Non-intrusive testing according to a
dictionary means: “testing that is transparent to the [software] under
test, i.e. does not change its timing or processing characteristics. Non-intrusive
testing usually involves additional hardware that collects timing or
processing information and processes
that information on other platforms”.
Non-intrusive board test. Does such a thing
really exist? If by the phrase you mean a test methodology that has no physical effect on the unit being
tested, then the answer is yes; it definitely exists. Non-intrusive board test
(NBT) uses soft access to onboard embedded instruments and test technologies like
BIST to test circuit boards. All it needs is a single point of connection – the
rest is software. Software to access, drive and collect data from test routines,
and then to make sense of it all for the user. Almost everything from the
processor out can be driven and tested without physical access to anything but
the processer itself. And the higher the speed, the more crucial this becomes.
Physically probing signals above 5 GHz is not a good thing.
Most engineers, present company included, probably assumed at one time or another that the only way to validate the functionality of system health monitors like those that operate on the I2C or SPI buses was to develop and apply functional tests. Makes sense, right? Well, if you’re interested in saving time, increasing your confidence in the functionality of these devices and keeping your product development on schedule, the real answer is: not really. Combining functional and structural test in one step early in the prototype board bring-up process and then transferring the whole process to manufacturing makes a lot more sense.
Last week we saw a $300,000 oscilloscope. This week, we look
at another one for $470,000. The sky’s the limit when it comes budgeting for
‘scopes. But aside from the price, what other advantages are there of embedded
instrumentation-based system marginality validation tools?