ag88/Makefile-stm32duino-stm32f407ve-black

## Makefile-stm32duino-stm32f407ve-black
# version 0 (alpha)
# this is only tested in linux
# this is for this board https://stm32-base.org/boards/STM32F407VET6-STM32-F4VE-V2.0.html
#
# This make file for stm32duino core is possibly *dangerous*
# i.e. it compiles the sources (in src and Arduino_Core_STM32) directory
# and overwrite all the stuff in $(out_dir)
# $(out_dir) is the binary directory where the object files are dumped there
#
# make clean *deletes* the *$(out_dir)* (coded here as build )
#
# this is a relative path makefile
# the directory structure needs to be
# Root (project folder)
#   +-- src (your sources e.g. the sketch
#   |        the files has to be cpp, c or h, no ino)
#   |
#   +-- Arduino_Core_STM32 (copy from the stm32duino core)
#   |
#   +-- CMSIS_5
#   |
#   +-- variants (see below)
#   |
#   +-- Makefile (this makefile)
#
# this makefile can't handle the brackets/paranthesis naming convention used for the variants
# hence you need to create a local variant folder and copy all the files in
#   Arduino_Core_STM32/variants/STM32F4xx/F407V(E-G)T_F417V(E-G)T/
# to
#   variants/F407VX/
#
# the make needs to be run from the root(project folder) of this file structure
# the make is relative path from this Root
# generated object files and binaries (elf, bin) are placed into the
# $(out_dir) - build
#
# make clean  - *deletes* $(out_dir)
#
# make all  - starts the build
#
# This software released into the public domain.
#
# Anyone is free to copy, modify, publish, use, compile, sell, or
# distribute this software, either in source code form or as a compiled
# binary, for any purpose, commercial or non-commercial, and by any
# means.
#
# In jurisdictions that recognize copyright laws, the author or authors
# of this software dedicate any and all copyright interest in the
# software to the public domain.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#

# this folder is deleted with make clean
out_dir := build

# this is the name of the subdirectory under STM32F1/variants
# it needs to match, this caters to a single variant
variant := F407VX
build_series := STM32F4xx
build_arch := STM32
#build_board := GenF4
build_board := BLACK_F407VE
variant_h := variant_BLACK_F407VX.h
product_line := STM32F407xx

#flash offset
ld_flash_offset := 0x0
#flash size
# 512K
ld_flash_size := 0x80000
#sram size
# 128K (sram)
ld_sram_size += 0x20000
# 64k (ccmram) - ccm ram is maint directly in ldscript

# these are the defines passed to gcc, g++ and the assembler
# use += to add more definitions
defines := ARDUINO=189
defines += $(build_series)
defines += ARDUINO_$(build_board)
defines += ARDUINO_ARCH_$(build_arch)
defines += BOARD_NAME=\"$(build_board)\"
defines += VARIANT_H=\"$(variant_h)\"
defines += $(product_line)
#defines += VECT_TAB_SRAM
defines += VECT_TAB_OFFSET=0
defines += DEBUG_LEVEL=DEBUG_NONE
defines += F_CPU=168000000L
defines += HSE_VALUE=8000000L
defines += HAL_UART_MODULE_ENABLED
defines += HAL_PCD_MODULE_ENABLED
defines += USBCON
defines += USBD_VID=0x0483
defines += USBD_PID=0x5740
defines += USB_MANUFACTURER=\"Unknown\"
defines += USB_PRODUCT=\"$(build_board)\"
# usb serial
defines += USBD_USE_CDC
# HID keyboard and mouse
#defines += USBD_USE_HID_COMPOSITE
defines += LED_BUILTIN=PA6
defines += HAVE_INITFINI_ARRAY


# points to the parent folder *containing* stm32duino core (e.g. Arduino_Core_STM32) in a sub-directory
# use of this is not encouraged, it is safer to copy the Arduino_Core_STM32
# folder into the current directory
# omit the final slash after the directory
core_root := .
core_name := Arduino_Core_STM32
build_core_path = $(core_root)/$(core_name)/cores/arduino
build_system_path = $(core_root)/$(core_name)/system
CMSIS_path := $(core_root)/CMSIS_5
# This is for the CMSIS math lib
CMSIS_LD_PATH := $(core_root)/CMSIS/DSP/Lib/GCC
cmsis_lib_gcc := arm_cortexM4lf_math
start_file_path := $(build_system_path)/Drivers/CMSIS/Device/ST/$(build_series)/Source/Templates/gcc

