How to flash bootloader to ATSAMD board?

[water]

I want to flash MicroPython .uf2 firmware to ATSAMD board, is it have specific MicroPython version of bootloader? how?

Or can I refer this:
https://github.com/adafruit/uf2-samdx1/ ... -README.md
To flash CircuitPython bootloader, then use the bootloader to flash MicroPython firmware?

Or if I use J-Link to flash .bin firmware to ATSAMD board, which address should I specific (SAMD21, SAMD51)?

[Roberthh]

The data sheet tells_:

After Reset has been released, the CPU starts fetching PC and SP values from the Reset address, 0x00000000. This points to the first executable address in the internal Flash memory.

The lowest area of the Flash is usually reserved for a bootloader. The MicroPython firmware is built to start at 0x2000 for SAMD21 and 0x4000 for SAMD51.

[water]

Thanks, that works.
And I try flash Adafruit UF2 bootloader to 0x0000, then flash MicroPython .uf2 firmware seems fine.