Javascript Disabled Detected

You currently have javascript disabled. Several functions may not work. Please re-enable javascript to access full functionality.

The Netduino forums have been replaced by new forums at community.wildernesslabs.co. This site has been preserved for archival purposes only and the ability to make new accounts or posts has been turned off.

For slow digital circuits, do I need ground between each wire?

Started by Verdris, May 20 2014 06:06 PM

signal integrity logic digital io

Best Answer Paul Newton, 21 May 2014 - 06:08 AM

You would not need to do it for the logic speed, but consider whether those grounds are carrying power between the boards.

If they are, you may still need a few grounds (rather than just one) to ensure they provide a low resistance path between the boards. The fewer grounds the higher the resistance, the hotter they could get, and there would be a voltage differential between the boards which could confuse the logic gates.

Paul

Go to the full post

Please log in to reply

2 replies to this topic

#1 Verdris

Advanced Member

Members
128 posts

LocationReno, NV

Posted 20 May 2014 - 06:06 PM

I'm designing a pass-through circuit for a project at work, and I'm running in to space issues. I have a block of thirteen digital signals and I'm wondering if I need a ground wire between each. The ribbon from my circuit to the next board is maybe 6 inches, and the signals are 0-5V logic that change states maybe once per minute. Seriously slow.

Do I really need to ground every other conductor in this case?

Back to top

#2 Paul Newton

Advanced Member

Members
724 posts

LocationBerkshire, UK

Posted 21 May 2014 - 06:08 AM Best Answer

You would not need to do it for the logic speed, but consider whether those grounds are carrying power between the boards.

If they are, you may still need a few grounds (rather than just one) to ensure they provide a low resistance path between the boards. The fewer grounds the higher the resistance, the hotter they could get, and there would be a voltage differential between the boards which could confuse the logic gates.

Paul

Mario Vernari likes this

Back to top

#3 Verdris

Advanced Member

Members
128 posts

LocationReno, NV

Posted 21 May 2014 - 03:13 PM

You would not need to do it for the logic speed, but consider whether those grounds are carrying power between the boards.

If they are, you may still need a few grounds (rather than just one) to ensure they provide a low resistance path between the boards. The fewer grounds the higher the resistance, the hotter they could get, and there would be a voltage differential between the boards which could confuse the logic gates.

Paul

Thanks for the reply. The grounds aren't carrying power, they're strictly logic reference. I've got many other power grounds.