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
o Show the configuration of the PWM channel:
pwm -f /dev/pwm/pwmc0.1 -C
o Configure a 50000 ns period and a 25000 ns duty cycle and enable the
channel:
pwm -f pwmc1.1 -E -p 50000 -d 25000
o 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
<
[email protected]>.
FreeBSD 14.1-RELEASE-p8 June 17, 2019 FreeBSD 14.1-RELEASE-p8