September 2010

Lattice Diamond Implementations and Strategies Increase Design Tool Functionality

Design projects in Lattice Diamond software offer increased functionality by allowing more robust projects and capabilities for design exploration. Key improvements to Diamond projects include the following:

• Implementations allow multiple versions of a design within a single project for easy design exploration. Implementations are primarily used to define the structure of a design.
• Strategies allow implementation “recipes” to be applied to any implementation within a project or shared between projects. Strategies tell the software tools how a design should be run or implemented.
• Diamond projects allow the mixing of Verilog, VHDL, EDIF, and schematic sources within any implementation. Projects no longer have to be created for a specific source file type.
• Multiple files are supported for constraints (lpf), timing analysis (tpf), power calculation (pcf), and hardware debug (rvl) tools. Files can be selected and set to be active or inactive as desired which can affect both how individual tools behave when opened and how the design is implemented.
• Run Manager view allows parallel processing of multiple implementations in order to explore design alternatives for the best results. Run Manager allows you to selectively choose implementations in your project and compare the results. You can also set how many cores to use for multi-core processors to manage the load on your system. Run Manager provides an easy way to exploit multiple implementations and strategies.

Implementations

Implementations define the design structural elements for a project including source code, constraint files, and debug insertion. An implementation can be thought of as the raw material necessary to create the design. Multiple implementations can be used within a project to try different architectures to determine which produces the best results.

For a simple example, one implementation of a design may use inferred memory and another implementation may use instantiated memory. There can be multiple implementations in a project, but only one implementation can be active at a time and there must be at least one implementation. You can effectively copy an existing implementation by creating a new one and selecting to use the source of the existing as the source of the new implementation. An implementation is automatically created whenever you create a new project. The figure below shows the Diamond file list view which shows the representation of the active implementation “mixedcounter”.

Diamond File List View

Strategies

Strategies are all the implementation-related tool settings collected in one convenient location. A strategy is the set of instructions that describe how to use the raw materials available in the implementation to build the design. The strategies within a project are automatically shared among all the implementations, and they can be saved and used in multiple projects. The following are key points to understanding strategies and their role in Diamond projects.

• Strategies are basically implementation “instructions” or "recipes".
• There are four predefined strategies in Lattice Diamond plus customized user strategies.
• Predefined strategies cannot be edited, but they can be cloned and then modified and saved as custom user strategies.
• Custom user strategies can be edited, cloned, and set as the active strategy and removed.
• There can be many strategies in a project, but only one can be active at a time for each implementation and each implementation must have an active strategy.

The figure below shows the strategy dialog. Each item in the list on the left can be selected and then all the available options for that item can be shown and modified.

Diamond Strategy Dialog

Example Usage

Two typical usages show how implementations and strategies are used together to achieve the desired results. Example 1 shows a case where the designer wants to evaluate the result of different implementation options on the same design. For this example, there would be multiple implementations that use the same source effectively being clones of each other. Then different strategies would be assigned to each implementation. Each strategy would have unique settings for the FPGA software engines such as Synthesis, Map, and PAR.

Example 1 – Exploring Different Implementation Options

Example 2 shows how a designer would evaluate different implementations using different structures (different source code) but using the same implementation options. This would be the case if the designer wanted to evaluate the effects of using inferred memory versus instantiated memory.

Example 2 – Exploring Different Implementation Architectures

Summary

The new project structure in Diamond provides several key benefits. Projects are now much simpler since a single project type can handle a variety of input source types and allow the management of multiple constraint, debug, and analysis files. Additionally, through the use of implementations and strategies, projects can now be much more powerful, allowing a single project to accomplish what would have taken several projects previously. Understanding the concepts of implementations and strategies is key to leveraging this functionality in the Diamond software.