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issue with data outputs from FIR compiler


hassan.ouayache

Question

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 and the testbench. 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

 

waves2.thumb.PNG.034298699cb3978bb2cacf5724dee18a.PNGwaves1.thumb.PNG.9dca077913310aed563638e1ab7b0164.PNGsummary.PNG.51d34c3884d8c381f21a891c7fbfd602.PNGregards response.PNG.ee4b07d4a71a8aa3e92e998561471b33.PNGimplementation.PNG.16c526a841f444dbfb238153e3383161.PNGdesign.thumb.PNG.92107407293916f0f1cb8faf3f2bae21.PNG

tb.vhd

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Hi,

could this be a signed-/unsigned issue?

BTW, once you've got it working, for XADC rates (up to 1 MSPS) "systolic" architecture using 45 DSP slices seems overkill. It can probably be done in one slice (you need 89 MMAC/s/channel, it's not hard to clock a DSP slice at 200 MHz).

And, the XADC actually outputs 16 bits. The lowest 4 bits are not specified e.g. no guarantees for no missing codes etc but useful in average. I would probably use them. Otherwise, for a non-dithered ADC, the quantization error becomes highly correlated with the input signal at low levels and causes weird artifacts.

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