MQ-135 Monitoring rev_03

/********* Pleasedontcode.com **********

    Pleasedontcode thanks you for automatic code generation! Enjoy your code!

    - Terms and Conditions:
    You have a non-exclusive, revocable, worldwide, royalty-free license
    for personal and commercial use. Attribution is optional; modifications
    are allowed, but you're responsible for code maintenance. We're not
    liable for any loss or damage. For full terms,
    please visit pleasedontcode.com/termsandconditions.

    - Project: MQ-135 Monitoring
    - Source Code NOT compiled for: XIAO ESP32S3
    - Source Code created on: 2025-10-24 00:16:05

********* Pleasedontcode.com **********/

/****** SYSTEM REQUIREMENTS *****/
/****** SYSTEM REQUIREMENT 1 *****/
    /* Integrate a gas sensor module (e.g., MQ-135) with */
    /* the XIAO ESP32S3 to enable real-time air quality */
    /* measurement, providing alerts when pollutant */
    /* levels exceed thresholds. */
/****** END SYSTEM REQUIREMENTS *****/


/* START CODE */

/****** DEFINITION OF LIBRARIES *****/
#include <MQUnifiedsensor.h>\t//https://github.com/miguel5612/MQSensorsLib

/****** FUNCTION PROTOTYPES *****/
void setup(void);
void loop(void);

/***** DEFINITION OF ANALOG INPUT PINS *****/
const uint8_t sensor_MQ135_AOUT_PIN_A0\t\t= A0;

/****** DEFINITION OF LIBRARIES CLASS INSTANCES*****/
// Gas sensor MQ-135 connected to analog A0 of the XIAO ESP32S3
// Board string to identify the MCU family
#define BOARD_STRING_MQ135        ("XIAO-ESP32S3")

// ADC and voltage resolution specifics for ESP32
#define VOLTAGE_RESOLUTION         (3.3) // ESP32 typically 3.3V reference
#define ADC_BIT_RESOLUTION         (12)  // 12-bit ADC on ESP32
#define MQ135_SENSOR_TYPE            ("MQ-135")

// Clean air RS/R0 ratio (from datasheet/examples)
#define RatioMQ135CleanAir         (3.6)

// LED alert output (optional, connect a LED with current limiting resistor to this pin)
#define LED_ALERT_PIN              (25)

// MQ-135 object
MQUnifiedsensor MQ135(BOARD_STRING_MQ135, VOLTAGE_RESOLUTION, ADC_BIT_RESOLUTION, sensor_MQ135_AOUT_PIN_A0, MQ135_SENSOR_TYPE);


void setup(void)
{
    // put your setup code here, to run once:

    // Initialize serial communication for debugging
    Serial.begin(115200);
    // Optional: set LED pin mode
    pinMode(LED_ALERT_PIN, OUTPUT);
    digitalWrite(LED_ALERT_PIN, LOW);

    // Gas concentration model for CO2 (common MQ-135 calibration data)
    // You can switch to another gas by setting A/B with MQ135.setA()/setB()
    MQ135.setRegressionMethod(1); //_PPM =  a*ratio^b
    MQ135.setA(110.47); MQ135.setB(-2.862); // Configure CO2 concentration equation

    // Initialize the sensor
    MQ135.init();

    // Calibrate in clean air (RS/R0 ratio)
    Serial.print("Calibrating please wait.");
    float calcR0 = 0;
    for(int i = 1; i <= 10; i++)
    {
        MQ135.update(); // read voltage from analog pin
        calcR0 += MQ135.calibrate(RatioMQ135CleanAir);
        Serial.print(".");
        delay(100);
    }
    MQ135.setR0(calcR0/10);
    Serial.println("  done!.");

    if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
    if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}

    // Optional: print debug header information
    MQ135.serialDebug(true);
}

void loop(void)
{
    static uint32_t lastMillis = 0;
    const uint32_t INTERVAL_MS = 1000; // 1 second interval for real-time updates

    uint32_t now = millis();
    if(now - lastMillis >= INTERVAL_MS)
    {
        lastMillis = now;
        MQ135.update();
        float correctionFactor = 0.0f; // can be extended with temperature/humidity compensation
        float co2ppm = MQ135.readSensor(false, correctionFactor); // CO2 ppm estimation using CO2 model
        // Print reading
        Serial.print("CO2 (ppm): "); Serial.println(co2ppm);

        // Simple alert mechanism: alert when CO2 exceeds threshold
        const float CO2_THRESHOLD = 1000.0f; // threshold in ppm
        if(co2ppm > CO2_THRESHOLD)
        {
            // Turn on alert LED (or buzzer)
            digitalWrite(LED_ALERT_PIN, HIGH);
            Serial.println("ALERT: CO2 concentration above threshold!");
        }
        else
        {
            digitalWrite(LED_ALERT_PIN, LOW);
        }
    }
}

/* END CODE */