Use this dialog box to find and choose the generated clock source from the list of available pins.
To open the Select Generated Clock Source dialog box (shown below) from the SmartTime Constraints Editor, open Create Generated Clock Constraint dialog box and click the Browse button for the Clock Pin.
Displays all available pins.
Explicit clock pins for the design is the default value. To identify any other pins in the design as the generated clock source pins, select Filter available pins - Type as Explicit clocks, Potential clocks, or Clock networks. You can also use the Filter to filter the generated clock source pin name in the displayed list.