AVR-Chat

Thanks.  I'm aware of ground loop issues.  My boards always have jumpers to
allow disconnecting ground lines when otherwise there would be multiple
ground connections.  Similarly for the shield, so that it can be grounded at
only one end.  The application is for a boat, which at times has strong
radio transmissions all through it.   My approach is that shielding cannot
hurt (properly implemented).

 

Steve

 

From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of David VanHorn
Sent: Tuesday, March 31, 2009 9:46 AM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] i2c and twisted pair

 

> I have other reasons for wanting to use Cat5:  shielding, quick & easy
> connect/disconnect, relatively cheap and easy to make up cables, and for
my
> situation cables that are flexible and easy to run convoluted paths is
very
> important.   I also have other uses for the remaining conductors in "RJ45"
> cable, so that, plus shielding, is the reason I'm not just using "RJ11" or
> "RJ12" modular cable (I've never been able to find such cable that is
> shielded).

Shielding is tricky, and may not buy you much.
If you have more than one ground connection between the systems, then
you risk "ground loop" noise.
Basically, any current flowing in the grounds gets expressed as a
voltage, which hoses up the logic thresholds.

Belden has all sorts of shielded cables, solid, stranded, 2 pair, no
problem.




 



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