER_VALUE, 0, 100);
  return constrain(pct, 0, 100);
}

void setup() {
  Serial.begin(115200);
  analogReadResolution(12);   // 12-bit ADC: 0–4095
  pinMode(LED_GREEN,  OUTPUT);
  pinMode(LED_YELLOW, OUTPUT);
  pinMode(LED_RED,    OUTPUT);
  pinMode(BUZZER,     OUTPUT);
  Serial.println("Soil Moisture Monitor started.");
  Serial.printf("Calibration: AIR=%d, WATER=%dn", AIR_VALUE, WATER_VALUE);
}

void loop() {
  int pct = readMoisturePercent();
  Serial.printf("Moisture: %d%%n", pct);

  // Turn all LEDs off first
  digitalWrite(LED_GREEN,  LOW);
  digitalWrite(LED_YELLOW, LOW);
  digitalWrite(LED_RED,    LOW);
  digitalWrite(BUZZER,     LOW);

  if (pct >= 60) {
    digitalWrite(LED_GREEN, HIGH);
    Serial.println("Status: Moist — plant is happy");
  } else if (pct >= 30) {
    digitalWrite(LED_YELLOW, HIGH);
    Serial.println("Status: Moderate — consider watering soon");
  } else {
    digitalWrite(LED_RED, HIGH);
    // Pulse buzzer 3 times for critical alert
    for (int i = 0; i < 3; i++) {
      digitalWrite(BUZZER, HIGH); delay(200);
      digitalWrite(BUZZER, LOW);  delay(200);
    }
    Serial.println("Status: DRY — water the plant now!");
  }

  delay(10000);   // Read every 10 seconds
}