Stateflow

before Temporal Logic Operator

The before operator has the following syntax:

• before(n, E)
  

where E is the base event for the before operator and n is one of the following:

• A constant integer greater than 0
• An expression that evaluates to an integer value greater than or equal to 0

The before operator is true if the base event E has occurred less than n times since activation of its associated state. Otherwise, it is false. In a chart with no input events, before(n,wakeup) or before(n,tick) evaluates to true before the chart has woken up n times.

Note    The before operator resets its counter for E to 0 each time the associated state is activated.

The following example illustrates the use of the before operator in a transition expression.

• ROTATION[before(10, CLK)]
  

This expression permits a transition out of the associated state only on occurrence of a ROTATION event but no later than 10 CLK cycles after activation of the state.

The next example illustrates usage of a before event in a state's during action.

• Heater_on
  on before(MAX_ON_TIME, CLK): temp++;
  

This example causes the Heater_on state to increment the temp variable once per CLK cycle until the MAX_ON_TIME limit is reached.

after Temporal Logic Operator

at Temporal Logic Operator