Circuit Documentation

Summary

This circuit is designed for an automatic system that interacts with various sensors and modules to perform specific actions based on environmental conditions and inputs. The system is capable of detecting smoke or gas using an MQ2 sensor, controlling power to an exhaust fan and a solenoid lock, and providing audio feedback through a buzzer and a DFPlayer Mini module. It also includes a voice recognition module for receiving voice commands and an ESP32 microcontroller for additional functionalities. The circuit is powered by a 12V battery, which is charged by a solar panel through a charge controller. An ATS (Automatic Transfer Switch) is used to switch between the battery and solar power. The main control unit is an Arduino Mega 2560, which manages the inputs and outputs and communicates with the ESP32 and other modules.

Component List

Power Sources

• 12V Battery (mini): Provides the main power supply for the circuit.
• Solar Panel: Charges the battery through the charge controller during daylight.

Sensors and Modules

• MQ2 Gas Sensor: Detects the presence of gases such as LPG, propane, methane, alcohol, smoke, and others.
• Voice Recognition Module: Receives and processes voice commands.
• DFPlayer Mini: A small and low-cost MP3 module that can directly play MP3 files stored on a USB or TF card.
• ESP32 (30 pin): A powerful microcontroller with Wi-Fi and Bluetooth capabilities for additional functionalities.

Actuators

• Exhaust Fan 12": Ventilates the area when activated by a relay.
• 12V Solenoid Lock: Electromechanical lock controlled by the Arduino.
• Speaker: Outputs audio signals from the DFPlayer Mini.

Control and Conversion

• Arduino Mega 2560: The main microcontroller board that controls the system.
• Step Down Buck Converter: Converts higher voltage to a lower voltage to power USB devices.
• ATS (Automatic Transfer Switch): Automatically switches between solar panel and battery power.
• Charge Controller: Manages the charging of the battery from the solar panel and protects against overcharging.
• 12V Single Channel Relay: Electrically operated switches that control the power to the exhaust fans.

Input Devices

• 4X4 Membrane Matrix Keypad: Allows user input through a simple interface.

Indicators

• Buzzer: Provides audible alerts or feedback.

Wiring Details

Power Distribution

• 12V Battery (mini): Powers the ATS and the Step Down Buck Converter.
• Solar Panel: Connects to the Charge Controller to charge the battery.

Sensors and Modules

• MQ2 Gas Sensor:

  • D0 connected to Arduino Mega D2 PWM.
  • A0 connected to Arduino Mega A0.
  • GND connected to common ground.
  • VCC connected to Arduino Mega 5V.

• Voice Recognition Module:

  • GND connected to common ground.
  • VCC connected to Arduino Mega 5V.
  • RDX connected to Arduino Mega D4 PWM.
  • RTX connected to Arduino Mega D5 PWM.

• DFPlayer Mini:

  • GND connected to common ground.
  • VCC connected to Arduino Mega 5V.
  • RX connected to Arduino Mega D16 PWM/TX2.
  • TX connected to Arduino Mega D17 PWM/RX2.
  • SPK1 and SPK2 connected to Speaker.

• ESP32 (30 pin):

  • TX0 connected to Arduino Mega D19/RX1.
  • RX0 connected to Arduino Mega D18/TX1.
  • GND connected to common ground.

Actuators

• Exhaust Fan 12":

  • Live connected to NO on respective 12V Single Channel Relays.
  • Neutral connected to common ground.

• 12V Solenoid Lock:

  • VCC connected to Arduino Mega D10 PWM.
  • GND connected to common ground.

Control and Conversion

• Arduino Mega 2560:

  • GND connected to common ground.
  • 5V connected to VCC on various components.
  • VIN connected to the output of the Step Down Buck Converter.

• Step Down Buck Converter:

  • IN + and IN - GND connected to ATS.
  • OUT + and OUT - GND connected to USB male 2 pin connection.

• ATS:

  • + and - connected to 12V Battery (mini).
  • + and - connected to various components and relays.

• Charge Controller:

  • Solar Positive and Solar Negative connected to Solar Panel.
  • Load Positive and Load Negative connected to ATS.

• 12V Single Channel Relay:

  • IN connected to respective Arduino Mega PWM pins (D11 PWM, D12 PWM, D13 PWM).
  • GND connected to common ground.
  • VCC connected to ATS +.
  • COM connected to ATS +.
  • NO connected to respective Exhaust Fan Live.

Input Devices

• 4X4 Membrane Matrix Keypad:
  • R1 to R4 and C1 to C4 connected to respective Arduino Mega pins (D22 to D36).

Indicators

• Buzzer:
  • PIN connected to Arduino Mega D3 PWM.
  • GND connected to common ground.

Documented Code

/*
 * This Arduino sketch is designed for an automatic system that opens a solenoid
 * lock and activates a buzzer when the MQ2 sensor detects smoke or gas. The
 * system also includes a DFPlayer Mini for audio output, a voice recognition
 * module, and an ESP32 for additional functionalities. The circuit is powered
 * by a 12V battery and a solar panel with a charge controller.
 */

#include <SoftwareSerial.h>

// Pin definitions
const int mq2DigitalPin = 2;
const int mq2AnalogPin = A0;
const int solenoidPin = 10;
const int buzzerPin = 3;
const int relay1Pin = 11;
const int relay2Pin = 12;
const int relay3Pin = 13;

// DFPlayer Mini
SoftwareSerial myDFPlayer(16, 17); // RX, TX

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  myDFPlayer.begin(9600);

  // Initialize pins
  pinMode(mq2DigitalPin, INPUT);
  pinMode(mq2AnalogPin, INPUT);
  pinMode(solenoidPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(relay1Pin, OUTPUT);
  pinMode(relay2Pin, OUTPUT);
  pinMode(relay3Pin, OUTPUT);

  // Initial states
  digitalWrite(solenoidPin, LOW);
  digitalWrite(buzzerPin, LOW);
  digitalWrite(relay1Pin, LOW);
  digitalWrite(relay2Pin, LOW);
  digitalWrite(relay3Pin, LOW);
}

void loop() {
  // Read MQ2 sensor
  int mq2DigitalValue = digitalRead(mq2DigitalPin);
  int mq2AnalogValue = analogRead(mq2AnalogPin);

  // Check for smoke or gas
  if (mq2DigitalValue == HIGH || mq2AnalogValue > 300) {
    // Activate solenoid lock and buzzer
    digitalWrite(solenoidPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
    delay(5000); // Keep activated for 5 seconds
    digitalWrite(solenoidPin, LOW);
    digitalWrite(buzzerPin, LOW);
  }

  // Add any additional functionalities here
}

Filename: sketch.ino