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SYiwe's avatar
SYiwe
Icon for Occasional Contributor rankOccasional Contributor
6 years ago

How can I eliminate negative slack in RapidIO IP Core

Hi,

In my design there's a 5G 4X Rapid IO IP Core. A single TX PLL is instantiated to drive

tx_bonding_clock_ch0~3.

I've tried to drive the sysclk signal with txclk(output from the RapidIO IP Core) and a

250MHz clock(output from a IO_PLL IP Core), both of the two cases got negative setup slacks

after timing analysis, which result in error data in rapidio packet, as you can see in the

following screenshot.

The frequency of reference clock is 100MHz.

Any suggestions?

Thanks, regards.

3 Replies

  • Nathan_R_Intel's avatar
    Nathan_R_Intel
    Icon for Contributor rankContributor
    6 years ago
    Hie, From your description alone, I cannot determine what is causing the timing error. Could you attach your design achieve (.qar), together with which Quartus version used for me to help you with this error. Regards, Nathan
    • SYiwe's avatar
      SYiwe
      Icon for Occasional Contributor rankOccasional Contributor
      6 years ago

      Thanks.

      Can you give me an email address so I can send my design to you?

      Regards.

  • Nathan_R_Intel's avatar
    Nathan_R_Intel
    Icon for Contributor rankContributor
    6 years ago

    Hie,

    Yes, please send your design to my email address nathan.ramachandran@intel.com

    Anyway from your latest description, I am able to identify some incorrect clock connection information. syslck is the avalon sysclk. Connecting to tx_clk (which is sourced from transceiver PLL) is not recommended. Hence, please connect to IO PLL IP core. Also ensure the recommended frequency for sysclk is met. Currently you seem to be suing 250MHz which does not meet the maximum recommended frequency .Its documented in Table 16 of the RapidIO User Guide below:

    https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug_rapidio.pdf

    Please update your clock connections following the user guide.

    Regards,

    Nathan