Periodic tasks in Ada

We did this in the previous lecture (under ‘Previous Activity’)

Aperiodic and Sporadic Activities in Ada

Again, covered these definitions in the previous lecture. To clarify; sporadic has a minimum inter-arrival time, otherwise it’s aperiodic.

For Aperiodics in Ada you need a task and a protected object. The protected object holds the trigger event that will trigger the release of the task. Then, the task just:

loop
	Aperiodic_Controller.Wait_For_Next_Interrupt;
	--action
end loop

Where Aperiodic_Controller is a protected object with a boolean variable as the barrier for entry.

Tasks and Events

You can use Tasks, or Events, for doing this sort of thing.

• Tasks are long lived with state, they repeat.
• Events are one-off and have no state.

Interrupts are events.

Timing Events

NEW (apparently). Timing events happen when a defined clock reaches a specified value. This is supported by the Ada.Real_Time.Timing_Events package. Apparently this package is also a good example of how newer packages look in Ada (the style, that is).