.\"	$NetBSD: hythygtemp.4,v 1.4 2015/09/09 17:42:35 wiz Exp $
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.\" Copyright (c) 2014 Frank Kardel
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.Dd September 9, 2015
.Dt HYTHYGTEMP 4
.Os
.Sh NAME
.Nm hythygtemp
.Nd Driver for IST-AG HYT-221/271/939 sensor chip via I2C bus
.Sh SYNOPSIS
.Cd "hythygtemp* at iic? addr 0x28"
.Sh DESCRIPTION
The
.Nm
driver provides measurements from the HYT-221/271/939 humidity/temperature
sensors via the
.Xr envsys 4
framework.
The
.Nm
.Ar addr
argument selects the address at the
.Xr iic 4
bus.
The sampling interval can be changed through the
.Xr sysctl 8
node
.Li hw.hythygtemp0.interval .
.Pp
The sensor chips can be reconfigured to respond to other addresses than the
default value of 0x28 by external utilities, like for example the
.Pa pkgsrc/sysutils/hytctl
package.
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 3
variables are provided:
.Bl -tag -width indent
.It hw.hythygtemp0.interval
Defines the sensor's sampling interval in seconds.
It defaults to 50 seconds.
.El
.Sh SEE ALSO
.Xr envsys 4 ,
.Xr iic 4 ,
.Xr envstat 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 7.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Frank Kardel Aq Mt kardel@NetBSD.org
and
.An Frank Wille Aq phx@NetBSD.org .