I read this thread after the solution had already been found, but I think
I'll add my tuppence because it might help someone else.

I was fiddling with a minimal circuit with an 18F452, an LCD on port C for
data, and port A for the control lines. A 33K pullup for reset. Most
everything else was floating.

I was getting random resets, junk characters on the LCD, all sorts.
Eventually solved it by tieing the (floating) programming pins high. I'd not
seen it before. I know you're supposed to "do something" with all the
"unused" io pins, but hey, I'm a hobbyist and I've got away without doing it
before.


jon

> -----Original Message-----
> From: Alan B. Pearce [mailto:A.B.Pearce@RL.AC.UK]
> Sent: 15 April 2004 09:29
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC:] Odd behavior... Fixed!
>
>
> >Thanks to everybody who helped me get this working again.
> >I must admit that I'm disappointed the problem was so simple!
> >
> >The problem was (primarily) the lack of a 100nf bypass
> capacitor, and
> >(secondarily, perhaps) a floating /MCLR.
> >
> >You were a great help to me tonight, I hope maybe some day
> >I can return the favor!
>
> It is not clear from your program if this is disabled
> automagically by the compiler, but my first reaction on
> reading your mail was that this could be a classic symptom of
> not disabling the watchdog timer.
>
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