MKR1000 COM port no longer recognized.

After I received my new MKR1000, I was able to successfully upload "Blink" and everything seemed to work.

Later, I added a Sparkfun thermocouple interface board and wired up MISO, VCC, GND, SCK. I connected CS to pin 0 and then uploaded the modified sample program in the Sparkfun MAX31855K library.

Now the computer's USB port will no longer acknowledge that the MKR1000 is connected. It doesn't show up anywhere in the device manager and I even reinstalled the Arduino SAMD board files with no luck. I've tried this on three different computers and it appears to be dead. Any ideas out there? Is there any way to reset back to factory settings on this board or did I just mail a check to the waste basket?


Hi @IoTMaker,

I would suggest you try manually entering boot loader mode by:

  1. Connecting the board to your PC via USB
  2. Then double press the reset button on the MKR1000

After this, please try uploading a simple sketch like Blink on it again.

It's back! Thanks!

It would seemm that the example sketch from the Sparkfun library for the MAX31855K found at :

does not play well with the MKR1000. I was able to build the digitizer readback functions manually and they don't cause any problems.


Hi @IoTMaker,

Great news!

I suspect something in the library is either hanging or crashing the board. Since the MKR1000 has a native USB port, it uses USB CDC to emulate a serial port. So, any crashes will cause the USB CDC port to not work. Double tapping the reset button causes the board to go back in boot loader mode.