123 lines
3.2 KiB
Groff
123 lines
3.2 KiB
Groff
.\" Copyright (c) 2018 Emmanuel Vadot <manu@freebsd.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 17, 2019
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.Dt PWM 8
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.Os
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.Sh NAME
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.Nm pwm
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.Nd configure PWM (Pulse Width Modulation) hardware
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.Sh SYNOPSIS
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.Nm
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.Op Fl f Ar device
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.Fl C
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.Nm
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.Op Fl f Ar device
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.Op Fl D | Fl E
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.Op Fl p Ar period
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.Op Fl d Ar duty
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.Sh DESCRIPTION
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The
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.Nm
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utility can be used to configure pwm hardware.
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.Nm
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uses a
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.Xr pwmc 4
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device to communicate with the hardware.
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Some PWM hardware supports multiple output channels within a single
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controller block; each
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.Xr pwmc 4
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instance controls a single PWM channel.
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.Pp
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.Xr pwmc 4
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devices are named
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.Pa /dev/pwm/pwmcX.Y ,
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where
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.Va X
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is the controller unit number and
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.Va Y
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is the channel number within that unit.
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.Pp
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The options are as follows:
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.Bl -tag -width "-f device"
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.It Fl f Ar device
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Device to operate on.
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If not specified,
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.Pa /dev/pwm/pwmc0.0
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is used.
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If an unqualified name is provided,
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.Pa /dev/pwm
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is automatically prepended.
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.It Fl C
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Show the configuration of the PWM channel.
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.It Fl D
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Disable the PWM channel.
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.It Fl d Ar duty
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Configure the duty cycle (in nanoseconds or percentage) of the PWM channel.
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Duty is the portion of the
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.Ar period
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during which the signal is asserted.
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.It Fl E
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Enable the PWM channel.
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.It Fl p Ar period
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Configure the period (in nanoseconds) of the PWM channel.
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.El
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.Sh EXAMPLES
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.Bl -bullet
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.It
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Show the configuration of the PWM channel:
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.Bd -literal
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pwm -f /dev/pwm/pwmc0.1 -C
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.Ed
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.It
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Configure a 50000 ns period and a 25000 ns duty cycle
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and enable the channel:
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.Bd -literal
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pwm -f pwmc1.1 -E -p 50000 -d 25000
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.Ed
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.It
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Configure a 50% duty cycle on the device and channel which
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were configured in
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.Xr pwmc 4
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to have the label
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.Pa backlight :
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.Bd -literal
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pwm -f backlight -d 50%
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.Ed
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.El
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.Sh SEE ALSO
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.Xr pwm 9 ,
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.Xr pwmbus 9
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Fx 13.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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utility and this manual page were written by
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.An Emmanuel Vadot Aq Mt manu@FreeBSD.org .
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