Forum Discussion
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):
- When P.C, setting the refclock_ready, en_refclk_fgt_0, en_refclk_fgt_1 to 3'd0, 1'b0, 1'b0, respectively.
- Stabling the transceiver's input reference clock (loading its config parameters)
- Setting refclock_ready, en_refclk_fgt_0, en_refclk_fgt_1 to 3'd1, 1'b1, 1'b1, respectively.
- 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
Regular 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
Regular Contributor
Dear Customer,
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