sht3xtemp —
Driver for Sensirion SHT30/SHT31/SHT35 sensor chip via I2C
  bus
sht3xtemp* at iic? addr 0x44
sht3xtemp* at iic? addr 0x45
The sht3xtemp driver provides measurements from the
  SHT30/SHT31/SHT35 humidity/temperature sensors via the
  envsys(4) framework. The
  sht3xtemp addr argument selects
  the address at the iic(4) bus. The
  mode of operation, repeatability, heater controls, periodic update rate and
  crc validity can be changed through
  sysctl(8) nodes.
The following sysctl(3) variables
  are provided:
  - hw.sht3xtemp0.modes
- Lists the modes supported by the driver and chip.
- hw.sht3xtemp0.mode
- Set the operation mode of the chip. The SHT3X chip can run in a
      single-shot measurement mode or a periodic update mode. Use one of the
      strings listed in hw.sht3xtemp.modes.
- hw.sht3xtemp0.rates
- List the periodic update rates supported by the driver and chip.
- hw.sht3xtemp0.rate
- Set the periodic update rate when the mode of operation is set to
      periodic. The unit for this is measurements per second, or ART which is a
      mode that operates at an update rate of 4Hz higher response time. Use one
      of the strings listed in hw.sht3xtemp.rates.Since it is possible to have subsecond periodic updates from
        the chip if so desired a device file is provided that can be used to get
        the raw temperature and humidity values outside of the
        envsys(4) framework. The
        structure of this output is the raw temperature plus an 8-bit CRC
        followed by the raw humidity plus an 8-bit CRC. 
- hw.sht3xtemp0.repeatabilities
- List the valid values for the repeatability used for a measurement.
- hw.sht3xtemp0.repeatability
- Set the repeatability for the measurement. The higher the repeatability
      the longer the measurement will take and the more power used. Use one of
      the strings listed in
      hw.sht3xtemp.repeatabilities.
- hw.sht3xtemp0.ignorecrc
- If set, the crc calculation for %RH and temperature in the measurement
      phrase will be ignored.
- hw.sht3xtemp0.heateron
- Turn the heater on and off.
- hw.sht3xtemp0.debug
- If the driver is compiled with SHT3X_DEBUG, this
      node will appear and can be used to set the debugging level.
- hw.sht3xtemp0.readattempts
- To read %RH or temperature the chip requires that the command be sent,
      then a delay must be observed before a read can be done to get the values
      back. The delays are documented in the datasheet for the chip. The driver
      will attempt to read back the values readattempts number of times. The
      default is 10 which should be more than enough for most purposes.
  - /dev/sht3xtempu
- SHT3X device unit u file.
Thesht3xtemp driver first appeared in
  NetBSD 10.0.
The datasheet did not provide enough information to get the alarm function of
  the chip working.