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SIMOOA: Object-Oriented Design and Simulation Platform for Embedded Electronic Systems and Real-Time Automation Systems

SIMOOA is a platform that provides object-oriented modeling and simulation for embedded electronic systems and real-time automation systems. It supports multiparadigm modeling, visual interactive simulation, and co-simulation. The platform includes features for hardware-software co-design, graphical description of system structure, behavior modeling in C++ or state diagrams, and design of real-time automation systems.

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SIMOOA: Object-Oriented Design and Simulation Platform for Embedded Electronic Systems and Real-Time Automation Systems

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  1. SIMOOA Platform for Object-Oriented Design and Simulation of Embedded Electronic Systems and Real-Time Automation Systems Flávio R. Wagner Universidade Federal do Rio Grande do Sul Porto Alegre, Brazil Paderborn, 4th November 1999 UFRGS

  2. Outline UFRGS 1. Introduction 2. Basic modeling and simulation infra-structure 3. Hardware-software co-design methodology 4. Co-simulation infra-structure 5. Embedded electronic systems 6. Real-time automation systems 7. Final remarks

  3. SIMOO main features 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • object-oriented modeling and simulation of discrete systems • multiparadigm modeling • visual interactive simulation • graphical description of the static structure • behavior described in C++ or state diagrams annotated with C++

  4. Design of embedded electronic systems 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • goal: control of physical processes and equipments • architecture • analog and digital hardware • off-the-shelf or dedicated processors • software • requirements for a design environment • appropriate specification mechanisms for various abstraction levels • stepwise refinement process • co-simulation

  5. Design of real-time automation systems 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • goal: control of physical processes • architecture • distributed system • off-the-shelf microcontrollers or microprocessors • real-time operating system • real-time constraints • analog interfaces • software • requirements for a design environment • appropriate specification mechanisms for various abstraction levels • stepwise refinement process • co-simulation

  6. Multiparadigm modeling and simulation 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • each class may have a different modeling paradigm • modeling paradigms are obtained by combining approaches for different modeling aspects • client or server perspective • behavior described by event-orientation or process-orientation • communication by messages or ports • active, semi-active or passive handling of messages • other simulation packages or languages usually ... • offer a single or limited repertory of paradigms • do not allow a combination of paradigms in the same model • SIMOO approach enhances the reusability of models and classes

  7. Autonomous and interface objects 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • autonomous objects • correspond to the entities of the model logic • each object has ist own execution thread • do not support shared variables • communication through messages • interface objects • visualization of results • data collection • interactive input of data • share a single thread

  8. Software architecture 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks Model Editor Tool C++ code executable code compiler library of autonomous objects SIMOO class library

  9. Model Editor Tool 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • supports construction of hierarchical object-oriented models • models defined by hierarchical class diagrams and instance diagrams • simulation-specific features: modeling paradigms • access to user-defined class library • class diagrams • relationships: inheritance, aggregation, acquaintance • instance diagrams • concrete instantiation of the class diagram • gives concrete values to n-to-m relationships and to class parameters

  10. Example of diagrams 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  11. MET - Describing behavior in C++ 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  12. MET - State diagrams 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  13. MET - State diagrams 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  14. User interface 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • default user interface automatically added to all models • specific user interface built by interface objects • separation between model logic and user interface • autonomous objects x interface objects • increased reusability of autonomous and interface objects • easier debugging of the model logic • tool-oriented approach • dynamic mapping from interface to autonomous objects • help verification and validation of models and closer inspection of desired model aspects • a monitor controls the mappings • intercepts messages that modify attributes of autonomous objects and sends copies to corresponding interface objects

  15. Basic user interface 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • tracking variables • modifying values of variables • querying the model structure • modifying the model structure • replacing methods that respond to messages • creating and removing objects • modifying mappings from interface objects to autonomous objects • querying and modifying the event list • time-stepping, stopping, resuming, setting breakpoints

  16. Future work 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • synchronization between objects • current version: conservative protocol • future: more optimistic protocol • distributed version • current version: objects already have their own execution threads • distributed platform yet to define • first prototype based on Java RMI is being implemented