# these are the source directories for the core
# and variant, normally they stay unchanged
# if you want to place the core directory somewhere else,
# define core_root above
coredir := $(core_root)/$(core_name)/cores/arduino
coredir += $(core_root)/$(core_name)/libraries/SrcWrapper/src
#coredir += $(build_system_path)/Drivers/$(build_series)_HAL_Driver/Src
#coredir += $(build_system_path)/$(build_series)
#coredir += $(build_system_path)/Middlewares/ST/STM32_USB_Device_Library/Core/Src
#variantdir := $(core_root)/variants/$(variant)
#local variannt dir
#variantdir := $(core_root)/$(core_name)/variants/$(variant)
#variantdir := $(core_name)/variants/$(build_series)/$(variant)
variantdir := variants/$(variant)
#coredir += $(variantdir)

# source directories
# these are the initial directories to search for sources
# relative to this build (root) directory
# if you use libraries either put them in a sub-directory in src
srcdir := src
# or add it here
#srcdir += library1
srcdir += $(variantdir)
srcdir += $(core_name)/libraries/SPI/src

$(info $(srcdir))

#this is the ld script in STM32F1/variants/$(variant)/ld to use
#ldscript := bootloader_20.ld
ldscript := ldscript.ld
LD_SCRIPT_PATH := $(variantdir)/$(ldscript)
#LD_SCRIPT_PATH := variants/Pill_F401CC/$(ldscript)
#add_ld_script:=src/board.ld

#this is the startup asm file, mcu specific
start_mcu_name := stm32f407xx
start_asm_file := ${start_file_path}/startup_${start_mcu_name}.s

#the includes i.e. the -Ipath needs to be exlicitly stated
#no automatic recursive searching
#if you use libraries you may want to add it here
includedir := $(srcdir)
includedir += $(variantdir)
includedir += $(CMSIS_path)/CMSIS/Core/Include
includedir += $(build_system_path)/Drivers/CMSIS/Device/ST/$(build_series)/Include/
#includedir += $(build_system_path)/Drivers/CMSIS/Device/ST/$(build_series)/Source/Templates/gcc/
includedir += $(CMSIS_path)/CMSIS/DSP/Include
includedir += $(build_core_path)
includedir += $(build_core_path)/avr
includedir += $(build_core_path)/stm32
includedir += $(build_core_path)/stm32/LL
includedir += $(build_core_path)/stm32/usb
includedir += $(build_core_path)/stm32/usb/hid
includedir += $(build_core_path)/stm32/usb/cdc
includedir += $(build_system_path)/Drivers/$(build_series)_HAL_Driver/Inc
includedir += $(build_system_path)/Drivers/$(build_series)_HAL_Driver/Src
includedir += $(build_system_path)/$(build_series)
includedir += $(build_system_path)/Middlewares/ST/STM32_USB_Device_Library/Core/Inc
includedir += $(build_system_path)/Middlewares/ST/STM32_USB_Device_Library/Core/Src


#if you use core_root, you would need to add that as a prefix
#includedir := $(addprefix $(core_root)/,$(includedir))

# update this to match
# this should be the install base location of ARM_NONE_EABI_GCC toolchain
ARM_NONE_EABI_PATH := /opt/arduino/gcc-arm-none-eabi-8-2018-q4-major
# this should be the location of the arm standard libraries c & c++
# the arm-none-eabi/lib select the folder matching the arch
# compile options e.g. thumb and v7-m
LD_TOOLCHAIN_PATH := $(ARM_NONE_EABI_PATH)/arm-none-eabi/lib/thumb/v7e-m+fp


# recursive wildcard function, call with params:
#  - start directory (finished with /) or empty string for current dir
#  - glob pattern
# (taken from http://blog.jgc.org/2011/07/gnu-make-recursive-wildcard-function.html)
rwildcard=$(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2) $(filter $(subst *,%,$2),$d))

cfiles := $(strip $(foreach s, $(srcdir), $(call rwildcard,$(s),*.c)))
cxxfiles := $(strip $(foreach s, $(srcdir), $(call rwildcard,$(s),*.cpp)))
asfiles := $(strip $(foreach s, $(srcdir), $(call rwildcard,$(s),*.s)))
asfiles += ${start_asm_file}
$(info $(asfiles))

core_cfiles += $(subst $(core_root)/,,$(strip $(foreach s, $(coredir), $(call rwildcard,$(s),*.c))))
core_cxxfiles += $(subst $(core_root)/,,$(strip $(foreach s, $(coredir), $(call rwildcard,$(s),*.cpp))))
core_asfiles += $(subst $(core_root)/,,$(strip $(foreach s, $(coredir), $(call rwildcard,$(s),*.s))))

