/*
  Session 2 — Core agricultural sensors on real hardware (ESP32 DevKit) — greenhouse microclimate
  DHT22  : DATA -> GPIO 4 (10kΩ pull-up to 3.3V if your module has none), VCC 3.3V
  Soil   : Capacitive Soil Moisture v1.2 AOUT -> GPIO 34 (ADC1), VCC 3.3V
  LDR    : 3.3V — LDR — GPIO 35 — 10kΩ — GND
  Library: "DHT sensor library" by Adafruit (+ "Adafruit Unified Sensor")
  NOTE: use ADC1 pins (32-39) — ADC2 pins stop working when Wi-Fi is on.
*/
#include <DHT.h>

#define DHT_PIN 4
#define SOIL_PIN 34
#define LDR_PIN 35
DHT dht(DHT_PIN, DHT22);

// Calibration values measured in the lab (dry air / glass of water). Capacitive sensors: wet = LOWER value
int SOIL_DRY = 3200;
int SOIL_WET = 1300;

void setup() {
  Serial.begin(115200);
  analogReadResolution(12);          // 0..4095
  analogSetAttenuation(ADC_11db);    // full 0..3.3 V range
  dht.begin();
  Serial.println("time_s,air_temp_c,air_hum_pct,soil_raw,soil_pct,light_raw");
}

void loop() {
  float t = dht.readTemperature();
  float h = dht.readHumidity();
  if (isnan(t) || isnan(h)) {
    Serial.println("# DHT22 read failed — check wiring / pull-up");
  }
  int soilRaw = analogRead(SOIL_PIN);
  float soilPct = constrain((float)(SOIL_DRY - soilRaw) / (SOIL_DRY - SOIL_WET) * 100.0, 0, 100);
  int light = analogRead(LDR_PIN);

  Serial.printf("%lu,%.1f,%.1f,%d,%.0f,%d\n", millis() / 1000, t, h, soilRaw, soilPct, light);
  delay(2500);                        // DHT22 needs >= 2 s between reads
}