I put a resistor between the PIC and the servo signal
wire and this does not seem to help. I get the same
slope on the falling edge whether to servo is
connected or not. I guess I will order a couple more
pics and see if that helps.


--- David VanHorn <dvanhorn@CEDAR.NET> wrote:
> At 10:12 AM 6/15/2003 -0700, Joel Middleton wrote:
>
> >I found this schematic on the web and this is my
> exact
> >circuit except the servo signal is connected to pin
> 3
> >on portb. Also I have all the unused pins connected
> to
> >ground. Anyone see anything wrong with the circuit?
>
> A couple potential problems. (pun)
>
> Running a servo motor from your logic supply is a
> bad idea.
> The motor has relatively large stall current
> demands, and produces a lot of noise. These both
> have the potential to reset or crash the micro.
>
> Try providing a separate supply for the servo motor,
> like four AA cells.
> Keep the ground tied between the supplies though as
> that provides the reference for the pulse.
>
> Also, I've found that I need a series resistor of
> 100 ohms to 1k between the micro and the servo's
> pulse input. I've never investigated why, but I've
> had a few chips blown (Atmel AVRs) when I didn't
> have that series resistor.
>
> It's never a real good idea to take uP I/O pins
> directly into the real world.
>
> --
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