Smart Air Quality Sensor

An ESP8266-based smart air quality monitoring system that measures temperature, humidity, and CO2 levels, displays the data on RGB LED matrices, and publishes to Home Assistant via MQTT.

Features

• Temperature & Humidity Monitoring: Using AM2302 DHT22 sensor
• CO2 Measurement: Using Sensirion SCD40 sensor (ppm)
• Visual Display: 3x 8x8 RGB LED matrices (NeoPixel) for real-time data visualization
• Home Assistant Integration: MQTT protocol for seamless integration
• Low Power: USB-C powered (5V)
• WiFi Connectivity: ESP8266 microcontroller

Hardware Requirements

Components

• Microcontroller: ESP8266 (NodeMCU, Wemos D1 Mini, or similar Wi-Fi capable MCUs)
• Temperature/Humidity Sensor: AM2302 DHT22
• CO2 Sensor: Sensirion SCD40
• Display: 4 pcs WS2812B 8x8 RGB LED matrices
• Power: USB-C connector with 5V power supply

Pin Connections

ESP8266 Pin Assignments

DHT22 Data Pin     -> GPIO2  (D4 on NodeMCU)
SCD40 SDA          -> GPIO4  (D2 on NodeMCU)
SCD40 SCL          -> GPIO5  (D1 on NodeMCU)
LED Matrix Data    -> GPIO14 (D5 on NodeMCU)

DHT22 Wiring

VCC  -> 3.3V or 5V voltage source
GND  -> GND
DATA -> GPIO2 (with 10kΩ pull-up resistor to VCC)

SCD40 Wiring

VDD  -> 3.3V voltage source
GND  -> GND
SDA  -> GPIO4
SCL  -> GPIO5

LED Matrix Wiring

VCC  -> 5V
GND  -> GND
DIN  -> GPIO14

Note: Chain the three 8x8 matrices together by connecting DOUT of one matrix to DIN of the next.

Software Requirements

• PlatformIO on VS Code or Arduino IDE

Required Libraries

• DHT sensor library (Adafruit)
• Adafruit Unified Sensor
• SparkFun SCD4x Arduino Library
• Adafruit NeoPixel
• Adafruit NeoMatrix
• Adafruit GFX Library
• PubSubClient (MQTT)

Installation

Using PlatformIO

1. Clone the repository:

   git clone https://github.com/mikoa001/smart-air-sensor.git
   cd smart-air-sensor

2. Configure your settings:

   cp src/config.h.example src/config.h

3. Edit src/config.h with your WiFi and MQTT credentials:

   #define WIFI_SSID "your_wifi_ssid"
   #define WIFI_PASSWORD "your_wifi_password"
   #define MQTT_SERVER "192.168.1.100"
   #define MQTT_USER "mqtt_user"
   #define MQTT_PASSWORD "mqtt_password"

4. Build and upload:

   pio run --target upload

5. Monitor serial output:

   pio device monitor

Using Arduino IDE

1. Install ESP8266 board support:

   • File → Preferences → Additional Board Manager URLs
   • Add: http://arduino.esp8266.com/stable/package_esp8266com_index.json
   • Tools → Board → Board Manager → Search "ESP8266 Boards" and install

2. Install required libraries:

   • Sketch → Include Library → Manage Libraries
   • Install all libraries listed in the Software Requirements section

3. Open the project:

   • Rename src/main.cpp to smart-air-sensor.ino
   • Open in Arduino IDE

4. Configure settings as described above

5. Select your board:

   • Tools → Board → ESP8266 Boards → Generic ESP8266 Module

6. Upload the sketch

Configuration

MQTT Topics

The sensor publishes to the following MQTT topics (configurable in config.h):

• home/sensor/temperature - Temperature in Celsius
• home/sensor/humidity - Relative humidity in percentage
• home/sensor/co2 - CO2 concentration in ppm
• home/sensor/status - Sensor online status

Update Intervals

Default intervals (configurable in config.h):

• Sensor reading & MQTT publish: 30 seconds
• Display rotation: 2 seconds (cycles through temp, humidity, CO2)

LED Matrix Display

The display cycles through three modes:

1. Temperature: Orange color
2. Humidity: Blue color
3. CO2 Level:
   • Green: < 1000 ppm (Good)
   • Yellow: 1000-2000 ppm (Warning)
   • Red: > 2000 ppm (Poor)

Home Assistant Integration

Add the following to your Home Assistant configuration.yaml:

mqtt:
  sensor:
    - name: "Air Quality Temperature"
      state_topic: "home/sensor/temperature"
      unit_of_measurement: "°C"
      device_class: temperature
      
    - name: "Air Quality Humidity"
      state_topic: "home/sensor/humidity"
      unit_of_measurement: "%"
      device_class: humidity
      
    - name: "Air Quality CO2"
      state_topic: "home/sensor/co2"
      unit_of_measurement: "ppm"
      icon: mdi:molecule-co2

Restart Home Assistant after adding the configuration.

Serial Monitor Output

Example output:

Smart Air Quality Sensor Starting...
LED Matrix initialized
DHT22 initialized
I2C initialized
SCD40 initialized
Connecting to WiFi...
WiFi connected
IP address: 192.168.1.50
Attempting MQTT connection...connected
Temperature: 22.5°C, Humidity: 45.2%
CO2: 678 ppm
Published temperature: 22.5
Published humidity: 45.2
Published CO2: 678

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request and I will reveiw it within 1-2 weeks.