A breakpoint is a simple way to specify a complex trigger expression.
A breakpoint behaves similar to a breakpoint in a software debugger except
that a breakpoint in the debugger does not stop the hardware. A break-
point in the debugger represents a trigger condition that causes all instru-
mented signal values to be captured and sent to the debugger. Figure 18-9
shows the breakpoint selected at the source line where current_state
equals Load12.
To activate this trigger, click on the Runbutton.
Clicking the Run button will download this trigger selection to the
IICE hardware on the device and arm the trigger to sample data. When
signal current_stateobtains the value Load12, the breakpoint triggers
and the sample buffer is sent to the debugger through the JTAG port of
the device. The actual signal values are displayed on the source code as
shown in Figure 18-10.
Notice that the value of current_stateis Load12. All the rest of the
signals contain values captured when current_statechanged to the value
Load12and the trigger condition was met. With this capability a designer
can use breakpoints to see the actual behavior of the real hardware to
make sure that the design is behaving properly.Figure 18-7
IICE Configuration
Dialog.
At Speed Debugging Techniques 407