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Hello,
I'm trying to drive the input clock of the a megawizzard-created Rx SerDes using the output clock of another PLL, and I get the following Fitter Error: "Input clock pin of fast PLL <name>, which drives at least one non-DPA-mode SERDES, must be driven by a compensated input." Here are my PLL and SerDes instantiations: wire Clk125MHz; DataClkPll DataClkPll_inst( .areset ( PllResetStrobe ), .inclk0 ( DataClkIn ), .c0 ( Clk125MHz ), .locked ( DataClkPllLocked ) ); wire RxSerDesClkOut; wire RxSerDesPllLocked; wire [111:0] RxDataWide; RxSerDes RxSerDes_inst( .pll_areset ( PllResetStrobe ), .rx_in ( {DataPort1,DataPort0} ), .rx_inclock ( Clk125MHz ), .rx_locked ( RxSerDesPllLocked ), .rx_out ( RxDataWide ), .rx_outclock ( RxSerDesClkOut ) ); Basically, I'm using the separate PLL to fine tune data/clock timing in my system (I intend to add in dynamic phase programming later). It seems like Quartus is complaining that I'm not using a dedicated clock input pin to directly drive the Rx SerDes. But I've done this sort of thing before using Quartus II v4 with a Stratix I part. I found a patch at that time to get around this problem, which included placing a "quartus.ini" file in the directory, with the compiler switch: FYGR_ALLOW_NONIO_CLKIN_TO_RXPLL = on Now I'm using Quartus II v8.1 with Stratix III, and the quartus.ini file doesn't fix the compiler error message any more. Is there another solution for Quartus II v8.1/Stratix III for this situation? Thanks, RonLink Copied
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Is Clk125MHz a compensated clock output? See Page 0 of PLL wizard.
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Yes, PLL is configured for "Normal Mode", feedback inside PLL.

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