Is USB polarity important?

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

Reply to
DaveC
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Not sure but I think I read somewhere that polarity somehow IDs the device connected to be one or the other status. Not a client/whatever, but somethi ng like that. One will be the master and the other the slave or something l ike that. Not that but something like that.

But don't take that to the bank.

Really, why don't you just experiment and find out ? Switch the wires and s ee what happens. Just don't do it with the power line.

Reply to
jurb6006

AND, if one or both are grounded it also tells it something.And/or like if they are shorted together it is a cell charger or something and there is no data so it does not look for data. something like that.

Actually, there is a chance that wiki has something on it. Try it.

Reply to
jurb6006

Yes it's imperative you get it right

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Reply to
TTman

Of *course* it is! Do you think you can replace every '0' with a '1' and still get the same *meaning*?

Yes.

Reply to
Don Y

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.

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Reply to
Jasen Betts

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?

Reply to
DecadentLinuxUserNumeroUno

Yes. A - B is different from B - A.

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Reply to
Tim Wescott

On 8 Aug 2015, Tim Wescott wrote

Thanks Tim. That explains it.

Reply to
DaveC

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

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Reply to
Tim Williams

Ummmm, you might want to check on that.

Reply to
jurb6006

On Sun, 9 Aug 2015 01:49:30 -0500, "Tim Williams" Gave us:

Make dew. Hahahahaha!

Reply to
DecadentLinuxUserNumeroUno

On Sun, 9 Aug 2015 02:07:38 -0700 (PDT), snipped-for-privacy@gmail.com Gave us:

You might want to learn how to quote what you are replying to dumbfuck.

Reply to
DecadentLinuxUserNumeroUno

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