The first issue was a missing header file "M5_Max3421E_Usb.h". I did not find any library through the Library Manager in the Arduino IDE, so I downloaded the M5-Max3421E-USBShield library ZIP file from github and installed it that way.

This allowed the USB mouse example Sketch to compile, but it fails to link due to duplicate symbols, like tuh_init, that already exist in the arduino_tinyusb.a library.

If I take arduino_tinyusb.a out of the platform.txt file, for the CoreS3, I still have a few tuh_ symbols missing as well as a __atomic_test_and_set symbol missing. I don't see any atomic library anywhere.

If I take steps to remove conflicts from the M5-Max3421E-USBShield library, I am still left with the missing _atomic_test_and_set symbols. I am not sure if changing the library is correct as I don't know if there is a version conflict between all the tuh functions in the M5-Max3421E-USBShield library and arduino_tinyusb.

Does anyone have any advice on correcting this issue?

I would really like to use the mass storage capability of the module, so any recent links for M5Stack projects that successfully use the module would be helpful.