Automatic FPGA-PCB Linking - Choosing the FPGA Configuration

The second page of the FPGA To PCB Project Wizard allows you to choose the configuration that will be used for targeting the FPGA design to the PCB. The configuration uses one or more constraint files to define the FPGA device to be used and its associated pin mappings.

Figure 1. Choose an existing configuration or specify the creation of a new one.

The configuration can either be an existing one that you have already defined as part of the FPGA project, or a new one, generated by the Wizard. In the case of the latter, the Wizard will generate a configuration and add to it a single, new constraint file. These will have default names (PCB Configuration and PCB Constraints.Constraint respectively) and the constraint file will be stored in the same location as the FPGA project file (*.PrjFPG), unless otherwise specified.

The constraint file that is added to a new configuration will contain a target device definition for the FPGA project, according to the device you specify in the Selected Device field. Type the required device directly into the field or browse for a device by clicking the ... button, to the right of the field. This will open the Choose Physical Device dialog (Figure 2), from where you can choose from a number of devices available across a spectrum of FPGA Vendor-Device families.

Figure 2. Choose the physical device into which the FPGA design will be programmed.

This page of the Wizard also allows you to decide whether unconstrained ports – ports in the FPGA design that have not been constrained to a specific pin number on the physical FPGA device – will have I/O pins assigned or not. For a new configuration, this will include all ports. However, this will not result in optimal pin allocation and better results can be obtained by importing pin allocations acquired from the vendor place and route tools.