As you may have heard, our new Express line of boards, starting with the Feather M0 Express, ship with a new UF2 capable, open source bootloader created by Microsoft. As Ladyada showed on her stream, this bootloader makes it faster and easier to load new code onto a microcontroller.
A bootloader is responsible making it easy to load new software onto a microcontroller. A good bootloader can make or break a project. For example, Arduino’s original bootloader was one reason for its success because it allowed for loading new software without expensive external hardware. The UF2 Bootloader goes one step further and removes the need for any additional software. Instead of needing to install software like Arduino or bossac, one simply plugs in the board, double taps reset and then drags a uf2 file onto the BOOT drive that appears. No extra software needed!
The bootloader works by emulating a removable disk in addition to the standard Arduino bootloader. Since all major operating systems support removable USB drives, support is built-in. At the same time, the UF2 bootloader still works as expected with Arduino.