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AR# 14149

XPower 4.2i - Warnings stating "Power:215...Power:205....Power: Can't change frequency of net_name to 20Mhz" appear after I use the Estimate Activity Rates tool


Keywords: XPower, Wizard, activity, rates

Urgency: Standard

General Description:
After I select "Tools -> Estimate Activity Rates", the following warnings appear:

"WARNING:Power: 215 - 'FB2_2_Q' is driven by a register and has not had its activity set. Activity rate estimates will not be accurate."
"WARNING:Power: 205 - Input net D0 has not has its activity set."
"WARNING:Power: Can't change frequency of net_name to 20Mhz."

Why do these warnings occur, and what can I do about them?


The response to these warnings will depend upon on how many times "Estimate Activity Rates" has been run successfully. "Estimate Activity Rates" can be run successfully only once. (A successful run is one in which no warnings are seen.)

For example, if you have run "Estimate Activity Rates" successfully, but you then change your clock frequency and rerun the feature, the above warnings will be reported. Additionally, the Wizard runs this feature automatically; therefore, if you use the Wizard, then run Tools -> Estimate Activity Rates from the menu, these warnings will also occur.

You will not be able to use the feature without reloading the design. The easiest way to work around this is to open a new Wizard (Tools -> New Design Wizard) and enter all the new information into it. The Wizard will automatically estimate the activity rates for you.

If "Estimate Activity Rates" has not yet run successfully and the above warnings are seen, the warning messages appear for the following reasons:

1. WARNING:Power:215 - 'FB2_2_Q' is driven by a register and has not had its activity set. Activity rate estimates will not be accurate.

This warning will occur if you have not set an activity on the signal "FB2_2_Q" (usually a % rate). To avoid this warning, set the activity rate of the signal, then rerun "Estimate Activity Rates".

2. WARNING:Power:205 - Input net D0 has not has its activity set.

This warning occurs for the same reason as the previous warning, only this error applies just to input nets. To avoid this warning, set the frequency of the input signal manually, then rerun "Estimate Activity Rates".

3. WARNING:Power:Can't change frequency of net name to 20Mhz.

This warning occurs if you have previously edited the signal, or run a VCD that changed the signal, and then run "Estimate Activity Rates". XPower assumes that you have entered more accurate data and will not set the frequency of this signal. This warning is for informational purposes only.

Xilinx recommends that users utilize the Wizard, as it will provide instructions for setting all of the appropriate signals.
AR# 14149
Date 12/07/2004
Status Archive
Type General Article
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