adafruit-circuitpython-sgp40

Introduction

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CircuitPython library for the Adafruit SGP40 Air Quality Sensor / VOC Index Sensor Breakouts

Dependencies

This driver depends on:

• Adafruit CircuitPython <https://github.com/adafruit/circuitpython>_
• Bus Device <https://github.com/adafruit/Adafruit_CircuitPython_BusDevice>_
• Register <https://github.com/adafruit/Adafruit_CircuitPython_Register>_

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle <https://circuitpython.org/libraries>_.

Installing from PyPI

On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI <https://pypi.org/project/adafruit-circuitpython-sgp40/>_. To install for current user:

.. code-block:: shell

pip3 install adafruit-circuitpython-sgp40

To install system-wide (this may be required in some cases):

.. code-block:: shell

sudo pip3 install adafruit-circuitpython-sgp40

To install in a virtual environment in your current project:

.. code-block:: shell

mkdir project-name && cd project-name
python3 -m venv .venv
source .venv/bin/activate
pip3 install adafruit-circuitpython-sgp40

Usage Example

.. code-block:: python3

import time
import board
import adafruit_sgp40

i2c = board.I2C()  # uses board.SCL and board.SDA
sgp = adafruit_sgp40.SGP40(i2c)

while True:
    print("Measurement: ", sgp.raw)
    print("")
    sleep(1)

For humidity compensated raw gas and voc index readings, we'll need a secondary sensor such as the bme280

.. code-block:: python3

import time
import board
import adafruit_sgp40
import adafruit_bme280

i2c = board.I2C()  # uses board.SCL and board.SDA
sgp = adafruit_sgp40.SGP40(i2c)
bme280 = adafruit_bme280.Adafruit_BME280_I2C(i2c)

while True:
    temperature = bme280.temperature
    humidity = bme280.relative_humidity

    # For compensated raw gas readings
    """
    compensated_raw_gas = sgp.measure_raw(
        temperature=temperature, relative_humidity=humidity
    )
    print("Raw Data:", compensated_raw_gas)
    """

    # For Compensated voc index readings
    voc_index = sgp.measure_index(
    temperature=temperature, relative_humidity=humidity)

    print("VOC Index:", voc_index)
    print("")
    time.sleep(1)

It may take several minutes for the VOC index to start changing as it calibrates the baseline readings. The voc algorithm expects a 1 hertz sampling rate. Run measure_index() once per second.

Documentation

API documentation for this library can be found on Read the Docs <https://docs.circuitpython.org/projects/sgp40/en/latest/>_.

For information on building library documentation, please check out this guide <https://learn.adafruit.com/creating-and-sharing-a-circuitpython-library/sharing-our-docs-on-readthedocs#sphinx-5-1>_.

Contributing

Contributions are welcome! Please read our Code of Conduct <https://github.com/adafruit/Adafruit_CircuitPython_SGP40/blob/master/CODE_OF_CONDUCT.md>_ before contributing to help this project stay welcoming.