obligatory obscure reference

I’m really liking Adafruits “Metro Express” version of the Arduino Zero.

Except for one thing.

The UF2 boot loader.  Every time I compile and load a sketch I get a whine notification from OSX about how I’ve unmounted a volume without the proper Steve Jobs NeXT dance.

The fix is actually pretty simple — tell fstab to stop mounting the filesystem in the first place.  Apple has one solution but it needs a few tweaks for the UF2 boot system.

I'll use Adafruit's METRO as an example.  

First, use diskutil to find the UUID of the METRO:

$ diskutil info /Volumes/METROBOOT/
 Device Identifier: disk3
 Device Node: /dev/disk3
 Whole: Yes
 Part of Whole: disk3
 Device / Media Name: Metro M0 Media

Volume Name: METROBOOT

Mounted: Yes
 Mount Point: /Volumes/METROBOOT

File System Personality: MS-DOS FAT16
 Type (Bundle): msdos
 Name (User Visible): MS-DOS (FAT16)

Content (IOContent): None
 OS Can Be Installed: No
 Media Type: Generic
 Protocol: USB
 SMART Status: Not Supported
 Volume UUID: CA043DAF-C1C3-33CC-A5C4-A4B0D2BFDE85

Total Size: 4.1 MB (4096000 Bytes) (exactly 8000 512-Byte-Units)
 Volume Free Space: 3.5 MB (3530240 Bytes) (exactly 6895 512-Byte-Units)
 Device Block Size: 512 Bytes
 Allocation Block Size: 512 Bytes

Read-Only Media: No
 Read-Only Volume: No

Device Location: External
 Removable Media: Yes
 Media Removal: Software-Activated

Virtual: No
 OS 9 Drivers: No
 Low Level Format: Not supported

Now, use vifs to change the fstab file:

$ sudo vifs

and add this line to the end of the file using the “Volume UUID” field to replace [Volume UUID]

UUID=[Volume UUID] none msdos ro,noauto

save and quit, then run

$ sudo automount -vc

to update your mac with the new fstab file.

This should stop the device from automounting under OSX and make the METRO work like a “normal” Arduino.