# export the CPU family so we can differentiate between them in the code
  FAM = $(shell echo $(CPU_FAM) | tr 'a-z-' 'A-Z_')
  export CFLAGS += -DCPU_FAM_$(FAM)
  
  # use common periph functions
  USEMODULE += periph_common
  
  # include nrf5x common periph drivers
  USEMODULE += nrf5x_common_periph
  
  # link common cpu code
  USEMODULE += cpu_common
  
  # export the common include directory
  export INCLUDES += -I$(RIOTCPU)/nrf5x_common/include