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AR# 19301

6.1i, Architecture Wizard, DCM - "ERROR: Only Low Frequency mode is valid for Cascading in Series. Please enter an Input Clock Frequency value within the valid Low Frequency Range..."

Description

General Description:

I am using the DCM Wizard to create a cascaded DCM using CLK2X. When I enter 30MHz as the input frequency, the following error occurs:

"Only Low Frequency mode is valid for Cascading in Series. Please enter an Input Clock Frequency value within the valid Low Frequency Range. Low Frequency Mode: 24 - 90 MHz."

The frequency entered is within the range specified in the error message. Why did I receive this error?

Solution

The Wizard did not check the frequency range correctly.

This problem has been fixed in the latest 6.2i Service Pack available at:

http://support.xilinx.com/xlnx/xil_sw_updates_home.jsp
The first service pack containing the fix is 6.2i Service Pack 2.

NOTE: The DRC itself is correct (i.e., cascading DCM is limited in the low-frequency range).

For more information, refer to (Xilinx Answer 18181).

AR# 19301
Date Created 09/03/2007
Last Updated 12/15/2012
Status Active
Type General Article