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Altera_Forum
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10 years ago

Altera Max II Cpld (EPM240T100C5N) and internal oscillator. How to use it?

Hi, I'm trying to use the Max II Cpld in a project and I'm trying to find a simple solution to my case. Well, seems that the Max II has an internal oscillator, so can I use it instead of an external clock?

The Max II has 4 pins for external clock, but if it has an internal clock I want to use it instead of worrying about this extra stuff.

Someone can please give me some information about this? What is the speed of this internal oscillator? What I need to do to use it? The result will be the same as using an external clock?

Thanks....

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  • Altera_Forum's avatar
    Altera_Forum
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    10 years ago

    --- Quote Start ---

    Someone can please give me some information about this? What is the speed of this internal oscillator? What I need to do to use it? The result will be the same as using an external clock?

    --- Quote End ---

    Here's example code to simulate and synthesize the internal oscillator.

    Read the comments in the files for details. For example, src/toggle.vhd 

    
--
-- MAX II CPLDs have a User Flash Memory (UFM) block that
-- includes an oscillator. The nominal frequency of the
-- oscillator is around 18MHz. A divided-by-4 version of the
-- oscillator is available to clock user logic.
-- Reference  indicates that the nominal frequency of the
-- user clock signal is 4.4MHz, with a range of 3.3MHz to
-- 5.5MHz (25% variation).
--

    Cheers.

    Dave