Datasheet

I can't get the Itsy/Feather USB device to show up - I get "USB Device Malfunctioning" errors!
This seems to happen when people select the wrong board from the Arduino Boards menu.
If you have a Feather 32u4 (look on the board to read what it is you have) Make sure you select Feather 32u4 for
ATMega32u4 based boards! Do not use anything else, do not use the 32u4 breakout board line.
If you have a Feather M0 (look on the board to read what it is you have) Make sure you select Feather M0 - do not
use 32u4 or Arduino Zero
If you have a ItsyBitsy M0 (look on the board to read what it is you have) Make sure you select ItsyBitsy M0 - do not
use 32u4 or Arduino Zero
I'm having problems with COM ports and my Itsy/Feather 32u4/M0
Theres two COM ports you can have with the 32u4/M0, one is the user port and one is the bootloader port. They
are not the same COM port number!
When you upload a new user program it will come up with a user com port, particularly if you use Serial in your user
program.
If you crash your user program, or have a program that halts or otherwise fails, the user COM port can disappear.
© Adafruit Industries
https://learn.adafruit.com/adafruit-feather-m0-express-designed-for-circuit-python-
circuitpython
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