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Altera_Forum
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19 years ago

Correct procedure for changing the clock speed

The Timing Analyzer reports that my fmax is 70MHz. So if I want to run at 70MHz, is this what I do?

1) In SOPC Builder, change clk to 70.0, then regenerate.

2) In the sdram_pll, change the inclock0 input to 70MHz. Click Finish and update the component

3) Recompile

The output clocks are running at 1/1 so they should operate at whatever inclock does. Is this the correct procedure for increasing the clock speed the board runs at?

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    --- Quote Start ---

    originally posted by bkucera@Mar 21 2006, 11:27 PM

    the timing analyzer reports that my fmax is 70mhz. so if i want to run at 70mhz, is this what i do?

    1) in sopc builder, change clk to 70.0, then regenerate.

    2) in the sdram_pll, change the inclock0 input to 70mhz. click finish and update the component

    3) recompile

    the output clocks are running at 1/1 so they should operate at whatever inclock does. is this the correct procedure for increasing the clock speed the board runs at?

    <div align='right'><{post_snapback}> (index.php?act=findpost&pid=13656)

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    --- Quote End ---

    Have you also set the input clk for your system to 70MHz?
  • Altera_Forum's avatar
    Altera_Forum
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    --- Quote Start ---

    originally posted by kalle leo@Mar 22 2006, 04:12 AM

    have you also set the input clk for your system to 70mhz?

    <div align='right'><{post_snapback}> (index.php?act=findpost&pid=13670)

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    No, how do I do that?
  • Altera_Forum's avatar
    Altera_Forum
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    --- Quote Start ---

    originally posted by bkucera+mar 22 2006, 11:39 am--><div class='quotetop'>quote (bkucera @ mar 22 2006, 11:39 am)</div>

    --- quote start ---

    <!--quotebegin-kalle leo@Mar 22 2006, 04:12 AM

    have you also set the input clk for your system to 70mhz?

    <div align='right'><{post_snapback}> (index.php?act=findpost&pid=13670)

    --- quote end ---

    --- Quote End ---

    No, how do I do that?

    <div align='right'><{post_snapback}> (index.php?act=findpost&pid=13686)</div>

    [/b]

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    I&#39;m not so sure if that is necessary.. you have an oscillator running at "X" which has not changed. You need to tell the PLL wizard what this input frequency "X" is... then to adjust your actual system clock speed, either tell the PLL wizard which output freq you want, or play with the multiplier/divisor numbers to get the desired output.