Re: Driving servos from a PC

CWatters wrote:
"Pete Verdon" <news@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote

I've not used servos before, but a little research suggests that
the required position is commanded by altering the pulse width of a ~5v
50Hz square-wave signal a little either side of 2ms.

Not a square wave. They need a pulse between 1 to 2mS long (depending on the
position) repeated about 50 times a second.

That's effectively what I wrote, isn't it? I suppose it's not quite a square wave because it's cut off at zero rather than going below, but presumably that just calls for a suitable diode.

I believe most people use a PIC micro to interface servos to a PC - possibly
because a PC running Windows doesn't have the real time capability to do it?

True; I hadn't considered the "real time" aspect of the problem, which would presumably frustrate any attempts to drive them directly from a serial port as well. But I don't think I have a) the knowledge and b) the budget to start programming embedded chips.

Pete
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