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

Scott Gravenhorst music.maker at gte.net
Sat Jul 7 01:47:09 CEST 2018

Eric Brombaugh <ebrombaugh1 at cox.net> wrote:

>In I2C mode the CSB pin is used to select one of two possible I2C
>addresses. The datasheet will tell you what the two options are.

Agh, this getting older crap isn't fun.  I now remember reading that.

>With flying wires between a Nucleo and a WM8731 breakout board you
>should be fine as long as you don't tightly bundle the MCLK and SCL
>lines together for long runs. In some of my early experiments I put a
>weak lowpass filter on the MCLK pin to reduce the hf harmonics which
>were leaking onto the SCL line and preventing the I2C interface from
>receiving properly.

That's interesting, I'd saved a bad SPI connection between stripboards running at 10
MHz by using 1K up and down termination resistors.  I'd not thought of a low pass. 
For something like this, I'd guess an Fc of maybe 1 MHz with 100R or 47R series
resistor?  I'm planning for 500 kHz SCLK.

I figured I'd have to be careful where the fly-wires are going.  I'll be using the
clock output from the WM8731, so that needs to stay away from the SPI lines.

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

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