77 lines
2.2 KiB
Groff
77 lines
2.2 KiB
Groff
.\" $NetBSD: aht20temp.4,v 1.1 2022/11/17 19:20:05 brad Exp $
|
|
.\"
|
|
.\" Copyright (c) 2022 Brad Spencer <brad@anduin.eldar.org>
|
|
.\"
|
|
.\" Permission to use, copy, modify, and distribute this software for any
|
|
.\" purpose with or without fee is hereby granted, provided that the above
|
|
.\" copyright notice and this permission notice appear in all copies.
|
|
.\"
|
|
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
|
|
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
|
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
|
|
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
|
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
|
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
|
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
|
.\"
|
|
.Dd November 15, 2022
|
|
.Dt AHT20TEMP 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm aht20temp
|
|
.Nd Driver for Guangzhou Aosong AHT20 sensor chip via I2C bus
|
|
.Sh SYNOPSIS
|
|
.Cd "aht20temp* at iic? addr 0x38"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver provides measurements from the AHT20 humidity/temperature
|
|
sensors via the
|
|
.Xr envsys 4
|
|
framework.
|
|
The
|
|
.Nm
|
|
.Ar addr
|
|
argument selects the address at the
|
|
.Xr iic 4
|
|
bus.
|
|
The crc validity can be changed through
|
|
.Xr sysctl 8
|
|
nodes.
|
|
.Sh SYSCTL VARIABLES
|
|
The following
|
|
.Xr sysctl 3
|
|
variables are provided:
|
|
.Bl -tag -width indent
|
|
.It Li hw.aht20temp0.ignorecrc
|
|
If set, the crc calculation for %RH and temperature will be ignored.
|
|
.It Li hw.aht20temp0.debug
|
|
If the driver is compiled with
|
|
.Dv AHT20_DEBUG ,
|
|
this node will appear and can be used to set the debugging level.
|
|
.It Li 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.
|
|
.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 10.0 .
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
The
|
|
.Nm
|
|
driver was written by
|
|
.An Brad Spencer Aq Mt brad@anduin.eldar.org .
|