aht20temp —
Driver for Guangzhou Aosong AHT20 sensor chip via I2C bus
aht20temp* at iic? addr 0x38
The aht20temp driver provides measurements from the
  AHT20 humidity/temperature sensors via the
  envsys(4) framework. The
  aht20temp addr argument selects
  the address at the iic(4) bus. The
  crc validity can be changed through
  sysctl(8) nodes.
The following sysctl(3) variables
  are provided:
  - hw.aht20temp0.ignorecrc
- If set, the crc calculation for %RH and temperature will be ignored.
- hw.aht20temp0.debug
- If the driver is compiled with AHT20_DEBUG, this
      node will appear and can be used to set the debugging level.
- hw.aht20temp0.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.
Theaht20temp driver first appeared in
  NetBSD 10.0.