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Visitor tallman
Visitor
235 Views
Registered: ‎06-06-2019

issue with data outputs from FIR compiler

Hello, 

can someone help me to get out of this situation, I am trying to get several analog signals and filter them using XADC and FIR compiler, in the following pictures there is the design and waveforms that I am getting. I configure FIR compiler to filter in multichannel mode, I don't know where the problem but the outputs aren't what I am expecting

 

regards 

summary.PNG
implementation.PNG
response.PNG
summary.PNG
waves1.PNG
waves2.PNG
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4 Replies
Visitor tallman
Visitor
224 Views
Registered: ‎06-06-2019

Re: issue with data outputs from FIR compiler

and here the testbench 

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Voyager
Voyager
186 Views
Registered: ‎06-20-2017

Re: issue with data outputs from FIR compiler

Looks like a classic signed as unsigned problem.  Did you select radix as unsigned or signed in the waveform viewer?  (Select wave, right click -> radix->signed decimal).  You still have to do the analog settings as usual.  I also recommend waveform style->Analog settings->Interpolation style-> o Hold (instead of linear)

Mike
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Visitor tallman
Visitor
168 Views
Registered: ‎06-06-2019

Re: issue with data outputs from FIR compiler

I did exactly what you told me, but the filter that i am using is a pass-low one as you can see on response picture. so from every input, I should get just the first harmonic (50hz). i think it works on the last signal vaux2 but not on others.

please what do you wanna say by this ('Adaptable Processing coming to an IP address near you.')

 

regards

waves3.PNG
waves4.PNG
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Voyager
Voyager
154 Views
Registered: ‎06-20-2017

Re: issue with data outputs from FIR compiler

Your vaux1[13:0] looks better.

Are you scaling correctly?  (Looks like you're clipping).

I like to normalize my coefficients between [-1.0, 1.0) -- signed fractional.  How big are your coefficients?  Looks like 16 bits with 18 fractional bits.  I am not sure what that means, but it might mean your coefficients are scaled between [-0.25, 0.25), or it might be nonesense.  If you have 16 bit coefficients, try 15 fractional bits.  You may have to recompute your coefficients.

Do an FFT and plot phase/magnitude versus frequency and verify your frequency response.

Mike
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