Table Of Contents

Shmoo Plot

Last Modified: November 23, 2020

Use the Shmoo plot to view a dynamically updated plot of pass and fail values for a sweep of up to two variables you specify using the specifications, timing, levels, pin and channel map, and pattern files in the project. An asterisk (*) next to a filename in the Project Explorer window and in the document tab indicates that the file has been modified but not saved.

Select File»New or click the Add Item button Add Item on the Project Explorer window toolbar to create a new document. Double-click a .digishmoo file in the Project Explorer window or right-click the file and select Open from the context menu to launch the Shmoo plot.

Running the Shmoo Plot

Select the Run»Connect Pins on Burst menu item to enable or disable automatically connecting I/O switches on burst operations. Use the Run Shmoo and Abort buttons on the toolbar to control the Shmoo operation.

Configuring the Shmoo Plot

Use the Site drop-down menu on the toolbar or below the Settling Time control to select the site for which you want to display plot results. Click the Enabled Sites button Enabled Sites to launch the Sites dialog box, which you use to enable and disable sites defined in the active pin and channel map, typically for debugging purposes. You can change the site for which you want to display plot results before the operation completes. You can also use the Site drop-down menu to specify the site to use for edge detection in edge traversal mode. In edge traversal mode, changing the site once the Shmoo operation starts does not change the site used for the edge traversal. Disabled sites do not return results.

You can sweep up to two levels, voltages, currents, edges, or specifications variables at a time. When you sweep a specification variable, all the levels and edges in the active timing and levels sheets affected by the change to the variable are updated at each sweep interval. You can specify the numeric start, stop, and number of step values to use for each variable. The start, stop, and number of step options determine the number of iterations the Shmoo operation executes. The start and stop values must use the same SI prefix. Using a large number of steps might generate too many points and negatively affect performance.
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The Shmoo operation does not validate that the variables you select remain within reasonable ranges. For example, if specifications formulas result in VIH < VIL for some points, the Shmoo operation continues to generate the plot, even though the points in this situation are not reasonable configurations.

You can execute the Shmoo operation in sweep, zigzag, progressive resolution, or edge traversal mode. The default Shmoo plot mode is progressive resolution, which provides a high-level view of the preliminary results and then increases the level of detail iteratively until the final results display. Digital pattern instrument settings restore to their original values when the Shmoo operation completes or when you abort the operation.

For specification variables, the Shmoo operation uses the values in the active levels file and the active timing file listed in the Project Explorer window.

The comma-separated list of pins or pin groups and the time set you specify must match valid values in the corresponding pin and channel map and timing file. Use the type-ahead drop-down menu to select valid pin, pin group, and time set values.

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You must install the NI-DCPower driver to access NI-DCPower-related functionality in the Digital Pattern Editor.

You can select <None> for the Type option on either axis to create a 1D Shmoo.

You can also define a settling time value to add a delay between when the Digital Pattern Editor applies the values to the instruments and when it bursts the pattern. If the Shmoo plot seems to take more time than you expect, ensure that the settling time value is not set to an unnecessarily high value.

You can apply the settings at a specific point on the Shmoo plot and burst the corresponding pattern by double-clicking the point on the Shmoo plot or by using the cursors to navigate to the point on the Shmoo plot and double-clicking the cursor target. The Digital Pattern Editor applies the settings specified at that point, initiates a burst, and retains those settings. The editor brings the pattern grid view or the History RAM view to the front and briefly highlights the Passed/Failed status icon to indicate that the pattern finished bursting. Alternatively, you can drag and dock the pattern document so you can view the pattern and Shmoo plot in the workspace at the same time.

Use the expander buttons to expand or collapse the settings section to create a larger display area for the Shmoo plot.

Use the buttons above the Shmoo plot to control panning and zooming, and use the cursor on the Shmoo plot to display the value for an individual point.

You can configure and save the settings for multiple Shmoo plots per project. The document stores the Shmoo settings but not the plot data itself.

You can select among various options to display simulated results when you run the Digital Pattern Editor in demo mode.

Saving the Shmoo Plot Information

Use the Save to PNG button Save Shmoo as PNG on the toolbar to save the current state of the Shmoo plot as an image file. You must expand the settings section to include it in the image.

Keyboard Shortcuts within the Shmoo Plot

Action Shortcut
Run Shmoo F5
Control panning <Ctrl+left-click> and drag
Zoom on a region you select <Shift+left-click> and drag
Zoom out <Shift+right-click>

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