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arik's avatar
arik
Icon for New Contributor rankNew Contributor
1 month ago

FPGA programming before XCVR's ref clock is ready

Hi,

I use F-Tile Agilex 7 and Q24.2.

On power cycle (P.C) my reference transceivers clock is not ready and stable, so I do the following reset sequence to the System PLL (created for no stable XCVR's ref clock, attached):

  1. When P.C, setting the refclock_ready, en_refclk_fgt_0, en_refclk_fgt_1 to 3'd0, 1'b0, 1'b0, respectively.
  2. Stabling the transceiver's input reference clock (loading its config parameters)
  3. Setting refclock_ready, en_refclk_fgt_0, en_refclk_fgt_1 to 3'd1, 1'b1, 1'b1, respectively.
  4. Then, waiting until refclock_status, refclk_fgt_enabled_0/1 and sys_pll_locked are asserted to 1'b1

 

Sometimes (not often), one of the statuses on section 4 are not asserted HIGH, and thus I need to do the reset sequence again and since it fails again and again I need to do P.C again.

Is there a problem with my reset sequence?  Is there a way not to P.C the FPGA and fixing this online?

Should I synchronize between the assertion of refclock_ready, en_refclk_fgt_0 and en_refclk_fgt_1?

Thanks a lot,

Arik

2 Replies

  • Ash_R_Altera's avatar
    Ash_R_Altera
    Icon for Regular Contributor rankRegular Contributor

    Hi,

    The F-tile user guide provides the right guidance on the topic. Refer: https://docs.altera.com/r/docs/683872/26.1/f-tile-architecture-and-pma-and-fec-direct-phy-ip-user-guide/guidelines-for-fgt-reference-clock

    Key things to look for are:

    1) F-tile system PLL IP settings for "Refclk #i is active at and after device configuration" 

    2) The reset assertion and de-assertion.

    3) Ensuring that the input reference clock is really stable before you assert the signal en_refclk_fgt_i.

     

    Please go through the guidance thoroughly and make sure it has been followed.

     

    Regards

  • Ash_R_Altera's avatar
    Ash_R_Altera
    Icon for Regular Contributor rankRegular Contributor

    Dear Customer,

    Just wanted to check if you have any further questions. We will continue to monitor this post for the next 5 days. If there are no further inquiries during this period, I will step back and allow the community to assist with any future follow-up questions.

    Thank you for engaging with us!

    Best regards,
    Altera Technical Support