Using PWMs with the sysfs interface
The PWM core sysfs
root path is /sys/class/pwm/
. It is the user space way to manage PWM devices. Each PWM controller/chip added to the system creates a pwmchipN
directory entry under the sysfs
root path, where N
is the base of the PWM chip. The directory contains the following files:
npwm
: This is a read-only file, printing the number of PWM channels that the chip supportsExport
: This is a write-only file, allowing you to export a PWM channel for use withsysfs
(this functionality is equivalent to the GPIO sysfs interface)Unexport
: This unexports a PWM channel fromsysfs
(write-only)
The PWM channels are numbered using an index from 0 to pwm<n-1>
. These numbers are local to the chip. Each PWM channel exportation creates a pwmX
directory in the pwmchipN
, which is the same directory as the one containing the export
file used. X is the number of the channel that was exported. Each channel directory contains the following files:
Period
: This is a readable...