Overviews

Commands

See Also

To create clock settings:

You can also specify all timing settings with the Timing wizard.

1. If you have not already done so, create a new project or open an existing project.

2. Choose Settings (Assignments menu).  Shortcut

3. In the Category list, select Clocks under Timing Settings.

4. Under Specify circuit frequency as, select Settings for individual clock signals.

5. Click New.

6. In the New Clock Settings dialog box, type a name for the new clock settings in the Clock settings name box.

7. If you want to specify timing requirements for an absolute clock, follow these steps:

1. Under Relationship to other clock settings, select Independent of other clock settings.

2. In the Required fmax box, type the required frequency (f_MAX) of the clock signal and select a time unit from the list.

3. In the Duty Cycle list, specify the required duty cycle for the clock.

4. If you want to include external delays to and from device pins in the f_MAX calculations, turn on Include external delays to and from device pins in fmax calculations.

5. Click OK.

8. If you have already specified timing requirements for an absolute clock, and you want to specify timing requirements for a derived clock, follow these steps:

1. In the Clocks page, click New.

2. In the New Clock Settings dialog box, type a name for the new clock settings in the Clock settings name box.

3. Under Relationship to other clock settings, select Based on and select an existing clock setting name in the list.

4. Click Derived Clock Requirements.

5. In the Derived Clock Requirements dialog box, specify one or more of the following options:

• If you want the required f_MAX of the derived clock to be a multiple of the absolute clock, specify a value in the Multiply base absolute clock fmax by box.

• If you want the required f_MAX of the derived clock to be a fraction of the absolute clock, specify a value in the Divide base absolute clock fmax by box.

• If you want the duty cycle of the derived clock to be different from the absolute clock, specify a value in the Duty cycle list.

• If you want the required f_MAX of the derived clock to be offset from the absolute clock by a specific time, type a value in the Offset from base absolute clock fmax box and select a time unit in the list.

• If you want the derived clock to be inverted from the absolute clock, turn on Invert base clock.

6. Click OK.

7. In the New Clock Settings dialog box, click OK.

9. In the Settings dialog box, click OK.

10. Assign the clock settings to a clock signal.

Back to Top