Automated Greenhouse Control

#include <Arduino.h>
#include <WiFi.h>
#include <WebServer.h>
#include <DHT.h>
#include <ESP32Servo.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// GPIO16 and GPIO17 are intentionally left unused for a future MH-Z19B CO2 sensor.
constexpr int DHT_PIN = 4;
constexpr int SOIL_PIN = 36;
constexpr int LDR_PIN = 32;
constexpr int RAIN_PIN = 33;
constexpr int FLOAT_PIN = 23;
constexpr int LCD_SDA_PIN = 21;
constexpr int LCD_SCL_PIN = 22;
// GPIO27 drives the relay that switches the 12 V cooler; it does not power the cooler directly.
constexpr int FAN_PIN = 27;
constexpr int SERVO_PIN = 13;
constexpr int PUMP_RELAY_PIN = 25;
constexpr int LAMP_RELAY_PIN = 26;

constexpr uint8_t DHT_TYPE = DHT22;
constexpr bool RELAY_ON = HIGH;
constexpr bool RELAY_OFF = LOW;
constexpr bool RAIN_DETECTED_LEVEL = LOW;
constexpr bool TANK_LOW_WHEN_CLOSED = true;

// Calibrate these two readings after installing the soil probe.
constexpr int SOIL_DRY_RAW = 2600;
constexpr int SOIL_WET_RAW = 1300;
constexpr int SOIL_START_WATERING_PERCENT = 35;
constexpr int SOIL_STOP_WATERING_PERCENT = 55;
// These thresholds use the AO output of the 3.3 V photoresistor module.
constexpr int LIGHT_ON_RAW = 1500;
constexpr int LIGHT_OFF_RAW = 1900;
constexpr float FAN_ON_C = 29.0f;
constexpr float FAN_OFF_C = 27.0f;
constexpr float HEAT_ON_C = 18.0f;
constexpr float HEAT_OFF_C = 20.0f;
constexpr int ROOF_OPEN_ANGLE = 105;
constexpr int ROOF_CLOSED_ANGLE = 15;

const char *AP_NAME = "Invernadero-ESP32";
const char *AP_PASSWORD = "Greenhouse2026";

DHT dht(DHT_PIN, DHT_TYPE);
Servo roofServo;
LiquidCrystal_I2C lcd(0x27, 16, 2);
WebServer server(80);

bool automaticMode = true;
bool pumpOn = false;
bool fanOn = false;
bool lampOn = false;
bool roofOpen = false;
bool tankLow = true;
bool raining = false;
float temperatureC = NAN;
float humidityPct = NAN;
int soilRaw = 0;
int soilPercent = 0;
int lightRaw = 0;
unsigned long lastReadMs = 0;
String lastLcdLine1;
String lastLcdLine2;

String paddedLcdLine(const char *text) {
  String line(text);
  while (line.length() < 16) line += ' ';
  return line.substring(0, 16);
}

void updateLcd() {
  char temperatureLine[24];
  char humidityLine[24];
  if (isnan(temperatureC)) {
    snprintf(temperatureLine, sizeof(temperatureLine), "Temp: --.- C");
  } else {
    snprintf(temperatureLine, sizeof(temperatureLine), "Temp: %4.1f C", temperatureC);
  }
  if (isnan(humidityPct)) {
    snprintf(humidityLine, sizeof(humidityLine), "Humed: --.- %%");
  } else {
    snprintf(humidityLine, sizeof(humidityLine), "Humed: %4.1f %%", humidityPct);
  }

  String line1 = paddedLcdLine(temperatureLine);
  String line2 = paddedLcdLine(humidityLine);
  if (line1 != lastLcdLine1) {
    lcd.setCursor(0, 0);
    lcd.print(line1);
    lastLcdLine1 = line1;
  }
  if (line2 != lastLcdLine2) {
    lcd.setCursor(0, 1);
    lcd.print(line2);
    lastLcdLine2 = line2;
  }
}

void setPump(bool on) {
  pumpOn = on;
  digitalWrite(PUMP_RELAY_PIN, on ? RELAY_ON : RELAY_OFF);
}

void setLamp(bool on) {
  lampOn = on;
  digitalWrite(LAMP_RELAY_PIN, on ? RELAY_ON : RELAY_OFF);
}

void setFan(bool on) {
  fanOn = on;
  digitalWrite(FAN_PIN, on ? HIGH : LOW);
}

void setRoof(bool open) {
  roofOpen = open;
  roofServo.write(open ? ROOF_OPEN_ANGLE : ROOF_CLOSED_ANGLE);
}

int soilPercentFromRaw(int raw) {
  long percent = map(raw, SOIL_DRY_RAW, SOIL_WET_RAW, 0, 100);
  return constrain(percent, 0, 100);
}

bool isTankLow() {
  bool contactClosed = digitalRead(FLOAT_PIN) == LOW;
  return TANK_LOW_WHEN_CLOSED ? contactClosed : !contactClosed;
}

void readSensors() {
  temperatureC = dht.readTemperature();
  humidityPct = dht.readHumidity();
  soilRaw = analogRead(SOIL_PIN);
  soilPercent = soilPercentFromRaw(soilRaw);
  lightRaw = analogRead(LDR_PIN);
  raining = digitalRead(RAIN_PIN) == RAIN_DETECTED_LEVEL;
  tankLow = isTankLow();
}

void runAutomaticControl() {
  if (tankLow) {
    setPump(false);
  } else if (soilPercent <= SOIL_START_WATERING_PERCENT) {
    setPump(true);
  } else if (soilPercent >= SOIL_STOP_WATERING_PERCENT) {
    setPump(false);
  }

