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opulo-inc / feeder

Source for LumenPnP Feeders
GNU General Public License v3.0
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Route RS485 as differential pair #5

Open G-Pereira opened 1 year ago

G-Pereira commented 1 year ago

Improve RS485 layout. Here is a Texas Instruments app note as reference.

sphawes commented 1 year ago

Hey @G-Pereira! Are you referring to trace length matching? RS485 is a differential signal, but it doesn't seem to require being routed with trace length matching. We're only driving the bus at 57600 baud at a distance of ~2m, so we're well under seeing the transmission line effect. It couldn't hurt to do, but I don't think it's necessary.

G-Pereira commented 1 year ago

Not specifically, I mean routing them side by side with KiCAD's bult-in feature for routing differential pairs. It's one of those things that takes one more minute to do it right and a pain to change down the road when you start having issues. This is a good article if you want to learn more: https://resources.altium.com/p/what-are-differential-pairs-and-differential-signals

sphawes commented 1 year ago

Yup, I understand the routing feature that you're referencing, it just isn't necessary for the speeds that we're running RS-485 at. That being said, I can't see any harm in routing them like that!