Updated: 2021/Dec/3


SHT4XTEMP(4)                 Device Drivers Manual                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 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.

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

HISTORY
     The sht4xtemp driver first appeared in NetBSD 10.0.

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

NetBSD 9.99                   September 28, 2021                   NetBSD 9.99