I’m using a feather M0 board with a SamD21 MCU. By double tapping, the reset bottom the COM port changes and the MCU is in bootloader mode. I can now select the COM of the “bootloader mode” and flash the MCU. After I flashed the chip the MCU changes like expected to the “run mode” COM port.
Now when in “run mode” without tapping the reset I can flash the MCU again without any problem. I do see the COM port switch for a second between “run mode” and “bootloader mode”.
So in someway PlatformIO is able via USB to force a double tap to my MCU and get into “bootloader mode”. Does anybody know how this is done?
When programming the MCU via Bossac (see command), I do need to put the MCU manually in “bootloader mode” via a double reset.