It is given in the USB 3.0 specification that USB super-speed lines support "polarity inversion". That is SSRX_P can be swapped with SSRX_M (or SSTX_M with SSTX_P).

Can we also swap SSTX lines with SSRX lines?

That is SSTX lines can be used in place of SSRX lines and vice versa.

Please help me to get a clear picture.

  • \$\begingroup\$ I think this sort of thing is supported in the shiny new USB Type-C connector - that's the one where there's no right way or wrong way to plug it in and both ends of the cable are identical. \$\endgroup\$ – brhans Feb 12 '15 at 15:54
  • \$\begingroup\$ @brhans No, the Type-C connector's SS pins are redundant and rotationally symmetrical, so for instance, SSTX+ is in the same position regardless. images.anandtech.com/doci/11667/usbtypec-pins_575px.png \$\endgroup\$ – endolith Jul 2 '18 at 21:32

No. The data only goes one way, from the SSTX pins to the SSRX pins. The SSTX pair is connected to pins 8 and 9 of the male A connector, and on the B connector side, these same pins are the SSRX pair. So the data goes from the male connector to the female connector over those pins. Likewise, the SSTX pair is connected to pins 5 and 6 of the female B connector, and on the A connector side, these same pins are the SSRX pair. So the data goes from the female connector back to the male connector over those pins.

If you buy a 3.0 cable with two male connectors, the lines are swapped inside the cable: pins 5 and 6 at one end connect to pins 8 and 9 of the other and vice versa, so you don't end up having two transmitters and two receivers facing each other.


No, not in general. I suppose there could be transceivers which support it, but I doubt it's widespread.

A part like this http://www.ti.com/lit/ds/symlink/tusb1310.pdf clearly identifies the two pairs as input and output.


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