# define the used CPU
  export CPU = nrf51
  export CPU_MODEL = nrf51x22xxaa
  
  # set default port depending on operating system
  PORT_LINUX ?= /dev/ttyUSB0
  PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.SLAB_USBtoUART*)))
  
  # define flash and debugging environment
  export FLASHER = $(RIOTBOARD)/$(BOARD)/dist/flash.sh
  export DEBUGGER = $(RIOTBOARD)/$(BOARD)/dist/debug.sh
  export DEBUGSERVER = JLinkGDBServer -device nrf51822 -if SWD
  export RESET = $(RIOTBOARD)/$(BOARD)/dist/reset.sh
  
  export OFLAGS = -O binary
  export HEXFILE = $(ELFFILE:.elf=.bin)
  export FFLAGS = $(BINDIR) $(HEXFILE)
  export DEBUGGER_FLAGS = $(BINDIR) $(ELFFILE)
  export RESET_FLAGS = $(BINDIR)
  
  # setup serial terminal
  include $(RIOTMAKE)/tools/serial.inc.mk