After running a Verilog simulation, you can read the dump file into Electric and display it in a waveform window. This is done with the Plot Verilog VCD Dump... command (in menu Tool / Simulation (Verilog). You can also use the Plot Verilog for This Cell command if the cell name and file name are the same.

When the Verilog output is read, a waveform appears in a new window. A sample waveform window is shown below. Note also that there is a Cell Explorer in the window, just like in all windows, but it has a "SIGNALS" section that lists the signals found in the Verilog output.

Figure 9.1

Wave Panels

The waveform window contains a list of panels, each with a signal name and signal waveform. In the waveform window, signal names are shown on the left, and their waveform on the right. Between the name and the waveform are 3 control buttons:

You can select a signal by selecting either its name or the actual waveform. Note that when you click on a signal, the equivalent network in the associated schematic or layout window is also highlighted.

You can rearrange the order of the signals by dragging their names to their desired location.

You can add a signal to the list by double-clicking on its name in the "SIGNALS" area (or by dragging that name to the waveform part on the right). If the layout or schematics cell that produced the verilog is being displayed in another window, and the currently selected network in that window is found in the Verilog output, then that output can be added to the waveform window with the Add to Waveform in New Panel command (in menu Edit / Selection).

The order of signals in the waveform window is saved in the original cell so that subsequent simulations will show the same signals.

Time Control

Two vertical cursors appear in the window, called "main" and "extension" (the extension cursor is yellow). Their time values and their difference are shown at the top of the window. You can click over the cursors and drag them to different time locations.

The time axis of the simulation window can be controlled with the appropriate Window menu commands. Use Zoom Out and Zoom In to scale the time axis by a factor of two. Use Focus on Highlighted to display the range between the main and extension cursors.

Figure 4.9
Besides controlling time with menu commands, you can also use the Pan and Zoom tools of the toolbar to change the view.
Figure 4.8

The pan tool lets you smoothly shift time when you click and drag. In the zoom tool, you zoom into an area by clicking and dragout out that area. To zoom out, hold the shift key and click in the center of the desired area.

The different panels in the waveform window are locked in time: they all show the same range of time, as shown at the top of the waveform window. If you click on the "time lock" button at the top of the waveform window (a lock with the time on it) then time is unlocked, and each panel has its own time scale. Now individual panels can be show a different range of time than the rest.

Electric does powerful crossprobing between the waveform window and an editing window with the original circuit. If the original cell is being displayed, selection in the waveform window is mirrored in that cell. Also, whenever the main time cursor changes, the electrical state of the circuit is drawn in over it. The color red is high, and black is low. If you connect Simulation Probe nodes to any part of the circuit, these nodes light up red/black instead, which allows better visualization of activity patterns.

For best visualization of the simulation activity, there are a set of VCR buttons to control an animation of the main time cursor. The Play rate can be controlled by the "F" and "S" buttons which make it go faster or slower. As the time cursor sweeps across the waveform window, the original circuit can be seen to change levels.

These window functions apply to the digital simulation windows:

Other Controls

At the top of the waveform window, above the signal names, are many useful controls. Those relating to time have already been discussed. Here are the remaining buttons: