153 lines
4.3 KiB
Groff
153 lines
4.3 KiB
Groff
|
.\"-
|
||
|
|
.\" SPDX-License-Identifier: BSD-2-Clause
|
||
|
|
.\"
|
||
|
|
.\" Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" $FreeBSD$
|
||
|
|
.\"
|
||
|
|
.Dd December 8, 2019
|
||
|
|
.Dt GPIOTHS 4
|
||
|
|
.Os
|
||
|
|
.Sh NAME
|
||
|
|
.Nm gpioths
|
||
|
|
.Nd driver for DHTxx and AM320x temperature and humidity sensors
|
||
|
|
.Sh SYNOPSIS
|
||
|
|
To compile this driver into the kernel,
|
||
|
|
place the following line in your
|
||
|
|
kernel configuration file:
|
||
|
|
.Bd -ragged -offset indent
|
||
|
|
.Cd "device gpioths"
|
||
|
|
.Ed
|
||
|
|
.Pp
|
||
|
|
Alternatively, to load the driver as a
|
||
|
|
module at boot time, place the following line in
|
||
|
|
.Xr loader.conf 5 :
|
||
|
|
.Bd -literal -offset indent
|
||
|
|
gpioths_load="YES"
|
||
|
|
.Ed
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
The
|
||
|
|
.Nm
|
||
|
|
driver supports the DHTxx and AM320x family of
|
||
|
|
temperature and humidity sensors.
|
||
|
|
The driver automatically reads the values from the sensor
|
||
|
|
once every 5 seconds, and makes the results available via
|
||
|
|
.Xr sysctl 8
|
||
|
|
variables.
|
||
|
|
.Sh HARDWARE
|
||
|
|
The
|
||
|
|
.Nm
|
||
|
|
driver provides support for the following devices:
|
||
|
|
.Pp
|
||
|
|
.Bl -column -compact -offset indent "XXXXXXXX" "XXXXXXXX"
|
||
|
|
.It DHT11 Ta DHT12
|
||
|
|
.It DHT21 Ta DHT22
|
||
|
|
.It AM3201 Ta AM3202
|
||
|
|
.El
|
||
|
|
.Pp
|
||
|
|
The supported devices are all similar to each other, varying
|
||
|
|
primarily in accuracy and resolution.
|
||
|
|
The devices require a single wire for data communications, using a
|
||
|
|
custom protocol which is not compatible with Maxim's 1-wire(tm).
|
||
|
|
The AM320x devices also support connection to an i2c bus,
|
||
|
|
but this driver supports only the single-wire connection option.
|
||
|
|
.Sh SYSCTL VARIABLES
|
||
|
|
Sysctl variables are used to access the most recent temperature and
|
||
|
|
humidity measurements.
|
||
|
|
.Bl -tag -width indent
|
||
|
|
.It Va dev.gpioths.<unit>.temp
|
||
|
|
The current temperature in integer deciKelvins.
|
||
|
|
Note that
|
||
|
|
.Xr sysctl 8
|
||
|
|
will convert those units to display in decimal degrees Celcius.
|
||
|
|
.It Va dev.gpioths.<unit>.hum
|
||
|
|
The current relative humidity, as an integer percentage.
|
||
|
|
.It Va dev.gpioths.<unit>.fails
|
||
|
|
The number of failed attempts to communicate with the sensor since
|
||
|
|
the last good access.
|
||
|
|
Cleared whenever a set of measurements is successfully retrieved.
|
||
|
|
.El
|
||
|
|
.Sh FDT CONFIGURATION
|
||
|
|
On an
|
||
|
|
.Xr fdt 4
|
||
|
|
based system, a
|
||
|
|
.Nm
|
||
|
|
device node is typically defined directly under the root node, or under
|
||
|
|
a simplebus node that represents a collection of devices on a board.
|
||
|
|
.Pp
|
||
|
|
The following properties are required in the
|
||
|
|
.Nm
|
||
|
|
device subnode:
|
||
|
|
.Bl -tag -width indent
|
||
|
|
.It Va compatible
|
||
|
|
Must be "dht11".
|
||
|
|
.It Va gpios
|
||
|
|
A reference to the gpio device and pin for data communications.
|
||
|
|
.El
|
||
|
|
.Ss Example of adding a sensor with an overlay
|
||
|
|
.Bd -unfilled -offset indent
|
||
|
|
/dts-v1/;
|
||
|
|
/plugin/;
|
||
|
|
#include <dt-bindings/gpio/gpio.h>
|
||
|
|
|
||
|
|
/ {
|
||
|
|
compatible = "wand,imx6q-wandboard";
|
||
|
|
};
|
||
|
|
|
||
|
|
&{/} {
|
||
|
|
dht0 {
|
||
|
|
compatible = "dht11";
|
||
|
|
gpios = <&gpio5 15 GPIO_ACTIVE_HIGH>;
|
||
|
|
};
|
||
|
|
};
|
||
|
|
.Ed
|
||
|
|
.Sh HINTS CONFIGURATION
|
||
|
|
On a
|
||
|
|
.Xr device.hints 5
|
||
|
|
based system, such as
|
||
|
|
.Li MIPS ,
|
||
|
|
these values are configurable for
|
||
|
|
.Nm :
|
||
|
|
.Bl -tag -width indent
|
||
|
|
.It Va hint.gpioths.<unit>.at
|
||
|
|
The
|
||
|
|
.Xr gpiobus 4
|
||
|
|
instance the
|
||
|
|
.Nm
|
||
|
|
instance is attached to.
|
||
|
|
.It Va hint.gpioths.pins
|
||
|
|
A bitmask with a single bit set to indicate which gpio pin on the
|
||
|
|
.Xr gpiobus 4
|
||
|
|
to use for data communications.
|
||
|
|
.El
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Xr fdt 4 ,
|
||
|
|
.Xr gpiobus 4 ,
|
||
|
|
.Xr sysctl 8
|
||
|
|
.Sh HISTORY
|
||
|
|
The
|
||
|
|
.Nm
|
||
|
|
driver first appeared in
|
||
|
|
.Fx 11.1 .
|