#include <Wire.h>

#define CO2_SENSOR_PIN 36  // Analog pin for MG811 sensor
#define CO2_PUMP_PIN 27    // GPIO pin to control CO2 pump/solenoid valve

float co2Level = 0.0;
const float CO2_LOW_THRESHOLD = 400.0;  // Minimum CO2 level (ppm)
const float CO2_HIGH_THRESHOLD = 1000.0; // Maximum CO2 level (ppm)

void setup() {
  Serial.begin(9600);

  // Initialize the CO2 pump control pin
  pinMode(CO2_PUMP_PIN, OUTPUT);
  digitalWrite(CO2_PUMP_PIN, LOW); // Turn off the CO2 pump initially

  Serial.println("CO2 Control System");
}

void loop() {
  co2Level = readCO2Sensor(); // Read the CO2 level from the sensor

  // Control the CO2 pump based on CO2 levels
  controlCO2Pump(co2Level);

  delay(2000); // Adjust delay as per the required sampling rate
}

// Function to read the CO2 sensor
float readCO2Sensor() {
  int co2Raw = analogRead(CO2_SENSOR_PIN); // Read raw value from sensor
  float co2 = map(co2Raw, 0, 4095, 0, 5000); // Convert to CO2 ppm range
  Serial.print("CO2 Level: ");
  Serial.print(co2);
  Serial.println(" ppm");
  return co2;
}

// Function to control the CO2 pump
void controlCO2Pump(float co2) {
  if (co2 < CO2_LOW_THRESHOLD) {
    // If CO2 level is too low, turn on the CO2 pump
    digitalWrite(CO2_PUMP_PIN, HIGH);
    Serial.println("Air Pump ON: Increasing CO2 levels...");
  } else if (co2 > CO2_HIGH_THRESHOLD) {
    // If CO2 level is too high, turn off the CO2 pump
    digitalWrite(CO2_PUMP_PIN, LOW);
    Serial.println("Air Pump OFF: CO2 levels stable or too high.");
  } else {
    // Within acceptable range, keep the pump off
    Serial.println("CO2 Level Stable: No action needed.");
  }
}