Trying to test Filter using NCO Megafunction and Signal Tap Analyzer?

I suspect its your trigger logic. You've got it setup to trigger when the NCO value is exactly all zeros. If you calculate how often that is likely to occur, you might find its infrequent. Try a different trigger source, eg. a push button, or Avalon-MM PIO signal.

Cheers,

Dave

To determine, if the the NCO is outputting data, you don't need a trigger at all. Just acquire a few sampler in free running mode.

I can't see however, if the signals unconnected in your schematic blocks have suitable defaults.

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I suspect its your trigger logic. You've got it setup to trigger when the NCO value is exactly all zeros. If you calculate how often that is likely to occur, you might find its infrequent. Try a different trigger source, eg. a push button, or Avalon-MM PIO signal.

Cheers,

Dave

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I thought if i had all the triggers set to don't care, it wouldn't matter what change occurred at that particular node and the signal tap would activate.

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I thought if i had all the triggers set to don't care, it wouldn't matter what change occurred at that particular node and the signal tap would activate.

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But you don't have them set to don't care, you have the first set to all zeros.

As FvM points out though, you can just start the capture, and then stop it manually, and you would see if data was changing.

Cheers,

Dave

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To determine, if the the NCO is outputting data, you don't need a trigger at all. Just acquire a few sampler in free running mode.

I can't see however, if the signals unconnected in your schematic blocks have suitable defaults.

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Can i please get more details on how to gather samples in free running mode? i'm not sure how to do that.

Testing a filter with NCO is of limited efficiency. A simple test is to inject impulse input i.e. first sample set high, others zero for some time and repeat this pattern. then you should get impulse response at output i.e. your coeffs scaled.

The best way however is to pass random data to both your design and matlab "filter" function and check for bit true performance.

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Testing a filter with NCO is of limited efficiency. A simple test is to inject impulse input i.e. first sample set high, others zero for some time and repeat this pattern. then you should get impulse response at output i.e. your coeffs scaled.

The best way however is to pass random data to both your design and matlab "filter" function and check for bit true performance.

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Thanks Kaz...i'm getting a lot of great ideas from all poster, but i'm relatively new to Quartus II and testing through hardware. i need a more comprehensive approach to doing these idea. a guide or a link to a manual will be very helpful. for example how do i pass random data to the filter on FPGA. i do know how to use the "filter" function on matlab though, the thing is i need to test it on the FPGA.

You basically need to learn how to do a testbench. For your filter, the testbench itself is very simple if you know how to read text files.

You need to start from Matlab. Generate your random data and convert it to integers then into text file. pass your input to "filter" function using your fixed point coeffs and round up result into integers as per design then convert to text file (thus you have input file and output file).

Go to ModelSim, run your testench to read random data file and pass it to filter by assignment, read output file into your design and compare.

There will be some delay depending on reset but you should get bit accurate result. If there is rounding error or scale issue then we can discuss that.

Note that you don't need to verify filter response in design as long as matlab can be used to study it. All you need is verify that your implementation matches that of matlab.

Normally you should use ModelSim before actual hardware testing.

In hardware stage, you can design a synthesisable testbench e.g. putting your above input /output ref data in RAM then testing through a flag passed to led or signaltap. Or if you have software control you may read files from PC and capture to PC then compare in Matlab... lots of ways...

Hi Dansong,

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i'm relatively new to Quartus II and testing through hardware. i need a more comprehensive approach to doing these idea. a guide or a link to a manual will be very helpful. for example how do i pass random data to the filter on FPGA. i do know how to use the "filter" function on matlab though, the thing is i need to test it on the FPGA.

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Here's some examples for you:

http://www.ovro.caltech.edu/~dwh/correlator/pdf/esc-100paper_hawkins.pdf (http://www.ovro.caltech.edu/%7edwh/correlator/pdf/esc-100paper_hawkins.pdf)

http://www.ovro.caltech.edu/~dwh/correlator/pdf/esc-100slides_hawkins.pdf (http://www.ovro.caltech.edu/%7edwh/correlator/pdf/esc-100slides_hawkins.pdf)

http://www.ovro.caltech.edu/~dwh/correlator/pdf/esc2011_fpga_dsp_code.zip (http://www.ovro.caltech.edu/%7edwh/correlator/pdf/esc2011_fpga_dsp_code.zip)

http://www.ovro.caltech.edu/~dwh/correlator/pdf/lfsr_tutorial.pdf (http://www.ovro.caltech.edu/%7edwh/correlator/pdf/lfsr_tutorial.pdf)

It has testbenches, MATLAB code, LFSRs, etc.

Cheers,

Dave