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MichaelB's avatar
MichaelB
Icon for Occasional Contributor rankOccasional Contributor
4 years ago
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E-Tile TX/RX out clock constraint

Hi,

I've defined a data rate in my E-Tile IP and I want to switch the data rate using the E-Tile Avalon reconfiguration interface by setting the internal PLL multiplier.

Now I have chosen the highest data rate in E-Tile and want to constraint the lowest data rate.

Do I have to set the constraint to the output clock of the E-Tiles?

Which clock do I have to constraint here?

I already tried a lot of combinations e.g.:

create_clock -period 3.531 -name freq_low [get_ports {u0|e_tile_phy_0|e_tile_phy_0|g_xcvr_native_insts[0].ct3_xcvr_native_inst|inst_ct3_xcvr_channel|out_pld_pcs_rx_clk_out1_dcm}]

This statement won't be recognised but I can see the port in my tech-map.

If I create a clock_group I can use [get_clocks {u0|e_tile_phy_*|e_tile_phy_*|rx_clkout|ch*}] but for create_clock I have to specify a port/pin/etc. instead of using an existing clock.

How can I apply the create_clock constraint to my E-Tile out clocks for the lowest data rate?

Best regards,

Michael

6 Replies

  • KennyT_altera's avatar
    KennyT_altera
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    What device that you were using?

    What you need to do is create clock at the port and use derive_pll_clocks to generate the correct output clocks.


    You can also open up timing analyzer to put the derive_pll_clocks inside the tcl command. It will show you a list of generated clock inside.


    Btw, if you want to change to different clock unit. Here is the command:

    set_time_format -unit ns -decimal_places 3


  • KennyT_altera's avatar
    KennyT_altera
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    Also, can you double check the user guide and reference design for the constrain needed?


    • MichaelB's avatar
      MichaelB
      Icon for Occasional Contributor rankOccasional Contributor
      4 years ago

      Hi Kenny,

      I'm using the Stratix 10 SM16BEU2 device.

      "What you need to do is create clock at the port and use derive_pll_clocks to generate the correct output clocks."

      Which port should have this create_clock constraint?

      I already tried a lot ports in the E-Tile native to constraint but without success.

      Best regards,

      Michael

      • MichaelB's avatar
        MichaelB
        Icon for Occasional Contributor rankOccasional Contributor
        4 years ago

        Hi,

        is there anyone who could help me with this topic?

        I'm still not able to assign any create_clock constraint on the E-Tile TX/RX output clock to support different frequencies and data rates.

        Best regards,

        Michael

  • SyafieqS's avatar
    SyafieqS
    Icon for Super Contributor rankSuper Contributor
    4 years ago

    Hi Michael,


    I'm checking for some user guide/sample design for reference how to constraint this. Will keep you posted.