ML300 Gigabit Ethernet Issues...

I'm trying to get a gigabit ethernet design to work with Xilinx's Gige MAC (gemac 5.0/pcs combination) through the rocket IOs/optical transcievers on the ML300 board.

I have a simple little design which drives two of the ethernets and prints out received info for one of the ethernets to the screen.

With a fibre between the two active ethernets, all is fine: The MGTs and the PCSs sync up within a short time (

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Nicholas Weaver
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The resolution: The ML300 manual lies, and the errata sheet doesn't seem to exist. The crystal is 62.5 MHz on later ML300 boards, not 125 MHz.

Paul Hartke told me that there was a change in the board type to have the 62.5 MHz crystal (to meet the RocketIO recommendations discussed in the previous post.).

Looking on the crystal itself (component X101) revealed that I had a newer board with the slower crystal.

Finding that out, and then changing the clocking of the design so

62.5 MHz (really) -> Refclk -> DLL -> userclk \x2 -> userclk2

And now all is happy, I can send between the board and PC.

Nicholas C. Weaver.  to reply email to "nweaver" at the domain
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Nicholas Weaver

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