Vivado automatically creates generated clocks for MMCM output when the input clock has been defined in XDC.
The generated clocks are named based on the MMCM instance name and output pin name.
This is not intuitive when I need to query them for use with other constraints.
Is there a way to rename the auto-derived clocks?
Starting from Vivado 2013.2, it is possible to rename the generated clock that is automatically created by the tool.
The renaming process consists of calling the create_generated_clock command with a limited number of parameters:
create_generated_clock -name new_name [-source master_pin] [-master_clock master_clk] source_object
The arguments that must be specified are the new generated clock name and the source object of the generated clock.
The -source and -master_clock parameters must be used only when more than one clock propagates through the source pin in order to remove any ambiguity.
In Vivado versions prior to 2013.2, you cannot rename an auto-derived clock.
You will need to either use the auto-named generated clock or add a complete create_generated_clock constraint to create a user-defined generated clock.