21.9.9 Specifying a False Path Constraint

You set options in the Set False Constraint dialog box to define specific timing paths as false.

To specify False Path constraints:
  1. Add the constraint in the editable constraints grid or open the Set False Path Constraint dialog box. You can do this by using one of the following methods:
    • From the SmartTime Actions menu, choose Constraints > False Path.
    • Click the þÿ icon.
    • Right-click False Path in the Constraint Browser.
    • Double-click any field in the False Path Constraints grid.
    The Set False Path Constraint dialog box appears (as shown below).
    Figure 21-69. Set False Path Constraint Dialog Box
    þÿ
  2. Specify the From pin(s). Click the Browse button next to From to open the Select Source Pins for False Path Constraint dialog box (as shown below).
    Figure 21-70. Select Source Pins for False Path Constraint Dialog Box
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  3. Select by explicit list. (Alternatively, you can select by keyword and wildcard. For details, refer to Select Source or Destination Pins for Constraint Dialog Box.)
  4. Select the input pin(s) from the Available Pin list. You can use Filter available objects to narrow the pin list. You can select multiple ports in this window.
  5. Click Add or Add All. The input pin(s) move from the Available Pins list to the Assigned Pins list.
  6. Click OK.

    The Set False Constraint dialog box displays the updated representation of the From pin(s).

  7. Click the Browse button for Through and To and add the appropriate pin(s). The displayed list shows the pins reachable from the previously selected pin(s) list.
  8. Enter comments in the Comment section.
  9. Click OK.

SmartTime adds the False Path constraints to the Constraints List in the SmartTime Constraints Editor.