USB uses differential signaling, D- and D+ signal lines. Since it?s differential, is absolute polarity important? If, for example, I mix up the two conductors on a USB device I?m rewiring, is this critical?
Just curious?
Thanks, Dave
Is USB polarity important?
Aug 08, 2015
8 Replies
Yes it's imperative you get it right
Of *course* it is! Do you think you can replace every '0' with a '1' and still get the same *meaning*?
Yes.
because it's differential doiong that would make a "1" look like a "0" and a "0" look like a "1", that seems unlikely to end well unless USB has been designed to detect and compensate for this fault.
On Sat, 08 Aug 2015 08:53:14 +0100, TTman Gave us:
Yes. ALL FOUR conductors, not just the signal pair.
Two are power. Does it make sense to you that reversing those would be OK?
Or mixing any from each set?
Yes. A - B is different from B - A.
On 8 Aug 2015, Tim Wescott wrote
Thanks Tim. That explains it.
Well why the hell not? Wifi manages to sort them out... :^)
(Radio encodings not having the advantage of DC and phase correct installations, of course, so they have to make do when they're doing PSK modulations.)
Tim
On Sun, 9 Aug 2015 01:49:30 -0500, "Tim Williams" Gave us:
Make dew. Hahahahaha!
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