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Explain the relationship between PWM hardware channels being controlled and

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pwmc(4) device filenames.  Also, use uppercase PWM when the term is being
used as an acronym, and expand the acronym where it's first used.
This commit is contained in:
Ian Lepore 2019-06-18 00:17:10 +00:00
parent 780c3de886
commit 123570fb92
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=349165
1 changed files with 26 additions and 9 deletions
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35
usr.sbin/pwm/pwm.8
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@ -27,7 +27,7 @@
.Os
.Sh NAME
.Nm pwm
.Nd configure pwm controller
.Nd configure PWM (Pulse Width Modulation) hardware
.Sh SYNOPSIS
.Nm
.Op Fl f Ar device
@ -47,9 +47,26 @@
.Sh DESCRIPTION
The
.Nm
utility can be used to configure pwm controllers.
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
The options are as follow:
.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.
@ -60,15 +77,15 @@ If an unqualified name is provided,
.Pa /dev/pwm
is automatically prepended.
.It Fl E
Enable the pwm channel.
Enable the PWM channel.
.It Fl D
Disable the pwm channel.
Disable the PWM channel.
.It Fl C
Show the configuration of the pwm channel.
Show the configuration of the PWM channel.
.It Fl p Ar period
Configure the period (in nanoseconds) of the pwm channel
Configure the period (in nanoseconds) of the PWM channel
.It Fl d Ar duty
Configure the duty (in nanoseconds or percentage) of the pwm channel.
Configure the duty (in nanoseconds or percentage) of the PWM channel.
Duty is the portion of the
.Ar period
during which the signal is asserted.
@ -76,7 +93,7 @@ during which the signal is asserted.
.Sh EXAMPLES
.Bl -bullet
.It
Show the configuration of the pwm channel:
Show the configuration of the PWM channel:
.Bd -literal
pwm -f /dev/pwm/pwmc0.1 -C
.Ed