I believe it's pulses as it moves. That's how I read the (admittedly bad) data sheet, and jives with my observation. What I did was plopped this sketch into an Arduino:
int pin = 13;
volatile int state = LOW;
void setup()
{
Serial.begin(9600);
attachInterrupt(1, talk, CHANGE);
}
void loop()
{
digitalWrite(pin, state);
}
void talk()
{
state = !state;
}
Then I ran the actuator using manual control. I saw pulses on LED13 as it moved. They were fairly fast, but did seem consistent. I do realize that the pulses won't be perfectly accurate, but for this application that's fine. And that's nice that there are cheaper options, but I only need to build this one item and I already have a couple of these actuators from another project.
My next plan was to write a sketch that uses a couple buttons to let me move the actuator using the Arduino and count pulses between movements and output the result each time I stop moving. Should be relatively straightforward to do that, I just got caught up in a different project using XBee (where I SWEAR I somehow got two bad XBee modules or I killed them both in some strange way because two new modules are working like they should).
--Donnie