#exclude due to repeat system init
#core_cfiles := $(filter-out libraries/SrcWrapper/src/stm32/system_stm32yyxx.c,$(core_cfiles))
#$(info $(core_cfiles))

src_files := $(cfiles) $(cxxfiles) $(asfiles)
core_files := $(core_cfiles) $(core_cxxfiles) $(core_asfiles)
files := $(src_files) $(core_files)
sdirs := $(sort $(dir $(files)))
$(info $(sdirs))

#hfiles := $(foreach s, $(includedir), $(call rwildcard,$(s),*.h))
#hfiles += $(foreach s, $(srcdir), $(call rwildcard,$(s),*.h))
#incdirs = $(sort $(dir $(hfiles)))

TOOLPREFIX := arm-none-eabi-
CC      = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)gcc
CXX     = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)g++
AS      = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)as
OBJCOPY = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)objcopy
OBJDUMP = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)objdump
AR      = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)ar
SIZE    = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)size
NM      = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)nm
LD      = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)ld
DFUUTIL = dfu-util


RM      = /usr/bin/rm
MKDIR   = /usr/bin/mkdir -p
TEST	= /usr/bin/test

DEFINES := $(addprefix -D,$(defines))
INCLUDES := $(addprefix -I,$(includedir))

#optimise
# -O0 - none
# -Os - optimise size
# -O1 - optimise
# -O2 - optimise more
# -O3 - optimise most
# -Og - optimise debug
OFLAG := -Os

#debug
# default none
# -g - debug
# -g1 - minimal
# -g3 - maximal
DFLAG = -g

COMMON_OFLAGS := -Wl,--gc-sections $(OFLAG) $(DFLAG) \
                 -ffunction-sections -fdata-sections \
                 -fmessage-length=0 -fsigned-char \
                 -ffreestanding -fno-move-loop-invariants \
                 --specs=nano.specs -Wall -Wextra

FPU_FLAGS := -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsingle-precision-constant
#FPU_FLAGS := -mfloat-abi=softfp -mfpu=fpv4-sp-d16 -fsingle-precision-constant


TARGET_FLAGS += -mcpu=cortex-m4 -march=armv7e-m+fp -mthumb \
                 $(FPU_FLAGS) \
                 $(INCLUDES) $(DEFINES)

GLOBAL_CFLAGS := $(COMMON_OFLAGS) $(TARGET_FLAGS)
TARGET_CFLAGS :=
GLOBAL_CXXFLAGS := -fno-rtti -fno-exceptions \
                   -fno-use-cxa-atexit -fno-threadsafe-statics \
                   $(COMMON_OFLAGS) \
                   $(TARGET_FLAGS)
TARGET_CXXFLAGS :=
GLOBAL_ASFLAGS  := $(TARGET_FLAGS)
#TARGET_ASFLAGS  := -Wl,--gc-sections $(OFLAG) $(DFLAG) -Xassembler -Wall
TARGET_ASFLAGS  := -Wl,--gc-sections $(OFLAG) $(DFLAG)

#				   -nostdlib
#                  -nodefaultlibs
#                  -nostartfiles
#                  -Wl,--gc-sections
GLOBAL_LDFLAGS := --specs=nano.specs \
                  -Xlinker --gc-sections

TARGET_LDFLAGS := $(TARGET_FLAGS) \
                  -Xlinker -T$(LD_SCRIPT_PATH) \
                  -L $(variantdir)
#                  -Xlinker -T$(add_ld_script)

TARGET_LDFLAGS += -Wl,--defsym,LD_FLASH_OFFSET=$(ld_flash_offset) \
                  -Wl,--defsym,LD_MAX_SIZE=$(ld_flash_size) \
                  -Wl,--defsym,LD_MAX_DATA_SIZE=$(ld_sram_size)

CFLAGS   = $(GLOBAL_CFLAGS) $(TARGET_CFLAGS)
CXXFLAGS = $(GLOBAL_CXXFLAGS) $(TARGET_CXXFLAGS)
CPPFLAGS =
ASFLAGS  = $(GLOBAL_ASFLAGS) $(TARGET_ASFLAGS)

