[TriEmbed] RPi & Port Expander Grounds

[Jon Wolfe]

Also, be careful of ground loop, tie the ground lines together as close to the power sources as possible. I think none of the pi's I/o are 5v tolerant,  so make sure they are either open drain or level shifted.

<div>-------- Original message --------</div><div>From: Glen Smith <mrglenasmith at gmail.com> </div><div>Date:09/17/2014  12:05 PM  (GMT-05:00) </div><div>To: Grawburg <grawburg at myglnc.com> </div><div>Cc: Triangle Embedded Devices <TriEmbed at triembed.org> </div><div>Subject: Re: [TriEmbed] RPi & Port Expander Grounds </div><div>
</div>No,

The grounds should always be tied together. Otherwise you can run into very strange results.

Glen

On Wed, Sep 17, 2014 at 12:03 PM, Grawburg <grawburg at myglnc.com> wrote:
Am I correct (based upon previous posts) that when I use a port expander with my Pi and use an external power source for the devices connected to the expander, I should always use the ground on the Pi. Therefore, the ground of an external 5 VDC is not utilized. 

Thanks,
Brian




_______________________________________________
Triangle, NC Embedded Computing mailing list
TriEmbed at triembed.org
http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
TriEmbed web site: http://TriEmbed.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.triembed.org/pipermail/triembed_triembed.org/attachments/20140917/1fe8a82c/attachment.htm>