sht4xtemp —
Driver for Sensirion SHT40/SHT41/SHT45 sensor chip via I2C
  bus
sht4xtemp* at iic? addr 0x44
The sht4xtemp driver provides measurements from the
  SHT40/SHT41/SHT45 humidity/temperature sensors via the
  envsys(4) framework. The
  sht4xtemp addr argument selects
  the address at the iic(4) bus. The
  resolution, heater controls and crc validity can be changed through
  sysctl(8) nodes.
The following sysctl(3) variables
  are provided:
  - hw.sht4xtemp0.resolutions
- Lists the resolutions supported by the driver and chip.
- hw.sht4xtemp0.resolution
- Set the resolution, or number of bits, used for %RH and temperature. Use
      one of the strings listed in
      hw.sht4xtemp.resolutions.
- hw.sht4xtemp0.ignorecrc
- If set, the crc calculation for %RH and temperature will be ignored.
- hw.sht4xtemp0.heateron
- Turn the heater on and off. Please note that the heater is turned on right
      before the measurement and runs for a pulse width of time. Then the
      measurement is taken and the heater is turned off. There is no way to keep
      the heater running with this chip.
- hw.sht4xtemp0.heaterstrength
- From 1 to 3, the amount of energy put into the heater. The higher the
      number, the more power used.
- hw.sht4xtemp0.heaterpulses
- Lists the valid heater pulses supported by the driver and chip.
- hw.sht4xtemp0.heaterpulse
- Set the heater pulse length. Use one of the strings listed in
      hw.sht4xtemp.heaterpulses.
- hw.sht4xtemp0.debug
- If the driver is compiled with SI70XX_DEBUG, this
      node will appear and can be used to set the debugging level.
- hw.sht4xtemp0.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.
Thesht4xtemp driver first appeared in
  NetBSD 10.0.