On 8/16/06, Nikhil Kakkar <nikekakkar@gmail.com> wrote:
>
> 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.



That's very scary,  and indicates some serious layout/connectivity problems.


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.


There shouldn't be any way for the scope probe or it's ground, to change
your internal R/C clock frequency.

One thing to check though, what's the precision of that oscillator?  You're
only allowed about 5% off on serial baud rates.
Simply touching the chip could heat it enough to start/stop working.
Normally resonators or crystals are used for systems that need serial comms.
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