AR# 7545

7.1i CPLD, CPLDFit - "WARNING:Cpld:158 - We have detected that a large number of internal signals may be switching..."

Description

General Description:

When I implement a XC9500 design, a warning message similar to the following occurs:

"WARNING:Cpld:158 - We have detected that a large number of internal signals may be switching at the same time. To avoid potential simultaneous switching/ground bounce issues, please contact Xilinx Customer Support for more information."

Solution

You can use one of the following methods to minimize ground bounce issues:

- Place some equations in low-power mode.

- Place some outputs in slow-slew mode.

Both of these methods include adding delay to signals. This delay helps keep all of the signals from switching simultaneously, and as a result, minimizes any ground bounce issues.

AR# 7545
Date 12/15/2012
Status Active
Type General Article