Uploading code to Adafruit Feather M0 breaks com port and upload port!

I can upload code with the Arduino IDE (it uses bossac 1.7.0)
I can upload code with


platform = atmelsam@3.6.1
board = adafruit_feather_m0
framework = arduino

But if I use
platform = atmelsam
I can upload the code only once but then it “kills” the port and I can’t read Serial data nor upload new code !
The only way to get it back to upload is to force a reset with a double clic.
(but still, the com port is not working)

can we force the version of bossac ?

Anyone with the same problem ?
or can you upload code via sam-ba ?


I am quite new to arduino and just discovered platformIO today which looks amazing!
I have the exact same problem. It has been driving me crazy all afternoon. Now I change platformio to be platform = atmelsam@3.6.1 and monitor is working.

I notice upload and monitor is too “fast” - the USB magic that happens in teh M0 hasn’t happened yet, but when I do monitor, it seems to work okay.

Is this a bossac problem or …?

I am on win10.

The problem is reproducible with Adafruit M0 wifi feather and an adalogger feather. I will get some other boards so I can test if that helps.
looking forward to using platformIO … fingers crossed.

Can’t help with the BOSSAC issue… don’t know anything about that side of things.

re: Serial monitor reopening too fast:


pfeerick, thank you!

That is the tip i needed. 500ms more and it seems reliable for me now.
it is good to be back in a proper editor.

1 Like

Still not working for me
after uploading code with 3.8.0 I can’t get the monitor port to appear
can you post more details of your solution?
I am doing this

The other poster reverted back to platform = atmelsam@3.6.1 and then had the issue of the serial monitor re-opening too fast. Meaning the underlying issue you have still hasn’t been resolved.

Please report to Issues · platformio/platform-atmelsam · GitHub

you can follow the issue here Uploading this code to Adafruit Feather M0 breaks com port and upload port! · Issue #77 · platformio/platform-atmelsam · GitHub