Circuit Documentation

Summary

This circuit involves an Arduino UNO microcontroller interfaced with an MQ2 gas sensor, two micro servo motors, a red LED, and a buzzer. The circuit is designed to monitor gas levels using the MQ2 sensor and trigger actions such as lighting an LED, sounding a buzzer, and moving servo motors when gas levels exceed a certain threshold.

Component List

1. Arduino UNO

   • Description: A 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. MQ2 Gas Sensor

   • Description: A gas sensor module used to detect gas levels.
   • Pins: VCC, GND, AOUT, DOUT

3. Micro Servo 9G (Servo 1)

   • Description: A small servo motor used for precise control of angular position.
   • Pins: GND, +5V, PWM

4. Micro Servo 9G (Servo 2)

   • Description: A small servo motor used for precise control of angular position.
   • Pins: GND, +5V, PWM

5. LED: Two Pin (Red)

   • Description: A red LED used for visual indication.
   • Pins: cathode, anode

6. Buzzer

   • Description: A buzzer used for audible alerts.
   • Pins: PIN, GND

Wiring Details

Arduino UNO

• 5V: Connected to VCC of MQ2, +5V of Servo 1, +5V of Servo 2
• GND: Connected to GND of MQ2, GND of Servo 1, GND of Servo 2, cathode of LED, GND of Buzzer
• A0: Connected to AOUT of MQ2
• D12: Connected to PIN of Buzzer
• D11: Connected to anode of LED
• D10: Connected to PWM of Servo 1
• D9: Connected to PWM of Servo 2

MQ2 Gas Sensor

• VCC: Connected to 5V of Arduino UNO
• GND: Connected to GND of Arduino UNO
• AOUT: Connected to A0 of Arduino UNO

Micro Servo 9G (Servo 1)

• GND: Connected to GND of Arduino UNO
• +5V: Connected to 5V of Arduino UNO
• PWM: Connected to D10 of Arduino UNO

Micro Servo 9G (Servo 2)

• GND: Connected to GND of Arduino UNO
• +5V: Connected to 5V of Arduino UNO
• PWM: Connected to D9 of Arduino UNO

LED: Two Pin (Red)

• cathode: Connected to GND of Arduino UNO
• anode: Connected to D11 of Arduino UNO

Buzzer

• PIN: Connected to D12 of Arduino UNO
• GND: Connected to GND of Arduino UNO

Code Documentation

#include <Servo.h>

Servo servo1;
Servo servo2;

const int mq2Pin = A0;  // MQ-2 sensor connected to A0
const int ledPin = 11;   // LED connected to pin 11
const int buzzerPin = 12; // Buzzer connected to pin 12

void setup() {
  Serial.begin(9600);
  servo1.attach(9);  // Attach servo 1 to pin 9
  servo2.attach(10); // Attach servo 2 to pin 10
  
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  
  // Initialize servos to 0 degrees
  servo1.write(0);
  servo2.write(0);
}

void loop() {
  int mq2Value = analogRead(mq2Pin); // Read the value from the MQ-2 sensor
  Serial.println(mq2Value); // Print the sensor value to the serial monitor

  // Check the MQ-2 sensor value to determine actions
  if (mq2Value > 300) { // Adjust threshold as necessary
    digitalWrite(ledPin, HIGH); // Turn on LED
    digitalWrite(buzzerPin, HIGH); // Turn on Buzzer
    servo1.write(90); // Move servo 1 to 90 degrees
    servo2.write(90); // Move servo 2 to 90 degrees
  } else {
    digitalWrite(ledPin, LOW); // Turn off LED
    digitalWrite(buzzerPin, LOW); // Turn off Buzzer
    servo1.write(0); // Move servo 1 back to 0 degrees
    servo2.write(0); // Move servo 2 back to 0 degrees
  }

  delay(1000); // Delay for a second before reading again
}

This code initializes the components and continuously reads the gas level from the MQ2 sensor. If the gas level exceeds a threshold, it activates the LED, buzzer, and moves the servos to 90 degrees. If the gas level is below the threshold, it deactivates the LED, buzzer, and returns the servos to 0 degrees.