# 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)
  
  # include common periph module
  USEMODULE += periph_common
  
  # include stm32 common functions and stm32 common periph drivers
  USEMODULE += stm32_common stm32_common_periph
  
  # export the common include directory
  export INCLUDES += -I$(RIOTCPU)/stm32_common/include