CD Player Model That Uses Enumerated Data

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Overview of CD Player Model Benefits of Using Enumerated Types in This Model Running the CD Player Model How the UserRequest Chart Works How the CdPlayerModeManager Chart Works How the CdPlayerBehaviorModel Chart Works

Overview of CD Player Model

This Simulink model implements a basic CD player using enumerated data in three Stateflow charts.

Model Component	Description	Details
UserRequest chart	Reads and stores user inputs	How the UserRequest Chart Works
CdPlayerModeManager chart	Determines whether the CD player operates in CD or radio mode	How the CdPlayerModeManager Chart Works
CdPlayerBehaviorModel chart	Describes behavior of the CD player mechanism	How the CdPlayerBehaviorModel Chart Works

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Benefits of Using Enumerated Types in This Model

This model uses two enumerated data types: RadioRequestMode and CdRequestMode.

Enumerated Data Type	Enumerated Values
RadioRequestMode	OFF(0) CD(1) FM(2) AM(3)
CdRequestMode	EMPTY(-2) DISCINSERT(-1) STOP(0) PLAY(1) REW(3) FF(4) EJECT(5)

By grouping related values into separate data types, you get these benefits:

• Enhance readability of data values in each chart.

• Avoid defining a long list of constants, which reduces the amount of data in your model.

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Running the CD Player Model

Follow these steps to run the model:

1. Type sf_cdplayer at the MATLAB command prompt.

2. Start simulation of the model.

   The CD Player Helper GUI appears.

   

   The Display blocks in the model show the default settings of the CD player.

   

3. In the CD Player Helper GUI, click CD in the Radio Request section.

   The Display blocks for enumerated data RR and CurrentRadioMode change from OFF to CD.

4. In the CD Player Helper GUI, click Insert Disc.

   The Display block for enumerated data CdStatus changes from EMPTY to DISCINSERT to STOP.

5. In the CD Player Helper GUI, click PLAY in the CD Request section.

   The Display blocks for enumerated data CR, MechCmd, and CdStatus change from STOP to PLAY.

Note   To see other changes in the Display blocks, you can select other operating modes for the CD player, such as FM or AM radio.

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How the UserRequest Chart Works

Key features of the UserRequest chart include:

• Enumerated data

• ml namespace operator (see ml Namespace Operator)

This chart reads user inputs from the CD Player Helper GUI and stores the information as output data.

Output Data Name	Data Type	Description
RR	Enumerated	Operating mode of the radio component
CR	Enumerated	Operating mode of the CD component
DiscInsert	Boolean	Setting for CD insertion
DiscEject	Boolean	Setting for CD ejection

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How the CdPlayerModeManager Chart Works

Key features of the CdPlayerModeManager chart include:

• Enumerated data

• Subcharts (see Using Subcharts to Encapsulate Modal Logic)

• Change detection (see Detecting Changes in Data Values)

Behavior of the CdPlayerModeManager Chart

1. When the chart wakes up, the ModeManager state is entered.

2. The previously active substate recorded by the history junction becomes active: Standby or ON.

   Note   Transitions between the Standby and ON substates occur as follows. If the enumerated data RadioReq is OFF, the Standby substate is entered. If the enumerated data RadioReq is not OFF, the ON substate is entered. (For details, see Control of CD Player Operating Mode.)

3. If the Boolean data DiscEject is 1 (or true), a transition to the Eject state occurs, followed by a transition back to the ModeManager state.

4. Steps 2 and 3 repeat until the chart goes to sleep.

Control of CD Player Operating Mode

In the ON substate, three subcharts represent the operating modes of a CD player: CD, AM radio, and FM radio. Each subchart corresponds to a different value of enumerated data RadioReq.

Value of Enumerated Data RadioReq	Active Subchart	Purpose of Subchart
CD	CDMode	Outputs play, rewind, fast forward, and stop commands to the CdPlayerBehaviorModel chart
AM	AMMode	Sets the CD player to AM radio mode
FM	FMMode	Sets the CD player to FM radio mode

The hasChanged operator detects changes in the value of RadioReq with an inner transition.

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How the CdPlayerBehaviorModel Chart Works

Key features of the CdPlayerBehaviorModel chart include:

• Enumerated data

• Temporal logic (see Using Temporal Logic in State Actions and Transitions)

Behavior of the CdPlayerBehaviorModel Chart

1. When the chart wakes up, the Empty state is entered.

2. If the Boolean data DiscInsert is 1 (or true), a transition to the Inserting state occurs.

3. After a short time delay, a transition to the DiscPresent state occurs.

4. The DiscPresent state remains active until the data CMD becomes EJECT.

5. If the enumerated data CMD is EJECT, a transition to the Ejecting state occurs.

6. After a short time delay, a transition to the Empty state occurs.

7. Steps 2 through 6 repeat until the chart goes to sleep.

Update of CD Player Behavior

Whenever a state transition occurs, the enumerated data CdStatus changes value to reflect the behavior of the CD player.

Active State	Value of Enumerated Data CdStatus	Behavior of CD Player
Empty	EMPTY	CD player is empty.
Inserting	DISCINSERT	CD is being inserted into the player.
DiscPresent.STOP	STOP	CD is present and stopped.
DiscPresent.PLAY	PLAY	CD is present and playing.
DiscPresent.REW	REW	CD is present and rewinding.
DiscPresent.FF	FF	CD is present and fast forwarding.
Ejecting	EJECT	CD is being ejected from the player.

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Best Practices for Using Enumerated Data in a Chart

Tutorial: Using Enumerated Values for Assignment

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