Cross between SSRXP and SSRXM in CY4609 design

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Sag
Level 3
Level 3
First like received 25 replies posted 25 sign-ins

Hey,

I saw that in the CY4609 schematics files there is a cross in all DS RX lines between the HX3 and the DS connector, USB_DS_RXM is connected to pin 5 of the DS connector which is StdA_SSRX+, what is the reason for that?

 

Sag_0-1644821674095.png

 

thanks, 

 

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Ajeethkumar_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 100 solutions authored

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_P
Moderator
Moderator
Moderator
50 likes received 500 replies posted 100 solutions authored

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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understood.

thanks!

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