Date: Mon, 9 Dec 2019 03:02:55 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r355548 - head/share/man/man4 Message-ID: <201912090302.xB932t8P050166@repo.freebsd.org>
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Author: ian Date: Mon Dec 9 03:02:54 2019 New Revision: 355548 URL: https://svnweb.freebsd.org/changeset/base/355548 Log: Add a man page for the gpioths(4) driver. Added: head/share/man/man4/gpioths.4 (contents, props changed) Added: head/share/man/man4/gpioths.4 ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/share/man/man4/gpioths.4 Mon Dec 9 03:02:54 2019 (r355548) @@ -0,0 +1,152 @@ +.\"- +.\" 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 .
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