Circuit Documentation

Summary

The circuit in question is designed to monitor environmental parameters such as temperature, humidity, air quality (CO2, NH3, NOx), and carbon monoxide (CO) levels. It utilizes an ESP32 Devkit V1 microcontroller to interface with various sensors and an LCD display for real-time data output. The circuit also includes a relay module to control an exhaust fan based on sensor readings or predefined conditions.

Component List

ESP32 Devkit V1

• Microcontroller with WiFi capability.
• It has multiple digital and analog pins for interfacing with sensors and other peripherals.

Lcd 20x4 i2c

• An LCD display with 20 characters per line and 4 lines.
• Uses I2C communication protocol for displaying data.

12v Power Supply

• Provides a 12V power source for the circuit.

Exhaust Fan 12"

• A 12-inch fan used for ventilation, controlled by the relay module.

DHT11

• A sensor for measuring temperature and humidity.

MQ-135 SENSOR AIR QUALITY

• A sensor for detecting various gases such as CO2, NH3, and NOx.

MQ-7 Breakout

• A sensor specifically designed for detecting carbon monoxide (CO) levels.

1 Channel 5V Relay Module

• A relay module for controlling high power devices such as the exhaust fan.

Wiring Details

ESP32 Devkit V1

• 3V3 connected to sensors and LCD VCC for power.
• GND connected to sensors, LCD, and relay module GND for common ground.
• D15 connected to DHT11 DATA for temperature and humidity data.
• D5 connected to Relay Module IN for controlling the relay.
• D21 connected to LCD SCA for I2C data.
• D22 connected to LCD SCL for I2C clock.
• D34 connected to MQ-135 A0 for analog gas readings.
• D35 connected to MQ-7 AO for analog CO readings.

Lcd 20x4 i2c

• GND connected to common ground.
• 5v connected to ESP32 3V3 for power.
• SCA connected to ESP32 D21 for I2C data.
• SCL connected to ESP32 D22 for I2C clock.

12v Power Supply

• + connected to Relay Module N.O. for supplying power to the fan.
• - connected to Exhaust Fan Neutral for completing the fan's power circuit.

Exhaust Fan 12"

• Live connected to Relay Module COM for controlled power.
• Neutral connected to 12v Power Supply - for completing the power circuit.

DHT11

• DATA connected to ESP32 D15 for data communication.
• GND connected to common ground.
• VCC connected to ESP32 3V3 for power.

MQ-135 SENSOR AIR QUALITY

• A0 connected to ESP32 D34 for analog gas readings.
• GND connected to common ground.
• VCC connected to ESP32 3V3 for power.

MQ-7 Breakout

• AO connected to ESP32 D35 for analog CO readings.
• GND connected to common ground.
• VCC connected to ESP32 3V3 for power.

1 Channel 5V Relay Module

• VCC+ connected to ESP32 3V3 for power.
• VCC- (GND) connected to common ground.
• IN connected to ESP32 D5 for control signal.
• N.O. connected to 12v Power Supply + for normally open contact.
• COM connected to Exhaust Fan Live for common contact.

Documented Code

LCD Display Code (sketch.ino)

#include <hd44780.h>                 
#include <hd44780ioClass/hd44780_I2Cexp.h> 

hd44780_I2Cexp lcd;
void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  delay(1500);

  // Initialize the LCD (20 columns x 4 rows)
  lcd.begin(20, 4);  
  lcd.backlight();
}

void loop() {
  // Variables for sensor data (placeholders)
  float t, h, co2_value, co_value;

  // Read sensor data here (code not provided)

  // Display Temperature
  lcd.setCursor(0, 0);
  lcd.print("Temp:");
  lcd.print(t);
  lcd.print(" C");

  // Display Humidity
  lcd.setCursor(0, 1);
  lcd.print("Humidity:");
  lcd.print(h);
  lcd.print(" %");

  // Display Air Quality
  lcd.setCursor(0, 2);
  lcd.print("CO2,NH3,NOx: ");
  lcd.print(co2_value);
  lcd.print(" ppm");

  // Display CO Level
  lcd.setCursor(0, 3);
  lcd.print("CO: ");
  lcd.print(co_value);
  lcd.print(" ppm");

  // Update every second
  delay(1000);
}

Note: The actual sensor data reading and processing code is not provided. The placeholders t, h, co2_value, and co_value should be replaced with actual sensor data variables obtained from the respective sensors.