Me again. I see where you wanted to use the L12 series actuator.
Here's a quote from the datasheet:
A square wave by definition is a 50% duty cycle wave, so how can you encode anything?
They should have said rectangular.
You will also need some sort of level translator to get from 3.3 V of the BBB to 5V. Can I assume that the BBB is Beagle Board Black?
Under the 0-5 V section:
and I quote again:
So, what does that mean?
Does "disconnecting" mean the position will "stay" or does disconnecting mean it would go to zero if using this mode? Same question is true for PWM.
The integrated controller lacks stall protection:
I think they did a pretty good job, but I'll analyze details like no tomorrow.
In your situation, actuator movement toward retract 0% on power down is not an issue if it happens at all. I would have made the 0-5 V linear mode, a 1 to 5V signal, so that 0 V is OFF.
Electrical limits don't exist in the internal version.
Other general comments about their controllers (embedded or otherwise) is:
a) A NOT ENABLE pin would be useful. 99% of the time it could stay at ground.
b) A STALL or NOT STALL output would also be useful.
c) DIRECTION AWAY FROM STALL would also be useful.
d) USB should also implement a, b and c.
e) A 5 V Ref signal so level translation would be easier.
Probably around 100 g-force or less is a ball park number for push button activation. I was unable to find any PC power switch specs.
Here is a force conversion website
http://www.unitconversion.org/unit_converter/force.html and 100 g-f is about 1 Newton so you could really smash the button.