to use the backlight via sysfs you will have to export it first.
Go to the directory of the PWM you want to use
and export it
echo 0 > export
Please note that this will only work if this PWM is not claimed by another device like backlight.
Now you should see a new subdirectory pwm0
There you shloud be able to set the period in nanosecond,
echo 5000000 > pwm0/period
the duty cycle in nanoseconds,
echo 2500000 > pwm0/duty_cycle
the polarity (this is only possible if the device is disabled),
echo "inversed" > pwm0/polarity
echo "normal" > pwm0/polarity
and enable/disable the device.
echo 1 > pwm0/enable
echo 0 > pwm0/enable
If you need an example on how to control pwm via a C-programm please see the pwm-example in your build directory of your release, e.g:
Your F&S Support Team