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AR# 30377

10.1 System Generator for DSP - Why do I receive an NGDBuild error specifying that my CE timespec is invalid?


Keywords: SysGen, clock enable, sample, upsample, downsample

When I attempt to generate my System Generator for DSP model, I receive an XFLOW error during NGDBuild similar to the following message:

"ERROR:XdmHelpers:647 - The specification "TS_ce_2_30c72b9b_group_to_ce_2_30c72b9b_group" is invalid because both its FROM group (ce_2_30c72b9b_group) and its TO group (ce_2_30c72b9b_group) were removed."


This error commonly occurs when there is no load on the clock enable net for the time group constraint to reference. This usually happens when a Gateway In is followed by an Up Sample or Down Sample block without a register in between. That is, the domain between the Gateway and the rate change block is never used; however, a CE for that domain and a constraint for that domain are still created.

To work around this issue, you can absorb the sample rate change into the Gateway In block and remove the Up/Down Sample or place an element with latency between the Gateway In and the Up/Down Sample blocks.
AR# 30377
Date 10/28/2008
Status Active
Type General Article
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