ASPI8-4 DSP Design Methodology

1. ASPI8-4 DSP Design Methodology ASPI8-4: DSP Design Methodologies, AAU

2. Practical issues • Webpage: http://www.cs.aau.dk/~moullec/aspi8-4/ • • Literature: available on the webpage and • in your mailbox (or ask Dorthe) • YOUR feedback about the course is most welcome: • during the lecture • after the lecture (moullec@cs.aau.dk) ASPI8-4: DSP Design Methodologies, AAU

3. Outline of the course • MM1: Design meta models • Introduction/Y-chart model/Rugby meta model • • MM2: Computational models • FSMD/SDFG/CDFG/HCDFG/ASM-charts • • MM3: Design Domains • Function/Communication/Data/Timing ASPI8-4: DSP Design Methodologies, AAU

4. MM1: • Design meta models • Introduction • Y-chart model • Rugby meta model • Conclusion ASPI8-4: DSP Design Methodologies, AAU

5. Introduction: the need for design methodologies • Pervasive computing with an always-on Internet infrastructure. • Voice activated controls enabled by speech synthesis. • Wireless communications that keep us in touch no matter where or when we need it. • A consumer industry dominated by a plethora of entertainment devices. ASPI8-4: DSP Design Methodologies, AAU

6. Introduction: the need for design methodologies “ Digital signal processing (DSP) has become the technology of focus with consensus expectations of exponential growth. Everybody knows that DSP is the technology driver for the semiconductor industry,” Will Strauss, analyst, Forward Concepts Co., Tempe, AZ. ASPI8-4: DSP Design Methodologies, AAU

7. Introduction: the need for design methodologies But ??? Source: Xilinx • NEW PLATFORMS (DSPs, FPGAs, SoC,…) • NEW METHODOLOGIES ASPI8-4: DSP Design Methodologies, AAU

8. Introduction: the need for design methodologies But ??? • INCREASED COMPLEXITY (multiple standards, Quality of Service, …) • NEW METHODOLOGIES ASPI8-4: DSP Design Methodologies, AAU

9. Introduction: the need for design methodologies What is a methodology ? • “The way in which you find out information; a methodology describes how something will be (or was) done. The methodology includes the methods, procedures, and techniques used to collect and analyze information” • “A documented approach for performing activities in a coherent, consistent, accountable, and repeatable manner” • “A collection of methods, procedures, and standards that defines an integrated synthesis of engineering approaches to the development of a product” • A method is not a methodology, it’s part of a methodology. ASPI8-4: DSP Design Methodologies, AAU

10. ASPI8-4: DSP Design Methodologies, AAU

11. Introduction: elements for a design methodology • Domains: functional, structural, physical, … • Abstraction levels: system, algorithmic, RTL, logic, circuit, … • Activities: analysis, synthesis, refinement, optimization … ASPI8-4: DSP Design Methodologies, AAU

12. Specification domains for digital systems • Functional domain: emphasis is on behavior (functionality, I/O), • no reference to the implementation of this behavior • Structural domain: interconnected functional components, • possibly hierarchical • Physical domain: a.k.a geometric, physical placement in space and • physical properties, no direct relation to functionality ASPI8-4: DSP Design Methodologies, AAU

13. Abstraction levels for digital systems • System level: subsystems (modules,…) interacting with each other • (for example exchanging messages). • Structural elements: processsors, communication channels, memories,… • Algorithmic level: a.k.a behavioral level, algorithm(s) describing • the functionality. • Structural elements: controller, netlist,… • Register Transfer Level: a.k.a RTL level, operations described as • transfer of data between registers and functional units. • Structural elements: registers, ALUs, multiplexers, controller,… ASPI8-4: DSP Design Methodologies, AAU

14. Abstraction levels for digital systems • Logic level: operations described as Boolean equations. • Structural elements: gates and interconnections. • Circuit level: differential equations describing the relation between • voltage, current, … • Structural elements: transistors, resistors, capacitors ASPI8-4: DSP Design Methodologies, AAU

15. Meta models : Y-chart and Rugby • Meta model: a model used to describe and analyze other models • Higher level of abstraction ASPI8-4: DSP Design Methodologies, AAU

16. Y-chart • The Y-chart is a representation proposed by Gajski and Khan to capture • specifications domains, abstraction levels and their inter-relation. • Specification domains are represented as three axes (hence the Y) • In each domain the specification can be at different abstraction levels. • The Y-chart tries to capture the relation between design activities • (synthesis activities) such as synthesis, partitioning, … ASPI8-4: DSP Design Methodologies, AAU

17. Domains and Levels of Modeling Functional Structural high level of abstraction low level of abstraction Geometric “Y-chart” by Gajski & Kahn ASPI8-4: DSP Design Methodologies, AAU

