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Chapter 3: Using the Logic Analyzer in Timing or State Mode
Displaying Captured Data
the actual write to this variable. Although the instruction is prefetched,
the analyzer can be set to only trigger when the write is executed.
Capacitive Loading on
the Device Under Test
Excessive capacitive loading can degrade signals, resulting in
suspicious data or even system lockup. All analysis probes add
capacitive loading, as can custom probes you design for your device
under test. To reduce loading, remove as many pin protectors,
extenders, and adapters as possible.
Careful layout of your device under test can minimize loading problems
and result in better margins for your design. This is especially
important for systems running at frequencies greater than 50 MHz.
If there are filtered data holes in display
memory
When an analyzer measurement occurs, acquisition memory is filled
with data that is then transferred to the display memory of the analysis
or display tools you are using, as needed by those tools. In normal use,
this demand driven data approach saves time by not transferring
unnecessary data.
Since acquisition memory is cleared at the beginning of a
measurement, stopping a run may create a discrepancy between
acquisition memory and the memory buffer of connected tools. Without
a complete trace of acquisition memory, the display memory will
appear to have 'holes' in it which appear as filtered data.
This situation will occur in these cases:
• If you stop a repetitive measurement after analyzer data has been cleared
and before the measurement is complete.
• If a trigger is not found by the analyzer and the run must be stopped to
regain control.
To make sure all of the data in a repetitive run is available for viewing:
1. In the workspace, attach a Filter tool to the output of the analyzer.
2. In the Filter, select "Pass Matching Data"