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    <p>Thanks for all the responses!</p>
    <p>The 'H7 looks interesting, though expensive. I love how STM sells
      these dev boards basically at cost.</p>
    <p>Here is another question. As i get my brain around this, with the
      small FFTs giving way to larger FFTs, I wonder- what format is the
      IR file? Is it just a time-domain recording of the reverberations
      of a room excited by an impulse? Admittedly I am getting lost in
      all the conversions going on. Its like I'm in church!???? ;-)</p>
    <p>-TimR<br>
    </p>
    <p><br>
    </p>
    <br>
    <div class="moz-cite-prefix">On 2/20/2018 1:51 PM, Mikko Helin
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAJ5nAj7817a8C+4-2BNRrdnnBeguXN9x4BERmWmjsGQ1i+z8Zg@mail.gmail.com">
      <div dir="ltr">
        <div class="gmail_default" style="font-family:"trebuchet
          ms",sans-serif">STM32H7 will be killer for DSP with 400
          MHz core clock frequency and 1 Mb of SRAM:</div>
        <div class="gmail_default" style="font-family:"trebuchet
          ms",sans-serif"><br>
        </div>
        <div class="gmail_default"><font face="trebuchet ms, sans-serif"><a
href="http://www.st.com/en/microcontrollers/stm32h7-series.html?querycriteria=productId=SS1951"
              moz-do-not-send="true">http://www.st.com/en/microcontrollers/stm32h7-series.html?querycriteria=productId=SS1951</a></font><br>
        </div>
        <div class="gmail_default"><font face="trebuchet ms, sans-serif"><br>
          </font></div>
        <div class="gmail_default"><font face="trebuchet ms, sans-serif"><span
              style="color:rgb(34,34,34);font-family:"trebuchet
ms",sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">There
              will be (not available yet) NUCLEO-H743ZI</span>??dev
            board. Would somebody please build a euro format base board
            with some knobs, jacks and maybe an LCD for that:<br>
          </font></div>
        <div class="gmail_default"><font face="trebuchet ms, sans-serif"><br>
          </font></div>
        <div class="gmail_default"><font face="trebuchet ms, sans-serif"><a
href="https://www.digikey.fi/product-detail/en/stmicroelectronics/NUCLEO-H743ZI/497-17786-ND/7809236"
              moz-do-not-send="true">https://www.digikey.fi/product-detail/en/stmicroelectronics/NUCLEO-H743ZI/497-17786-ND/7809236</a><br>
          </font></div>
      </div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On Tue, Feb 20, 2018 at 6:25 PM, Ben
          Stuyts <span dir="ltr"><<a href="mailto:ben@stuyts.nl"
              target="_blank" moz-do-not-send="true">ben@stuyts.nl</a>></span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div style="word-wrap:break-word">Not only floating point
              operations, they also have DSP and SIMD instructions.
              There???s a library of functions (CMSIS-DSP) which makes
              these operations easy to use.<span class="HOEnZb"><font
                  color="#888888">
                  <div><br>
                  </div>
                  <div>Ben</div>
                </font></span>
              <div>
                <div class="h5">
                  <div><br>
                    <div>
                      <blockquote type="cite">
                        <div>On 20 Feb 2018, at 14:19, Martin Klang <<a
                            href="mailto:mars@pingdynasty.com"
                            target="_blank" moz-do-not-send="true">mars@pingdynasty.com</a>>
                          wrote:</div>
                        <br
                          class="m_-7844208555221621269Apple-interchange-newline">
                        <div>
                          <div text="#000000" bgcolor="#FFFFFF">
                            <p><br>
                            </p>
                            <p>STMs: the F4 and F7 are Cortex M4F with
                              single cycle floating point operations.
                              Not sure there's much to gain from going
                              fixed point, assuming 32bits. With 16 bits
                              fixed point you can potentially get two
                              operations per cycle. Or you could go
                              8-bit...<br>
                            </p>
                            <p><br>
                            </p>
                            <p>Martin<br>
                            </p>
                            <br>
                            <div
                              class="m_-7844208555221621269moz-cite-prefix">On
                              18/02/18 19:20, Bruno Afonso wrote:<br>
                            </div>
                            <blockquote type="cite">
                              <div dir="ltr">If you're willing to go
                                into DSP land then you could also look
                                at blackfin, Monome's Aleph uses open
                                source tools for develop it. For STMs,
                                the only shot would be to attempt to use
                                fixed point, not a lot of juice for
                                floating point stuff but like other's
                                mention, it may be a lot of work.. maybe
                                more for as a challenge? :)
                                <div><br>
                                </div>
                                <div>b<br>
                                  <div><br>
                                  </div>
                                </div>
                              </div>
                              <br>
                              <div class="gmail_quote">
                                <div dir="ltr">On Sat, Feb 17, 2018 at
                                  5:24 AM <<a
                                    href="mailto:rsdio@audiobanshee.com"
                                    target="_blank"
                                    moz-do-not-send="true">rsdio@audiobanshee.com</a>>
                                  wrote:<br>
                                </div>
                                <blockquote class="gmail_quote"
                                  style="margin:0 0 0
                                  .8ex;border-left:1px #ccc
                                  solid;padding-left:1ex">I haven???t
                                  developed for SHARC, yet, but I can
                                  say that I shipped the Soundplane
                                  without spending much on the
                                  compiler/assembler. That was based on
                                  the TMS320VC5506, a member of the
                                  lowest-power C55x line. You might want
                                  to look at the C6000 series or OMAP,
                                  such as the OMAP-L1x line. I recall
                                  that the tools run free when you have
                                  one of the evaluation boards connected
                                  to your computer.<br>
                                  <br>
                                  What about some of the less ???fancy"
                                  SHARC DSP options, like the ADSP-2191M
                                  used in the DSI eVoLver? For some
                                  reason, I assume that a 16-bit DSP
