[sdiy] STM32 (or other) audio DSP learning recommendations

[Scott Gravenhorst]

That would be me.  I was playing with one of the demo programs which used the digital
microphones for recording audio.  The code worked, so I wanted to mess with the code and
noticed the sample rate was very low (can't remember exact number, but well below 44.1kHz
- 8 kHz seems to nag me).  I decided to try to raise it to see what would happen. 
Depending on how much I raised the rate, I got different results from "DMA error" printed
on the screen to nothing at all.  

My look at the code was more cursory than complete, so I'm only guessing that the
STM32F746 ran out of CPU when the sample rate was raised.  The display uses SDRAM
connected to the CPU and not RAM inside the display.  As such it appeared that the
display needed constant attention, enough so that the audio sample rate couldn't be
raised.  My purpose was to ascertain if this display type could be used in conjunction
with a synth running at a sample rate of at least 44.1kHz.  Again - some of that is
guesswork, but it was enough to put me off trying to add the display to working synths
I'd developed for the board.

At the very least, I can say that the STM32F746 CPU is quite capable of digital synthesis
to the point of 32 voices for a Karplus-Strong MIDI polysynth with numerous features and
a chorus effect.

The synths are all makefile projects using some of the source code (drivers and device
initialization code mainly) supplied by ST.  Development was done on Fedora25 compiling
with gcc and edits done with my favorite text editor.

"Jay Schwichtenberg" <jschwich53 at comcast.net> wrote:
>There is a STM32F769I-DISC1 Discovery board that does not have the display
>for $49 at mouser.
>
>At some point I'm hoping to get my STM32F769I Disco and STM32F767 Nucleo
>boards going. Those and the Raspberry Pi Zero, Teensy 3.6s and a couple
>more.
>
>At some point (and I can't find it now, thinking it might have been in
>electro-music.com) I read that someone was using a development board (might
>have been a Disco board) or Raspberry Pi with a display with no display
>controller and was having problems with audio. The display sucked up so much
>CPU time and memory that you had to drop the audio rate to something pretty
>slow.
>
>Jay S.

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- http://scott.joviansynth.com/
-- When the going gets tough, the tough use the command line.
-- Matt 21:22