Picozed Ethernet pair swapping possible?

Question

Dear All, I am making a carrier board for the Picozed, and I was wondering if it is possible to swap pairs for the ethernet lines (not polarity swapping, but pairs e.g. 3<=>4) Thank you all, Peter

narrucmot · Answer

Hi Peter,

By default for the Vivado hw platforms that Avnet provides for the PicoZed the signals for the Ethernet interface are connected to the Processing System (PS) inside the Zynq device and their locations are thus fixed on the MIO pins on the device. It isn't possible to swap them.

However, since you are creating a custom carrier, you may be able to modify or create your own PicoZed design in Vivado to change the Ethernet interface from MIO to EMIO. Putting the interface on EMIO will route the Ethernet MAC signals to PL I/Os, thus giving you greater control over how they are arranged on the device I/Os and across the carrier PCB routed to the Ethernet PHY. Keep in mind, though, that the Ethernet interface is RGMII when on MIO and GMII when on EMIO. This means the Ethernet interface uses a lot more pins when on EMIO. The Xilinx Zynq TRM (UG585, Ch. 16) has more information.

https://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000-TRM.pdf

--Tom