Design Compiler再了解(五十四)

Using Multiple Clocks

有三種可能的多重clocks
1. Synchronous,
2. Asynchronous,
3. Exclusive Clocks

比較特別的是set_clock_groups的使用

If you specify more than two groups, each group is exclusive with respect to the other
specified groups. For example,
pt_shell> set_clock_groups -logically_exclusive \
          -group {CK1 CK2} -group {CK3 CK4} -group {CK5}

If you specify just one group, that group is exclusive with respect to all other clocks in the
design. For example,
pt_shell> set_clock_groups -logically_exclusive  -group {CK1 CK2}


You can optionally assign a name to a clock group declaration, which makes it easier to later
remove that particular declaration:
pt_shell> set_clock_groups -logically_exclusive -name EX1 \
          -group {CK1 CK2} -group {CK3 CK4}
Use the remove_clock_groups command to remove a clock grouping declaration:
pt_shell> remove_clock_groups -logically_exclusive -name EX1


To remove all exclusive clock grouping declarations made with the set_clock_groups
command:
pt_shell> remove_clock_groups -logically_exclusive -all