Integrate the Carbon Dioxide (CO2) Module

Integrate the Carbon Dioxide (CO2) Module

Enhance your Everything Presence Pro with CO₂ monitoring for air quality awareness.

What You Need

  • Everything Presence Pro (powered off)

  • CO₂ sensor module (SCD40, sold separately, available here)

Remove the front cover

We need to remove the front cover of the EP Pro first to install the CO2 sensor. Find more details here on the best way to do that.

Install the CO₂ Sensor

Locate the GPIO Header

  1. Remove power from your Pro device

  2. Locate the GPIO header on the Pro board


Connect the Module

  1. Align the CO₂ sensor module with the GPIO pins, ensuring:

    • 3.3V on the sensor matches 3.3V on the board

    • GND on the sensor matches GND on the board

    • SDA (GPIO4) and SCL (GPIO16) pins are correctly aligned

  2. Firmly push the CO₂ module onto the GPIO pins


Important: The module only fits one way. Do not force it if the pins don't align.

There is a foam cushion that will sit on the PCB to support the CO2 sensor pre-installed.

Enable CO₂ in Firmware

After physically installing the module, you need to enable CO₂ support in the firmware.

Option 1: Switch Firmware from Home Assistant (Recommended)

If your Pro is already connected to Home Assistant:

  1. Go to Settings → Devices & Services → ESPHome

  2. Find your Pro device and click Configure

  3. Locate the CO2 Sensor select entity

  4. Change from Disabled to Enabled

  5. Press the Apply update button

  6. Wait for the device to update and restart (takes 1-2 minutes)

The CO₂ sensor entities will appear automatically after the restart.

Option 2: Flash via Web Browser

This option will be available soon, use option 1 for now.

If you prefer to flash directly or are setting up for the first time:

  1. Connect your Pro to your computer via USB-C

  2. Visit the firmware flasher below

  3. Select your options:

    • Network: WiFi or Ethernet (match your current setup)

    • CO2 Module: Yes

    • Bluetooth Proxy: Your preference

  4. Click Connect and follow the on-screen instructions

https://docs.everythingsmart.io/flash/everything-presence-pro.html

Verify in Home Assistant

Once the firmware update is complete, the CO₂ sensor should automatically appear in Home Assistant:

  • CO2 - Carbon dioxide concentration in ppm

  • Calibrate CO2 - Button to calibrate the sensor

Understanding CO₂ Readings

The CO₂ sensor measures carbon dioxide concentration in parts per million (ppm). Here's what typical readings mean:

CO₂ Level

Air Quality

Action

400-450 ppm

Fresh outdoor air

Ideal

450-700 ppm

Good indoor air

No action needed

700-1000 ppm

Acceptable

Consider ventilation

1000-2000 ppm

Poor

Open windows

2000+ ppm

Very poor

Improve ventilation immediately

Tip: CO₂ levels are an excellent indicator of ventilation quality. Use automations to trigger fans, send notifications, or change the LED colour when levels exceed your preferred threshold.

LED Environmental Mode

With the CO₂ module installed, you can use Environmental Mode for the RGB LED:

  1. Set LED Mode to "Environmental" or "Environmental + Presence"

  2. The LED will indicate air quality:

    • Green (steady) - Good air quality (< 800 ppm)

    • Yellow (slow pulse) - Moderate (800-1200 ppm)

    • Red (fast pulse) - Poor (> 1200 ppm)

See LED Modes & Customization for more details.

Calibrating the CO₂ Sensor

The SCD40 CO₂ sensor is factory-calibrated but may need recalibration over time for best accuracy.

When to Calibrate

  • After installing the sensor for the first time

  • If readings seem consistently off by more than 50-100 ppm

  • After the sensor has been stored for extended periods

  • Periodically (every 6-12 months) for best accuracy

How to Calibrate

  1. Place the Pro in fresh outdoor air, or near an open window with good airflow

  2. Wait at least 5 minutes for the sensor to stabilize

  3. In Home Assistant, find the Calibrate CO2 button entity

  4. Press the button to calibrate to 419 ppm (current atmospheric CO₂ average)

Important: The sensor must be exposed to fresh air during calibration. Indoor air typically has higher CO₂ levels due to human respiration.

Troubleshooting

CO₂ Entity Not Appearing

  1. Verify the module is firmly seated on the GPIO pins

  2. Check that CO₂ firmware is installed (CO2 Sensor entity should show "Enabled")

  3. Restart the device from Home Assistant

  4. If still not working, try reflashing the CO₂ firmware via USB

Readings Seem Inaccurate

  • Allow 24-48 hours for the sensor to stabilize after first install

  • Calibrate the sensor in fresh outdoor air

  • Ensure the sensor isn't near heat sources or in direct sunlight

Environmental LED Mode Not Working

Environmental LED mode requires the CO₂ module to be installed and the CO₂ firmware variant enabled. Without the module, this mode has no effect.