User`s guide

14
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18 Di
g
ital Simulation
Usin
g
the FILESTIM Device
FILESTIM has a single pin for connection to the rest of the
circuit. The digital stimulus specification must be defined in an
external file. Using this technique, stimulus definitions can be
created from scratch or extracted with little modification from
another simulation’s output file.
Table 14-3
lists the attributes of the FILESTIM part. The
IO_MODEL, IO_LEVEL, and IPIN attributes describing this
part’s I/O characteristics are provided with default values that
rarely need modification. However, the FILENAME attribute
must be defined with the name of the external file containing the
digital stimulus specification.
The SIGNAME attribute specifies the name of the signal inside
the stimulus file which is to be output by the FILESTIM part. If
left undefined, the name of the connected net (generally a
labeled wire) determines which signal is used.
For example, a FILESTIM part can be used to reset a counter
which could appear as shown in Figure 14-1.
In this case, the FILESTIM part instance, U2, generates a reset
signal to the CLR pin of the 74393 counter.
Table 14-3
FILESTIM Part Attributes
Attribute Description
FILENAME name of file containing the stimulus
specification
SIGNAME name of output signal
IO_MODEL I/O model describing the stimulus’
driving characteristics
IO_LEVEL interface subcircuit selection from
one of the four AtoD or DtoA
subcircuits provided with the part’s I/
O model
IPIN(<
power pin name
>) hidden digital power pin used by the
interface subcircuit
IPIN(<
ground pin name
>) hidden digital ground pin used by the
interface subcircuit
Refer to the online MicroSim
PSpice A/D Reference Manual
for more information about
creatin
g
di
g
ital stimulus
specifications and files.