sht3xtemp(4) - NetBSD Manual Pages

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SHT3XTEMP(4)            NetBSD Kernel Interfaces Manual           SHT3XTEMP(4)


NAME

     sht3xtemp -- Driver for Sensirion SHT30/SHT31/SHT35 sensor chip via I2C
     bus


SYNOPSIS

     sht3xtemp* at iic? addr 0x44
     sht3xtemp* at iic? addr 0x45


DESCRIPTION

     The sht3xtemp driver provides measurements from the SHT30/SHT31/SHT35
     humidity/temperature sensors via the envsys(4) framework.  The sht3xtemp
     addr argument selects the address at the iic(4) bus.  The mode of opera-
     tion, repeatability, heater controls, periodic update rate and crc valid-
     ity can be changed through sysctl(8) nodes.


SYSCTL VARIABLES

     The following sysctl(3) variables are provided:

     hw.sht3xtemp0.modes
             Lists the modes supported by the driver and chip.

     hw.sht3xtemp0.mode
             Set the operation mode of the chip.  The SHT3X chip can run in a
             single-shot measurement mode or a periodic update mode.  Use one
             of the strings listed in hw.sht3xtemp.modes.

     hw.sht3xtemp0.rates
             List the periodic update rates supported by the driver and chip.

     hw.sht3xtemp0.rate
             Set the periodic update rate when the mode of operation is set to
             periodic.  The unit for this is measurements per second, or ART
             which is a mode that operates at an update rate of 4Hz higher
             response time.  Use one of the strings listed in
             hw.sht3xtemp.rates.

             Since it is possible to have subsecond periodic updates from the
             chip if so desired a device file is provided that can be used to
             get the raw temperature and humidity values outside of the
             envsys(4) framework.  The structure of this output is the raw
             temperature plus an 8-bit CRC followed by the raw humidity plus
             an 8-bit CRC.

     hw.sht3xtemp0.repeatabilities
             List the valid values for the repeatability used for a measure-
             ment.

     hw.sht3xtemp0.repeatability
             Set the repeatability for the measurement.  The higher the
             repeatability the longer the measurement will take and the more
             power used.  Use one of the strings listed in
             hw.sht3xtemp.repeatabilities.

     hw.sht3xtemp0.ignorecrc
             If set, the crc calculation for %RH and temperature in the mea-
             surement phrase will be ignored.

     hw.sht3xtemp0.heateron
             Turn the heater on and off.

     hw.sht3xtemp0.debug
             If the driver is compiled with SHT3X_DEBUG, this node will appear
             and can be used to set the debugging level.

     hw.sht3xtemp0.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.


FILES

     /dev/sht3xtempu  SHT3X device unit u file.


SEE ALSO

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


HISTORY

     The sht3xtemp driver first appeared in NetBSD 10.0.


AUTHORS

     The sht3xtemp driver was written by Brad Spencer <brad@anduin.eldar.org>.


BUGS

     The datasheet did not provide enough information to get the alarm func-
     tion of the chip working.

NetBSD 10.99                   October 31, 2021                   NetBSD 10.99