15-10
Expressions
Trigger Types
The trigger expression can specify the negative edge, positive edge,
or both edges of a signal to trigger on. To specify the edge to trigger
on, the trigger expression should include the appropriate event-
control statement (see
Table 15-1, Trigger Expressions).
Table 15-1 Trigger Expressions
Trigger Expression Signal Edge
clkt
Trigger on both negative and positive edge.
Verilog:
negedge clkt
VHDL:
clk’event and clk=’0’
Trigger on negative edge.
Verilog:
posedge clkt
VHDL:
clk’event and clk=’1’
Trigger on positive edge.
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