Notice the effect this step
has on the D0 trace in the Timing window.
Pin delays can be used to customize path delays in subcircuit
devices without opening and modifying their internal delays. Setting
pin delays on a subcircuit device affects only the single device
modified., whereas changing internal delays of primitive devices will
affect all copies of the same type of device.
Moving Timing Traces
- Click and vertically drag the name CLK in the Timing window
to reposition it relative to the other traces:
You can reposition any group of traces for ease in making timing
comparisons. Any number of traces can be moved at once by holding the
SHIFT key while clicking on the trace names.
- Click on the name D0 in the Timing window. Hold the SHIFT
key down while you click on the names D1, D2, and D3 so that they are
- Click the right mouse button on any of the four selected
- In the pop-up menu, select the Group command.
You will now see that the four traces D0 to D3 collapse into a single
grouped trace showing their combined value in hexadecimal.
The same pop-up menu can be used to ungroup the signals again or to set
the signal order used to create the hexadecimal value.
Note that the grouped trace has double vertical bars on some values.
This is due to the delay we inserted in the QA output pin. If you set
the pin delay back to zero, the double bars will revert back to single
The hexadecimal value of a grouped signal will be displayed only if
there is sufficient space between the signal changes to display the text.
You can use the zoom In and Zoom Out buttons (
) to change the
scale factor in order to see the values.
Using the Trigger
- Click on the Trigger button () in the Simulator toolbar.
The trigger mechanism allows you to detect various timing and
- Type the name CLK in the Names box.
- Type the value 1 in the Value box.
- Select the Reference Line option. The dialog should not
appear as follows: