Padu,

I don't know for sure.  It looks like RC5 is not connected to any analog
functions within the PIC, 
so that may be the reason.  But I couldn't say for sure.  I guess if
it's working, that's what counts. 
Let me think on it for a while, and if I come up with anything, I'll let
you know.

I'm glad the pullup/pulldown resistors helped you out.


	
Regards,

	
Jim  

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Padu
Sent: Wednesday, May 14, 2008 5:20 PM
To: Microcontroller discussion list - Public.
Subject: Re: [PIC] Weird input behavior

>
> Padu,
>
> I don't know what kind of drive capability your input device(s) has 
> (have), but I would put a pullup or pulldown, whichever is 
> appropriate, on the PIC inputs to keep them in the opposite state 
> until driven by the input device.
> Also, make sure you have bypass caps ( both high and low capacitance 
> values like .1 uF in parallel with .001 uF) on all IC's from Vcc to 
> Gnd., especially the PIC.  Maybe even use an optoisolator at the PIC 
> input from the ring signal.
>
> Let us know what you do as a final fix.
>
> Regards,
>
>
> Jim
>


Jim,

Thanks for the suggestions, we thought that since the signal was coming
from an IC, we wouldn't need pull downs... it turns out, as you
suggested, we do. 
That seemed to do the trick. Thanks.

Now, regards the other part of my original post (PIC being in a state of
quasi-powered by an input line in high while Vdd disconnected), we
solved that changing the input pin from RC0 to RC5.... does that make
any sense? We did that because RC5 is the only one that doesn't share
functions (comparators for example) with other features. Do you think
those additional components might be leaking throughout the PIC?

Cheers

Padu 

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