The Global tab window is the first window to appear when you load a file. It is used to specify clock periods, pad-to-setup, clock-to-pad, and pad-to-pad constraints. Clicking the right mouse button in a row associated with a clock and a column associated with a constraint, opens a pop-up window. Making a selection from the pop-up window opens a dialog box which is used to specifying a constraint.
To open the Global tab window, click the Global tab on the main window.
To save information, click OK on a dialog box.
To close the window, click the Ports or Advanced tab.
Figure 5.2 Global Tab Window |  |
| Field | Description |
|---|---|
| Clock Net Name | Lists all of the clock nets for the design. |
| Period | Specifies a period for a clock. See “Clock Period” in the "Using the Constraints Editor" chapter. |
| Pad to Setup | The time allowed for data to propagate from the input to meet the setup requirement at the synchronous element. This is a global constraint for all input ports. Using the Pad to Setup constraint under the Ports tab can override the global constraint with a specific value for the selected port. See “Pad to Setup” in the "Using the Constraints Editor" chapter. |
| Clock to Pad | This is the value representing the clock-to-out of the synchronous element plus the propagation time to the pad.This is a global constraint for all output ports. Using the Clock to Pad constraint under the Ports tab can override the global constraint with a specific value for the selected port. See “Clock to Pad” in the "Using the Constraints Editor" chapter. |
| Pad to Pad | A value representing the maximum allowable propagation delay from the input pin of the device to the output pin of the device for combinatorial logic. See “Pad to Pad” in the "Using the Constraints Editor" chapter. |
