21.8.63 set_min_delay
(Ask a Question)Description
Specifies
the required minimum delay for timing paths in the current design. The path length
should be such
that the
delay along the specified path should be more than the value mentioned for the
delay_value
switch. The timing engine automatically derives the
individual minimum delay targets from clock waveforms and port input or output
delays. For more information, refer to the create_clock,
set_input_delay
, and set_output_delay
commands. The
minimum delay constraint is a timing exception. This constraint overrides the
default single cycle timing relationship for one or more timing paths. This
constraint also overrides a multi-cycle path constraint.
You must specify at least one of the –from
, -to
, or –through
arguments for this constraint to be valid.
set_min_delay delay_value [-from from_list ] [-to to_list ] [-through through_list ]
Arguments
Parameter | Type | Description |
---|---|---|
delay_value | floating point | Specifies a floating point number in nanoseconds that represents the required minimum delay value for specified paths.
|
from | list of strings | Specifies a list of timing path starting points. A valid timing starting point is a clock, a primary input, an inout port, or a clock pin of a sequential cell. |
to | list of strings | Specifies a list of timing path ending points. A valid timing ending point is a clock, a primary output, an inout port, or a data pin of a sequential cell. |
through | list of string | Specifies a list of pins, ports, nets, or instances (cells) through which the timing paths must pass. |
Return Type | Description |
---|---|
integer | Returns the ID of the clock minimum delay constraint. |
Error Codes
Error Code | Description |
---|---|
Error: SDC0021 | Invalid min delay constraint: the -from value is incorrect. |
Error: SDC0022 | Invalid min delay constraint: the -from is empty. |
Error: SDC0023 | Invalid min delay constraint: the -to value is incorrect. |
Error: SDC0024 | Invalid min delay constraint: the -to is empty. |
Error: SDC0026 | Invalid min delay constraint: the -through is empty. |
Error: SDC0061 | Invalid min delay constraint: Missing or Illegal parameter/value. |
Warning | port (get_ports) is incorrect type;"-through " objects must be of type net (get_nets ), or pin (get_pins ). |
Supported Families
PolarFire® |
PolarFire SoC |
SmartFusion® 2 |
IGLOO® 2 |
RTG4™ |
Example
The following example sets a minimum delay by constraining all paths from ff1a:CLK or
ff1b:CLK to ff2e:D
with a delay
more
than 5 ns.
set_min_delay 5 -from {ff1a:CLK ff1b:CLK} -to {ff2e:D}
The following example sets a minimum delay by constraining all paths to output ports whose names start by "out" with a delay more than 3.8 ns.
set_min_delay 3.8 -to [get_ports out*]