DIRECTIVES/CONSTRAINTS_FOR_CLOCK_DOMAIN_CROSSING_IN_VLSI

Directives/Constraints for CDC:

Following are some example of cdc directive commands:

• netlist clock — Identify clocks characteristics (including which clocks belong to the same clock groups).
netlist clock core_clk_a -period 10

• netlist port domain — Override the default clock groups assigned to DUT or instance ports.
netlist port domain input_port_in1 -clock core_clk_1

• netlist blackbox — Identify modules/architectures that should be treated as “black boxes” for CDC analysis.
netlist blackbox mem32_8

• netlist constant — Identify signals that should be considered constant for CDC analysis.
netlist constant test_sel 1'b0

• netlist memory — Identify large memories that are modeled as single sequential elements for CDC analysis.
netlist memory -module memory -abstract mem

• cdc preference — Set the preferences for static CDC analysis.
cdc preference -fifo_scheme -handshake_scheme

• cdc report scheme — Set severities for CDC schemes.
cdc report scheme port_combo_logic –severity caution

• cdc promote crossing and cdc promote scheme — Set promotion attributes for CDC crossings and schemes.
cdc promote crossing –promotion {off | on | protocol | fx} [–scheme scheme_name]