The Clocking Wizard selects optimal settings for the parameters of the clocking primitive. You can override any of these calculated parameters as per your requirement. By selecting Allow override mode , the overridden values are used rather than the calculated values as primitive parameters. The Wizard uses the settings shown in This Figure for any timing calculations, and any settings changed here are reflected in the summary pages.
IMPORTANT: It is important to verify that the values you are choosing to override are correct because the Wizard implements what you have chosen even if it causes issues with the generated network.
The parameters listed are relevant for the physical clocks on the primitive, rather than the logical clocks created in the source code. For example, to modify the settings calculated for the highest priority CLK_OUT1 , you actually need to modify the CLKOUT0* parameters, and not the CLKOUT1* parameters for a MMCM or PLL.
Note: The OVERRIDE_PRIMITIVE parameter is disabled when the selected primitive is Auto . You can only update the attributes of the resulting primitive.