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AR# 14784

4.2i XPower - "Warning: Signal Mshreg_q__n0000 activity rate 10.0 is assumed to be a percentage of a clock rate"


Keywords: Wizard, activities, XPower, frequency, toggle, synchronous

Urgency: Standard

General Description:
In the "Activities" section of the Design Wizard, after I attempt to enter a frequency for a synchronous signal, the following warning message is displayed in the history bar:

"Warning: Signal Mshreg_q__n0000 activity rate 10.0 is assumed to be a percentage of a clock rate."

What does this warning mean? Has the frequency been set?


The warning message will be displayed only when you have attempted to apply a frequency (Hz) to a synchronous signal. XPower requires you to set the toggle rate (%) of synchronous signals.

The warning indicates that, as you have specified a frequency in Hz, the required signal should be a percentage. XPower assumes that the units have been entered incorrectly and changes them (i.e., if you enter "10 MHz", XPower assumes a toggle rate of 10%).

If you would like the setting to be a frequency in Hz, you must follow these steps:

1. Complete the Design Wizard.
2. Calculate the toggle rate. (Please see below for more information on toggle rates.)
3. Search for the signal. This can be done using the search feature (Edit -> Find) or by manually inspecting the signal's folder.
4. Enter the toggle rate.

You may also start a new Design Wizard by selecting Tools -> New Design Wizard. If you do this, ensure that a percentage is entered for all signals with a star symbol (*) next to them in the "Activities" section of the Wizard. The (*) indicates synchronous signals.

The toggle rate for a signal is defined as a percentage (%) of the clock's active edges. For example, a clock frequency of 10 MHz and a toggle rate of 50% means that the output signal of the synchronous element will be 2.5 MHz; therefore: Toggle Rate = (Output Frequency/Clock Frequency) x 2
AR# 14784
Date Created 05/30/2002
Last Updated 04/05/2006
Status Archive
Type General Article