Embedded Software Engineering

Transcription

1 Embedded Software Engineering 3 Unit Course, Spring 2002 EECS Department, UC Berkeley Christoph Kirsch

2 It s significant $4 billion development effort > 50% system integration & validation cost 2002 C. Kirsch -2-

3 It s tricky Mars, July 4, 1997 Lost contact due to embedded software failure 2002 C. Kirsch -3-

4 It s risky French Guyana, June 4, 1996 $800 million embedded software failure 2002 C. Kirsch -4-

5 It s fun 2002 C. Kirsch -5-

6 Problem Man-Machine Interface Instrumentation Interface Operator Real-Time Computer System Controlled Object Kopetz97 Methodologies for the implementation of embedded real-time applications Methodology: tool-supported, abstract, compositional Implementation: compositional, scalable, dependable 2002 C. Kirsch -6-

7 Engine Controller 6000rpm, 10ms for 360º Temporal accuracy of 3µsec Up to 100 concurrent software tasks Hard real-time: no missed deadlines 2002 C. Kirsch -7-

8 Video Streaming 25 frames/sec Dynamic resource allocation Soft real-time: degraded QoS 2002 C. Kirsch -8-

9 Real-Time Systems Characteristics Response time Peak-load performance Control of pace Redundancy Error detection Hard Hard-required Predictable Environment Active Autonomous Soft Soft-desired Degraded Computer Checkpoint User assisted Kopetz C. Kirsch -9-

10 Microcontroller Market Cost Performance 2002 C. Kirsch -10-

11 Mechatronics Drive-by-wire Fly-by-wire 2002 C. Kirsch -11-

12 Embedded Software Engineering Functionality Models Programs Tasks You Solver/Checker Compiler Real-Time Operating System Design Simulation/Verification Execution Scheduling 2002 C. Kirsch -12-

13 Not later than for Time-instant Duration Deadline Time 2002 C. Kirsch -13-

14 Concurrency Task1 Task2 Message1 Host In addition: Other resource constraints Time constraints Network Message C. Kirsch -14-

15 Sequential Programming 1 2 Time 2002 C. Kirsch -15-

16 Multiprogramming Time 2002 C. Kirsch -16-

17 Real-Time Programming Time 2002 C. Kirsch -17-

18 Embedded Software Environment Environment Processes Software Processes Software 2002 C. Kirsch -18-

19 Environment vs. Platform Time Environment Environment Time Platform Time Software 2002 C. Kirsch -19-

20 The Art of Embedded Programming Environment Embedded Programming Software 2002 C. Kirsch -20-

21 Embedded Programming requires the integration of: 1. Real-time operating system concepts 2. Embedded programming languages 3. Embedded compilers 4. SE, modeling, and simulation techniques 5. Formal methods 2002 C. Kirsch -21-

22 Real-Time Task Input f Output Worst case execution time 2002 C. Kirsch -22-

23 Real-Time Scheduling Activation Passive activate Active terminate 2002 C. Kirsch -23-

24 Off-Line Scheduling Table Passive activate Active terminate Static System 2002 C. Kirsch -24-

25 On-Line Scheduling Algorithm Passive activate Active terminate Dynamic System 2002 C. Kirsch -25-

26 Non-Preemptive Scheduling Activation Passive schedule activate Ready Run terminate 2002 C. Kirsch -26-

27 Preemptive Scheduling Activation Passive schedule activate Ready preempt Run terminate 2002 C. Kirsch -27-

28 Shared Resources Activation Passive schedule activate Ready preempt Run terminate free Wait busy 2002 C. Kirsch -28-

29 Scheduling Problem Real-Time Scheduling Soft Hard Off-line On-line Preemptive Non-preemptive Preemptive Non-preemptive 2002 C. Kirsch -29-

30 Earliest Due Date T 1 T 2 T 3 T 4 C i T 5 d i Processors d 1 d 5 d 3 d 4 d 2 Buttazzo97 P 1 T 1 T 5 T 3 T 4 T 2 10 Time 2002 C. Kirsch -30-

31 Earliest Deadline First Tasks T 1 T 2 T 3 T 4 T 5 T 1 a i T 2 T 2 T 3 C i d i T 4 T 4 Buttazzo97 T 5 10 Time 2002 C. Kirsch -31-

32 Real-Time Periodic Task Input f Output Worst case execution time Frequency 2002 C. Kirsch -32-

33 Rate Monotonic Analysis T 1 T 2 C i 2 1 p i 5 10 Tasks T 2 T 2 T 1 T 1 T 1 T 1 10 Time 2002 C. Kirsch -33-

34 Scheduling Anomalies Processors T 1 T 9 T 4 T 5 T 6 T 7 T 8 P 3 T 3 T 6 T 8 P 2 T 2 T 4 T 5 T 7 P 1 T 1 T 9 12 Time 2002 C. Kirsch -34-

35 Shorter Computation Times Processors T 1 T 9 T 4 T 5 T 6 T 7 T 8 P 3 T 3 T 7 P 2 T 2 T 4 T 6 T 9 P 1 T 1 T 5 T 8 13 Time 2002 C. Kirsch -35-

36 More Processors Processors T 1 T 9 T 4 T 5 T 6 T 7 P 4 T 4 T 7 T 8 P 3 T 3 T 6 P 2 T 2 T 5 T 9 P 1 T 1 T 8 15 Time 2002 C. Kirsch -36-

37 Weaker Precedence Processors T 5 T 1 T 9 T 4 T 6 P 3 T 3 T 7 T 6 P 2 T 2 T 4 T 5 P 1 T 1 T 8 T 9 16 Time 2002 C. Kirsch -37-

38 Real-Time Communication Message1 Network Message C. Kirsch -38-

39 Real-Time Message Source m Target Latency 2002 C. Kirsch -39-

40 Explicit Flow Control Message1 Network Send time not known a priori Sender can detect errors Message C. Kirsch -40-

41 Implicit Flow Control Message1 Network Send time is known a priori Receiver can detect errors Message C. Kirsch -41-

42 Explicit Flow Control: Priority Message1 Network Medium-Access Protocols: CSMA/CD - LON, Echelon 1990 CSMA/CA -CAN, Bosch 1990 FTDMA - Byteflight, BMW 2000 TDMA - TTP, Kopetz 1993 Message C. Kirsch -42-

43 Control Area Network Messages M 1 M 2 M M Time 2002 C. Kirsch -43-

44 Implicit Flow Control: Time Message1 Network Medium-Access Protocols: FTDMA - Byteflight, BMW 2000 TDMA - TTP, Kopetz 1993 Message C. Kirsch -44-

45 Time-Triggered Protocol M 1 M 2 Network N 1 M 1 M 2 Time Slot 1 Slot C. Kirsch -45-

46 Literature RT scheduling: Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications. G. Buttazzo. Kluwer, RT communication: Real-Time Systems Design Principles for Distributed Embedded Applications. H. Kopetz. Kluwer, Byteflight, CAN papers C. Kirsch -46-

47 Embedded Programming requires the integration of: 1. Real-time operating system concepts 2. Embedded programming languages 3. Embedded compilers 4. SE, modeling, and simulation techniques 5. Formal methods 2002 C. Kirsch -47-

48 Concurrency Parallel Composition I/O Decomposition Task1 Task2 Task1 Task2 Control Data 2002 C. Kirsch -48-

49 Control Operators Sequential Parallel Choice Loop 2002 C. Kirsch -49-

50 Real-Time Change of state State Function Event Time Frequency Time 2002 C. Kirsch -50-

51 Real World Data Time 2002 C. Kirsch -51-

52 Discrete Data Data d 3 d 2 d 1 d 0 Time 2002 C. Kirsch -52-

53 State Data d 3 d 2 d 1 d 0 State 0 State 1 State 2 Time d 0 d 1 d 1 d 2 d 2 d C. Kirsch -53-

54 Continuous Time Data Start Event Terminating Event t 1 State 1 t 2 Time Interval 2002 C. Kirsch -54-

55 Digital Clock Data Clock 1/(t2-t1) Hz t 1 t 2 Time Granule 2002 C. Kirsch -55-

56 Discrete Time Data t 1 t 2 Time State C. Kirsch -56-

57 Event-Triggered (ET) System Data Change of state Time 2002 C. Kirsch -57-

58 Time-Triggered (TT) System Data Clock tick Time 2002 C. Kirsch -58-

59 Esterel - Giotto Esterel: Synchronous reactive language Event-triggered semantics Giotto: Time-triggered semantics Distributed platforms 2002 C. Kirsch -59-

60 Event - Reaction Event f Reaction 2002 C. Kirsch -60-

61 Esterel: Event Event: emit S await S Time Loop: P loop P each S 2002 C. Kirsch -61-

62 Esterel: Operators Sequential: P Q P ; Q P P Parallel: Choice: Q Q P Q present S then P else Q 2002 C. Kirsch -62-

63 Esterel: Controller module normal: input A, B, R; output O; loop [ await A await B ]; emit O R? R? A?.~R? B?.~R? A?.B?.~R?.O! R? each R end module B?.~R?.O! A?.~R?.O! 2002 C. Kirsch -63-

64 Sensor - Control Law - Actuator Sensors f Actuators 2002 C. Kirsch -64-

65 Giotto: Time Sequential: Task Input Output Time 2002 C. Kirsch -65-

66 Giotto: Operators Sequential: Task Parallel: Choice: Mode Program 2002 C. Kirsch -66-

67 Giotto: Helicopter Control mode normal ( ) period 20ms { taskfreq 1 do servo = Control ( position ) ; taskfreq 4 do position = Navigation ( GPS, position ) ; } 2002 C. Kirsch -67-

68 Semantics Task 50Hz 200Hz msec 2002 C. Kirsch -68-

69 Input Task msec 2002 C. Kirsch -69-

70 Computation Task msec Control Law Navigation Integrator 2002 C. Kirsch -70-

71 Output Task msec 2002 C. Kirsch -71-

72 Literature Esterel: The Foundations of Esterel. G. Berry. In Proof, Language and Interaction: Essays in Honour of Robin Milner. G. Plotkin, C. Stirling and M. Tofte, editors. MIT Press, Synchronous programming of reactive systems. N. Halbwachs. Kluwer, Giotto: Embedded Control Systems Development with Giotto. B. Horowitz, T. Henzinger, C. Kirsch Giotto: A Time-Triggered Language for Embedded Programming. B. Horowitz, T. Henzinger, C. Kirsch C. Kirsch -72-

73 Embedded Programming requires the integration of: 1. Real-time operating system concepts 2. Embedded programming languages 3. Embedded compilers 4. SE, modeling, and simulation techniques 5. Formal methods 2002 C. Kirsch -73-

74 Concurrency Parallel Composition I/O Decomposition Task1 Task2 Task1 Task2 Task1 Task2 ; ; Task2 Task1 Task1 Task2 Task2 Task C. Kirsch -74-

75 Real-Time Task1 ; Task2 Task3 ; Task1 ; Task2 Task1 Event Time Frequency Deadline Time 2002 C. Kirsch -75-

76 Helicopter Control Task 50Hz 200Hz msec 2002 C. Kirsch -76-

77 Read Task msec Input 2002 C. Kirsch -77-

78 Write Task msec Output 2002 C. Kirsch -78-

79 Worst Case Execution Time Task msec Control Law Navigation Integrator 2002 C. Kirsch -79-

80 Deadline Task msec 2002 C. Kirsch -80-

81 Code Task msec 2002 C. Kirsch -81-

82 Literature Some compiler books: Compiler Construction, N. Wirth, Addison-Wesley, Compilers, Principles, Techniques, and Tools. A.V. Aho, R. Sethi, J.D. Ullman. Addison- Wesley, Compiler Design. R. Wilhelm, D. Maurer. Addison- Wesley, C. Kirsch -82-

83 Embedded Programming requires the integration of: 1. Real-time operating system concepts 2. Embedded programming languages 3. Embedded compilers 4. SE, modeling, and simulation techniques 5. Formal methods 2002 C. Kirsch -83-

84 Real-Time Task Input f Output Worst case execution time 2002 C. Kirsch -84-

85 Abstract Data Type Type Interface: Set of methods 2002 C. Kirsch -85-

86 Abstract Interface Empty Interface: Set of methods 2002 C. Kirsch -86-

87 Framework Application-dependent Application-dependent Application-independent 2002 C. Kirsch -87-

88 Type vs. Task Input? Output Interface: Set of methods 2002 C. Kirsch -88-

89 Literature Patterns & Frameworks: Design Patterns: Elements of Reusable Object Oriented Software. E. Gamma, J. Vlissides, R. Johnson, R. Helm. Addison Wesley, Design Patterns for Object-Oriented Software Development. W. Pree, E. Gamma. Addison Wesley, C. Kirsch -89-

90 Embedded Programming requires the integration of: 1. Real-time operating system concepts 2. Embedded programming languages 3. Embedded compilers 4. SE, modeling, and simulation techniques 5. Formal methods 2002 C. Kirsch -90-

91 Formal Verification Property Space Data Time Control Safety Liveness Safety: Wrong things never happen! Liveness: Something useful will happen eventually! 2002 C. Kirsch -91-

92 Language Hierarchy Universal expand Design Macros Non-Deterministic Model Automata synthesize analyze Deterministic Sequential Program compile Executable Code Machine 2002 C. Kirsch -92-

93 E Non-Determinism Sequential Parallel Choice Non-Determinism A Programming Operators Modeling Operator 2002 C. Kirsch -93-

94 Esterel: Verification Model Checking Automata Automata Automata Esterel Abstraction Bisimulation Property Esterel 2002 C. Kirsch -94-

95 Esterel: Hierarchy Design Model Checking compile Model Esterel Executable Bisimulation Non-Det. Automata Deterministic Code Sequential Circuit 2002 C. Kirsch -95-

96 Giotto: Verification Model Checking Masaccio Automata Masaccio Abstraction Refinement Property Giotto 2002 C. Kirsch -96-

97 Giotto: Hierarchy Model Checking expand? Masaccio Hybrid Modules synthesize Refinement Giotto Deterministic Code compile Executable Seq. Stack Machine 2002 C. Kirsch -97-

98 Giotto: Hierarchy given Model-check DESIGN SLDL 1 SLDL SLDL Hierarchical Hybrid Modules MASACCIO REQUIREMENTS ATL Synthesize Refine MODEL CONSTRAINTS Time-Triggered Blocks of C Code Compile PROGRAM GIOTTO GIOTTO-HSC EXECUTABLE RTOS 1 SLDL SLDL HARDWARE SCHEDULER COMMUNICATION 2002 C. Kirsch -98-

99 Literature Esterel: Giotto: T.A. Henzinger. Masaccio: A Formal Model for Embedded Components. LNCS 1872, Springer, 2000, pp C. Kirsch -99-

100 End 2002 C. Kirsch -100-