AR #33016 - Spartan-6 FPGA Clocking - DCM de-skew calculations incorrect

AR#	33016
Part	FPGA-Spartan-Clock Manager
Last Modified	2009-10-30 00:00:00.0
Status	Active
Keywords	deskew, adjust, default, dcm, feedback,

Solution

In the ISE 11.2 software, the default de-skew setting for the DCM is incorrectly set. The tools default to a setting of "9" for the de-skew value, when the actual value should be "0". This will result in added skew to your output clock when compared to your input reference clock.

To correct the issue, you can manually set the DCM de-skew value to "0". To do this, you must enter the FPGA Editor tool, locate the DCM, change to "Edit Mode", and check the "0" box.

This issue will be fixed in a future version of ISE software.