---
name: "pwm"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/pwm/8"
---

# pwm(8)

configure PWM (Pulse Width Modulation) hardware

## 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)](/pwmc/4.md) device to communicate with the hardware. Some PWM hardware supports multiple output channels within a single controller block; each [pwmc(4)](/pwmc/4.md) instance controls a single PWM channel.

[pwmc(4)](/pwmc/4.md) 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)](/pwmc/4.md) to have the label *backlight*:

  ```
  pwm -f backlight -d 50%
  ```

## SEE ALSO

[pwm(9)](/pwm/9.md), [pwmbus(9)](/pwmbus/9.md)

## 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*⟩.