Answers Database
Foundation F1.x Simulator: Selective preset feature may disrupt the operation of counters, state machines
Record #3124
Product Family: Software
Product Line: Aldec
Product Part: Foundation Logic Simulator
Product Version: 1.4
Problem Title:
Foundation F1.x Simulator: Selective preset feature may disrupt the operation of counters,
state machines
Problem Description:
Urgency: Standard
General Description:
Executing a Selective preset feature occasionally disrupts the
functionality of state machines, such as counters.
After assigning D inputs of the counter flip-flops to some
value (i.e. ff) using this feature, execute a preset, and step.
Then, the counter either gets stuck at the preset value or
starts counting incorrectly.
This happens to feedback-looped flip-flops (such as counters).
Solution 1:
For selective preset functionality, follow these steps instead.
1. Use Signal->Add Signals to select all D pins of flip-flops
that you want to set the preset value to:
a. To select a flip flop pin, navigate the design hierarchy
displayed on the right hand side of the Component Selection
window.
b. When the desired flip flop is listed in the center pane,
double-click on it to bring up a list of pins for this
flip flop on the right side.
c. Now, double-click on the D input pin to add it to the
Waveform Viewer.
2. Use Signal->Add Stimulators to assign stimulus (preset
values) to all of these D inputs.
3. Step the simulation once.
4. Disable the stimulators by selecting the signal and clicking
on the DS button in the Stimulator Selection window.
5. Now keep stepping the simulation.
End of Record #3124 - Last Modified: 03/03/99 11:36 |
