ITEA 2 – 09033: TIMMO-2-USE

Timing Model –Tools, algorithms, languages, methodology, USE cases

2012-09-24..25 AMST Workshop - Berlin Slide 1

Modeling timing constraints, parameterized and multi-clock

systems in TADL2

Johan Nordlander, Chalmers University of Technology

System models & constraints

2012-09-24..25 AMST Workshop - Berlin Slide 2

A system model:

Industry objective: specify / characterize / verify models using constraints

logical...

resource usage...

cost...timing...

structural...

TADL2 (Timing Augmented Description Language)

2012-09-24..25 AMST Workshop - Berlin Slide 3

A language of timing constraints (and timing constraints only)

TADL2

Model

ConstraintsConnecting points:the events exposedby a system model

Delay... Periodic...

Events & occurrences

2012-09-24..25 AMST Workshop - Berlin Slide 4

For each execution / simulation / prediction of a system,every event occurs a some points in time.

Model

time

TADL2 constraintsput demands on therelative placementof such occurrences

Source-to-target delay• What if source repeats?• Can multiple target

occurrences match?• Are stray target

occurrences allowed?

The need for semantic precision

2012-09-24..25 AMST Workshop - Berlin Slide 5

• But what about jitter?• What if jitter > period?• What if repetition stops?

• Is jitter meaningful here too?• Same as upper-lower difference?• Accumulating vs. non-accumulating drift?

Some well-known occurrence patterns:

Periodic repetition

Sporadic repetition

DelayConstraint

2012-09-24..25 AMST Workshop - Berlin Slide 6

DelayConstraint (source, target, lower, upper)x source : y target : lower ≤ y – x ≤ upper

time

source

target

lowerupper

duplicate and stray occurrences allowed

StrongDelayConstraint

2012-09-24..25 AMST Workshop - Berlin Slide 7

StrongDelayConstraint (source, target, lower, upper)i : x : x = source(i) y : y = target(i) : lower ≤ y – x ≤ upper

time

source

target

lowerupper

1 2 3

1 2 3

duplicate and stray occurrences disallowed(lock-step enforced)

ReactionConstraint

2012-09-24..25 AMST Workshop - Berlin Slide 8

time

minimummaximum

stimulus

response

scope

ReactionConstraint ( scope, minimum, maximum )x scope.stimulus : y scope.response :

x.color = y.color (y’ scope.response : y’.color = y.color y ≤

y’) minimum ≤ y – x ≤ maximum

only first related response of interest

TADL2 constraint overview

2012-09-24..25 AMST Workshop - Berlin Slide 9

DelayConstraint (source, target, lower, upper)StrongDelayConstraint (source, target, lower, upper)RepetitionConstraint (event, lower, upper, span, jitter)SynchronizationConstraint (event, tolerance)StrongSynchronizationConstraint (event, tolerance)ExecutionTimeConstraint (start, stop, preempt, resume, lower, upper)OrderConstraint (source, target)ComparisonConstraint (leftOperand, rightOperand, operator)SporadicConstraint (event, lower, upper, jitter, minimum)PeriodicConstraint (event, period, jitter, minimum)PatternConstraint (event, period, offset, jitter, minimum)ArbitraryConstraint (event, minimum, maximum)BurstConstraint (event, length, maxOccurrences, minimum)ReactionConstraint (scope, minimum, maximum)AgeConstraint (scope, minimum, maximum)OutputSynchronizationConstraint (scope, tolerance) InputSynchronizationConstraint (scope, tolerance)

+ mode-dependencyparameter (optional)

... but quite ok when restricted to mode M!

M

A mode-dependent DelayConstraint

2012-09-24..25 AMST Workshop - Berlin Slide 10

time

source

target

lowerupper

Not satisfied overall...start(M)

stop(M)

(a mode is defined by its start- and stop-events)

M

A borderline mode-example

2012-09-24..25 AMST Workshop - Berlin Slide 11

time

source

target

lowerupper

start(M)

stop(M)

Should this trace be accepted by the mode-dependent DelayConstraint?

There’s no matchingtarget occurrence inside M...

TADL2 thus chooses to answers yes! (the optimistic assumption)

... but a matching occurrence is stillpossible outside M(where we don’t look!)