The output is locked to the input the is no frequency drift. If the input was 33.333333333333333333333Mhz the DCM would report a clock output of 33.333MHz, but you will have an output that is the same frequency as the input clock. Rounding and significant bits are at play here.
yes, I want the output frequency to be equal to the input frequency. But the ipcore generator indicates there would be a slight difference between them. Input : 9.14285Mhz. Output: 9.143Mhz.
Is it inevitable?
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Does this mean there's no difference between input and DCM output frequency? The displayed output frequency is just for show purpose?
Thanks.
The displayed output isn't just for "show purpose" - sometimes the DCM can't meet the requested frequency and it displays the nearest best.
However, in your case as ads-ee noted it's clearly a rounding issue. The DCM has no problem to output a 1:1 ratio clock from the 9.14285Mhz input.