Software modeling for embedded systems static and dynamic

Software modeling for embedded systems: static and dynamic behavior

Important concepts in embedded systems: --concurrency: the system can handle multiple active independent or cooperating objects at the same time --thread [of control]—models sequential execution of a set of instructions; embedded system may have several concurrent threads operating simultaneously --persistence—how long does a software object last? Examples: Temporary variable Global variable Software module

Recall: “UML” syntax can vary among implementations; table_05_00 Previously we looked at one implementation, here we consider examples from the text

UML: Use case diagram (graphical) fig_05_00

UML Use case diagram--example fig_05_01

UML: Use case diagram (text); note exceptions fig_05_02

UML—static modeling

UML: Class diagram (“CRC card”) Class name data Methods (responsibilities and collaborators) (+ collaborators) fig_05_03

UML: class relationships: inheritance fig_05_04

UML: “interface”—similar to inheritance but different public appearance Hidden operation fig_05_05

UML: containment of one class within another Type 1: aggregation—statistical analysis has a number of algorithm “parts” fig_05_06

UML: containment of one class within another Type 2: composition—here the intervals are meaningless outside the schedule (~ “local variables”) fig_05_07

UML—dynamic modeling

UML: interaction diagram—call and return fig_05_08

UML: interaction diagram—create and destroy fig_05_09

UML: interaction diagram—send (no response expected) fig_05_10

UML: sequence diagram: sequence of actions; carries out a use case fig_05_11

UML sequence diagram--example fig_05_12

UML: concurrent behavior. Example: fork and join fig_05_13

UML: concurrent behavior. Example: branch and merge fig_05_14

UML activity diagram—captures all actions and control flows within a task fig_05_15

UML state machine models--4 types of events: UML state chart is a directed graph fig_05_16

UML state chart: types of transitions initial state final state fig_05_18

UML state chart: actions and guard conditions If guard condition is false, transition does not happen fig_05_19

UML: can decompose state into sequential substates fig_05_20

UML: can define a “history” state (e. g. , for an interrupt)— system will probably eventually return to this state fig_05_21

UML: can have concurrent substates fig_05_22

UML is a tool for a structured design methodology It helps manage the design and development process We can also look at modifying / refining the PROCESS itself CMM : capability maturity model-defines level of the development process itself 1. Initial: ad hoc 2. Repeatable: basic project management processes in place 3. Defined: documented process integrated into an organization-wide software process 4. Managed: detailed measures are collected 5. Optimizing--desired level: Continuous process improvement from quantitative feedback

Another methodology: control flow and data flow diagrams (Note: in a processor we usually have a data path and a control path) fig_05_23

Control and data flow diagrams: tasks (with hierarchy levels) fig_05_24

Control and data flow diagrams: Data sources and sinks fig_05_25

Control and data flow diagrams: Data stores fig_05_26

Control and data flow diagrams: Example fig_05_27

Control and data flow diagrams: Hierarchical view of an input / output task fig_05_28