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6156 Discussions

FIR Compiler output is zero

Altera_Forum
Honored Contributor II
‎03-08-2011 05:43 PM
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I have a design that is using a FIR Compiler generated FIR filter containing several coefficient sets. To be exact I had 5 sets loaded into the FIR filter. Everything was working fine. Then I tried to add a 6th set and now the output I get from the filter is all zeros even though I use one of my previous filter sets.  

 

When the output is all zeros the output format is still correct. I verified this with SignalTap.  

 

I was wondering if anyone has seen anything like this.
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Altera_Forum
Honored Contributor II
‎03-08-2011 07:49 PM
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I found the problem myself. Looks like the FIR compiler is scaling all the coefficient sets with the same factor. This means that you can't mix floating and fixed point coefficient sets. I just converted the fixed point set to floating point and things started working.

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