Using PWM from a Linux Shell

This mini guide explains how to enable and test a pwm signal using linux command line.

Instructions

To enable a PWM the steps are as follows (some details might differ depending on the product)

1. Maneuver to the /sys/class/pwm folder
   In this folder the pwm controllers should be visible as folders pwmchip0, pwmchip1, ...
2. Enter the chosen pwmchip folder.

    $ cd pwmchip0

3. Export the first pwm (the iMX pwm controllers have one pwm each) by

    $ echo 0 > export

This exposes the actual PWM in folder pwm0.

4. Enter the pwm folder

    $ cd pwm0

and configure the pwm:

    $ echo 10000 > period
    $ echo 6000 > duty_cycle
    $ echo 1 > enable

This should set the PWM frequency to 100 kHz and set the duty cycle to 60 kHz.