am2315temp —
Driver for Aosong AM2315 sensor chip via I2C bus
am2315temp* at iic? addr 0x5c
The am2315temp driver provides measurements from the
  AM2315 humidity/temperature sensors via the
  envsys(4) framework. The
  am2315temp addr argument selects
  the address at the iic(4) bus. The
  AM2315 has limits on how often the measurements can be read. Adjustments to
  the number of times to take reading before considering it valid, and the
  number of ticks to wait between readings can be changed through
  sysctl(8) nodes.
There are other oddities about the AM2315 that should be
    mentioned. The datasheet says that the device should read no more often then
    every 2 seconds, further, it also implies that a measurement is not
    performed until the device is 1) awake 2) has been asked for a measurement.
    From observation, it has been noted that it is possible to ask for
    measurements more often than every 2 seconds, and actually get something
    that looks to be valid. It may, in fact, be valid, but it has also been
    noted that the measurements do not appear to change. This implies that a
    measurement was done, and then returned time and time again. It has also
    been noticed that if measurements are taken very close to every 2 seconds,
    that sometimes the device will return a I2C error on a read. If this happens
    a lot, increase hw.am2315temp0.readticks a bit.
The following sysctl(3) variables
  are provided:
  - hw.am2315temp0.readcount
- The number of times to take a reading before considering it valid. This
      defaults to 2.
- hw.am2315temp0.readticks
- The number of ticks to wait in between readings. The default is 100.
- hw.am2315temp0.debug
- If the driver is compiled with AM2315_DEBUG, this
      node will appear and can be used to set the debugging level.
Theam2315temp driver first appeared in
  NetBSD 8.0.
The device does not appear to work with the
  gpioiic(4) bitbang controller.
  When tried, reads would not error, but no data was returned.