# Add toolchain directory to LD search path
TOOLCHAIN_LDFLAGS := -L $(LD_TOOLCHAIN_PATH) -L $(CMSIS_LD_PATH) -l $(cmsis_lib_gcc)
LDFLAGS = $(GLOBAL_LDFLAGS) $(TARGET_LDFLAGS) $(TOOLCHAIN_LDFLAGS)

#build lists of object files relative to $(out_dir)
COBJS = $(addprefix $(out_dir)/,$(patsubst %.c,%.o,$(cfiles)))
CXXOBJS = $(addprefix $(out_dir)/,$(patsubst %.cpp,%.o,$(cxxfiles)))
ASOBJS =  $(addprefix $(out_dir)/,$(patsubst %.s,%.o,$(asfiles)))

CORE_COBJS = $(addprefix $(out_dir)/,$(patsubst %.c,%.o,$(core_cfiles)))
CORE_CXXOBJS = $(addprefix $(out_dir)/,$(patsubst %.cpp,%.o,$(core_cxxfiles)))
CORE_ASOBJS =  $(addprefix $(out_dir)/,$(patsubst %.s,%.o,$(core_asfiles)))


variant.ELF = $(out_dir)/$(variant).elf
variant.BIN = $(out_dir)/$(variant).bin

.PHONY: all clean mkdir
all: mkdir $(variant.BIN)
	@echo
	@$(SIZE) $(variant.ELF)
	@echo
	@ls -l $(variant.BIN)
	@echo
	@$(OBJDUMP) --section-headers $(variant.ELF)
	@echo
	@echo Source dirs
	@echo $(srcdir) $(coredir) | sed 's/ /\n/g'
	@echo
	@echo $(sort $(dir $(src_files))) | sed 's/ /\n/g'
	@echo $(addprefix $(core_root)/,$(sort $(dir $(core_files)))) | sed 's/ /\n/g'
	@echo
	@echo Includes
	@echo $(INCLUDES) | sed 's/ /\n/g'
	@echo
	@echo Defines
	@echo $(DEFINES) | sed 's/ /\n/g'


install: all
	$(DFUUTIL) -d 0483:df11 -a 0 -s 0x8000000 -D $(variant.BIN)

$(variant.BIN): $(variant.ELF)
	$(OBJCOPY) -v -Obinary $(variant.ELF) $@

$(variant.ELF): $(ASOBJS) $(COBJS) $(CXXOBJS) \
                $(CORE_COBJS) $(CORE_CXXOBJS) $(CORE_ASOBJS)
	$(CXX) $(LDFLAGS) -o $@ -Wl,-Map,$(out_dir)/$(variant).map $+

# General directory independent build rules, generate dependency information
$(COBJS): $(out_dir)/%.o: %.c
	$(CC) $(CFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

$(CXXOBJS): $(out_dir)/%.o: %.cpp
	$(CXX) $(CXXFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

$(ASOBJS): $(out_dir)/%.o: %.s
	@echo $(ASOBJS)
	$(CC) $(ASFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

$(CORE_COBJS): $(out_dir)/%.o: $(core_root)/%.c
	$(CC) $(CFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

$(CORE_CXXOBJS): $(out_dir)/%.o: $(core_root)/%.cpp
	$(CXX) $(CXXFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

$(CORE_ASOBJS): $(out_dir)/%.o: $(core_root)/%.s
	$(CC) $(ASFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<


# create the build directories
tgtdirs := $(addsuffix .dir,$(addprefix $(out_dir)/,$(sdirs)))

mkdir: $(tgtdirs)

# the .dir file is a marker file that the directory is created
$(tgtdirs) : $(out_dir)/.dir
	$(MKDIR) $(dir $@)
	@touch $@

$(out_dir)/.dir:
	$(MKDIR) $(dir $@)
	@touch $@

clean:
	@echo clean
	$(RM) -r $(out_dir)

DEPENDS := $(COBJS:%.o=%.d) $(CXXOBJS:%.o=%.d) $(ASOBJS:%.o=%.d)
DEPENDS += $(CORE_COBJS:%.o=%.d) $(CORE_CXXOBJS:%.o=%.d) $(CORE_ASOBJS:%.o=%.d)

