Design Review
A design review, whether
formal or informal, can be one of the most important things done during
the development cycle of the hardware. The earlier an issue is found,
the easier/cheaper it is to change. The review should verify the
design:
-
Meets the requirements
-
Follows the coding
standard
-
Code is properly
commented to make it understandable
-
Is testable
-
Is transferable.
Another engineer should be able to understand and change or complete
the design as needed
-
Passed a worst case
timing analysis
-
Special pins on
each device are used properly
-
Design interfaces
match those specified by the hardware and other devices. This includes
signal types and levels.
-
If a state machine,
no unused state should cause lock-up
-
A part reset line exists
Any item found during the review should be documented and
then fixed. Another design review is then held to verify the fix. All members
of the review team should concur with any fixes and the CE design. The
goal of any design review should be to increase the quality of the
design. To do this at least one of the reviewers should be independent
of the design team.
Remember that management is sometimes more interested in cost
and schedule then quality.
Each reviewer will need:
- Design documentation
- Design requirements and or specification
- Interface control document
- Access to the design
- Access to the designer/design team
- To understand the design and its relationship with the whole system
- Not to assume that the developer understands the whole design
- Use your favorite tool to analyze the design. Run Lint on the design to look for possible problems
- Model/Simulate as needed
- To ask questions
- Remember that VHDL hides design details and is not WYSIWYG
Additionally, at least one reviewer should be able to perform analysis of selected circuits. However, the reviewer is not there to test and verify the part. That is the designer's responsibility.
And finally, things not to do include:
- Wait until the design is complete and tested then do the design review
- Wait until the design is complete to start analysis
- Allow the designer to verify the design
- Skip the design review
Consistency is the name of the game. One good part does
not indicate you have a good process. You should define a methodology
to use for all parts produced. This should include:
- Complete, reviewed and approved requirements
- A coding standard
- A configuration management system
- Simulation and analysis
- Complete part testing
Remember, it is better to spend the time in the beginning
of the process to get the requirements right then spend the time
debugging. Safety, reliability and quality are designed into the
system, not patched in later.
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