pwm8

Usage

Overview

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%