Problem with hold timing violation

Hi Rysc,

You are right, rx_clk is a clock. It feeds an ethernet_mac. The code I posted comes from the MII to RMII converter.

Please note that I never had problems with this design. It works perfectly, but I'm concerned about this timing warning.

Initially I thought the problem was within the mac, but I tried to apply another rx clock to the mac (from a pll), but the timing violation was always exactly the same.

In that case rx_clk wasn't used for anything at all outside the RMII converter: so I restricted the problem to those few lines of code you see above.

I don't have a generated clock statement for rx_clk, but this one:

create_clock -name {MAC_rx_clk} -period 40.000 -waveform { 0.000 20.000 } [get_registers {RMII*rx_clk}]

Maybe this is the problem? Should I use create_generated_clock?

I tried but I get a warning: Ignored assignment

Cris