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. To open the Global tab window, click the Global tab on the main window.
To close the window, click the Ports or Advanced tab.
Field
| Description
|
|---|
Clock Net Name
| Lists all of the root clock nets for the design. Root clock nets are nets that clock synchronous elements. The name presented is the name at which the clock is derived, such as a pad, a gate, or a flip-flop.
|
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 per clock.
|
Clock to Pad
| This is the value representing the clock delay, the clock-to-out of a synchronous element plus propagation time to the pad.This is a global constraint for all output ports per clock. Using the Clock to Pad constraint under the Ports tab can override the global constraint with a specified 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 an input pin of the device through combinatorial logic to an output pin of the device. See “Pad to Pad” in the "Using the Constraints Editor" chapter.
|
Figure 5.2 Global Tab Window