/*
 * This ESP32 code is created by esp32io.com
 *
 * This ESP32 code is released in the public domain
 *
 * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-cooling-system-using-ds18b20-temperature-sensor
 */

 //Modified by Kishore Gaikwad, 11-May-2022

#include <Wire.h> 
#include <OneWire.h>
#include <DallasTemperature.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);

#define TEMP_UPPER_THRESHOLD  36 // upper temperature threshold
//#define TEMP_LOWER_THRESHOLD  34 // lower temperature threshold

#define SENSOR_PIN     12  // ESP32 pin connected to DS18B20 sensor's DQ pin
#define RELAY_FAN_PIN  26 // ESP32 pin connected to relay
int Gas_analog = 4;    // used for ESP32
int Gas_digital = 16;   // used for ESP32

OneWire oneWire(SENSOR_PIN);
DallasTemperature DS18B20(&oneWire);

void setup() {
  Serial.begin(115200); // initialize serial
  DS18B20.begin();    // initialize the DS18B20 sensor
  pinMode(RELAY_FAN_PIN, OUTPUT);
  pinMode(Gas_digital, INPUT);
  pinMode(Gas_analog, INPUT);
  lcd.begin();
  lcd.backlight();
}

void loop() {
  DS18B20.requestTemperatures();                  // send the command to get temperatures
  float temperature = DS18B20.getTempCByIndex(0); // read temperature in Celsius
  Serial.print(temperature);
  Serial.println("ºC");
  lcd.clear();
  lcd.setCursor(0, 0);                          // set cursor to first column, first row
  lcd.print(temperature);                   // print temp on lcd
  lcd.print((char)223); // display ° character
  lcd.print("C");
  int GasSensorValue = analogRead(Gas_analog);
  int gassensorDigital = digitalRead(Gas_digital);
  Serial.print("Gas Sensor: ");
  Serial.print(GasSensorValue);
  Serial.print("\t");
  Serial.print("Gas Class: ");
  Serial.print(gassensorDigital);
  Serial.print("\t");
  Serial.print("\t");
  if ((temperature > TEMP_UPPER_THRESHOLD)&& (GasSensorValue > 200)){
    Serial.println("Turn the fan on");
    lcd.setCursor(0, 1);
    lcd.print("Turn the fan on");
    digitalWrite(RELAY_FAN_PIN, LOW); // turn on
  } else if ((temperature < TEMP_UPPER_THRESHOLD)&& (GasSensorValue < 200)) {
    Serial.println("Turn the fan off");
    lcd.setCursor(0, 1);
    lcd.print("Turn the fan off");
    digitalWrite(RELAY_FAN_PIN, HIGH); // turn off
  }
  
   if ((temperature > TEMP_UPPER_THRESHOLD)|| (GasSensorValue > 200)){
    Serial.println("Turn the fan on");
    lcd.setCursor(0, 1);
    lcd.print("Turn the fan on");
    digitalWrite(RELAY_FAN_PIN, LOW); // turn on
  } else if ((temperature < TEMP_UPPER_THRESHOLD)&& (GasSensorValue < 200)) {
    Serial.println("Turn the fan off");
    lcd.setCursor(0, 1);
    lcd.print("Turn the fan off");
    digitalWrite(RELAY_FAN_PIN, HIGH); // turn off
  }

  delay(500);
}