AutoFocus User’s Guide
54
©1989-2018 Lauterbach GmbH
With the background information provided above, it is easy to understand why data eyes change with the
clock threshold level. The following scans where made with different clock threshold levels. The
Analyzer.ShowFocusEye
graphs show the same data signal.
The corresponding
Analyzer.ShowFocusClockEye
window looks like the following:
Color Legend:
•
Green
and
red
- Data is instable because of setup-time violations and/or hold time violations of the
input register:
-
Green color means sampled on rising clock edge.
-
Red color means sampled on falling clock edge.
•
White
color indicates stable areas.
•
White
areas enclosed by green and/or red color are referred to as stable data eyes.
•
Olive green
areas mean instable data (setup violations) on rising and falling clock edges.
Clock threshold at 0.8V
Clock threshold at 1.7V
This setup would give suitable trace results.
Clock threshold at 2.6V
Sampling on rising clock edges
Sampling on both clock edges
Stable data eye
Stable areas
Stable areas
On the other targets, e.g. ETMv3, the graph may look like this:
