| SGP40MOX(4) | Device Drivers Manual | SGP40MOX(4) | 
sgp40mox —
sgp40mox* at iic? addr 0x59
sgp40mox driver provides an air quality measurement
  from the SGP40 sensor via the
  envsys(4) framework. The
  sgp40mox addr argument selects
  the address at the iic(4) bus. The
  crc validity and temperature and %RH compensation can be changed through
  sysctl(8) nodes.
In order to calculate the VOC index, the volatile organic compounds index, which is the measure of air quality the sensor is polled once a second and the raw sensor value is fed into the Sensirion VOC algorithm. This VOC algorithm used in this driver is licensed under a 3 clause BSD license and was pulled from the Sensirion Github repository at https://github.com/Sensirion/embedded-sgp.
hw.sgp40mox0.compensation.temperaturehw.sgp40mox0.compensation.humidityFor the best performance of the VOC algorithm it is important that the temperature and %RH compensation values be current and set using the sysctl(3) variables mentioned above. This data will need to be pulled from another source, such as a another sensor in the environment that the SGP40 is in.
hw.sgp40mox0.ignorecrchw.sgp40mox0.debugSGP40_DEBUG, this
      node will appear and can be used to set the debugging level.hw.sgp40mox0.readattemptssgp40mox driver first appeared in
  NetBSD 10.0.
sgp40mox driver was written by Brad
  Spencer
  <brad@anduin.eldar.org>.
The temperature and humidity compensation could be allowed to contain fractional degrees Celsius and %RH. The driver only supports setting whole numbers for either of those.
| October 7, 2021 | NetBSD 10.0 |