Stateflow

Create the Model and Stateflow Diagram

To learn how to debug some typical run-time errors, create the following Simulink model and Stateflow diagram:

Using the graphics editor Add menu, add the Switch Input from Simulink event and the Shift Input from Simulink data object.

The Stateflow diagram has two states at the highest level in the hierarchy, Power_off and Power_on. By default Power_off is active. The event Switch toggles the system between the Power_off and Power_on states. Switch is defined as an Input from Simulink event. Power_on has three substates, First, Second, and Third. By default, when Power_on becomes active, First also becomes active. Shift is defined as an Input from Simulink data object. When Shift equals 1, the system transitions from First to Second, Second to Third, Third to First, and then the pattern repeats.

In the Simulink model, there is an event input and a data input. A Sine wave block is used to generate a repeating input event that corresponds with the Stateflow event Switch. The Step block is used to generate a repeating pattern of 1 and 0 that corresponds with the Stateflow data object Shift. Ideally, the Switch event occurs in a frequency that allows at least one cycle through First, Second, and Third.

Define the sfun Target

Choose Open Simulation Target from the Tools menu of the graphics editor. Ensure that Enable Debugging/Animation is enabled (checked). Click Close to apply the changes and close the dialog box.

Invoke the Debugger and Choose Debugging Options

Choose Debug from the Tools menu of the graphics editor. Click the Chart entry option under the Break Controls border. When the simulation begins, execution halts on entry into the chart. Click Enabled under the Animation border to turn animation on.

Start the Simulation

Click the Start button to start the simulation. Informational messages are displayed in the MATLAB Command Window. The graphics editor toolbar and menus change appearance to indicate a read-only interface. The Stateflow diagram is parsed, the code is generated, and the target is built. Because you specified a breakpoint on chart entry, the execution stops at that point and the Debugger display status indicates the following.

Stopped: Just after entering during function of Chart debug__power

Executing: sf_debug_ex_debug_power

Current Event: Input event Switch

Debug the Simulation Execution

At this point, you can single-step through the simulation and see whether the behavior is what you expect. Click the Step button and watch the Stateflow diagram animation and the Debugger status area to see the sequence of execution.

Single-stepping shows that the desired behavior is not occurring. The transitions from Power_on.First to Power_on.Second, etc., are not occurring because the transition from Power_on to Power_off takes priority. The output display of code coverage also confirms this observation.

Resolve Run-Time Error and Repeat

Choose Stop from the Simulation menu of the graphics editor. The Stateflow diagram is now writeable. The generation of event Switch is driving the simulation and the simulation time is passing too quickly for the input data object Shift to have an effect. The model might need to be completely rethought.

In the meantime, there is a test that verifies the conclusion. Modify the transition from Power_on to Power_off to include a condition. The transition is not to be taken until simulation time is greater than 10.0. Make this modification and click the Start button to start the simulation again. Repeat the debugging single-stepping and observe the behavior.

Debugged Stateflow Diagram

This is the corrected Stateflow diagram with the condition added to the transition from Power_on to Power_off.

Debugging Run-Time Errors Example

Debugging State Inconsistencies