  17. Basic design methodology 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • initial specification • abstract behavior • C++ or state diagrams annotated with C++ • objects corresponding to the physical world may be modeled by a continuous behavior • validation by simulation • design proceeds through a stepwise refinement • hierarchical refinement: same abstraction level • abstraction refinement: design decisions are taken • abstract objects are mapped into objects of a target architecture • digital or analog hardware, software

  18. Target architectures 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • 1 or more processors • off-the-shelf microprocessors • DSPs, RISCs, microcontrollers • ASIPs • specialized digital hardware • FPGAs • ASICs • analog hardware • DA and AD converters • sensors and actuators • software running on top of the chosen processor(s)

  19. Library-based synthesis 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • selection of hardware objects from a previously built library of classes for the possible target architectures • software objects may be automatically generated from the abstract specification • from C to assembly languages of the selected processors • hardware objects must be described in an appropriate language (VHDL)

  20. Conclusions 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • this methodology applies both to ... • embedded electronic systems • real-time automation systems • target architectures are similar • distributed systems containing analog and digital hardware parts, processors, software • specializations are necessary • in the target architecture • in the design methodology • co-simulation is necessary • future work: hardware-in-the-loop

  21. Co-simulation requirements 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • co-simulation for the validation of the initial specification • discrete behavior - algorithms or state diagrams • continuous behavior - physical world • co-simulation for the validation of possible implementations • discrete behavior - algorithms or state diagrams • for parts that have not been refined yet • for software parts • continuous behavior • for the physical world • for analog hardware • VHDL • for digital hardware

  22. Coupling SIMOO and VHDL 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  23. Coupling SIMOO and VHDL 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks SIMOO simulator VHDL simulator

  24. Coupling SIMOO and VHDL 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • interfaces in both domains are automatically generated • C-file in the VHDL domain • interface object in the SIMOO domain • interfaces are responsible for ... • communication - exchange of data and format conversion • synchronization between simulators • conservative approach • communication between simulators by sockets • distributed simulation is possible • SIMOO currently runs on Windows • VSS runs on Unix workstations

  25. Hybrid discrete-continuous simulation 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • objects with analog behavior • modeled by a set of differential equations • implement the numerical integration method • object attribute defines integration time step • signal-flow approach • mathematical functions from inputs to outputs • appropriate for objects that ... • don´t have a physical implementation yet • model the physical world • are modeled at a higher abstraction level than basic components (PID controllers, converters, filters)

  26. Hybrid discrete-continuous simulation 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • current situation • differential equations directly described in C++ • integration time step must be defined by the programmer • scheduling the execution of analog objects • if there are more than one AO and they communicate with each other, they must be scheduled at each time step and exchange messages • if not, an AO may be scheduled at intervals that depend on the discrete objects and then execute several integration steps • future work • better time advancement mechanism, including automatic time step definition • integration with Matlab / Simulink

  27. Design methodology 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • object-oriented specification • stepwise refinement • co-simulation combining C++, VHDL, analog behavior • synthesis to a multiprocessor platform • each object or group of objects may be mapped to a different processor

  28. Example: crane 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • benchmark for specification of heterogeneous systems • physical plant: crane with a load, moving along a track • control • assures smooth movement, without bumps and oscillations • verifies if displacement does not exceed limits and if angle of the load is acceptable (emergency break) • auto-test of sensors

  29. First modeling of the crane 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks physical plant controls car movement, sensor checking, output forces to Actuators drives the dc motor (speed), control breaks and emergency break checks plausibility of car position and load angle

  30. First modeling of the crane 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • physical plant Plant_rk is an object with continuous behavior • all other objects have discrete behavior • M_Control combines two computation models • control algorithm for movement is a discrete computation of the state-variable method q n+1=A*q n + B*[Motor_Voltage Car_Position]T at each 10 ms • sensor checking is an FSM • Diagnosis is an FSM • Actuators is an algorithm

  31. Second modeling of the crane 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks M_Control split into two objects FSM for sensor checking main control algorithm, arithmetic operations

