AN 704: FPGA-based Safety Separation Design Flow for Rapid Functional Safety Certification

ID 683720
Date 9/01/2018
Public
Document Table of Contents

Design Modification Flow

This flow describes the necessary steps for you to modify the nonsafety IP in your design. This flow ensures that the previously compiled safety IP that the project uses remains unchanged when you change or compile nonsafety IP.
CAUTION:
Use the design modification flow only after you qualify your design in the design creation flow.

For a general description of the global assignments required to enable this flow refer to the Intel® Quartus® PrimeSoftware Handbook.

Figure 5. Design Modification Flow


Note: The hash uses the MD5 algorithm.
Note: If your safety IP is a sub-block in a Qsys system, every time you regenerate HDL for the Qsys system, the timestamp for the safety IP HDL changes. When you change any HDL source file that belongs to a safety IP partition, by default the Intel® Quartus® Prime software resynthesises the partition and performs a clean place and route for that partition. For a clean place and route, the design creation flow is active for the safety IP. To change the default so that HDL changes do not cause resynthesis, and to keep the design modification flow active, you can either:
  1. Use the partition export and import flow
  2. Use the design partition window menu to modify the design partition properties and turn on Ignore changes in source files and strictly use the specified netlist, if available.

As the design modification flow preserves the placement and routing from the design creation flow compilation, Intel recommends that you try the design modification flow with representative changes to ensure that the FPGA placement and routing is not adversely affected by the design creation flow place and route. Adjust the safety partition LogicLock region size and/or location, clock routing and pin placement as necessary. If you have specific pin placement and or logic placement requirements for the non-safe logic ensure these resources are reserved during the design creation flow.

To check the Intel® Quartus® Prime software acheives the expected strict preservation, for each safety IP partition check the Intel® Quartus® Prime Fitter report sub-section Incremental Compilation Placement Preservation and Incremental Compilation Routing Preservation. In the design modification flow you see entries showing that the Intel® Quartus® Prime software preserves placement and routing for the safety IP partitions.

For more information, refer to the Intel® Quartus® PrimeSoftware Handbook, chapter 3, Incremental Compilation for Hierarchical and Team based Design