The Gen3 (formerly "mesh") Particle product line has a header that is
structurally related to the Adafruit Feather, and is generally
compatible with Featherwing shields. Provide nexus maps for both the
native header layout, and for the subset feather header layout, and
add alias labels for the peripherals that would be referenced from
shield overlays.
Signed-off-by: Peter A. Bigot <pab@pabigot.com>
Provide a dtsi file that sets up common capabilities for all
Feather-based Particle Mesh devices. Provide additional dtsi files for
some obvious peripheral options.
Remove the xtensa esp32 image: it didn't build, and there's no
indication of how the ESP32 firmware can be updated on the Argon board.
Use particle_argon as the nRF52840 side of the board.
Add Particle Boron support.
Note that dtsi files must be replicated in each board directory until
tooling supports DTS includes from a shared area.
Signed-off-by: Peter A. Bigot <pab@pabigot.com>
