PWM(8)                  FreeBSD System Manager's Manual                 PWM(8)

NAME
     pwm - configure PWM (Pulse Width Modulation) hardware

SYNOPSIS
     pwm [-f device] -C
     pwm [-f device] [-D | -E] [-I] [-p period] [-d duty]

DESCRIPTION
     The pwm utility can be used to configure pwm hardware.  pwm uses a
     pwmc(4) device to communicate with the hardware.  Some PWM hardware
     supports multiple output channels within a single controller block; each
     pwmc(4) instance controls a single PWM channel.

     pwmc(4) devices are named /dev/pwm/pwmcX.Y, where X is the controller
     unit number and Y is the channel number within that unit.

     The options are as follows:

     -f device  Device to operate on.  If not specified, /dev/pwm/pwmc0.0 is
                used.  If an unqualified name is provided, /dev/pwm is
                automatically prepended.

     -C         Show the configuration of the PWM channel.

     -D         Disable the PWM channel.

     -d duty    Configure the duty cycle (in nanoseconds or percentage) of the
                PWM channel.  Duty is the portion of the period during which
                the signal is asserted.

     -E         Enable the PWM channel.

     -p period  Configure the period (in nanoseconds) of the PWM channel.

     -I         Invert PWM signal polarity

EXAMPLES
     •   Show the configuration of the PWM channel:

         pwm -f /dev/pwm/pwmc0.1 -C

     •   Configure a 50000 ns period and a 25000 ns duty cycle and enable the
         channel:

         pwm -f pwmc1.1 -E -p 50000 -d 25000

     •   Configure a 50% duty cycle on the device and channel which were
         configured in pwmc(4) to have the label backlight:

         pwm -f backlight -d 50%

SEE ALSO
     pwm(9), pwmbus(9)

HISTORY
     The pwm utility appeared in FreeBSD 13.0.

AUTHORS
     The pwm utility and this manual page were written by Emmanuel Vadot
     <manu@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6          June 17, 2019         FreeBSD 13.1-RELEASE-p6