[sdiy] IR Reverb

Mikko Helin maohelin at gmail.com
Tue Feb 20 22:51:53 CET 2018


STM32H7 will be killer for DSP with 400 MHz core clock frequency and 1 Mb
of SRAM:

http://www.st.com/en/microcontrollers/stm32h7-series.html?querycriteria=productId=SS1951

There will be (not available yet) NUCLEO-H743ZI dev board. Would somebody
please build a euro format base board with some knobs, jacks and maybe an
LCD for that:

https://www.digikey.fi/product-detail/en/stmicroelectronics/NUCLEO-H743ZI/497-17786-ND/7809236

On Tue, Feb 20, 2018 at 6:25 PM, Ben Stuyts <ben at stuyts.nl> wrote:

> 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.
>
> Ben
>
> On 20 Feb 2018, at 14:19, Martin Klang <mars at pingdynasty.com> wrote:
>
>
> 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...
>
>
> Martin
>
> On 18/02/18 19:20, Bruno Afonso wrote:
>
> 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? :)
>
> b
>
>
> On Sat, Feb 17, 2018 at 5:24 AM <rsdio at audiobanshee.com> wrote:
>
>> 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.
>>
>> 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.
>>
>> Brian
>>
>>
>> On Feb 16, 2018, at 3:50 PM, Tim Ressel <timr at circuitabbey.com> wrote:
>> > 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.
>> >
>> > --tr
>> >
>> > On 2/16/2018 1:48 PM, rsdio at audiobanshee.com wrote:
>> >> 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.
>> >>
>> >> 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.
>> >>
>> >> 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).
>> >>
>> >> Another good option would be SHARC.
>> >>
>> >> 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.
>> >>
>> >> Brian Willoughby
>> >> Sound Consulting
>> >>
>> >> On Feb 16, 2018, at 11:47 AM, Tim Ressel <timr at circuitabbey.com>
>> wrote:
>> >>> 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...
>> >>>
>> >>> On 2/16/2018 11:38 AM, Eric Brombaugh wrote:
>> >>>> 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.
>> >>>>
>> >>>> On 02/16/2018 12:24 PM, Tim Ressel wrote:
>> >>>>> 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�
>>
>>
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