Smart Plant Monitor & Alert Kit - ESP32 Soil Moisture, Water Level & BME280

/*
  Smart Plant Monitor & Alert Kit
  Board: ESP32U / ESP32 DevKit
  Parts: capacitive soil moisture sensor, water level sensor, BME280, active buzzer.
  Libraries: Adafruit BME280 Library + Adafruit Unified Sensor.

  Wiring:
    Soil sensor AOUT -> GPIO34, VCC -> 3V3, GND -> GND
    Water level SIG  -> GPIO35, VCC -> 3V3, GND -> GND
    BME280 SDA -> GPIO21, SCL -> GPIO22, VCC -> 3V3, GND -> GND
    Buzzer IO -> GPIO23, VCC -> 3V3, GND -> GND

  Calibration:
    Open Serial Monitor. Note SOIL_DRY with the sensor in air/dry soil and
    SOIL_WET in wet soil. Adjust WATER_LOW after testing the water sensor.
*/

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

const int SOIL_PIN = 34;
const int WATER_PIN = 35;
const int BUZZER_PIN = 23;

const int SOIL_DRY = 3200;
const int SOIL_WET = 1300;
const int WATER_LOW = 900;
const int DRY_ALERT_PERCENT = 30;

Adafruit_BME280 bme;

int percentFromSoil(int raw) {
  int pct = map(raw, SOIL_DRY, SOIL_WET, 0, 100);
  return constrain(pct, 0, 100);
}

void setup() {
  Serial.begin(115200);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);

  Wire.begin(21, 22);
  if (!bme.begin(0x76)) {
    if (!bme.begin(0x77)) {
      Serial.println("BME280 not found. Check SDA/SCL wiring and address.");
    }
  }
}

void loop() {
  int soilRaw = analogRead(SOIL_PIN);
  int waterRaw = analogRead(WATER_PIN);
  int soilPct = percentFromSoil(soilRaw);

  bool drySoil = soilPct < DRY_ALERT_PERCENT;
  bool lowWater = waterRaw < WATER_LOW;
  bool alert = drySoil || lowWater;

  digitalWrite(BUZZER_PIN, alert ? HIGH : LOW);

  Serial.print("Soil raw: "); Serial.print(soilRaw);
  Serial.print("  Soil: "); Serial.print(soilPct); Serial.print("%");
  Serial.print("  Water raw: "); Serial.print(waterRaw);
  Serial.print("  Temp: "); Serial.print(bme.readTemperature(), 1); Serial.print(" C");
  Serial.print("  Humidity: "); Serial.print(bme.readHumidity(), 0); Serial.print("%");
  Serial.print("  Status: ");
  if (lowWater) Serial.println("LOW WATER");
  else if (drySoil) Serial.println("DRY SOIL");
  else Serial.println("OK");

  delay(2000);
}