this adds and option to set the LFCLK on the nRF52DK which can also be used on custom boards with or without an external 32.xxxkhz crystal, defaults to use external crystal

Author: Paul Adams

boards.txt

@@ -18,6 +18,7 @@
 menu.chip=Chip
 menu.softdevice=Softdevice
 menu.version=Version
+menu.lfclk=Low Frequency Clock
 
 nRF52DK.name=nRF52 DK
 
@@ -56,6 +57,12 @@ nRF52DK.menu.softdevice.s132.upload.maximum_size=409600
 nRF52DK.menu.softdevice.s132.build.extra_flags=-DNRF52 -DS132 -DNRF51_S132
 nRF52DK.menu.softdevice.s132.build.ldscript=armgcc_s132_nrf52832_xxaa.ld
 
+nRF52DK.menu.lfclk.lfxo=Crystal Oscillator
+nRF52DK.menu.lfclk.lfxo.build.lfclk_flags=-DUSE_LFXO
+nRF52DK.menu.lfclk.lfrc=RC Oscillator
+nRF52DK.menu.lfclk.lfrc.build.lfclk_flags=-DUSE_LFRC
+nRF52DK.menu.lfclk.lfsynt=Synthesized
+nRF52DK.menu.lfclk.lfsynt.build.lfclk_flags=-DUSE_LFSYNT
 
 BluzDK.name=Bluz DK
 

platform.txt

@@ -50,6 +50,7 @@ compiler.define=-DARDUINO=
 
 # this can be overriden in boards.txt
 build.extra_flags=
+build.lfclk_flags=
 
 nrf.sdk.path={runtime.platform.path}/cores/nRF5/SDK
 
@@ -69,13 +70,13 @@ compiler.elf2hex.extra_flags=
 # ----------------
 
 ## Compile c files
-recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {build.lfclk_flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Compile c++ files
-recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags}  {includes} "{source_file}" -o "{object_file}"
+recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {build.lfclk_flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Compile S files
-recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {build.lfclk_flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Create archives
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"