Triggering On Symbols And Source Code; To Avoid Triggering On Prefetched Instructions - HP 16600A Series User Manual

Chapter 5: Symbols and Source Code in the Analyzer

Triggering on Symbols and Source Code

Triggering on Symbols and Source Code
When setting up trigger specifications to capture processor execution:
• Use the logic analyzer trigger alignment to avoid missed triggers.
• Use the logic analyzer address offset to compensate for relocated code.
• Use the logic analyzer storage qualification to capture the software
execution you're interested in and filter out library code execution (whose
source file lookups can take a long time if the library source code is not
available).

To avoid triggering on prefetched instructions

A CPU32 microcontroller may prefetch one instruction following a
taken branch (BRx, JMP, JSR). The preprocessor does not filter these
prefetches. This means that the prefetched states will be collected by
the analyzer, and that a trigger set to the address of the prefetched
instruction will cause a false trigger on the prefetch.
The recommended way to avoid false triggering for a CPU32 device (16
bit data bus) in this case is to offset the address of the trigger by 4. An
offset field is provided in the symbolic trigger menu to allow offsetting
the symbol address.
Note that this is not a foolproof scheme, since this may result in an
inappropriate trigger if the offset address is a point where control
transfers (branch destination). Be aware of prefetches and adjust your
triggering to compensate for it as you gain experience with the
120 Solutions for CPU32