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I have been using State machine based design tools for some time, and have seen UML modeling tools that allow you to execute your logic (call functions, do other stuff) inside a state. However, after spending a couple days with IAR VisualState, it appears that you cannot execute your logic inside a state without a trigger. I am confused as it does not make sense TO HAVE A TRIGGER for every single action inside a state !

Here is what I expect from a state chart tool: If I enter StateA, upon entering the state I set my values in entry section, then I would like to call a function (I just want to call it, NO TRIGGER), and inside that function, I want to trigger an event based on some logic, and that event would trigget state transition from StateA to StateB or StateC.

Is there something wrong with this expectation? Is it possible in VisualSTATE?

Help is greatly appreciated.

Dave Clemmer
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Rob
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2 Answers2

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VisualSTATE imposes the event-driven paradigm, just like any Graphical User Interface program. Anything and everything that happens in such systems is triggered by an event. The system then responds by performing actions (computation) and possibly by changing the state (state transition).

Probably the most difficult aspect of event-driven systems is the inversion of control, that is, your (state machine) code is called only when there is an event to process. Otherwise, your code is not even active. This means that you are not in control, the events are. Your job is to respond to events.

Perhaps before you play with visualSTATE, you could pick up any book on GUI programming for Windows (Visual Basic is a good starting point) and build a couple of event-driven applications. After you do this, the philosophy behind visualSTATE will become much clearer.

Miro Samek
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  • thank you. Dont need a book though, different philosophy, not a good fit for my work. – Rob Jun 05 '11 at 18:21
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Create 3 states: A, B, C where state A is a default state. By entering state A, call action function [that sets you variables a and b following some algorithm], followed by ^Signal1.

Entry/ action()^Signal1

Make a transition driven by Signal1 [will serve you as an event] from state A with 2 guards:

a <= b, transition to state C

a > b, transition to state B

madth3
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Leonid
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