SCD30 Environmental Monitor

A comprehensive IoT environmental monitoring device built with ESP32 and SCD30 sensor for real-time CO2, temperature, and humidity monitoring with Home Assistant integration.

Features

• Real-time Environmental Monitoring: CO2, temperature, and humidity sensing using SCD30 sensor
• Visual Display: Live readings on integrated TFT display with color-coded alerts
• WiFi Connectivity: Automatic connection with fallback captive portal configuration
• MQTT Integration: Publishes data to MQTT broker with Home Assistant auto-discovery
• Battery Monitoring: Smart battery level monitoring with low-power sleep mode
• Web Configuration: Easy setup via captive portal web interface
• Visual Alerts: Color-coded warnings for CO2 levels (blue warning, red critical)

Hardware Requirements

• ESP32: TTGO T-Display (with integrated TFT display)
• SCD30 Sensor: CO2, temperature, and humidity sensor
• Battery: For portable operation (optional)
• Connections: I2C interface for sensor communication

Pin Configuration

• Battery Monitor: Pin 34 (ADC)
• Display: Integrated on TTGO T-Display
• SCD30 Sensor: I2C (SDA/SCL default pins)

Software Dependencies

Libraries Required

Install these libraries through Arduino IDE Library Manager:

TFT_eSPI [2.5.43]
SensirionI2cScd30 [0.1.0]
PubSubClient [2.8]
ESPAsyncWebServer [3.6.2]
DNSServer 
LittleFS 
ArduinoJson [0.2.0]
AsyncTCP [3.3.2]

ESP32 Board Package

Important: Use ESP32 Arduino Core version 3.0 (not 3.1) to avoid compatibility issues.

Configuration

Initial Setup

1. Flash the code to your ESP32 TTGO T-Display
2. On first boot, the device will create a WiFi access point named "SCD30-Setup"
3. Connect to this network and navigate to any website (captive portal will redirect)
4. Configure WiFi and MQTT settings through the web interface

Web Configuration Interface

The captive portal provides fields for:

WiFi Settings

• SSID: Your WiFi network name
• Password: WiFi password

MQTT Settings

• Server: MQTT broker address (IP or hostname)
• Port: MQTT port (default: 1883)
• Username: MQTT username (Not working)
• Password: MQTT password (Not working)
• Topic Prefix: Base topic for sensor data (e.g., "home/sensors/scd30")

Home Assistant Integration

The device automatically publishes Home Assistant discovery messages for:

• CO2 Level (ppm)
• Temperature (°C)
• Humidity (%)
• Battery Voltage (V)

Topics published:

• home/sensor/co2
• home/sensor/temperature
• home/sensor/humidity
• home/sensor/batteryVoltage

Display Features

Real-time Display Shows:

• CO2 concentration (ppm)
• Temperature (°C)
• Humidity (%)
• Battery voltage

Visual Alerts:

• Normal: Green text
• Warning (CO2 > 1000 ppm): Blue Display Border
• Critical (CO2 > 1500 ppm): Red/Blue Display Border

Power Management

Battery Monitoring

• Continuous voltage monitoring with smoothing algorithm
• Automatic deep sleep when battery drops below 3.5V
• Low-power WiFi transmission settings

Power Optimization

• Reduced WiFi transmission power
• Smart sleep modes for battery conservation
• Efficient sensor reading intervals

Technical Specifications

Sensor Thresholds

• CO2 Warning: 1000 ppm
• CO2 Critical: 1500 ppm
• Low Battery: 3.5V

Timing Configuration

• Sensor Warmup: readings skipped on startup
• MQTT Publish: Every 5 seconds
• Display Update: 1 second intervals
• WiFi Timeout: 20 seconds

Memory Management

• Uses LittleFS for configuration storage
• JSON-based configuration files

Installation

1. Hardware Setup:

   • Connect SCD30 sensor to ESP32 via I2C
   • Ensure proper power connections
   • Optional: Connect battery for portable operation

2. Software Installation:

   • Install Arduino IDE
   • Add ESP32 board package (version 3.0)
   • Install required libraries
   • Upload the code to your device

3. Configuration:

   • Connect to "SCD30-Setup" WiFi network
   • Browse to 192.168.4.1
   • Configure WiFi and MQTT settings
   • Device will restart and begin normal operation

Troubleshooting

Common Issues

WiFi Connection Problems:

• Check SSID and password in configuration
• Ensure WiFi network is 2.4GHz
• Device will restart and enter setup mode if connection fails

MQTT Connection Issues:

• Verify MQTT broker address and port
• Check username/password if authentication is required
• Monitor serial output for connection status

Sensor Reading Errors:

• Ensure I2C connections are secure
• Check sensor power supply
• Monitor serial output for error messages
• Recalibrate SCD30

Serial Monitor Output

The device provides detailed logging via Serial (115200 baud):

• System initialization status
• WiFi connection attempts
• MQTT publishing confirmation
• Sensor readings and errors
• Battery voltage monitoring

Author

Peter Penglis
Date: July 13, 2025