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Application Specific Systems Design and Prototyping

Application Specific Systems Design and Prototyping. Luigi Carro Universidade Federal do Rio Grande do Sul Departamento de Engenharia Elétrica Agosto 1998 carro@iee.ufrgs.br. Synthesis of dedicated architectures. HW is not the only problem “what if” questions open specifications

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Application Specific Systems Design and Prototyping

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  1. Application Specific Systems Design and Prototyping Luigi Carro Universidade Federal do Rio Grande do Sul Departamento de Engenharia Elétrica Agosto 1998 carro@iee.ufrgs.br

  2. Synthesis of dedicated architectures • HW is not the only problem • “what if” questions • open specifications • Application specific processor • tuned to application • reprogrammable • microarchitecture level • High Level Language level

  3. Application Specific processors • Speed increase with VLIW organization • area and power savings: only useful instructions are implemented • costs reduction by integration of the system Problem: application software Contradiction: it is easy to make HW, not SW

  4. Application Specific Processors II • Retargetable compilers • try to generate an efficient compiler from HW architectural specifications • bottom up approach • who defines the architecture? • Application and architecture are studied separately • how efficient is the compiler in using the extra added features?

  5. Automatic Synthesis of HW and SW • Possible in specific niches • co-operating FSMs • modem? • SDL • Siera • operating system like framework • complex applications: mechanical arms • There is a need for communication synthesis

  6. HW functions HW-SW codesign based on ASIPs memory processor • Asip based designs • without and without core-processor • application program analysis dictates instruction set • compiler must be created afterwards

  7. ASIP design process

  8. Core-processor HW-SW codesign

  9. Core processor based HW-SW codesign II • Critical program segments are converted to HW • the instruction set is not altered • the compiler is the same, and calls to specific HW functions must be made

  10. Outline of the course • Problem modeling, hardware modeling. • Configurable HW families • Application Specific System Design Tools • Case Studies • Microcontroller ASIPs • Special Embedded compilers • Conclusion

  11. MbSG tool

  12. MbSG tool • Based on Risc microprocessor

  13. MbSG design flow

  14. MbSG optimizations I

  15. MbSG optimizations II Not all problems have arithmetic behavior control flow breaks pipeline

  16. MbSG optimizations III Data driven optimizations HW function and processor should work in parallel

  17. MbSG optimizations IV

  18. MbSG and other approaches • New compiler is not needed • optimizations developed at the instruction level • instead of complex partitioning, program classification • MbSG is in the middle of core based design space

  19. MbSG and other approaches

  20. MbSG results

  21. Application Specific Microcontroller • Microcontrollers play a main role in present days Brazilian electronic systems industry • Embedded control and automation system are equipped wiht the 8051 or DSP architectures • to create new developments, those systems requires mainly, SW availability and mantainability.

  22. Application Specific Microcontroller • Low cost in small and medium Industries must be achieved even with with a small number of parts per year, 10 thousand or less • Old architectures like the 8051 are still largely used in the worldwide industry, because they have: • low cost; • large number of engineers trained to use them; • low cost SW available.

  23. Application Specific Microcontroller • These architectures can be changed, and this is justified in: • an application where speed is premium; or • in the complete integration of a system • In order to integrate the system, we removed some instructions of the 8051 instruction-set that were never used for specific applications. • This change the original CISC architecture to a RISC approach, and gave us area by eliminating the decoders of that instructions. • the saved area can be used to integrate the system

  24. Application Specific Microcontroller • Two applications were tested: • motor vector control; and • a Profibus protocol for field-bus. • Each program was analyzed statically (assembly source) and dynamically (really executed instructions).

  25. Instruction usage analysis • Groups of often used instructions for the induction motor control

  26. Static analysis

  27. Dynamic analysis

  28. Area savings

  29. The pipelined version of the 8051 • The necessity of pipeline comes from the idea that not all instructions will be implemented: • RISC codes are greater than the CISC ones and pipeline serves to compensate this gap in terms of instruction speed execution; • Pipeline was applied in most used instructions and one special C compiler able to use only these instructions was developed

  30. Pipeline cycles

  31. Synthesis results

  32. The optimized C compiler • CCC51 - C Cross Compiler to MCS8051 was optimized to work with a reduced instruction set. • The compiler will generate only a few different instructions and will try to avoid breaking the pipeline

  33. Optimizations • Three CCC51otimized versions were created: • CCC51 - I: operand address modes and system stack optimization. Jump instructions that broke the pipeline were replaced by equivalents jumps instructions; • CCC51 - II: replaces of some instructions types, include 3 bytes instructions that broke the pipeline. Ex: MOV direct, direct; • CCC51 - III: replaces MOV instructions which did not have accumulator as one of the operands.

  34. Number of needed instructions

  35. Number of Different instructions

  36. Photo of the board

  37. Outline of the course • Problem modeling, hardware modeling. • Configurable HW families • Application Specific System Design Tools • Case Studies • Microcontroller ASIPs • Special Embedded compilers • Conclusion

  38. Conclusions I - doubts • There is still not available a consolidated design methodology for application specific systems • Design methodology should support: • executable specification • allow SW and HW reuse • allow fast technological migration • Importance of IP is increasing • where is the added value • SW development will dominate designs

  39. Conclusion II - more doubts • Will HW-SW codesign be a commercial reality? • Is dedicated HW-SW synthesis really needed? • Most examples claim processor is idle, and so? • Will configurable devices be a real option for future designs based on unseen applications? • Will CAD support fast configurability, so that SW=HW?

  40. Time for lunch! • To follow: • there will be exciting new developments to be studied • system design is a really open issue For more: carro@iee.ufrgs.br until Friday, around here

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