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Observer ru551n
Observer
4,189 Views
Registered: ‎02-09-2010

Simulation error in Xilinx FIR compiler

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Hello all,

 

Im simulating an FIR filter which does interpolation by a factor of two, and I keep receiving this simulation error:

 

interpolator_2_inst/U0/g_mac/mac/ : Warning: NUMERIC_STD.TO_SIGNED: vector truncated

 

What can cause this? XCO file of filter is attached

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1 Solution

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Advisor eilert
Advisor
4,898 Views
Registered: ‎08-14-2007

Re: Simulation error in Xilinx FIR compiler

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Hi,

first of all, it's no error, but a warning.

 

Warnings highlight situations that can lead to malfunction but they can be ignored if the design can deal with such situations.

 

So you have to decide.

Truncation in MAC structures is one solution to keep the word width in a reasonable size.

Another method would be rounding. Both cause some loss of information, but have different influence on the stability of your filter.

So, if your filter is stable with truncated values everything is just fine.

Use Matlab for a comprehensive test of your filters numerical stability.

 

Have a nice synthesis

  Eilert

2 Replies
Advisor eilert
Advisor
4,899 Views
Registered: ‎08-14-2007

Re: Simulation error in Xilinx FIR compiler

Jump to solution

Hi,

first of all, it's no error, but a warning.

 

Warnings highlight situations that can lead to malfunction but they can be ignored if the design can deal with such situations.

 

So you have to decide.

Truncation in MAC structures is one solution to keep the word width in a reasonable size.

Another method would be rounding. Both cause some loss of information, but have different influence on the stability of your filter.

So, if your filter is stable with truncated values everything is just fine.

Use Matlab for a comprehensive test of your filters numerical stability.

 

Have a nice synthesis

  Eilert

Observer ru551n
Observer
4,175 Views
Registered: ‎02-09-2010

Re: Simulation error in Xilinx FIR compiler

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Yes of course, you are correct. It is no error, my mistake! :smileywink:

 

I have simulated the filter chain and analyzed the outputs of respective filters using octave.

The filter precision (and noise..) is within our tolerance, both in simulation and synthesis.

 

I am using the non-truncated output of the filters. I round the output outside the filter core itself.

 

In conclusion, everything works ok, I was just wondering if this something I should consider investigating more.

 

Regards

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