Creating a Stub FPGA Project

Frozen Content

Modified by Admin on Sep 13, 2017

A Stub FPGA project can be created in one of two ways:

By running the PCB To FPGA Project Wizard

As a result of changing signal characteristics within the PCB project

The following sections take a closer look at the creation of the Stub FPGA project in these two cases.

Running the Wizard

With the FPGA Component schematic document in the PCB project open as the active view in the main design window, simply choose the PCB To FPGA Project Wizard entry on the Tools menu. The Wizard will appear (Figure 1).

Figure 1. PCB To FPGA Project Wizard.

Selecting the FPGA Component

The second page of the Wizard enables you to choose which FPGA component in the PCB project (if there are more than one) to be used when generating the FPGA project. Simply select the required component and click Next>.

Configuring the FPGA Project

The next page of the Wizard enables you to define where, and under what name, the FPGA project will be stored. By default, the project will have the name FPGA Project1.PrjFpg and will be stored in the same location as the PCB project.

From this page of the Wizard, you can also define the name of the top-level schematic sheet in the FPGA project. Define the name and location for this sheet as required. By default, the sheet will be created in the same location as the PCB project, with the name FPGA_Project1.SchDoc.

An option is also available for linking the FPGA component schematic sheet (in the PCB project) to this newly created FPGA project. Ensure that this option is enabled. The PCB project must remain linked to this Stub FPGA project to be able to synchronize design changes.

Configuring the FPGA Constraints

The final page of the Wizard allows you to define the name of a configuration for the FPGA project, as well as the name and location for a constraint file which will be associated to it. The constraint file will target the FPGA device on the PCB project's FPGA component schematic sheet. By default, the configuration will be given the name Configuration 1. The constraint file will be given the name Constraint 1.Constraint and will also be stored in the same location as the PCB project.

After defining the options in the Wizard as required, click Finish. The Stub FPGA project is created – complete with top-level schematic sheet, configuration and constraint file – as reflected in the Projects panel, when configured in File View mode. Figure 2 illustrates this for an example Stub FPGA project named FPGAStub.PrjFpg, generated with the following:

Top-level schematic, FPGAStub.SchDoc

Configuration, Stub

Constraint file, Stub.Constraint.

Figure 2. Example of a generated Stub FPGA project.

The Stub FPGA project is automatically linked to the PCB project, provided you enabled the option to do so in the Wizard. The projects are linked by the configuration defined in the Wizard when creating the FPGA project. This is reflected in the Projects panel, when in Structure Editor mode, by the FPGA project / Linked Configuration entry appearing as a sub-design of the PCB project's FPGA component.

Figure 3 illustrates this for the example Stub FPGA project considered previously. In this case, the FPGAStub.PrjFpg / Stub entry appears as a sub-design of the FPGA device, U1.

Figure 3. Linked PCB and Stub FPGA projects.

Changing Signal Characteristics

If you are working within a PCB project – either on the schematic sheet for the FPGA component or the PCB document itself – and you try to launch the FPGA Signal Manager dialog (Tools » FPGA Signal Manager), the No Linked FPGA Project dialog will appear if there is currently no linked FPGA project (Figure 4).

Figure 4. You must have an FPGA project linked to the PCB project before performing any changes to signal characteristics.

The reason the dialog appears lies in the fact that signal electrical characteristics are stored in a constraint file and not in the PCB document or project. An FPGA project must therefore be linked to the PCB project – through a specified configuration – and the relevant signal characteristics stored in a constraint file assigned to that configuration.

The dialog gives you the option of browsing for an existing FPGA project with which to link the PCB project to, or to create a new one. The FPGA project created will act as the Stub FPGA project for use when passing changes on to the FPGA Designer.

If you choose to create a new FPGA project, the PCB TO FPGA Project Wizard will appear. Follow the steps detailed in the previous sections for information on how to use this Wizard.