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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>When its works at non-real time, but doesn’t at real-time,
its almost certain that you aren’t waiting for the DMA completion
correctly. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Take a look at the wait_for_dma() function in the notes.
It is doing something that you aren’t doing – namely it looks for
the CIPR bit to be set, but then makes sure to clear it for the next
time. If that bit in the CIPR remains high, you will think your next DMA
transfer is complete right away – even though it has barely started<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Doug<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal style='margin-left:.5in'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> dspforum-bounces@echelonembedded.com
[mailto:dspforum-bounces@echelonembedded.com] <b>On Behalf Of </b>O'Connor,
Sean R.<br>
<b>Sent:</b> Thursday, October 22, 2009 11:41 AM<br>
<b>To:</b> dspforum@echelonembedded.com<br>
<b>Subject:</b> [Dspforum] FFT QDMA help<o:p></o:p></span></p>
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<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>Doug/Joseph,</span><o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'> <o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>I am having issues with this assignment, so I
have uploaded my project directory to the website. </span><o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'> <o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>The QDMA portion appears to work fine.
I verified this by loading increasing integers (cast
as floats) into the RAM starting at address 0x80000000, QDMAing
the data to the internal memory and then QDMAing it out starting
at 0x803A9800 without doing any FFT functions. I exported this file
and analyzed it in matlab, and it was perfectly intact. </span><o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'> <o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>Performing the STFT on the data produces
QNANs and INFs in the data output, however, a single FFT works fine.
I can QDMA any chunk of 8192 complex samples, take the FFT, QDMA it out to
0x803A9800, export it to matlab and it looks fine. It seems
multiple FFTs cause issues... I will continue to work at it, but any input you
might have would be greatly appreciated.</span><o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'> <o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>Thanks,</span><o:p></o:p></p>
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<p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>Sean </span><o:p></o:p></p>
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