                                  would cost less. Dave (and/or his
                                  firmware programmer) managed to coax
                                  24-bit audio out of this 16-bit DSP by
                                  using specific features. I haven???t
                                  looked into the tools for that chip,
                                  but maybe they???re priced lower than
                                  the tools for the flagship chips.<br>
                                  <br>
                                  Brian<br>
                                  <br>
                                  <br>
                                  On Feb 16, 2018, at 3:50 PM, Tim
                                  Ressel <<a
                                    href="mailto:timr@circuitabbey.com"
                                    target="_blank"
                                    moz-do-not-send="true">timr@circuitabbey.com</a>>
                                  wrote:<br>
                                  > I hear ya. My comment about the
                                  cost of tools referred to the
                                  compilers. I'd love to use a Sharc,
                                  but it looks like at least $1K for the
                                  compiler.<br>
                                  ><br>
                                  > --tr<br>
                                  ><br>
                                  > On 2/16/2018 1:48 PM, <a
                                    href="mailto:rsdio@audiobanshee.com"
                                    target="_blank"
                                    moz-do-not-send="true">rsdio@audiobanshee.com</a>
                                  wrote:<br>
                                  >> You really need a DSP for
                                  this, and not a general-purpose CPU
                                  like ARM. Even though ARM has a DSP
                                  instruction or two, it's a far cry
                                  from a total system designed for
                                  signal processing. Families like the
                                  TMS320 have been evolving for decades
                                  - literally 35 years - to optimize
                                  this sort of thing. Literally every
                                  aspect of the chip has been tweaked to
                                  optimize signal processing.<br>
                                  >><br>
                                  >> Texas Instruments has cheap
                                  demo platforms with audio I/O and the
                                  tools come free with those $50
                                  evaluation boards. There are a lot of
                                  open-source routines, so if you need
                                  FFT in TMS320 assembly then it's
                                  there. You can call that from C and
                                  keep your overall design simple.<br>
                                  >><br>
                                  >> Texas Instruments even has
                                  chips that are dual-processor inside -
                                  one TMS320 for DSP, plus and ARM for
                                  the higher level stuff and maybe even
                                  some audio processing. Look for OMAP
                                  chips. The C6000 series of DSP would
                                  be a good choice because it supports
                                  floating point (I've worked with the
                                  C5500 series that is fixed point, and
                                  that's a lot of tedium but worth it if
                                  you want to run off of batteries).<br>
                                  >><br>
                                  >> Another good option would be
                                  SHARC.<br>
                                  >><br>
                                  >> If you choose a non-DSP chip,
                                  everything will be less efficient.
                                  That either means loss of features or
                                  higher temperatures and shorter
                                  battery life.<br>
                                  >><br>
                                  >> Brian Willoughby<br>
                                  >> Sound Consulting<br>
                                  >><br>
                                  >> On Feb 16, 2018, at 11:47 AM,
                                  Tim Ressel <<a
                                    href="mailto:timr@circuitabbey.com"
                                    target="_blank"
                                    moz-do-not-send="true">timr@circuitabbey.com</a>>
                                  wrote:<br>
                                  >>> I wonder if it would be
                                  possible to do a parallel processor
                                  scheme where one proc handles the
                                  early stuff and another to handle the
                                  longer time stuff. each proc would
                                  output via a codec and those outputs
                                  would get summed. Hmm...<br>
                                  >>><br>
                                  >>> On 2/16/2018 11:38 AM,
                                  Eric Brombaugh wrote:<br>
                                  >>>> I suspect that STM32
                                  doesn't have the horsepower you'll
                                  need to do a useful IR reverb. There
                                  are several fairly efficient FFT in
                                  the CMSIS libraries from ARM but even
                                  using those the best you can do is
                                  about a 4096 FFT running at less than
                                  48kHz with long latency and large
                                  overlaps.<br>
                                  >>>><br>
                                  >>>> On 02/16/2018 12:24
                                  PM, Tim Ressel wrote:<br>
                                  >>>>> Still, even with
                                  all that jigery-pokery, we're going to
                                  need a bigger boat, er, processor. I'd
                                  like to avoid processor choices that
                                  needs pricey tools. STM32 would be
                                  nice. Of course some good ol' fashion
                                  assembly code, highly optimized, would
                                  help things. Its been a while since I
                                  went down that rabbit hole. I wonder
                                  if someone has an optimozed FFT
                                  library for Cortex Mn??????<br>
                                  <br>
                                  <br>
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    <br>
    <pre class="moz-signature" cols="72">-- 
--Tim Ressel
Circuit Abbey
<a class="moz-txt-link-abbreviated" href="mailto:timr@circuitabbey.com">timr@circuitabbey.com</a></pre>
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