  32. Third modeling of the crane 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks FSMs (Job_Control and Diagnosis) merged into a single object to be implemented as digital hardware and modeled in VHDL

  33. Library of processors 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • processors are characterized by attributes size of binary word types of instructions memory operand addressing modes execution time (in clock cycles) of each instruction number of busses to access memory type of memory number of registers use of pipeline and depth of eventual pipeline use of harvard architecture • current library: C25, 8051, RISCO

  34. Characterizing the application 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks application is characterized as: - data-dominated - memory-dominated - control-dominated C++ CDFG machine- independent 3-address code M P APP = APM = P + M + C P + M + C C APC = P + M + C

  35. Selecting the processor 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • performance profiles measure, for the given application, the relative cost of the processor for each aspect (data, control, memory) • selection algorithm weighs the performance profiles and chooses the processor best suited for the application Pi PPPi = Pi + Mi + Ci Mi PPMi = Pi + Mi + Ci Ci PPCi = Pi + Mi + Ci

  36. Future work 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • selection of processors considering a multi-dimensional space of aspects • cost, area, power consumption, performance • automatic algorithm for exploring various partitionings of objects into processors • library-based synthesis of communication • map abstract communication mechanisms of SIMOO (ports, messages) to busses and channels • measure communication costs • select communication protocol according to application requirements

  37. Introduction 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • SIMOO used as a front-end • extensions for the specification of real-time constraints • back-end is AO/C++, an extension of C++ adapted for real-time systems • target architecture is a distributed system composed of low-cost microcontrollers connected by an industrial bus • methodology for the transition from the simulation model to the implementation code

  38. cyclic methods Extensions in the specification 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  39. timed methods (deadline) default value for the deadline Extensions in the specification 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  40. code for handling exceptions Extensions in the specification 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  41. AO/C++ target language 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • combines OO properties of C++ with benefits of Unix-RTOS • maps logically distributed OO model of C++ to physically distributed process-oriented model of Unix-RTOS • primitives added to C++ • definition of active objects (own execution thread) • time-triggered methods • timing constraints (deadlines, cyclic operations, exception handling code) • AO/C++ programs are parsed and converted to standard C++ with calls to the underlying run-time environment (Unix-RTOS)

  42. Example 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks

  43. Example 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks physical plant cyclic method for sampling timed method for activating the pump

  44. Example 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks physical plant cyclic method for sampling timed method for activating the pump interface objects are mapped to these autonomous objects

  45. Generating the implementation model 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • simulation model must be transformed into a model which is amenable for the physical implementation • objects corresponding to the physical plant are removed • objects corresponding to physical interfaces from the controlling host to the physical plant must be inserted • interface objects are replaced by autonomous objects • messages between objects are modified according to the AO/C++ communication paradigm • in the example • SIMOO / Windows 2690 lines • AO/C++ 730 lines • C++ / QNX 2310 lines

  46. Example 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks physical interfaces

  47. Example 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks interfaceobjects

  48. Future work 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • more automatic generation of the implementation model • automatic generation of the supervisory system • user interface in the simulation model is automatically transformed into the supervisory system • hardware-in-the-loop • smooth transition from the simulation model to the implementation • selective replacement of simulation objects by physical objects • user interface is maintained

  49. Conclusions 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • SIMOO is used as a high-level modeling and verification front-end • back-ends for two different application fields • embedded electronic systems • real-time automation systems • co-simulation: SIMOO is used as a seamless environment for both high-level design and implementation • stepwise refinement: progressive replacement of abstract descriptions by implementation descriptions

  50. Future work 1 Introduction 2 SIMOO 3 Hw-Sw codesign 4 Co-simulation 5 Embedded systems 6 Real-time automation 7 Final remarks • basic simulation infra-structure • optimize the hybrid simulation mechanisms • distributed simulation with an optimistic protocol • embedded electronic systems • communication synthesis • find optimal selection algorithms • explore partitioning of objects into processors • model larger examples where multiprocessor platforms are needed • real-time automation systems • automatic generation of the supervisory systems • hardware-in-the-loop: progressive replacement of simulation objects by physical objects

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