Cross between SSRXP and SSRXM in CY4609 design

[Sag]

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?

thanks, 

[Ajeethkumar · Accepted solution]

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

[Sag]

understood.

thanks!