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Altera_Forum's avatar
Altera_Forum
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15 years ago

Help me about measure clock on osciloscope.

Hi everyone,

I have project on board DE2. I use PLL in megafunction to create the clock 500MHz from 50MHz. Then i use clock counter to decrease the clock from 500MHz to clock_out 250KHz, 125KHz, 60KHz.... and the clock_out is mapped to pin GPIO_1[0].

I use osciloscope to measure frequency of clock_out, but i can not see the the pulse ( square pulse), it only show the line . anybody know why?

Thanks.

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  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    If you use a phase-lock loop - yes

    Dont bother if you're tryimng to create it using counters - that goes for any clock in the MHz range.
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    I understand, i used pll with inclk0 = 50MHz and 2 output clock that 500, 400MHz. Can u tell me why i can not create the second output clock 400MHz??? it said that :

    "Cannot implement the request PLL".

    "Cause : Request mult/div factor not achievable".

    And the output clock parameter : mul = 20 , div = 3 why???(50*20/3 != 400MHz)

    if right , they must be mul = 8, div = 1 because 50MHz * 8 = 400.