Datasheet

When the user COM port disappears, Arduino will not be able to automatically start the bootloader and upload
new software.
So you will need to help it by performing the click-during upload procedure to re-start the bootloader, and upload
something that is known working like "Blink"
I don't understand why the COM port disappears, this does not happen on my Arduino UNO!
UNO-type Arduinos have a seperate serial port chip (aka "FTDI chip" or "Prolific PL2303" etc etc) which handles all
serial port capability seperately than the main chip. This way if the main chip fails, you can always use the COM port.
M0 and 32u4-based Arduinos do not have a seperate chip, instead the main processor performs this task for you. It
allows for a lower cost, higher power setup...but requires a little more effort since you will need to 'kick' into the
bootloader manually once in a while
I'm trying to upload to my 32u4, getting "avrdude: butterfly_recv(): programmer is not responding" errors
This is likely because the bootloader is not kicking in and you are accidentally trying to upload to the wrong COM
port
The best solution is what is detailed above: manually upload Blink or a similar working sketch by hand by manually
launching the bootloader
I'm trying to upload to my Feather M0, and I get this error "Connecting to programmer: .avrdude: butterfly_recv():
programmer is not responding"
You probably don't have Feather M0 selected in the boards drop-down. Make sure you selected Feather M0.
I'm trying to upload to my Feather and i get this error "avrdude: ser_recv(): programmer is not responding"
You probably don't have Feather M0 / Feather 32u4 selected in the boards drop-down. Make sure you selected
Feather M0 (or Feather 32u4).
I attached some wings to my Feather and now I can't read the battery voltage!
Make sure your Wing doesn't use pin #9 which is the analog sense for the lipo battery!
© Adafruit Industries
https://learn.adafruit.com/adafruit-feather-m0-express-designed-for-circuit-python-
circuitpython
Page 53 of 199