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trigger Trigger is a reference
event around which you want to
gather information. In the analyzer,
you might want to trigger on a glitch
in hardware or entry to a subroutine
in software. When beginning, you
might want to trigger on the first oc-
currence of any kind (trigger on
“anystate”). As you learn more about
the problem you are trying to isolate,
you may enter more specific trigger
conditions. When you want to gather
a continuous stream of activity lead-
ing up to a system crash, you will
want to trigger on “no state.” Note
that some microprocessors fetch in-
structions on 32-bit boundaries. If
you are tracing activity of one of
these processors, and you specify
trigger on an address that is not on a
32-bit boundary, that address will
never appear on the address bus;
therefore, the analyzer will never
find its trigger. Make sure you spec-
ify triggers that the analyzer will
find. The state analyzer, timing ana-
lyzer, and oscilloscope cannot
complete their measurement unless
they find a trigger.
TRIGGER on specification A
special kind of sequence-advance
specification for the analyzer. When
the analyzer finds combination of
patterns, occurrences, and time
matching the trigger on term, it
locks the contents of acquisition
memory to this point and fills remain-
ing locations with subsequent states,
then stops acquiring data.
trigger point In the oscilloscope,
the point at which the voltage on the
input waveform equals the trigger
level voltage value set in the Level
field of the trigger menu.
trigger position Trigger position
specifies where you want the trigger
to be placed in memory. “Start”
places the trigger at the start of
memory and fills the remainder of
memory with activity that occurs af-
ter the trigger is captured. “Center”
places the trigger in the center of
memory and fills the first half of
memory with activity that occurs be-
fore the trigger, and the last half of
memory with activity that occurs af-
ter the trigger. “End” places the
trigger at the end of memory and fills
the remainder of memory with activ-
ity that occurs before the trigger.
“User-Defined” lets you specify cap-
ture of a desired amount of
posttrigger activity. Once a trigger is
found by a state or timing analyzer,
it is identified as the occurrence at
analyzer memory location 0. All
other states in memory are num-
bered to show their occurrence
relative to the trigger location: states
captured before the trigger are num-
bered with negative numbers (-001,
Glossary
Glossary–6