Ancient python code which I coded ages ago to analyse air quality with the BME680 and SGP30 sensors. Has some nifty calibration stuff in there which I couldn't find anywhere else, at least not in this combination. It was part of a django app, that's why it imports the "models". That's also how it persists data.

sgp30_bme680.py

import math
import time
import threading

import adafruit_sgp30
import bme680
import board
import busio

from piaq.monitor.models import SensorReading, SensorSettings


def absolute_humidity(temperature, humidity):
    """Taken from a Pull Request to the Adafruit SGP30 Arduino library:
    https://github.com/adafruit/Adafruit_SGP30/pull/4

    This refers to a formula mentioned in the SGP30 sensor docs:
    https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/9_Gas_Sensors/Sensirion_Gas_Sensors_SGP30_Driver-Integration-Guide_SW_I2C.pdf

    """
    t = temperature
    rh = humidity
    ah = 216.7 * \
        ((rh / 100.0) * 6.112 * math.exp((17.62 * t) / (243.12 + t))) / \
        (273.15 + t)
    return ah


class PollingThread(threading.Thread):
    def __init__(self, polling_interval):
        self.polling_interval = polling_interval
        self.stoprequest = threading.Event()

        self.bme680 = None
        self.sgp30 = None

        self._init_bme680()
        self._init_sgp30()

        super().__init__()

    def _init_bme680(self):
        try:
            sensor = bme680.BME680(bme680.I2C_ADDR_PRIMARY)
        except IOError:
            sensor = bme680.BME680(bme680.I2C_ADDR_SECONDARY)

        sensor.set_humidity_oversample(bme680.OS_2X)
        sensor.set_pressure_oversample(bme680.OS_4X)
        sensor.set_temperature_oversample(bme680.OS_8X)
        sensor.set_filter(bme680.FILTER_SIZE_3)
        sensor.set_gas_status(bme680.ENABLE_GAS_MEAS)
        sensor.set_gas_heater_temperature(320)
        sensor.set_gas_heater_duration(150)
        sensor.select_gas_heater_profile(0)

        self.bme680 = sensor

    def _init_sgp30(self):
        i2c = busio.I2C(board.SCL, board.SDA, frequency=100000)
        sgp30 = adafruit_sgp30.Adafruit_SGP30(i2c)
        sgp30.iaq_init()

        self.sgp30 = sgp30

        self._set_sgp30_baseline()

    def _set_sgp30_baseline(self):
        last_reading = SensorReading.objects.exclude(
            # Exclude readings where both values are 0, this can
            # happen when the sensor is warming up
            baseline_eCO2=0,
            baseline_TVOC=0,
        ).order_by('-time').first()

        if last_reading:
            self.sgp30.set_iaq_baseline(
                eCO2=last_reading.baseline_eCO2,
                TVOC=last_reading.baseline_TVOC,
            )

    def _set_sgp30_humidity_compensation(self, humidity, temperature):
        """Update humidity compensation on the SGP30"""

        self.sgp30.set_iaq_humidity(
            gramsPM3=absolute_humidity(
                humidity=humidity,
                temperature=temperature,
            ),
        )

    def _should_stop(self):
        settings = SensorSettings.objects.first()
        return (not settings.is_started) or self.stoprequest.isSet()

    def _read_and_save(self):
        got_data = self.bme680.get_sensor_data()

        if not got_data:
            return

        temperature = self.bme680.data.temperature
        humidity = self.bme680.data.humidity

        SensorReading.objects.create(
            temperature=temperature,
            humidity=humidity,
            pressure=self.bme680.data.pressure,
            gas_resistance=self.bme680.data.gas_resistance,
            eCO2=self.sgp30.eCO2,
            TVOC=self.sgp30.TVOC,
            baseline_eCO2=self.sgp30.baseline_eCO2,
            baseline_TVOC=self.sgp30.baseline_TVOC,
        )

        self._set_sgp30_humidity_compensation(temperature, humidity)

    def join(self, timeout=None):
        self.stoprequest.set()
        super().join(timeout)

    def run(self):
        while not self._should_stop():
            self._read_and_save()
            time.sleep(self.polling_interval)