User guide

12-7
Delays and Timing
Enabling Transport Delays
Transport delays are never the default delay.
You can specify transport delays on module path delays with the
+transport_path_delays compile-time option. For this option to
work you must also include the +pulse_e/number and +pulse_r/
number compile-time options. See "Pulse Control" on page 12-7.
You can specify transport delays on a net to which you backannotate
SDF INTERCONNECT delays with the +transport_int_delays
compile-time option. For this option to work you must also include the
+pulse_int_e/number and +pulse_int_r/number
compile-time options. See "Pulse Control" on page 12-7.
The +pulse_e/number, +pulse_r/number, +pulse_int_e/
number, and +pulse_int_r/number options define specific
thresholdsfor pulse width, which let you tell VCS to filter out only some
of the pulses and let the other pulses through. See "Pulse Control" on
page 12-7.
Pulse Control
So far we’ve seen that with pulses narrower than a module path or
INTERCONNECT delay, you have the option of filtering all of them
out by using the default inertial delay or allowing all of them to
propagate through, by specifying transport delays. VCS also provides
a third option - pulse control. With pulse control you can:
• Allow pulses that are slightly narrower than the delay to propagate
through.