In analogy to the existing GPIO mappings, this provides (write-only)
SAUL entries for PWM'd LEDs in a single-LED (as SAUL_ACT_DIMMER) and an
RGB (as SAUL_ACT_RGB_LED) mode.
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
- Add the new EXTERNAL_BOARD_DIRS variable that can contain a space separated
list of folders containing external boards
- Introduce $(BOARDDIR) as shortcut for $(BOARDSDIR)/$(BOARD)
- Map the existing BOARDSDIR to the new approach
- If BOARDSDIR is provided by the user, it will be added to
EXTERNAL_BOARD_DIRS for backward compatibility. (And a warning is issued
to encourage users migrating to EXTRA_BOARDS.)
- BOARDSDIR is updated after the board is found to "$(BOARDDIR)/..".
- Useful for `include $(BOARDSDIR)/common/external_common/Makefile.dep`
- Provides backward compatibility
