1.\" Copyright (c) 2018 Emmanuel Vadot <manu@freebsd.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 13.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 14.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 15.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 16.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 17.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 18.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 19.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 20.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 21.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 22.\" 23.\" $FreeBSD$ 24.\" 25.Dd June 17, 2019 26.Dt PWM 8 27.Os 28.Sh NAME 29.Nm pwm 30.Nd configure PWM (Pulse Width Modulation) hardware 31.Sh SYNOPSIS 32.Nm 33.Op Fl f Ar device 34.Fl C 35.Nm 36.Op Fl f Ar device 37.Op Fl D | Fl E 38.Op Fl I 39.Op Fl p Ar period 40.Op Fl d Ar duty 41.Sh DESCRIPTION 42The 43.Nm 44utility can be used to configure pwm hardware. 45.Nm 46uses a 47.Xr pwmc 4 48device to communicate with the hardware. 49Some PWM hardware supports multiple output channels within a single 50controller block; each 51.Xr pwmc 4 52instance controls a single PWM channel. 53.Pp 54.Xr pwmc 4 55devices are named 56.Pa /dev/pwm/pwmcX.Y , 57where 58.Va X 59is the controller unit number and 60.Va Y 61is the channel number within that unit. 62.Pp 63The options are as follows: 64.Bl -tag -width "-f device" 65.It Fl f Ar device 66Device to operate on. 67If not specified, 68.Pa /dev/pwm/pwmc0.0 69is used. 70If an unqualified name is provided, 71.Pa /dev/pwm 72is automatically prepended. 73.It Fl C 74Show the configuration of the PWM channel. 75.It Fl D 76Disable the PWM channel. 77.It Fl d Ar duty 78Configure the duty cycle (in nanoseconds or percentage) of the PWM channel. 79Duty is the portion of the 80.Ar period 81during which the signal is asserted. 82.It Fl E 83Enable the PWM channel. 84.It Fl p Ar period 85Configure the period (in nanoseconds) of the PWM channel. 86.It Fl I 87Invert PWM signal polarity 88.El 89.Sh EXAMPLES 90.Bl -bullet 91.It 92Show the configuration of the PWM channel: 93.Bd -literal 94pwm -f /dev/pwm/pwmc0.1 -C 95.Ed 96.It 97Configure a 50000 ns period and a 25000 ns duty cycle 98and enable the channel: 99.Bd -literal 100pwm -f pwmc1.1 -E -p 50000 -d 25000 101.Ed 102.It 103Configure a 50% duty cycle on the device and channel which 104were configured in 105.Xr pwmc 4 106to have the label 107.Pa backlight : 108.Bd -literal 109pwm -f backlight -d 50% 110.Ed 111.El 112.Sh SEE ALSO 113.Xr pwm 9 , 114.Xr pwmbus 9 115.Sh HISTORY 116The 117.Nm 118utility appeared in 119.Fx 13.0 . 120.Sh AUTHORS 121.An -nosplit 122The 123.Nm 124utility and this manual page were written by 125.An Emmanuel Vadot Aq Mt manu@FreeBSD.org . 126