tinygo/targets/feather-m4.json

{
    "inherits": ["atsamd51j19a"],
    "build-tags": ["sam", "atsamd51j19a", "feather_m4"],
    "flash-1200-bps-reset": "true",
    "flash-method": "msd",
    "msd-volume-name": "FEATHERBOOT",
    "msd-firmware-name": "firmware.uf2"
}