Robert,

You'll probably find the servo is causing enough power supply disruption
to the PIC to cause it to fail.  If you don't have plenty of decoupling
caps on the PIC and the servo, you'll need them.  A better approach is to
keep the power supplies separate if you can.  If you're running on battery
power this is especially true, and if you're using a DC power supply that
can't keep up with the servo's current spikes you're bound to have
trouble.

A servo can draw a surprising amount of current.

Dale


On Sat, 10 Feb 2001, Robert Shady wrote:

> Okay, I've gotten the code done, but now
> I am seeing something very interesting.
>
> I'm running my code against a scope, and
> everything looks beautiful... Then..
>
> If I power the circuit & the servo from
> the same +5V power supply, things work
> okay for a minute but then the 16F84
> "locks" (sorry for the technical term,
> but I'm really not sure what happens,
> it just quits running my code).
>
> If I power the servo seperately from
> the circuit, the servo continuously
> rotates (still watching the scope, the
> signal is perfect).
>
> If I power the servo seperately, but
> connect the grounds of the two power
> supplies together, things work okay
> for a minute and then the 16F84 "locks".
>
> I've tried the servo signal wire directly
> into PORTB/0, through a resistor to PORTB/0,
> through a diode to PORTB/0, through a
> resistor and a diode to PORTB/0, all with
> the same results...
>
> Does anybody have any ideas??  This one is
> really stumping me.
>
> I've checked power power supplies, voltages
> are correct (+4.9V) and the signal looks
> clean.  I have tied MCLR & VDD to +5V, and
> VSS to GND.
>
> -- Rob
>
>
>
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