HP 16600A Series User Manual page 254

Erratic trace measurements
❏ 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 microcontroller.
Ensure that you have ambient temperature conditions and airflow that
meet or exceed the requirements of the microcontroller manufacturer.
Capacitive loading
Excessive capacitive loading can degrade signals, resulting in incorrect
capture by the analysis probe, or system lockup in the microcontroller.
All analysis probe 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.
Solutions for CPU32
Chapter 12: Troubleshooting the Analysis Probe
Analysis Probe Problems
253