UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 3124

Foundation F1.x Simulator: Selective preset feature may disrupt the operation of counters, state machines

Description

Keywords: selective preset, simulate, simulator, counter

Urgency: Standard

General Description:
Executing a Selective preset feature occasionally disrupts the
functionality of state machines or 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).

解决方案

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.
AR# 3124
创建日期 11/25/1997
Last Updated 04/04/2000
状态 Archive
Type 综合文章