18. Domains and Levels of Modeling Functional Structural Algorithm(behavioral) Register-TransferLanguage Boolean Equation Differential Equation Geometric “Y-chart” by Gajski & Kahn ASPI8-4: DSP Design Methodologies, AAU

19. Domains and Levels of Modeling Functional Structural Processor-MemorySwitch Register-Transfer Gate Transistor Geometric “Y-chart” by Gajski & Kahn ASPI8-4: DSP Design Methodologies, AAU

20. Domains and Levels of Modeling Functional Structural Polygons Sticks Standard Cells Floor Plan Geometric “Y-chart” by Gajski & Kahn ASPI8-4: DSP Design Methodologies, AAU

21. Inverted as compared to previous slides ASPI8-4: DSP Design Methodologies, AAU

22. ASPI8-4: DSP Design Methodologies, AAU

23. Design activities ASPI8-4: DSP Design Methodologies, AAU

24. Rugby meta model Axel Jantsch, Shashi Kumar*, Ahmed Hemani Royal Institute of Technology Department of electronics Electronic systems design laboratory Electrum 229 S – 164 40 Kista, Sweden * School of Engineering, Jönköping University, Jönköping, Sweden ASPI8-4: DSP Design Methodologies, AAU

25. Rugby meta model “A conceptual framework, in which designs, design processes and design tools can be studied. The model has similar objectives as the well known Y chart but its scope is extended to handle designs and design processes required for complex systems requiring concurrent processes and mixed HW/SW implementation. The Rugby model has four domains, namely, Computation, Communication, Data and Time. “ Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

26. Rugby meta model “The behavioral domain of the Y chart is replaced with more restricted computation domain. The structural and physical domain of the Y chart are merged into a more generic domain called Communication. The new domains Data and Time have become necessary to model data abstractions used at various levels of design, and to explicitly model timing constraints at various levels in the design process, respectively”. Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

27. Rugby meta model “The Rugby model is able to represent mixed HW/SW designs and design processes for HW/SW codesign at various levels of abstraction. It not only can represent state-of-the-art of current electronic systems and electronic system design automation, but it also points to gaps in the availability of tools and methodologies for designing complex system”. Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

28. Rugby meta model Domain, Hierarchy, and Abstraction: “Abstraction and hierarchy are two different means to handle complexity. Hierarchy partitions a system into smaller parts; abstraction replaces one model with another model which contains significantly less detail and information. Both reduce the amount of information and details that must be considered for a particular purpose. A third way to tackle complexity is the analytical slicing of models into domains. Unlike hierarchy and abstraction it does not lead to physically separate models or parts of a model, but it is an analytical means to study different aspects of a model separately”. Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

29. Rugby meta model Hierarchy: “A hierarchy is a, possibly recursive, partitioning of a design model such, that the details of each part is hidden into a lower hierarchical level. Hierarchy defines the amount of information presented and visible at a particular hierarchical level of a model. At all hierarchy levels the same modelling concepts are used. The motivation for hierarchy is to hide information when it is not needed and to display details when they are useful”. Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

30. Rugby meta model Abstraction: “An abstraction level defines the modelling concepts and their semantics for representing a system. The type of information available at different levels is different. A higher level ignores some irrelevant information at a lower level and encodes it using different concepts. Abstraction defines the type of information present in a model. Unlike hierarchy, abstraction is not concerned with the amount of information visible, but with the semantic principles of a model. In general, the movement from high to low abstraction levels includes a decision making process”. Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

31. Rugby meta model Domain: “A domain is an aspect of a model which can logically be analysed independently from other aspects. A domain focuses on one design aspect. Real models always contain several aspects or domains but different models may emphasize one domain more than another. Models, which focus on one particular domain use modelling notations and constructs to model the design aspect of concern explicitly. Other design aspects may be implicitly part of the models. Whereas hierarchy and abstraction simpli- fies the design, domain partitioning helps the developers of tools and methodologies to cope with the complexity. The domains considered in this article are computation, communication, data, and time.” Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

32. Rugby meta model “While hierarchical partitioning is mostly a manual endeavour, the definition of abstraction levels and transformations between them, is behind most of the advances in design automation. While hierarchy is a general and important concept, it is not explicit in the Rugby model. We assume, hierarchy is possible at all abstraction levels in any domain. The Rugby model is based on these definitions and identifies four domains, computation, communication, time and data, and several abstraction levels for each domain. Hierarchy is not further discussed but we assume, that a model at any abstraction level can have an arbitrary number of hierarchy levels.” Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

33. “The model derives its name from the similarity of its visual representation (see figure 4) to the shape of a Rugby, with the domain lines forming the seams.” Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

34. Axel Jantsch, Shashi Kumar, Ahmed Hemani ASPI8-4: DSP Design Methodologies, AAU

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