Guidelines help smooth the
implementation of new TopCAT features
TopCAT™ (Topology and Cluster
Analysis Technology) is a new set of ScanWorks capabilities
that dramatically reduces the time needed to achieve
an acceptable level of test coverage. For example, TopCAT's
test automation features reduced the test development
time to less than a day for a complex printed circuit
board with almost 9,000 nets, over 40,000 solder joints
and approximately 6,000 components, including more than
60 memory clusters and over 40 logic clusters.
The following guidelines will help
users implement TopCAT's features as effectively as
- Be consistent with device type names
in all designs. This simplifies the creation of a
library of models with matching names. Then, ScanWorks'
TopCAT capabilities can match the appropriate model
to a device name and automatically insert the correct
model into test actions.
- Use consistent names for power nets.
This allows ScanWorks' TopCAT features to automatically
determine the power nets during netlist translation.
This is important because ScanWorks will be able to
automatically detect the pull-up and pull-down resistors
and identify the pins that are tied to power nets.
- The naming conventions for JTAG
TAP signals should be consistent among all designs.
This will make it easier to describe the scan path
to ScanWorks and enable automatic scan path discovery
in future versions of ScanWorks.
- Reference designators should be
consistent throughout all designs. For example, ‘Ux”
could refer to digital devices, while “Jx”
and “Px” designated connectors, “Cx”
capacitors, “Rx” resistors and so on.
Designator consistency makes net list management and
model assignment much easier.
- Certain attributes of devices should
be defined so that some sort of identifier can be
added to the standard schematic symbols that identify
a device as “special.” Examples are boundary-scan
devices, memory devices, flash devices, programmable
logic devices (PLDs), processors and others. Attributes
also can be added to a device's schematic symbol to
identify the programming source file. ScanWorks has
access to all of this information through its design
browser. In the future, enhancements to TopCAT technology
will enable ScanWorks to automatically identify the
device type and create the proper action to test or
- Limit the use of special characters
in the names that are used during schematic capture.
ScanWorks uses the path name as the name for specific
models. As a result, a backslash (\) in a name could
indicate a directory level to ScanWorks and this would
make it difficult to find a model. In addition, dashes
(-) are used as the separator between reference designator
and pin number (for example, U1-1). Consequently,
a dash in a name also can confuse the ScanWorks tools.
- Create a master copy of the "usersettings.ini"
file so that all ScanWorks stations are set up consistently.
Also, use the same default settings for parameters
such as default names for power and ground nets and
limits during test generation.
- Define a master cross reference
list of Memory Access Verification (MAV) models that
will be used with all designs. This will enable the
auto-create MAV and MAV replicate features of TopCAT.
- Create department- or company-wide
libraries of models of all types of devices and make
them available to all test developers across the entire
organization. Developers will be able to reuse models
previously verified by others, and duplication of
model creation and validation effort will be avoided.
- Use the model libraries provided
by ASSET on the ASSET support web site as the first
sources for new models. Thousands of models are available
to ASSET maintenance customers for downloading. Models
can easily be copied to a company library and renamed
to match a design's device names.
- Invest a little time in learning
all you can about the new features of ScanWorks. A
few minutes now could save hours on each ScanWorks
project. ASSET provides a free web-based seminar on
the new features of each release. The support web
site, which is available through the ScanWorks user
interface, lists the training schedule. Local application
engineers can also provide this information.