get_speed_models - 2024.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

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2024.1 English

Get a list of speed_models in the device.


get_speed_models [‑of_objects <args>] [‑regexp] [‑nocase] [‑patterns <arg>]
    [‑filter <arg>] [‑speed_pattern <arg>] [‑quiet] [‑verbose]




Name Description
[-of_objects] Get 'speed_model' objects of these types: 'node bel pip cell'.
[-regexp] Patterns are full regular expressions
[-nocase] Perform case-insensitive matching. (valid only when -regexp specified)
[-patterns] Match the 'speed_model' objects against patterns. Default: *
[-filter] Filter list with expression
[-speed_pattern] Returns a single model that exactly matches the pattern.
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution


Device, Object, XDC


Get speed models for AMD UltraScale™ architecture device resources in the current design.

Speed files are provided by AMD for each device and speed grade. Speed files contain speed models. There are speed models for the various elements of a device: nodes, pips, bels. There are speed models for setup and hold, propagation delays, and jitter.

The speed models include information on the delays in nanoseconds (ns) associated with device resources like BELs and SITEs and routing resources. Speed models are used by the AMD Vivado™ timing engine to perform analysis of the current design in the context of the target part.

The objects returned are the speed models associated with specific physical resources like pips and wires, drawn directly from the speed files. These can include capacitance and resistance values and buffer models.

Note: To improve memory and performance, the get_* commands return a container list of a single type of objects (e.g. cells, nets, pins, or ports). You can add new objects to the list (using lappend for instance), but you can only add the same type of object that is currently in the list. Adding a different type of object, or string, to the list is not permitted and will result in a Tcl error.

This command returns the specified speed model objects, or returns an error if the command fails.


-regexp - (Optional) Specifies that the search <patterns> are written as regular expressions. Both search <patterns> and -filter expressions must be written as regular expressions when this argument is used. Xilinx® regular expression Tcl commands are always anchored to the start of the search string. You can add ".*" to the beginning or end of a search string to widen the search to include a substring. See for help with regular expression syntax.
Note: The Tcl built-in command regexp is not anchored, and works as a standard Tcl command. For more information refer to

-nocase - (Optional) Perform case-insensitive matching when a pattern has been specified. This argument applies to the use of -regexp only.

-filter <args> - (Optional) Filter the results list with the specified expression. The -filter argument filters the list of objects returned by get_speed_models based on property values on the objects. You can find the properties on an object with the report_property or list_property commands. In the case of the speed_model object, "NAME", "TYPE" and "DELAY" are some of the properties that can be used to filter results.

The filter search pattern should be quoted to avoid having to escape special characters. String matching is case-sensitive and is always anchored to the start and to the end of the search string. The wildcard “*” character can be used at the beginning or at the end of a search string to widen the search to include a substring of the property value.
Note: The filter returns an object if a specified property exists on the object, and the specified pattern matches the property value on the object. In the case of the "*" wildcard character, this will match a property with a defined value of "".
For string comparison, the specific operators that can be used in filter expressions are "equal" (==), "not-equal" (!=), "match" (=~), and "not-match" (!~). Numeric comparison operators <, >, <=, and >= can also be used. Multiple filter expressions can be joined by AND and OR (&& and ||). The following gets input pins that do NOT contain the “RESET” substring within their name:
get_pins * -filter {DIRECTION == IN && NAME !~ "*RESET*"}
Boolean (bool) type properties can be directly evaluated in filter expressions as true or not true:
-of_objects <arg> - (Optional) Get the speed models for the specified node, bel, pip, or cell objects.
Note: The -of_objects option requires objects to be specified using the get_* commands, such as get_cells or get_pins, rather than specifying objects by name. In addition, -of_objects cannot be used with a search <pattern>.
-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.
Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.
-verbose - (Optional) Temporarily override any message limits and return all messages from this command.
Note: Message limits can be defined with the set_msg_config command.


The following example reports the properties on the speed model for an A6LUT:

report_property -all [lindex [get_speed_models -of \
[get_bels SLICE_X0Y0/A6LUT]] 0]
Property              Type    Read-only  Value
CLASS                 string  true       speed_model
DELAY                 double  true       0.043
FAST_MAX              double  true       0.035
FAST_MIN              double  true       0.028
IS_INSTANCE_SPECIFIC  bool    true       1
NAME                  string  true       bel_d_lut6_a1_o6
NAME_LOGICAL          string  true       bel_d_lut6_a1_o6
SLOW_MAX              double  true       0.043
SLOW_MIN              double  true       0.036
SPEED_INDEX           int     true       65535
TYPE                  string  true       bel_delay

The following example returns the delays, in nanoseconds, for a specific A6LUT on the device, followed by the delay name for the specified object:

set x [get_speed_models -of [get_bels SLICE_X0Y0/A6LUT]]
puts [format "%6.3f : %s" [get_property DELAY [lindex $x 0 ]] \
[get_property NAME [lindex $x 0 ]]]