Article ID: 000084149 Content Type: Troubleshooting Last Reviewed: 11/09/2011

Some CPRI MegaCore Function Variations Have Invalid cpri_clkout Frequency

Environment

  • Quartus® II Subscription Edition
  • BUILT IN - ARTICLE INTRO SECOND COMPONENT

    Critical Issue

    Description

    CPRI MegaCore function variations with data rate 6.144 Gbps and with auto-rate negotiation disabled that target an Arria II GX device are generated with an invalid cpri_clkout frequency.

    This issue affects all CPRI MegaCore function variations with data rate 6.144 Gbps and with auto-rate negotiation disabled that target an Arria II GX device.

    As a result of the invalid cpri_clkout frequency, the physical link cannot achieve link synchronization.

    Resolution

    To avoid this issue, implement one of the following two workarounds:

    • Turn on auto-rate negotiation in your CPRI MegaCore function.
    • Modify the source or generated files to fix this issue.
    • If you have write access to your IP installation files, before you generate your CPRI MegaCore function, follow these steps:

      Open the <IP installation>/altera/cpri/src/altera_cpri.vhd file in a text editor.

      On line 3251, replace clk0 => tx_clkout with clk0 => txclk_div2.

      On line 3259, replace clk0 => rx_clkout with clk0 => rxclk_div2.

      If you do not have write access to your IP installation files, you can modify the top-level file after you generate your CPRI MegaCore function. After generation, the file appears in your project directory.

    This issue is fixed in version 10.1 SP1 of the CPRI MegaCore function.

    Related Products

    This article applies to 1 products

    Arria® II FPGAs

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