Samd21 Firmware Upgrade(Edbg)

Operation mode
Power LED
Status LED

Normal operation
Power LED is lit when power is applied to the board.
Activity indicator, LED flashes every time something happens on the EDBG.
Bootloader mode (idle)
The power LED and the status LED blinks simultaneously.
Bootloader mode (firmware upgrade)
The power LED and the status LED blinks in an alternating pattern.

1->   C:\Users\xxxxx\Documents>atfw -h


Usage: atfw [options] [arguments]

Options:
  -a, --archive .zip
                                 Archive containing firmware upgrade image.

  -h, --help                     Display help information.

  -l, --list                     List connected tools.

  -i, --id                       Print boot loader id (edbg only).

  -t, --tool                Tool name: edbg, medbg, avrone, jtagicemkii, jtagice3
                                 stk600, qt600, avrispmkii or avrdragon.

  -s, --serialnumber        The programmer/debugger serial number.

  -q, --quiet                    Do not display activity indicator.

  -V, --version                  Display version number.

  -r, --read                     Read firmware version on tool.

  -n --nographics                No progress bar, but result alone will be displayed

Example:
  atfw -a myImage.zip -t jtagice3 -s 123456789ABC


2-> C:\Users\xxxxx\Documents>atfw -t edbg -a "C:\Program Files (x86)\Atmel\Atmel Studio 6.2\tools\EDBG\edbg_fw.zip"
Found edbg:ATML2130021800001691
Waiting for bootloader usb enumeration: [==========]
Upgrading MCU: [==========]
Successful upgrade