🌧️🧪 Smart Acid Rain Prediction System

#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

#include "DHT.h"

#define DHTPIN 6
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);




#define NO2_PIN A0


const float Vcc = 5.0;
const float RL = 4700.0;


float R0 = 12000.0;
float A = 1.0;
float B = -1.25;

const float scaleFactor = 0.001;







#define MQ136_PIN A7

float Vcc1 = 5.0;
float RL1 = 10000.0;
float R01;
float A_1 = 10.0;
float B_1 = -1.3;






#define TOUCH_PIN 11
#define LED_PIN 2
void setup() {
  Serial.begin(9600);

  pinMode(TOUCH_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  lcd.begin(16, 2);
  lcd.clear();
  lcd.setCursor(1, 0);
  lcd.print("Smart Acid Rain");
  lcd.setCursor(0, 2);
  lcd.print("Detection System");

  delay(1000);
  Serial.println("DFRobot Fermion / MEMS NO2 Sensor Reading");
  Serial.println("Output in ppb (Calibrated for clean air ~1 ppb)");
  delay(3000); // short warm-up

  Serial.println("Calibrating MQ136 sensor...");
  Serial.println("Ensure the sensor is in clean, fresh air for accurate R0 calculation.");
  //delay(2000);
  delay(180000);
  R01 = calibrateR01();
  delay(2000);

  Serial.print("Calibration complete. R0 = ");
  Serial.print(R01, 0);
  Serial.println(" Ohms.");
  Serial.println("Starting measurement loop in 5 seconds...");

  digitalWrite(LED_PIN, LOW);

  dht.begin();
  delay(10000);

  lcd.clear();






}

void loop() {
  digitalWrite(LED_PIN, LOW);
  /*
    int touchState = digitalRead(TOUCH_PIN);  // Read touch sensor
    if (touchState == HIGH) {  // Touched
      /digitalWrite(LED_PIN, HIGH);

    } else {  // Not touched


    }


    lcd.setCursor(0,0);
    lcd.print("ditance:");
     lcd.setCursor(8,0);

  */

  float h = dht.readHumidity();
  float t = dht.readTemperature();
  float f = dht.readTemperature(true);

  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);

  int sensorValue1 = analogRead(MQ136_PIN);
  float sensorVoltage1 = (sensorValue1 / 1023.0) * Vcc1;
  float Rs1 = (Vcc1 * RL1 / sensorVoltage1) - RL1;
  float ratio1 = Rs1 / R01;
  float ppm1 = A_1 * pow(ratio1, B_1);
  float ppb1 = ppm1 * 1000.0;






  int sensorValue = analogRead(NO2_PIN);
  float sensorVoltage = (sensorValue / 1023.0) * Vcc;
  if (sensorVoltage < 0.05) {
    Serial.println("Low sensor voltage  check wiring or sensor warm-up.");
    delay(2000);
    return;
  }
  float Rs = (Vcc * RL / sensorVoltage) - RL;
  float ratio = Rs / R0;
  float ppm = A * pow(ratio, B);
  ppm = ppm * scaleFactor;
  float ppb = ppm * 1000.0;

  Serial.print("ADC: "); Serial.print(sensorValue1);
  Serial.print(" | Voltage: "); Serial.print(sensorVoltage1, 3);
  Serial.print(F("Humidity: "));
  Serial.print(h);
  Serial.print(F("%  Temperature: "));
  Serial.print(t);
  Serial.print(F("C "));
  Serial.print(" | SO2: "); Serial.print(ppm1, 3);
  Serial.print(" ppm");
  Serial.print(" | SO2: "); Serial.print(ppb1, 1);
  Serial.print(" ppb");
  Serial.print(" | NO2: "); Serial.print(ppm, 3); Serial.print(" ppm");
  Serial.print(" ("); Serial.print(ppb, 1); Serial.println(" ppb)");


  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("TEMP:");
  lcd.setCursor(5, 0);
  lcd.print(t);
  lcd.setCursor(11, 0);
  lcd.print("C");

  lcd.setCursor(0, 1);
  lcd.print("HUMI:");
  lcd.setCursor(5, 1);
  lcd.print(h);
  lcd.setCursor(11, 1);
  lcd.print("%");

  delay(5000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("SO2:");
  lcd.setCursor(4, 0);
  lcd.print(ppb1, 1);
  lcd.setCursor(8, 0);
  lcd.print("% PPB");


  lcd.setCursor(0, 1);
  lcd.print("NOX:");
  lcd.setCursor(4, 1);
  lcd.print(ppb, 1);
  lcd.setCursor(8, 1);
  lcd.print("% PPB");
  delay(5000);
  lcd.clear();
  lcd.setCursor(2, 0);
  lcd.print("Air Quality");
  if (ppb1 < 25 && ppb < 20) {
    lcd.setCursor(3, 1);
    lcd.print("Clean Air");
  }
  else  if (ppb1 > 25 && ppb1 < 55 &&ppb1 > 40 && ppb < 60) {
    lcd.clear();
    lcd.setCursor(2, 1);
    lcd.print("Slight pollution");
  }
  else if (ppb1 > 80 && ppb1 < 100 && ppb > 80 && ppb < 140) {
    lcd.clear();
    lcd.setCursor(2, 0);
    lcd.print("Acid rain may");
    lcd.setCursor(2, 1);
    lcd.print("start forming");
    digitalWrite(LED_PIN, HIGH);
  }
  else if (ppb1 > 180 && ppb > 180) {
    lcd.clear();
    lcd.setCursor(2, 0);
    lcd.print("Acid rain may");
    lcd.setCursor(2, 1);
    lcd.print("start Soon");
    digitalWrite(LED_PIN, HIGH);
  }

  delay(2000);

}


float calibrateR01() {
  int readings1 = 100;
  float sumRs1 = 0;

  for (int i1 = 0; i1 < readings1; i1++) {
    int sensorValue1 = analogRead(MQ136_PIN);
    float sensorVoltage1 = (sensorValue1 / 24.0) * Vcc1;
    if (sensorVoltage1 < 0.1) sensorVoltage1 = 0.1; // avoid division by zero
    float Rs1 = (Vcc1 * RL1 / sensorVoltage1) - RL1;
    sumRs1 += Rs1;
    delay(50);
  }

  return sumRs1 / readings1;  // Average R0
}