VariableClock
ptolemy.actor.lib.VariableClock

This actor is identical to Clock except that it has an additional input port, periodControl. If this port has a token when the actor fires, then the value read from that port is used to set the parameter value. The initial value of the period parameter is used before any input is observed on periodControl.

This actor can be fairly tricky to use with multiple values and offsets because of the constraint that all offsets must be less than the period. Thus, the default values and offsets are different from those of the base class. The output value, by default, is just the constant integer 1, and the offset is 0.0. The default value of period is changed to 1.0. This gives a very simply behavior, where the output is always the same, but the time between outputs is controlled by the periodControl input.

In some domains, such as DE, an input at periodControl is sufficient to trigger a firing. This can be somewhat counterintuitive, since an output from the clock may not be expected at that time. To avoid this, simple ensure that events at periodControl arrive only at times when an output is expected.

Author(s): Edward A. Lee
Version:$Id: VariableClock.java,v 1.29 2005/07/08 19:56:11 cxh Exp $
Pt.Proposed Rating:Yellow (eal)
Pt.Accepted Rating:Yellow (yuhong)


periodControl
The port that controls the value of the period parameter.