CircuitPython test if board connected to USB

code.py

# SPDX-FileCopyrightText: 2024 Paulus Schulinck
#
# SPDX-License-Identifier: Unlicense
# Tested on board: Adafruit MAGTAG (ID: 4800)
def is_usb():
    # Test if we're connected to USB
    # If an error occurs we are on USB
    ret = False
    try:
        from storage import remount
        remount("/", False)
    except RuntimeError as e:
        ret = True
    return ret

def main():
    print(f"Are we connected to USB? {"Yes" if is_usb() else "No"}")
  
  if __name__ == '__main__':
    main()