Can't upload code using SAM-BA UART

Hi there,

I've designed a custom board using the ATSAMD21G18. I burn the Arduino Zero bootloader and then use the USB port to upload sketches with no issues whatsoever.

Now, I wanted to be able to upload sketches using the UART using the SAM-BA. According to the Arduino Zero bootloader github page, to enter the bootloader you just need to press twice on the reset and then it'll be waiting for a communication on either the USB or the UART. Using BOSSA I just get a message saying "device unsupported" and using SAM-BA v2.18 (for some reason version 3.31 doesn't have a GUI) and choosing "samd21_xplained_pro" (which is the only samd21 option) just says it can't connect. To the right, the JTAG option is selected and grayed out, which I think is the problem ...

Has anyone been able to successfully upload code via the UART to an arduino zero ?

Hi LMagalhaes,

When uploading with the Arduino Zero bootloader via the UART on pins D0 and D1, the native USB port must first be disconnected from the board.