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6-6
Controlling the Fitting Process Using the .pi File
If a PLA such as the S6001 is the target device, PLSyn will use
only 60 of the 64 product terms.
Fitting a Node as an
OUTPUT or NODE
To control whether a node is fit as an OUTPUT or
as a NODE
1
Use the FIT_AS_OUTPUT property.
FIT_AS_OUTPUT has no effect on output signals, which are
already destined to be fit on a visible output pin of a device. For
node signals, this property alerts the PLSyn fitter to place this
node signal on an output pin.
Controlling How Signals
Are Fit Together
Early in the fitting process, the PLSyn decides which signals to
fit together as one inseparable block of functionality. For PLDs,
this means signals are fit in the same output macrocell. Signals
can be fit together if a NODE is the only signal feeding another
NODE or OUTPUT that has no register or latch equations.
To control how signals are fit
1
Use the NO_COLLAPSE and FIT_WITH properties.
NO_COLLAPSE The NO_COLLAPSE property tells
PLSyn to fit this signal individually, separate from the fitting of
any other signal.