CCS811 CO_2 and Volatile Organic Compound Sensor

The ccs811 sensor platform allows you to use CCS811 CO_2 and volatile organic compound sensors (Adafruit) with ESPHome.

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CCS811 Sensor. Image by Adafruit

The communication with this sensor is done via I²C Bus, so you need to have an i2c: section in your config for this integration to work.

# Example configuration entry
i2c:
  sda: D0
  scl: D1

sensor:
  - platform: ccs811
    eco2:
      name: "CCS811 eCO2 Value"
    tvoc:
      name: "CCS811 Total Volatile Organic Compound"
    address: 0x5A
    update_interval: 60s

Configuration variables:

  • eco2 (Required): The eCO_2 data from the sensor in parts per million (ppm).
    • name (Required, string): The name for the CO_2 sensor.
    • id (Optional, ID): Set the ID of this sensor for use in lambdas.
    • All other options from Sensor.
  • tvoc (Required): The information for the total volatile organic compound sensor in parts per billion (ppm).
    • name (Required, string): The name for the tvoc sensor.
    • id (Optional, ID): Set the ID of this sensor for use in lambdas.
    • All other options from Sensor.
  • update_interval (Optional, Time): The interval to check the sensor. Defaults to 60s.

Advanced:

  • address (Optional, int): The I²C address of the sensor.
  • baseline (Optional, int): The baseline value for the unit, for calibration purposes. See Calibrating Baseline for more info.
  • temperature (Optional, ID): Give an external temperature sensor ID here. This can improve the sensor’s internal calculations.
  • humidity (Optional, ID): Give an external humidity sensor ID here. This can improve the sensor’s internal calculations.

Calibrating Baseline

The CCS811 sensor will re-calibrate itself each time it is powered on. Unfortunately that also means that if the sensor reboots at a time when the air is less clean than normal, the values will have a constant offset and cannot be compared to the values before the last boot.

To have consistent values, you need to specify a static baseline value (the calibration factor). To do this, first let the sensor boot up with no baseline set and let the sensor calibrate itself. After around 20-30 minutes you can then view the remote logs on the ESP. The next time the sensor is read out, you will see a log message with something like baseline=0xA483.

Now set the baseline property in your configuration file like so with the value you got via the logs:

# Example configuration entry
sensor:
  - platform: ccs811
    # ...
    baseline: 0xA483

The next time you upload the code, the CCS811 will be informed of this static baseline and you will get consistent values.

Please note that after some time (a couple of months), the baseline will need to be re-calibrated because the internal sensor has a slight value drift over time.