Circuit Documentation

Summary

This circuit is a Lung Cancer Detector using six gas sensors connected to an Arduino UNO. The sensor values are read and displayed on a 20x4 LCD display and the serial monitor. Additionally, a buzzer and an LED are activated if any sensor value exceeds a predefined threshold.

Component List

1. Arduino UNO

   • Description: Microcontroller board based on the ATmega328P.
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

2. Buzzer

   • Description: An electronic device that produces a sound when a voltage is applied.
   • Pins: +, GND

3. Lcd 20x4 i2c

   • Description: 20x4 character LCD display with I2C interface.
   • Pins: GND, 5v, SCA, SCL

4. LED: Two Pin (red)

   • Description: A red LED with two pins.
   • Pins: cathode, anode

5. MQ 135

   • Description: Gas sensor for detecting air quality.
   • Pins: D OUT, A OUT, GND, VCC

6. MQ-4

   • Description: Gas sensor for detecting methane.
   • Pins: A0, D0, GND, VCC

7. MQ6

   • Description: Gas sensor for detecting LPG.
   • Pins: VCC, GND, A0, DO

8. MQ-3 Breakout

   • Description: Gas sensor for detecting alcohol.
   • Pins: VCC, GND, DO, AO

9. MQ-136

   • Description: Gas sensor for detecting hydrogen sulfide.
   • Pins: GND, OUT1, OUT2, VCC

10. MQ 138

    • Description: Gas sensor for detecting various gases.
    • Pins: gnd, AOUT, DOUT, VCC

Wiring Details

Arduino UNO

• A0: Connected to MQ-4 (A0)
• A1: Connected to MQ-3 Breakout (AO)
• A2: Connected to MQ 135 (A OUT)
• A3: Connected to MQ-136 (OUT1)
• A4: Connected to MQ 138 (AOUT) and Lcd 20x4 i2c (SCA)
• A5: Connected to Lcd 20x4 i2c (SCL) and MQ6 (A0)
• D8: Connected to Buzzer (+)
• D9: Connected to LED: Two Pin (red) (anode)
• 5V: Connected to Lcd 20x4 i2c (5v), MQ-3 Breakout (VCC), MQ-4 (VCC), MQ6 (VCC), MQ 135 (VCC), MQ-136 (VCC), MQ 138 (VCC)
• GND: Connected to LED: Two Pin (red) (cathode), Buzzer (GND), Lcd 20x4 i2c (GND), MQ-3 Breakout (GND), MQ-4 (GND), MQ6 (GND), MQ 135 (GND), MQ 138 (gnd), MQ-136 (GND)

Buzzer

• +: Connected to Arduino UNO (D8)
• GND: Connected to Arduino UNO (GND)

Lcd 20x4 i2c

• GND: Connected to Arduino UNO (GND)
• 5v: Connected to Arduino UNO (5V)
• SCA: Connected to Arduino UNO (A4)
• SCL: Connected to Arduino UNO (A5)

LED: Two Pin (red)

• cathode: Connected to Arduino UNO (GND)
• anode: Connected to Arduino UNO (D9)

MQ 135

• A OUT: Connected to Arduino UNO (A2)
• GND: Connected to Arduino UNO (GND)
• VCC: Connected to Arduino UNO (5V)

MQ-4

• A0: Connected to Arduino UNO (A0)
• GND: Connected to Arduino UNO (GND)
• VCC: Connected to Arduino UNO (5V)

MQ6

• A0: Connected to Arduino UNO (A5)
• GND: Connected to Arduino UNO (GND)
• VCC: Connected to Arduino UNO (5V)

MQ-3 Breakout

• AO: Connected to Arduino UNO (A1)
• GND: Connected to Arduino UNO (GND)
• VCC: Connected to Arduino UNO (5V)

MQ-136

• OUT1: Connected to Arduino UNO (A3)
• GND: Connected to Arduino UNO (GND)
• VCC: Connected to Arduino UNO (5V)

MQ 138

• AOUT: Connected to Arduino UNO (A4)
• gnd: Connected to Arduino UNO (GND)
• VCC: Connected to Arduino UNO (5V)

Code Documentation

/*
 * Lung Cancer Detector using 6 Gas Sensors
 * This code reads values from 6 gas sensors connected to the Arduino UNO
 * and displays the values on a 20x4 LCD display and the serial monitor
 * in the format: S1 S2 S3 S4 S5 S6. Additionally, it activates a buzzer
 * and an LED if any sensor value exceeds a predefined threshold.
 */

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Initialize the LCD with the I2C address 0x27
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Define pin connections
const int buzzerPin = 8;
const int ledPin = 9;

// Define sensor thresholds
const int threshold = 500;

void setup() {
  // Initialize serial communication at 9600 baud rate
  Serial.begin(9600);
  
  // Initialize the LCD
  lcd.begin();
  lcd.backlight();
  
  // Initialize buzzer and LED pins
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  
  // Print a message to the serial monitor and LCD
  Serial.println("Lung Cancer Detector Initialized");
  lcd.setCursor(0, 0);
  lcd.print("Lung Cancer Detector");
  lcd.setCursor(0, 1);
  lcd.print("Initialized");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read values from the gas sensors
  int mq4Value = analogRead(A0); // MQ-4 sensor
  int mq3Value = analogRead(A1); // MQ-3 sensor
  int mq135Value = analogRead(A2); // MQ-135 sensor
  int mq136Value = analogRead(A3); // MQ-136 sensor
  int me3H2SValue = analogRead(A4); // ME3-H2S sensor
  int mq6Value = analogRead(A5); // MQ-6 sensor
  
  // Print the sensor values to the serial monitor in the format: S1 S2 S3 S4 S5 S6
  Serial.print("S1: ");
  Serial.print(mq4Value);
  Serial.print("\tS2: ");
  Serial.print(mq3Value);
  Serial.print("\tS3: ");
  Serial.print(mq135Value);
  Serial.print("\tS4: ");
  Serial.print(mq136Value);
  Serial.print("\tS5: ");
  Serial.print(me3H2SValue);
  Serial.print("\tS6: ");
  Serial.println(mq6Value);
  
  // Display the sensor values on the LCD
  lcd.setCursor(0, 0);
  lcd.print("S1:");
  lcd.print(mq4Value);
  lcd.setCursor(10, 0);
  lcd.print("S2:");
  lcd.print(mq3Value);
  lcd.setCursor(0, 1);
  lcd.print("S3:");
  lcd.print(mq135Value);
  lcd.setCursor(10, 1);
  lcd.print("S4:");
  lcd.print(mq136Value);
  lcd.setCursor(0, 2);
  lcd.print("S5:");
  lcd.print(me3H2SValue);
  lcd.setCursor(10, 2);
  lcd.print("S6:");
  lcd.print(mq6Value);
  
  // Check if any sensor value exceeds the threshold
  if (mq4Value > threshold || mq3Value > threshold || mq135Value > threshold ||
      mq136Value > threshold || me3H2SValue > threshold || mq6Value > threshold) {
    digitalWrite(buzzerPin, HIGH); // Activate buzzer