Before any timing exceptions are created, it is helpful to go back to
report_clock_networks
to identify which primary
clocks exist in the design. If all primary clocks are asynchronous to each other, you
can use a single constraint to decouple the primary clocks from each other and to
decouple their generated clocks from each other. Using the primary clocks in report_clock_networks
as a guide, you can decouple each
clock group and associated clocks as shown in the following figure.
Figure 1. Report Clock Networks
### Decouple asynchronous clocks
set_clock_groups -asynchronous \
-group [get_clocks sysClk -include_generated_clocks] \
-group [get_clocks gt0_txusrclk_i -include_generated_clocks] \
-group [get_clocks gt2_txusrclk_i -include_generated_clocks] \
-group [get_clocks gt4_txusrclk_i -include_generated_clocks] \
-group [get_clocks gt6_txusrclk_i -include_generated_clocks]