Felix; thanks for the tip in the Grove pinout; exactly where I was stuck after experimenting.

https://docs.m5stack.com/en/arduino/arduino_development mentions the new stamp-pico, but falls short of mentioning what library/header one uses in an Arduino Stamp sketch for it.
Would it use M5Atom.h?
Thanks!

@josestevez; no habla espanol muy bien, pero Visual Studio Code con PlatformIO es mas rapido siguente el primero vez.

3 & 4. Plus PlatformIO as well.

Replace #include <M5Stack.h> with #include <M5Core2.h>.

It would be nice to have a Magnetometer Unit.
I'd like to experiment with using one to do course correction for an autonomous robot.
Something simple to calibrate would be nice.

Rop, all the included examples run fine.
I found that the problem is that Button::_hidden is uninitialized. I will open an issue.

Now I can easily add hit and miss sounds to my button testing app. Will update soon.

Thanks for the checkRotation function!
I've just glanced at the Sound stuff (very nice!) but am still working on Touch.
I wrote a test to determine what the minimal effective touch button size is (https://github.com/vkichline/ButtonSizeTest).
When I moved it from PlatformIO (for development) to Arduino (for publishing) I moved from your master branch to the M5Sound branch. The app built, but did not run in M5Sound. (It drew one button and stopped. I haven't looked into it yet.)

Are you making touch changes in M5Sound as well?

I wrote a program to see what a reasonable minimum size touch button is: https://github.com/vkichline/ButtonSizeTest
It's a test you play: it lets you choose what size button and what spacing; it makes a bunch of buttons and asks you to press eight of them. At some point you should stop getting perfect scores.
I'd be interested in hearing what people find a usable minimum to be.

Caution: to use this app, you need RopG's PR for M5Core2. You can download the touch button version of the lib here: https://github.com/ropg/M5Core2.

Rop's latest sample (M5Sound, in this forum) make me wonder what a reasonable, minimum size and spacing should be for TouchButtons. At almost 80 X 60 pixels, the DTMF buttons are usable, but already require some care with only 12 on the screen.
I dug up an old passive capacitive stylus (the kind that looks like a soft pencil eraser) and found it increases speed and accuracy. Maybe a 50 X 50 pixel button would be usable with the passive stylus (doubling the number of buttons available.)
I see that there are active capacitive styluses available with much smaller tips. Does anyone have one? Does it work well with the Core2?