@bobolink FYI to myself
If you have an engineering background--part of Micropython--
module 'dba: calculate dBA (A-weighting decibels) from an input stream of digital audio samples
module 'i2stools': function to efficiently extract sample data from a buffer filled by I2S
Signal processing (logical shifts--fractional multiply) on the PCM samples instead of hardware volume control gets the job done also.

@zontex OK thanks for the reply. I guess you could set the volume of the .WAV files in the pc program “Audacity”.
But user volume control would be nice.

Is there a C/C++ way to set volume?

@thrasher
As always, GPIO 14 is already in use for the display.

“All the pins other then GPIO14 are availiable, however for some reason it was used for LCD CS on the M5Stack rendering JTAG unuseable.”

@ajb2k3 Of course we are talking about two different levels of debugging.

The BBC micro is also for beginners but allows both.

microbit jlink upgrade

@thrasher But don’t you need the LCD display operating while you use JTAG to debug your code?
Some kind of demultiplexer hardware added maybe?

@rleinfellner
Wouldn’t you want the JTAG scan path clear for automated factory testing?

@cregganna
Bump -
Now (last month) JTAG debugging went free on PlatformIO/Visual Studio Code and Andreas Spiess did a YouTube video on debugging with the Espressif ESP-prog board JTAG interface for the ESP-32.
First thing I did was check into M5Stack Core and found it wouldn't work.
Another version with IO12-15 available for JTAG inline debugging would be necessary and appreciated.
thank you

Example of using the M5Stack’s DAC to make a tone v.s. Arduino tone()
DAC v.s. Digital pin.
3 sec. DAC v.s. 3 Sec. digital pin

sinf() via DAC v.s. Arduino tone(pin, frequency, duration)

I really like M5ez so I gave it its own core. Justified it by saying that’s real MVC architecture! Real Computer Science stuff.
/*

GLOBAL INFO
core 0 is the communications processor.
Uses the ESP-NOW protocol
on the 2.4 GHz radio
This process runs as a task created
on core 1
core 1 is the UI processor.
Maintains the M5Stack M5ez LCD menu
Runs Arduino setup() and loop()

*/
Use RTOS semaphores when accessing the global vars to/from the local versions.