Article ID: 000077095 Content Type: Troubleshooting Last Reviewed: 06/29/2014

Can timing violations for the pif_interface_sel signal be safely ignored for the Stratix V and Arria V GZ device transceiver Reconfiguration Controller when compiled in Quartus II software, version 12.1?

Environment

  • Stratix® V FPGAs
  • Stratix® V GS FPGA
  • Stratix® V GX FPGA
  • Stratix® V GT FPGA
  • Quartus® II Subscription Edition
  • BUILT IN - ARTICLE INTRO SECOND COMPONENT
    Description

    Hold time violations for the pif_interface_sel signal can be safely ignored for the Stratix® V GX and Arria V GZ device reconfiguration controller when compiled in Quartus® II Software version 12.1. However, setup violations must be resolved.

    Resolution

    Due to a bug in the Quartus II software version 12.1, an extraneous false path exception was introduced in the alt_xcvr_reconfig.sdc file. The false path exception is shown below.

    set_false_path -from {*|alt_xcvr_reconfig_basic:basic|sv_xcvr_reconfig_basic:s5|pif_interface_sel}

    This exception needs to be replaced with the SDC constraint below.

    if { [string equal "quartus_sta" $::TimeQuestInfo(nameofexecutable)] } {
         # Sets a False path for hold time violations on the pif_interface_sel
         set_false_path -from {*|alt_xcvr_reconfig_basic:basic|sv_xcvr_reconfig_basic:s5|pif_interface_sel} -hold
     }

    Quartus II Software versions before and after 12.1 do not contain the above exception, but the new constraint can be applied to remove all hold violations of the pif_interface_sel signal from being reported in TimeQuest.

    This problem will be fixed in a future version of the Quartus II software.

    The following recommendations can also be used to help meet setup pif_interface_sel signal timing.

    • For slower speed grade devices consider using a 100MHz instead of a 125MHz clock to drive the mgmt_clk_clk signal on the Reconfiguration Controller.
    • Use multiple Reconfiguration Controllers in the design. This minimizes the fanout of the pif_interface_sel signal which helps in routing congestion for the design. For example, instead of using a single Reconfiguration Controller to drive all channels in a device you can try using one Reconfiguration Controller per transceiver six-pack.

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