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AR# 41042

LogiCORE IP v1.0 Cascaded Integrator Comb Compiler (CIC Compiler) - Why when using programmable interface do I see zeros on the output?

Description

For the LogiCORE IP CIC Compiler, why when using the programmableinterface do I see zeros on the output?

The moment there is a change to the upsampling rate on-the-fly by asserting a rate write enable with the new value on the rate input,the CIC Compiler starts to output zeros, and remains in this state. This also manifests itself in structural simulation.

Solution

There is an issue with the CIC Compiler seen in the interpolation mode where there are zeros on the output of the filter. The CIC Compiler v1.0 also shows a difference between behavioral and structural simulation. The structural simulation manifests itself as zeros on the output. This issue (and others) has been dealt with and the advice is to use v2.0 of the IP.

To work around this issue, perform the following:

  • If possible, consider a fixed/hardwired upsampling rate; the CIC filter will operate as expected.
  • Create a HDL CIC compiler.
  • Use the CIC Compiler example from System Generator reference block set and modify it for programmable interface

For a detailed list of LogiCORE IP Cascaded Integrator Comb Compiler (CIC Compiler) Release Notes and Known Issues, see (Xilinx Answer 29297).

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
29297 LogiCORE IP Cascaded Integrator Comb Compiler (CIC Compiler) - Release Notes and Known Issues N/A N/A
AR# 41042
Date Created 03/16/2011
Last Updated 05/20/2012
Status Archive
Type Known Issues
IP
  • Cascaded Integrator Comb (CIC) Compiler