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USB superspeed peripherals Forum Discussions

UM
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The SuperSpeed Explorer Kit schematic.pdf on Page 2 J1 Pin 9 (STDB_SSRX+) connects to net SS_RX_M. Is this wrong? Usually, Positive connects to Positive and negative connects to negative (as is the case in SS_TX_? pair). I am designing a PCB at this time. Can someone get back to me and tell me whether there is an error in the document.

Udayan Mallik

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Ajeethkumar
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250 sign-ins 50 solutions authored 10 likes received

Hi,

SSRX+ and SSRX-, SSTX+ and SSTX- could be swapped to make it easier when you design PCB.

You can swap the SSTX and SSRX pairs but not the USB2 (D+/D-) pair. This is because, during SuperSpeed enumeration, certain training sequences (called TSEQs) are sent and the D10.2 symbol in this is used to detect if lane polarity inversion is done (refer to section 6.4.2 of the USB 3.0 spec). However, such lane inversion detection is not done in USB 2.0 enumeration.

Thanks,
Ajeeth

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Ajeethkumar
Moderator
Moderator
Moderator
250 sign-ins 50 solutions authored 10 likes received

Hi,

SSRX+ and SSRX-, SSTX+ and SSTX- could be swapped to make it easier when you design PCB.

You can swap the SSTX and SSRX pairs but not the USB2 (D+/D-) pair. This is because, during SuperSpeed enumeration, certain training sequences (called TSEQs) are sent and the D10.2 symbol in this is used to detect if lane polarity inversion is done (refer to section 6.4.2 of the USB 3.0 spec). However, such lane inversion detection is not done in USB 2.0 enumeration.

Thanks,
Ajeeth