Ambit BuildGates Synthesis User Guide

Using the GUI

Constraints Tool

The constraints screen (a sample is shown in Figure 3-27) displays the current timing constraints and allows you to change data in the input fields. The constraints screen consists of three panels: ideal clock panel, port clock panel, and port constraints panel. The panels contain both editable input fields and uneditable data fields. The port clock panel has seven columns and is too wide to fully display in the figure below, therefore this panel is defined in the cutout at the bottom of the figure. On the actual screen, left click the scroll arrow under the panel to access all columns.

Figure 3-27 Sample Constraints Screen

Port

Constraints

Panel

Clock Port Panel Cutout

Ambit BuildGates Synthesis User Guide

Using the GUI

Note: If you begin typing in an input field and change your mind, press ESC to abort the process.

Clicking the right mouse button in any of the three panels displays a pop-up menu with additional functions. The following tables define the pop-up functions.

Table 3-28 Ideal Clock Panel Pop-Up Menu

Table 3-29 Port Clock Panel Pop-Up Menu

Table 3-30 Port Constraints Panel Pop-Up Menu

Ambit BuildGates Synthesis User Guide

Using the GUI

Table 3-30 Port Constraints Panel Pop-Up Menu, continued

Figure 3-28 Sample Port Timing Constraints Report

After updating constraints, you can optimize the design by selecting Main Menu – Commands – Optimize, or generate a timing report by selecting Main Menu – Reports– Timing Report.

The values in the columns of all three panels are color-coded: red text indicates a “none” or missing entry, blue text indicates a zero value, and black text indicates values that you specified.

When the constraints tab is selected, the first constraint screen displayed contains the data for the default ideal clock, which is indicated by the “@” symbol in the clock column of port constraints panel. To display the port constraints data for an ideal clock listed on the ideal clock panel, left click the ideal clock name to update the port constraints panel.

To display the constraints screen such that it occupies the whole main screen window instead of only a portion of the window, place the cursor anywhere in the constraints screen and press the Control-m keys. Repeatedly pressing Control-m toggles between the standard splitscreen and the whole-screen display.

Ambit BuildGates Synthesis User Guide

Using the GUI

For additional information on the methodology of setting constraints, refer to Setting Timing Constraints in the Envisia Timing Analysis User Guide.

Important

To save all constraint and other changes made to your design, select Main Menu – File – Save and specify a file name before exiting Ambit BuildGates synthesis.

Changing Values in Input Fields

1.Click left mouse button in any panel input field that you want to change.

2.Type the new value (you do not need to erase the current value).

3.Press the Return key.

4.Click right mouse button anywhere in the port clock panel to display the pop-up menu for adding a port clock. See Adding a New Port Clock below for procedure.

5.Click right mouse button anywhere in the port constraints panel to display the pop-up menu for additional functions. See Changing Port Constraints below for procedure.

6.To save your changes, click left mouse button on the Save Timing Assertions icon on the constraints screen.

Adding an Ideal Clock

1.Click left mouse button on New Ideal Clock icon on the constraints screen.

2.In the dialog box that is displayed, enter the new clock name and period. Click Ok.

3.The new clock is added to the ideal clock panel.

4.To display and update the port constraints for the new clock, click left mouse button on the new ideal clock.

5.Set the constraints for the new ideal clock as described above in Changing Values in Input Fields.

Deleting Timing Constraints

1.Click left mouse button on Delete All Constraints icon on the constraints screen.

2.In the warning dialog that is displayed, click Ok to delete the constraints.