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.\" Copyright (c) 2018 Emmanuel Vadot <manu@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 DEVELOPERS ``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 DEVELOPERS 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 June 17, 2019
.Dt PWM 8
.Os
.Sh NAME
.Nm pwm
.Nd configure PWM (Pulse Width Modulation) hardware
.Sh SYNOPSIS
.Nm
.Op Fl f Ar device
.Fl C
.Nm
.Op Fl f Ar device
.Op Fl D | Fl E
.Op Fl I
.Op Fl p Ar period
.Op Fl d Ar duty
.Sh DESCRIPTION
The
.Nm
utility can be used to configure pwm hardware.
.Nm
uses a
.Xr pwmc 4
device to communicate with the hardware.
Some PWM hardware supports multiple output channels within a single
controller block; each
.Xr pwmc 4
instance controls a single PWM channel.
.Pp
.Xr pwmc 4
devices are named
.Pa /dev/pwm/pwmcX.Y ,
where
.Va X
is the controller unit number and
.Va Y
is the channel number within that unit.
.Pp
The options are as follows:
.Bl -tag -width "-f device"
.It Fl f Ar device
Device to operate on.
If not specified,
.Pa /dev/pwm/pwmc0.0
is used.
If an unqualified name is provided,
.Pa /dev/pwm
is automatically prepended.
.It Fl C
Show the configuration of the PWM channel.
.It Fl D
Disable the PWM channel.
.It Fl d Ar duty
Configure the duty cycle (in nanoseconds or percentage) of the PWM channel.
Duty is the portion of the
.Ar period
during which the signal is asserted.
.It Fl E
Enable the PWM channel.
.It Fl p Ar period
Configure the period (in nanoseconds) of the PWM channel.
.It Fl I
Invert PWM signal polarity
.El
.Sh EXAMPLES
.Bl -bullet
.It
Show the configuration of the PWM channel:
.Bd -literal
pwm -f /dev/pwm/pwmc0.1 -C
.Ed
.It
Configure a 50000 ns period and a 25000 ns duty cycle
and enable the channel:
.Bd -literal
pwm -f pwmc1.1 -E -p 50000 -d 25000
.Ed
.It
Configure a 50% duty cycle on the device and channel which
were configured in
.Xr pwmc 4
to have the label
.Pa backlight :
.Bd -literal
pwm -f backlight -d 50%
.Ed
.El
.Sh SEE ALSO
.Xr pwm 9 ,
.Xr pwmbus 9
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 13.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
utility and this manual page were written by
.An Emmanuel Vadot Aq Mt manu@FreeBSD.org .
|
