Circuit Documentation

Summary

This circuit is designed to interface an MQ-3 gas sensor with an Arduino UNO. The circuit includes a buzzer and an LED to provide visual and auditory alerts based on the sensor readings. The Arduino UNO reads both digital and analog signals from the MQ-3 sensor and controls the LED and buzzer accordingly.

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. Buzzer

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

3. Resistor

   • Description: A passive electrical component with a resistance of 180 Ohms.
   • Pins: pin1, pin2

4. MQ-3 Breakout

   • Description: A gas sensor module that detects alcohol.
   • Pins: VCC, GND, DO, AO

5. LED: Two Pin (green)

   • Description: A green light-emitting diode.
   • Pins: cathode, anode

Wiring Details

Arduino UNO

• 5V connected to VCC of MQ-3 Breakout
• GND connected to GND of MQ-3 Breakout
• GND connected to GND of Buzzer
• GND connected to cathode of LED: Two Pin (green)
• A1 connected to AO of MQ-3 Breakout
• D4 connected to pin2 of Resistor
• D3 connected to PIN of Buzzer
• D2 connected to DO of MQ-3 Breakout

Buzzer

• GND connected to GND of Arduino UNO
• PIN connected to D3 of Arduino UNO

Resistor

• pin1 connected to anode of LED: Two Pin (green)
• pin2 connected to D4 of Arduino UNO

MQ-3 Breakout

• VCC connected to 5V of Arduino UNO
• GND connected to GND of Arduino UNO
• DO connected to D2 of Arduino UNO
• AO connected to A1 of Arduino UNO

LED: Two Pin (green)

• cathode connected to GND of Arduino UNO
• anode connected to pin1 of Resistor

Code Documentation

/* MQ-3 sensor with Arduino.
   created by the SriTu Tech team.
   Read the code below and use it for any of your creations.
   Home Page
*/

#define sensorDigital 2
#define LED 3
#define buzzer 4
#define sensorAnalog A1

void setup() {
  pinMode(sensorDigital, INPUT);
  pinMode(LED, OUTPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  bool digital = digitalRead(sensorDigital);
  int analog = analogRead(sensorAnalog);

  Serial.print("Analog value : ");
  Serial.print(analog);
  Serial.print("\t");
  Serial.print("Digital value :");
  Serial.println(digital);

  if (digital == 0) {
    digitalWrite(LED, HIGH);
    digitalWrite(buzzer, HIGH);
  } else {
    digitalWrite(LED, LOW);
    digitalWrite(buzzer, LOW);
  }
}

Code Explanation

• sensorDigital: Digital pin connected to the digital output (DO) of the MQ-3 sensor.
• LED: Digital pin connected to the buzzer.
• buzzer: Digital pin connected to the LED.
• sensorAnalog: Analog pin connected to the analog output (AO) of the MQ-3 sensor.

In the setup function, the pins are initialized, and the serial communication is started. The loop function reads the digital and analog values from the MQ-3 sensor and prints them to the serial monitor. If the digital value is low, the LED and buzzer are turned on; otherwise, they are turned off.