report_ssn - 2024.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

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2024.1 English

Run SSN analysis on the current package and pinout


report_ssn [‑name <arg>] [‑return_string] [‑format <arg>] [‑file <arg>]
    [‑append] [‑phase] [‑quiet] [‑verbose]


Ssn report


Name Description
[-name] Output the results to GUI panel with this name
[-return_string] Return report as string
[-format] Report format. Valid arguments are CSV, HTML, TXT Default: csv
[-file] Filename to output results to. (send output to console if -file is not used)
[-append] Append the report to the specified file
[-phase] Account for multi-clock phase in the analysis
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution




Perform a simultaneous switching noise (SSN) analysis of the current design. The SSN analysis is an accurate method for predicting how output switching affects interface noise margins. The calculation and estimates are based on a range of variables intended to identify potential noise-related issues in your design and should not be used as final design "sign off" criteria.

SSN analysis provides estimates of the disruption that simultaneously switching outputs can cause on other output ports in the I/O bank. The SSN predictor incorporates I/O bank-specific electrical characteristics into the prediction to better model package effects on SSN.

The report_ssn command can be affected by the temperature grade of the selected device as defined by the -grade option of the set_operating_condition command. Setting the temperature grade prior to running noise analysis lets you see how noisy signals can be on Commercial, Extended, Industrial, Q-Grade, or Military grade devices.

By default, report_ssn assumes that every port toggles asynchronously. This results in a worst-case noise analysis, which may be overly pessimistic. The -phase option lets you consider clocking information available in the design to more accurately report SSN noise. Clocks must be defined using the create_clock and create_generated_clock commands. The period, phase shift and duty cycle of the generated clocks have significant impact on SSN analysis.

The report_ssn command provides a detailed SSN analysis for AMD UltraScale™ architecture devices, AMD Virtex™ 7, AMD Kintex™ 7, and AMD Artix™ 7 devices. The report is returned to the standard output, unless the -file, -return_string, or -name arguments are specified.

Tip: Not all parts support the report_ssn command. The AMD Vivado™ Design Suite returns an error if you run report_ssn on a target part that does not support SSN analysis. You can query the SSN_REPORT property of a part to see if it supports the command. Refer to the Examples for more information.


-name <arg> - (Optional) Specifies the name of the results to output to the GUI.

-return_string - (Optional) Directs the output to a Tcl string. The Tcl string can be captured by a variable definition and parsed or otherwise processed.

Note: This argument cannot be used with the -file option.

-format [ CSV | HTML | TXT ] - (Optional) Specifies the format of the output as either comma-separated values (CSV), HTML, or an ASCII (TXT) file. The default output is CSV.

Note: The format applies when -file is specified, but is otherwise ignored.

-file <arg> - (Optional) Write the SSN report into the specified file. The specified file will be overwritten if one already exists, unless -append is also specified.

Note: If the path is not specified as part of the file name, the file will be written into the current working directory, or the directory from which the tool was launched.

-append - Append the output of the command to the specified file rather than overwriting it.

Note: The -append option can only be used with the -file option.

-phase - (Optional) Consider clock switching cycles in SSN analysis to provide a more accurate result.

-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 performs an SSN analysis on the current design, formats the output as HTML, and writes the output to the specified file:

report_ssn -format html -file C:/Data/devSSN.html

The following example performs an SSN analysis, with phase analysis, and returns the output to a string which is stored in the specified variable:

set devSSN [report_ssn -phase -format html -return_string]
Note: The -format argument in the preceding example is ignored in the absence of -file.

The following example queries the part in the current project to see if it supports the report_ssn command, and then gets a list of parts from the same part family that support the command:

get_property SSN_REPORT [get_property PART [current_project]]
get_parts -filter "FAMILY == [get_property FAMILY [get_property PART \
[current_project]]] && SSN_REPORT"