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2001 Microchip Technology Inc. DS51159B-page 111
Advanced Features
6.3.5 Complex Triggering Examples
The following examples show some of the ways that complex triggers can be
used to help debug or characterize a problem.
6.3.5.1 Sequential Example - Program Memory
An application has several subroutines. A particular subroutine
(RoutineA) functions correctly to begin with, but after a time, it begins to
function incorrectly. This subroutine is called many times, so it would
be nice to skip the executions where the subroutine functions properly
and breaks just before the subroutine starts to fail. It is observed that
the routine functions correctly until another after subroutine (RoutineB)
is called.
This problem can be solved by a Sequential trigger with two events. The first
event that must occur is the execution of
RoutineB
, so the Event 3 tab is
specified with the fetch of program memory address
RoutineB
. The trigger
should fire when
RoutineA
is called, so the Trigger tab is specified with the
fetch of program memory address
RoutineA
. The Ignore FNOP Cycles is left
checked so prefetches are ignored, and Halt On Trigger is checked so the
improperly executing subroutine can be stepped.
Figure 6.9: Setting the First of Two Sequential Events