I dont have the circuit in front of me now, but I have seen the
oscilloscope affect the performance, when just the ground of the cable
was connected to the same ground as the circuit. I have also seen it
show me different outputs when connected to the RX pin(I am using
serial communication) and at the TX pin.
I am using the internal oscillator, so my guess was that the
oscillator some how loads the clock and shifts the period etc. That
could some how cause the outputs to wary. But that was just a shot in
the dark.


On 8/16/06, David VanHorn <dvanhorn@microbrix.com> wrote:
> On 8/16/06, Nikhil Kakkar <nikekakkar@gmail.com> wrote:
> >
> > I am using a PIC18F1320 with the MPLAB compiler. I wrote the code, and
> > while testing it I get a set of outputs with the oscilloscope, but
> > when i disconnect the oscilloscope, the outputs are different.
> > For example, I read in a byte over the serial port and compare it with
> > a variable. If it matches then I light an LED. With the oscilloscope
> > connected the LED never lights, without it it does.
> > I am using the internal oscillator of the PIC. Could it be that the
> > oscillation times change because of the oscilloscope?
>
>
> You've not said yet where you are connecting the scope.
> That's a very interesting bit of information
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