嵌入式系统导论-实验课-3-Exercise.pdfVIP

Institut für Technische Informatik und Kommunikationsnetze Kai Huang Introduction to Embedded Systems Exercise Sheet 3 Issue Date: 07.11. 2014 1.1 StateCharts The lecture has introduced Harel’s StateChart formalism. StateCharts are a popular specification model for embedded systems. 1.1.a) Advantages of StateCharts What are the most important extensions of the StateChart model in comparison to an ordinary finite state machine (FSM)? 1.1.b) Disadvantages of StateCharts What are the disadvantages of the StateChart formalism? 1.1.c) Tree of states for StateChart Given the StateChart in Figure 1. Draw the state space of the StateChart as a tree, which shows the hierarchy CB e d a/c ec b[D2] A 1 2 G D1 D D2 Figure 1: StateChart of states and denotes the state types (basic state, sequential states, and parallel states). 1.1.d) Formal computation of state space How would you formally compute the set of states? Compute the set of states for the hierarchical automata which is defined by the StateChart from Fig. 1. 1.1.e) Analysis The automaton defined by the StateChart from Fig. 1 passes through a number of states, when external events are applied. Show the sequence of state that are passed through, starting from the initial state, for the following sequence of events: a,b,e,b,d,b. Use a table notation. 1.1.f) Conversion of StateChart to a finite state machine (FSM) Draw a finite state machine which is equivalent to the StateChart from Fig. 1. Minimize the number of states. 1.1.g) StateChart model of a vending machine The StateChart model of a simplified vending machine is shown in Figure 2. 1 A2 A1 D 0 A C 1 B Trigger: req_coffee Action: start_coffee Trigger: reset Trigger: ok Trigger: drink_ready Action: done Trigger: drink_ready Action: done Trigger: req_tea Action: start_tea Trigger: coin_in Action: ok Trigger: done Trigger: cancel reset Action: coin_out; drink_ready req_coffee cancel coin_in req_tea coin_out start_tea start_coffee from the environment Input events to th