Analysis Probe Problems
Erratic trace measurements
Erratic trace measurements
There are several general problems that can cause erratic variations in trace
lists and inverse assembly failures.
Do a full reset of the target system before beginning the measurement.
Some analysis probe designs require a full reset to ensure correct
configuration.
Ensure that your target system meets the timing requirements of the
processor with the analysis probe installed.
See ?Capacitive Loading? in this chapter. While analysis probe loading is
slight, pin protectors, extenders, and adapters may increase it to
unacceptable levels. If the target system design has close timing margins,
such loading may cause incorrect processor functioning and give erratic trace
results.
Ensure that you have sufficient cooling for the microprocessor.
Some microprocessors generate substantial heat. This is exacerbated by the
active circuitry on the analysis probe board. You should ensure that you have
ambient temperature conditions and airflow that meet or exceed the
requirements of the microprocessor manufacturer.
Capacitive loading
Excessive capacitive loading can degrade signals, resulting in incorrect
capture by the analysis probe, or system lockup in the microprocessor. All
analysis probes add additional capacitive loading, as can custom probe
fixtures you design for your application.
Careful layout of your target system can minimize loading problems and
result in better margins for your design. This is especially important for
systems that are running at frequencies greater than 50 MHz.
Remove as many pin protectors, extenders, and adapters as possible.
If multiple analysis probe solutions are available, use one with lower
capacitive loading.
5-6E2459A MC68040/060 Analysis Probe |
ACEC
