hythygtemp —
Driver for IST-AG HYT-221/271/939 sensor chip via I2C bus
hythygtemp* at iic? addr 0x28
The hythygtemp driver provides measurements from the
  HYT-221/271/939 humidity/temperature sensors via the
  envsys(4) framework. The
  hythygtemp addr argument selects
  the address at the iic(4) bus. The
  sampling interval can be changed through the
  sysctl(8) node
  hw.hythygtemp0.interval.
The sensor chips can be reconfigured to respond to other addresses
    than the default value of 0x28 by external utilities, like for example the
    pkgsrc/sysutils/hytctl package.
The following sysctl(3) variables
  are provided:
  - hw.hythygtemp0.interval
- Defines the sensor's sampling interval in seconds. It defaults to 50
      seconds.
Thehythygtemp driver first appeared in
  NetBSD 7.0.
The hythygtemp driver was written by
  Frank Kardel
  <kardel@NetBSD.org>
  and Frank Wille ⟨phx@NetBSD.org⟩.