Chapter 19. Navigating the Toggle Coverage Window

Table of Contents

19.1. Understanding the Layout
19.2. Excluding/Including a Signal for Toggle Coverage
19.3. Displaying a New Signal for Toggle Coverage

The verbose toggle window allows the user to see which bits for a given signal have toggled from a 0->1 or a 1->0 during simulation. To display this window, simply click on a highlighted/underlined uncovered signal in the file viewer of the main window. This will cause the verbose toggle viewer to be created for the specified signal as well as display a "-->" symbol in the Coverage Viewer on the same line as the selected signal. This symbol is simply meant to help the user identify in the Coverage Viewer which signal is currently displayed in the Toggle Viewer window. Figure 19.1, “Verbose Toggle Window” shows the Toggle Viewer loaded with a 4-bit signal called "err_vec" in which bits 3:2 have successfully toggled from a 0->1.

Figure 19.1. Verbose Toggle Window

Verbose Toggle Window

19.1. Understanding the Layout

The bit vector displayed is a binary bit vector, each value (0 or 1) represents whether that bit in the signal either toggled (1) or did not toggle (0) during simulation. There are two bit vectors displayed for the signal, the top vector shows the 0->1 toggle information while the bottom vector shows the 1->0 toggle information.

The name of the signal along with its MSB:LSB information is displayed at the bottom of the window; however, if the mouse cursor is placed over a specific bit in the toggle box, the MSB:LSB will be changed to show the displayed bit, making it easy for the user to discern exactly which bit has toggled/not toggled. If the width of the signal exceeds the given space for the toggle window, a scrollbar will be allowed to slide left and right to view the rest of the toggle information.

To exit this window, simply click on Close button. To see this help page from the toggle window, click on the help (?) button.

19.2. Excluding/Including a Signal for Toggle Coverage

The user may exclude/include any uncovered signal in the design for toggle coverage by simply clicking on the Excluded checkbutton. If this checkbutton is checked, the exclusion reason popup window will be displayed, allowing the user to specify a reason for excluding this signal from toggle coverage. Once a reason has been specified, the summary coverage information will automatically be recalculated and redisplayed in the listbox and the background color of the underlined signal in the file viewer will change from the uncovered background color to the covered background color. However, the signal will still remain underlined, allowing the user to see the verbose toggle coverage information, if necessary. If the Excluded checkbutton is unchecked, the summary coverage information and background colors will be readjusted to include the coverage information for this signal.

If the user excludes any signal for toggle coverage in the design, the Save CDD... option in the file menu will be enabled. This allows the user to save the excluded property either back to the CDD file (or to a newly named CDD file). Doing so will allow the user to load the CDD file at a different time and retain the knowledge of which signals have been excluded/included for toggle coverage. Additionally, if a saved CDD file with coverage exclusion is merged with another CDD file, the excluded signal information is preserved for the resulting merged CDD file.

If a signal has been excluded from coverage and an exclusion reason was specified, you can view the reason for exclusion by right-click-and-holding on the Excluded checkbutton. This will cause a tooltip-style window to be displayed specifying the reason for exclusion. The background color of the tooltip will be the same color as the "covered" background color to help distinguish it from a normal tooltip. To cause the exclusion reason tooltip to disappear, simply release the button.

19.3. Displaying a New Signal for Toggle Coverage

If the Verbose Toggle Coverage window is currently displayed with a signal, the user may select a new signal in the file viewer of the Main window. When a new signal is selected, its value immediately replaces the currently selecting signal value. This feature allows many different signals to be viewed one after the other without having to create/destroy a new window for each signal.

The user may also see the previous or next uncovered signal in the main viewer by clicking either the left arrow button (for previous signal viewing) or the right arrow button (for next signal viewing). Note that the left arrow button will be disabled if there is not a signal previous to the current signal in the given module and the right arrow button will be disabled if there is not a signal after the current signal in the given module.