Dr. Vered Gafni – Real time systems development by the formal approach 1 The Design Language of Statecharts

Dr. Vered Gafni – Real time systems development by the formal approach 2 The Design Language of Statecharts Finite State Machine R, S, T – States a, b, c, d - Events Arrows - State transitions Event: a, b, c,... a or/and b not a dly(t), tm(a,t) tr(C)/fs(C) Conditions: A, B,... A or/and B not(A) in(S) x=y, x<y,…. Actions: a,b,… tr!(C)/fs!(C) x := v rd!(x) Initial state optional

Dr. Vered Gafni – Real time systems development by the formal approach 3 Examples Split on condition

Dr. Vered Gafni – Real time systems development by the formal approach 4 Sub-States: Sequential Refinement S is a super-state w.r.t {S1, S2, S3 } Super-state transitions (priority) History entrance (H* -deep history)

Dr. Vered Gafni – Real time systems development by the formal approach 5 Example of Sequential Refinement Equivalence up to priorities

Dr. Vered Gafni – Real time systems development by the formal approach 6 Sub-states: Parallel Refinement Events broadcasting

Dr. Vered Gafni – Real time systems development by the formal approach 7 Delay: To turn on the furnace open the oil valve, and after 3 seconds activate ignition Specification of Time Constraints RTC: Execute control loop at 10Hz rate

Dr. Vered Gafni – Real time systems development by the formal approach 8 Delay as Deadline Deadline: Whenever train enters XR, gate should be closed within 10 seconds; otherwise an alarm will be activated

Dr. Vered Gafni – Real time systems development by the formal approach 9 Where Timeout is useful ?

Dr. Vered Gafni – Real time systems development by the formal approach 10 Synchronization Techniques I

Dr. Vered Gafni – Real time systems development by the formal approach 11 Synchronization Techniques II

Dr. Vered Gafni – Real time systems development by the formal approach 12 Synchronization Techniques III

Dr. Vered Gafni – Real time systems development by the formal approach 13 Example: Railroad crossing

Dr. Vered Gafni – Real time systems development by the formal approach 14 Crossing Control: Sequential Design

Dr. Vered Gafni – Real time systems development by the formal approach 15 Crossing Control: Parallel Design

Dr. Vered Gafni – Real time systems development by the formal approach 16 Example: Automatic Cruise Control

Dr. Vered Gafni – Real time systems development by the formal approach 17 Automatic Cruise Control

Dr. Vered Gafni – Real time systems development by the formal approach 18 State Operating (sub-state of Active)

Dr. Vered Gafni – Real time systems development by the formal approach 19 State CommandMonitor (component of Operating)

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Dr. Vered Gafni – Real time systems development by the formal approach 21 Statemate A Real-Time Design Tool Provides for representation of 3 system views: What: - the activities the system should do, and inter-activities data flow When: - the timing and synchronization of activities activation and data transfer Where: - in what subsystem the each activity should be implemented

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Dr. Vered Gafni – Real time systems development by the formal approach 23 Basic Components A A1 A2 A3 C A2_1 A2_2 E1 E2 E3 CC u v w q e f h r x s fff

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