SHT4XTEMP(4)

NAME
sht4xtemp - Driver for Sensirion SHT40/SHT41/SHT45 sensor chip via I2C bus

SYNOPSIS
sht4xtemp* at iic? addr 0x44

DESCRIPTION
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.

SYSCTL VARIABLES
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 SHT4X_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.

SEE ALSO
envsys(4), iic(4), envstat(8), sysctl(8)

HISTORY
The sht4xtemp driver first appeared in NetBSD 10.0.

AUTHORS
-nosplit The sht4xtemp driver was written by Brad Spencer <brad@anduin.eldar.org>.