  if (!isnan(temperatureC)) {
    if (temperatureC >= FAN_ON_C) setFan(true);
    else if (temperatureC <= FAN_OFF_C) setFan(false);

    bool needsLamp = temperatureC <= HEAT_ON_C || lightRaw <= LIGHT_ON_RAW;
    bool canTurnLampOff = temperatureC >= HEAT_OFF_C && lightRaw >= LIGHT_OFF_RAW;
    if (needsLamp) setLamp(true);
    else if (canTurnLampOff) setLamp(false);

    setRoof(!raining && temperatureC >= FAN_ON_C);
  } else {
    setPump(false);
    setFan(false);
    setLamp(false);
    setRoof(false);
  }

  if (raining) setRoof(false);
}

String stateJson() {
  String json = "{";
  json += "\"automatic\":" + String(automaticMode ? "true" : "false");
  json += ",\"temperatureC\":" + String(temperatureC, 1);
  json += ",\"humidityPct\":" + String(humidityPct, 1);
  json += ",\"soilRaw\":" + String(soilRaw);
  json += ",\"soilPercent\":" + String(soilPercent);
  json += ",\"lightRaw\":" + String(lightRaw);
  json += ",\"raining\":" + String(raining ? "true" : "false");
  json += ",\"tankLow\":" + String(tankLow ? "true" : "false");
  json += ",\"pump\":" + String(pumpOn ? "true" : "false");
  json += ",\"fan\":" + String(fanOn ? "true" : "false");
  json += ",\"lamp\":" + String(lampOn ? "true" : "false");
  json += ",\"roofOpen\":" + String(roofOpen ? "true" : "false");
  json += "}";
  return json;
}

void sendHome() {
  const char page[] PROGMEM = R"HTML(
<!doctype html><html><head><meta name="viewport" content="width=device-width,initial-scale=1">
<style>body{font-family:Arial;margin:20px;background:#eef6ee;color:#173d1d}button{padding:10px;margin:4px;border-radius:8px;border:1px solid #497a50;background:white}pre{background:white;padding:12px;border-radius:8px;white-space:pre-wrap}</style></head>
<body><h1>Invernadero automatizado</h1><p>Conéctate a esta página desde el teléfono para ver el estado y elegir automático o manual.</p>
<button onclick="go('/auto?enabled=1')">Modo automático</button><button onclick="go('/auto?enabled=0')">Modo manual</button><br>
<button onclick="go('/control?pump=1')">Bomba ON</button><button onclick="go('/control?pump=0')">Bomba OFF</button>
<button onclick="go('/control?fan=1')">Ventilador ON</button><button onclick="go('/control?fan=0')">Ventilador OFF</button>
<button onclick="go('/control?lamp=1')">Lámpara ON</button><button onclick="go('/control?lamp=0')">Lámpara OFF</button>
<button onclick="go('/control?roof=open')">Abrir techo</button><button onclick="go('/control?roof=close')">Cerrar techo</button>
<pre id="s">Cargando...</pre><script>function go(u){fetch(u).then(load)}function load(){fetch('/state').then(r=>r.json()).then(x=>{document.getElementById('s').textContent=JSON.stringify(x,null,2)})}load();setInterval(load,2000);</script></body></html>
)HTML";
  server.send(200, "text/html; charset=utf-8", page);
}

void setupWebServer() {
  server.on("/", HTTP_GET, sendHome);
  server.on("/state", HTTP_GET, []() { server.send(200, "application/json", stateJson()); });
  server.on("/auto", HTTP_GET, []() {
    if (server.hasArg("enabled")) automaticMode = server.arg("enabled") == "1";
    server.send(200, "application/json", stateJson());
  });
  server.on("/control", HTTP_GET, []() {
    if (automaticMode) {
      server.send(409, "application/json", "{\"error\":\"Cambia primero a modo manual\"}");
      return;
    }
    if (server.hasArg("pump")) setPump(server.arg("pump") == "1" && !tankLow);
    if (server.hasArg("fan")) setFan(server.arg("fan") == "1");
    if (server.hasArg("lamp")) setLamp(server.arg("lamp") == "1");
    if (server.hasArg("roof")) setRoof(server.arg("roof") == "open" && !raining);
    server.send(200, "application/json", stateJson());
  });
  server.begin();
}

void setup() {
  Serial.begin(115200);
  pinMode(RAIN_PIN, INPUT);
  pinMode(FLOAT_PIN, INPUT_PULLUP);
  pinMode(FAN_PIN, OUTPUT);
  pinMode(PUMP_RELAY_PIN, OUTPUT);
  pinMode(LAMP_RELAY_PIN, OUTPUT);
  setPump(false);
  setFan(false);
  setLamp(false);
  dht.begin();
  analogReadResolution(12);
  roofServo.setPeriodHertz(50);
  roofServo.attach(SERVO_PIN, 500, 2500);
  setRoof(false);
  Wire.begin(LCD_SDA_PIN, LCD_SCL_PIN);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Invernadero");
  lcd.setCursor(0, 1);
  lcd.print("Iniciando...");
  WiFi.mode(WIFI_AP);
  WiFi.softAP(AP_NAME, AP_PASSWORD);
  setupWebServer();
  Serial.print("Panel del invernadero: http://");
  Serial.println(WiFi.softAPIP());
}

void loop() {
  server.handleClient();
  unsigned long now = millis();
  if (now - lastReadMs >= 2000) {
    lastReadMs = now;
    readSensors();
    updateLcd();
    if (automaticMode) runAutomaticControl();
  }
  delay(10);
}