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Steve-Mowbray-ENL's avatar
Steve-Mowbray-ENL
Icon for Occasional Contributor rankOccasional Contributor
1 month ago
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How to tell Quartus my Arria10 target system CLKUSR frequency is 100MHz?

Timing analyser reports CLKUSR at 125MHz but target system has 100MHz on this pin to accommodate AS in combination with transceiver calibration as per the manuals -- there doesn't seem to be any cons...
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  • AqidAyman_Altera's avatar
    AqidAyman_Altera
    5 days ago

    Hi Steve,

     

    Based on the response that I provided, you need not worry about the constraint on the pin for XCVRs.
    As the Quartus is assuming a 125MHz frequency, it is basically constraining it to the maximum allowed frequency for the XCVR applications. If the timing analyzer reports that 125MHz is achieved, then 100MHz will definitely work.

     

    Regards,
    Aqid

FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
1 month ago

Hi Steve,
I'm not quite sure where 125 MHz comes from may be it's a default. You can include CLKUSR as top level pin in your design and assign 100 MHz clock in .sdc. The specification should be used for all instances of automatic "~ALTERA_CLKUSR~" signal in your design.

Regards
Frank


Steve-Mowbray-ENL's avatar
Steve-Mowbray-ENL
Icon for Occasional Contributor rankOccasional Contributor
1 month ago

Thanks Frank -- seems straightforward -- couple of questions before I fire up quartus -- is there any consequences for being explicit on this pin -- also any chance this clock is useable in the user logic as this would be useful "free" clock source?

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