Infineon XENSIV™ PAS CO2 Sensor

The xensiv_pas_co2_i2c component allows you to use Infineon’s XENSIV™ PAS CO2 sensor with ESPHome. This photoacoustic spectroscopy-based CO2 sensor provides accurate carbon dioxide concentration measurements from 0 to 32,000 ppm. The I²C Bus is required to be set up in your configuration for this sensor to work.

Compatible Hardware:

EVAL-CO2-5V-MINIBOARD (5V version)
EVAL-PASCO2-MINIBOARD (12V version)

Documentation:

# Example configuration entry
sensor:
  - platform: xensiv_pas_co2_i2c
    interrupt_pin: GPIOXX
    co2:
      name: "CO2"

Configuration Variables

Platform Configuration

interrupt_pin (Required, Pin Schema): The GPIO pin connected to the sensor’s INT pin. The sensor uses an active-low interrupt signal.
id (Optional, ID): Manually specify the ID used for code generation.
address (Optional, int): The I²C address of the sensor. Defaults to 0x28. The sensor has a fixed hardware address that cannot be changed.
sensor_rate (Optional, Time): The measurement interval for continuous mode. Valid range: 5 seconds to 4095 seconds. Defaults to 60s. Accepts formats like 10s, 1min, 60s.

ℹ️ Note
Sensor accuracy may be affected when sampling rates is <1min.

operation_mode (Optional, string): Sensor operation mode. One of continuous, single_shot. Defaults to continuous.
pressure_compensation (Optional, pressure): Atmospheric pressure reference for improved accuracy. Accepts values with units like 1013.25hPa, 101325Pa, etc. If not specified, the sensor uses its default reference pressure of 1015 hPa.
pressure_compensation_source (Optional, ID): ID of a pressure sensor to use for automatic pressure compensation updates. When specified, the CO2 sensor will automatically update its pressure compensation whenever the referenced sensor reports a new value.

ℹ️ Note
Use either pressure_compensation for a static value or pressure_compensation_source for dynamic updates from another sensor, not both.

Sensor Configuration

co2 (Required): The CO2 sensor configuration.
- name (Required, string): The name for the CO2 sensor.
- All other options from Sensor.

Operation Modes

Continuous Mode (Default)

In continuous mode, the sensor automatically takes measurements at the specified sensor_rate and triggers an interrupt when new data is ready. This is the recommended mode for most applications.

Single-Shot Mode

In single-shot mode, measurements are only taken when explicitly triggered. This mode is useful for battery-powered applications or when measurements are needed on-demand.

ℹ️ Note
Each measurement may take up to about 2 seconds to complete.

Hardware Differences

5V Version (EVAL-CO2-5V-MINIBOARD)

Operating voltage: 5V
Lower power consumption
Recommended for embedded applications

12V Version (EVAL-PASCO2-MINIBOARD)

Operating voltage: 12V
Higher sensitivity
Suitable for industrial applications

Both versions use the same I²C interface and are fully compatible with this component.

Triggering Single-Shot Measurements

You can trigger a single-shot CO2 measurement using a lambda action:

sensor:
  - platform: xensiv_pas_co2_i2c
    id: pasco2
    co2:
      name: "CO2"

button:
  - platform: template
    name: "Measure CO2 Now"
    on_press:
      - lambda: |-
          id(pasco2).measure_now();

This is useful in single_shot operation mode or for triggering additional measurements in continuous mode.

Pressure Compensation

For improved accuracy, you can configure atmospheric pressure compensation. The sensor’s CO2 measurement accuracy is affected by ambient air pressure:

Static Pressure Value

Set a fixed atmospheric pressure value:

sensor:
  - platform: xensiv_pas_co2_i2c
    interrupt_pin: GPIOXX
    co2:
      name: "CO2"
    pressure_compensation: 1013.25hPa  # Standard sea level pressure

You can also dynamically update the pressure compensation at runtime if you have a separate pressure sensor. You can update the pressure compensation in two ways:

Option 1: Using a Lambda Method Call

Call the set_pressure_compensation() method in a lambda action whenever your pressure sensor updates:

sensor:
  - platform: xensiv_pas_co2_i2c
    id: co2_sensor
    interrupt_pin: GPIOXX
    co2:
      name: "CO2"

  - platform: bmp280
    pressure:
      name: "Atmospheric Pressure"
      id: atm_pressure
      on_value:
        - lambda: |-
            // Update PASCO2 pressure compensation in Pascals
            id(co2_sensor).set_pressure_compensation(x * 100);  // x is in hPa, convert to Pa

Option 2: Linking Pressure Sensor Directly

Set the pressure_compensation_source field to the pressure sensor’s ID. ESPHome will automatically handle updates and unit conversion:

sensor:
  - platform: bmp280
    pressure:
      name: "Atmospheric Pressure"
      id: atm_pressure
  - platform: xensiv_pas_co2_i2c
    id: co2_sensor
    interrupt_pin: GPIOXX
    co2:
        name: "CO2"
    pressure_compensation_source: atm_pressure

ℹ️ Note
When using a sensor ID for pressure_compensation, ESPHome will automatically convert the pressure value to Pascals and update the PASCO2 sensor whenever the pressure sensor reports a new value.

Advanced Example

i2c:
  sda: GPIOXX
  scl: GPIOXX

sensor:
  - platform: xensiv_pas_co2_i2c
    id: co2_sensor
    interrupt_pin: GPIOXX
    co2:
      name: "CO2"
      filters:
        - sliding_window_moving_average:
            window_size: 5
            send_every: 1
    address: 0x28
    sensor_rate: 60s
    operation_mode: continuous
    pressure_compensation: 1013.25hPa

button:
  - platform: template
    name: "Measure CO2 Now"
    on_press:
      - lambda: |-
          id(co2_sensor).measure_now();

Troubleshooting

Sensor Not Responding

Verify I²C address (default: 0x28)
Check I²C wiring (SDA, SCL, GND, VCC)
Ensure correct voltage (5V or 12V depending on module)
Check ESPHome logs for “I2C communication test failed” error

No Interrupt Triggering

Verify interrupt pin is correctly connected to the sensor’s INT pin
Check that operation_mode is set to continuous
Ensure interrupt_pin is configured correctly in the YAML
The sensor uses an active-low interrupt signal (triggers on falling edge)

Inaccurate Readings

Allow 2-3 minutes warm-up time after power-on
Ensure adequate ventilation around the sensor
Check that sensor_rate is appropriate for your application (minimum 5s, maximum 4095s)
Consider using pressure_compensation if not at sea level or if ambient pressure varies
Use sensor filters like sliding window moving average to smooth readings

Sensor Ready Check Fails

This is normal during initial setup - the sensor needs time to stabilize after soft reset
The component will continue operation and verify sensor readiness during first measurement
Check logs for “Sensor is ready and operational” or “Sensor ready check inconclusive” messages
Restart the device (cut off power to both the MCU and the sensor)