Configuring test stimulus, 6 configuring test stimulus – Achronix ACE Version 5.0 User Manual
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Running the SnapShot Debugger
Chapter 4. Tasks
Each sequential trigger is configured in 2 parts: the ”Pattern” and the ”Dont Care” mask. The trigger
”Pattern” defines the binary value of each of the 36 monitor channel signals that is required to detect a
match. The trigger ”Dont Care” mask defines which of the 36 monitor channels to ignore when computing
a match. If a ”Dont Care” bit is set to 1, then the corresponding signal will be ignored in the trigger match
comparison. Trigger ”Patterns” and ”Dont Care” masks may be entered in hex, binary, or via the ”Monitor
Channels” table for convenience.
The values within a trigger pattern may be triggered with ANDing or ORing. If ANDing, then all signal
values not masked must match their pattern before the trigger is activated. If ORing, then the trigger will be
activated if any of the non-masked signal values match the specified pattern. The AND/OR configuration
is set for all active patterns at once using the Select using AND or Select using OR radio buttons. This
selection applies uniformly across all triggers it is currently not possible to configure this differently for
each sequential trigger.
In the ”Monitor Channels” table of the SnapShot Debugger View, the trigger patterns/masks can also be
viewed and edited. (Reminder: the trigger patterns only apply to the first 36 monitor channels, regardless
of the configured monitor channel width.) For each channel, a value of X (dont care), 0, or 1 can be specified
via a pull-down menu under each ”Trigger” column.
NOTE:
As of ACE v3.1, if any active Trigger is configured with a ”Don’t Care” mask of
fffffffff
hex (this is the default mask), the trigger will activate on the first clock
cycle that trigger is evaluated, regardless of the trigger’s pattern, and
regardless of whether ANDing or ORing.
Configuring Test Stimulus
SnapShot has the capability to send 36 bits of test stimuli (the
ACX SNAP SHOT
macro output signal Stimuli )
to the Design Under Test (DUT). This data is sent once per arming session, is only valid while the Arm
signal is high, and becomes invalid when Rstn out activates.
This Stimuli output is optional, and need not be connected to the DUT - it may safely be left floating when
the user wants to use SnapShot to only read signals.
The current SnapShot is restricted in that the third Trigger Pattern plays double duty - it is also used as the
value sent out as Stimuli. Thus it is recommended that when Stimuli is connected to the DUT, only one or
two sequential Triggers be used.
The recommended means of populating the Stimuli value via the
is to temporarily
enable the ”Trigger 3” Pattern textfield by following the procedure below:
1. Select the radio button to the left of the ”Trigger 3” section.
2. Populate the desired 36-bit Stimuli value in one of the two ”Trigger 3” Pattern textfields (either hex or
binary).
3. The ”Trigger 3” Don’t Care value should be set to all Fs (
fffffffff
) for safety. (If the user
accidentally leaves ”Trigger 3” active when arming SnapShot, this will ensure that the ”Trigger 3”
Pattern
bits are all ignored during the match check, allowing the match to succeed the first time it is
checked.)
4. Select the radio button for ”Trigger 1” or ”Trigger 2” (whichever corresponds to the needed number
of sequential pattern checks), which will disable ”Trigger 3” so that the ”Trigger 3” Pattern value may
be used as the Stimuli without also requiring a pattern match.
Note:
When SnapShot is Armed, the Stimuli macro output will always contain the value in the ”Trigger
3” Pattern field, regardless of whether ”Trigger 3” is enabled.
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UG001 Rev. 5.0 - 5th December 2012