Regular readers will recall that in our last Newsletter
we presented a design analysis example in the form of a block diagram and made
reference to using "design patterns" and "templates" as a means
to document our analyses of the design. It's probably worth expanding on that a
little more and bringing you up-to-date with what this activity has revealed so far.
Design Patterns and Templates
Although the concept of design patterns was originally applied to architecture (by
Christopher Alexander), the principles have been adopted in many fields. We have
chosen to base our use on the methods commonly applied to object oriented software
engineering. This reflects our belief that the main challenge facing SJTAG is one
of software management rather than anything bound into the hardware we are testing.
A number of apparently distinct problems may fit a design pattern if they share
a range of characteristics and traits such that the solving of each problem can be
approached in the same way. Implementation details will obviously vary, but the
method is the same across all problems conforming to the design pattern.
"Templates" are a means of documenting a "design pattern" in a tangible,
readable form. These templates provide a common language and grammar to describe
similar problem spaces to aid in identifying what characteristics may be common
and where domains differ. For now, we are collecting these templates as simple text
files in our wiki, but we intend to move them into a database in due course to help
with searching and comparing templates.
Progress and Discoveries
We have worked up a small number of templates over recent weeks and while our
first candidate, a structural test of the interconnect between a processor and a
RAM, was relatively unremarkable, we unearthed a number of issues when we started
to consider AC coupled data lanes between two devices. There were several subtly
different methods that could be used to test those lanes: Some cases needed new
templates but others were variations due to implementation choices and it is
important that we construct the templates carefully so that we don't suffer an
unnecessary explosion in the number of templates. From this, we are beginning
to form some "rules" on best practice for completing templates and ways
in which the templates themselves can be improved.
We hope these templates provide a basis to which others will be able to describe
their problem domain based on their use cases. This information is quite necessary
to aid in scoping the reaches of the SJTAG standardization effort. These templates
also present a good educational resource that may be useful for academic research
into how to manage tests over these various and sometimes conflicting problem
domains. We feel it is imperative that we employ the test community in assisting
with understanding the problems faced for testing at the board and system levels.
Recently, there has been quite a bit of interest in this area now that IEEE 1149.1-2013
has been published with support for IEEE 1500. The recent balloting of the IEEE P1687 draft has
also sparked renewed interest by the community. We hope you will join us by reviewing
these templates and providing ones yourself as well.
The group is hoping to offer a brief insight into this work during the Board
Test Workshop in December in order to gain some feedback on the value of this
Newsletter link: http://www.sjtag.org/newsletters/2013_July.htm
Wiki link: http://wiki.sjtag.org/index.php?title=Category:Design_Analysis
From the Chair
New look for our website and Newsletter
I'm sure you've already noticed, at least those of you who take the HTML version,
that our newsletter looks a little different for this issue. While the layout is roughly similar to the last few
issues, there's a new color scheme and a new, simpler logo for SJTAG - and it doesn't stop with the Newsletter.
Throughout October we've been working in the background to update and enhance the SJTAG website with the same
clean, simplified look and a host of new usability features. We know that many of you can't join our conference
calls and our website is the main way you stay informed on SJTAG activities. We wanted to make it as easy as
possible for you to stay informed by introducing:
- Mobile device support
- Better site navigation
Read more on the website:
We hope you find these improvements helpful!
There are several newsfeeds available on the SJTAG website. On the main site,
you can obtain feeds from:
The forums offer a range of feeds at the overall board, forum or individual discussion thread level to
suit your preferences, while our wiki supplies a feed from the
Recent Changes page.
The Q1-2014 edition of this newsletter will be published towards the end of January 2014. Copies
of past newsletters are always available on the SJTAG website.
Please use the link at the foot of the page to forward this newsletter to colleagues who may be interested in the work of
the SJTAG Group - new recipients will be offered a link to subscribe to these newsletters.