Visible to Intel only — GUID: mwh1410383726085
Ixiasoft
Visible to Intel only — GUID: mwh1410383726085
Ixiasoft
2.3.4.5.1. Exclusive Clock Groups (-exclusive)
If you define multiple clocks for the same node, you can use clock group assignments with the -exclusive option to declare clocks as mutually exclusive. This technique can be useful for multiplexed clocks.
For example, consider an input port that is clocked by either a 100-MHz or 125-MHz clock. You can use the -exclusive option to declare that the clocks are mutually exclusive and eliminate clock transfers between the 100-MHz and 125-MHz clocks, as the following diagrams and example SDC constraints illustrate:
Example SDC Constraints for Internal Clock Mux
# Create a clock on each port create_clock -name clk_100 -period 10 [get_ports clkA] create_clock -name clk_125 -period 8 [get_ports clkB] # Set the two clocks as exclusive clocks set_clock_groups -exclusive -group {clk_100} -group {clk_125}
Example SDC Constraints for External Clock Mux
# Create two clocks on the port clk create_clock -name clkA -period 10 [get_ports clk] create_clock -name clkB -period 8 [get_ports clk] -add # Set the two clocks as exclusive clocks set_clock_groups -exclusive -group {clkA} -group {clkB}