-include $(DEPENDS)
	# version 0 (alpha)
	# this is only tested in linux
	# this is for this board https://stm32-base.org/boards/STM32F407VET6-STM32-F4VE-V2.0.html
	#
	# This make file for stm32duino core is possibly dangerous
	# i.e. it compiles the sources (in src and Arduino_Core_STM32) directory
	# and overwrite all the stuff in $(out_dir)
	# $(out_dir) is the binary directory where the object files are dumped there
	#
	# make clean deletes the $(out_dir) (coded here as build )
	#
	# this is a relative path makefile
	# the directory structure needs to be
	# Root (project folder)
	# +-- src (your sources e.g. the sketch
	# \| the files has to be cpp, c or h, no ino)
	# \|
	# +-- Arduino_Core_STM32 (copy from the stm32duino core)
	# \|
	# +-- CMSIS_5
	# \|
	# +-- variants (see below)
	# \|
	# +-- Makefile (this makefile)
	#
	# this makefile can't handle the brackets/paranthesis naming convention used for the variants
	# hence you need to create a local variant folder and copy all the files in
	# Arduino_Core_STM32/variants/STM32F4xx/F407V(E-G)T_F417V(E-G)T/
	# to
	# variants/F407VX/
	#
	# the make needs to be run from the root(project folder) of this file structure
	# the make is relative path from this Root
	# generated object files and binaries (elf, bin) are placed into the
	# $(out_dir) - build
	#
	# make clean - deletes $(out_dir)
	#
	# make all - starts the build
	#
	# This software released into the public domain.
	#
	# Anyone is free to copy, modify, publish, use, compile, sell, or
	# distribute this software, either in source code form or as a compiled
	# binary, for any purpose, commercial or non-commercial, and by any
	# means.
	#
	# In jurisdictions that recognize copyright laws, the author or authors
	# of this software dedicate any and all copyright interest in the
	# software to the public domain.
	#
	# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
	# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
	# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	# OTHER DEALINGS IN THE SOFTWARE.
	#

	# this folder is deleted with make clean
	out_dir := build

	# this is the name of the subdirectory under STM32F1/variants
	# it needs to match, this caters to a single variant
	variant := F407VX
	build_series := STM32F4xx
	build_arch := STM32
	#build_board := GenF4
	build_board := BLACK_F407VE
	variant_h := variant_BLACK_F407VX.h
	product_line := STM32F407xx

	#flash offset
	ld_flash_offset := 0x0
	#flash size
	# 512K
	ld_flash_size := 0x80000
	#sram size
	# 128K (sram)
	ld_sram_size += 0x20000
	# 64k (ccmram) - ccm ram is maint directly in ldscript

	# these are the defines passed to gcc, g++ and the assembler
	# use += to add more definitions
	defines := ARDUINO=189
	defines += $(build_series)
	defines += ARDUINO_$(build_board)
	defines += ARDUINO_ARCH_$(build_arch)
	defines += BOARD_NAME=\"$(build_board)\"
	defines += VARIANT_H=\"$(variant_h)\"
	defines += $(product_line)
	#defines += VECT_TAB_SRAM
	defines += VECT_TAB_OFFSET=0
	defines += DEBUG_LEVEL=DEBUG_NONE
	defines += F_CPU=168000000L
	defines += HSE_VALUE=8000000L
	defines += HAL_UART_MODULE_ENABLED
	defines += HAL_PCD_MODULE_ENABLED
	defines += USBCON
	defines += USBD_VID=0x0483
	defines += USBD_PID=0x5740
	defines += USB_MANUFACTURER=\"Unknown\"
	defines += USB_PRODUCT=\"$(build_board)\"
	# usb serial
	defines += USBD_USE_CDC
	# HID keyboard and mouse
	#defines += USBD_USE_HID_COMPOSITE
	defines += LED_BUILTIN=PA6
	defines += HAVE_INITFINI_ARRAY


	# points to the parent folder containing stm32duino core (e.g. Arduino_Core_STM32) in a sub-directory
	# use of this is not encouraged, it is safer to copy the Arduino_Core_STM32
	# folder into the current directory
	# omit the final slash after the directory
	core_root := .
	core_name := Arduino_Core_STM32
	build_core_path = $(core_root)/$(core_name)/cores/arduino
	build_system_path = $(core_root)/$(core_name)/system
	CMSIS_path := $(core_root)/CMSIS_5
	# This is for the CMSIS math lib
	CMSIS_LD_PATH := $(core_root)/CMSIS/DSP/Lib/GCC
	cmsis_lib_gcc := arm_cortexM4lf_math
	start_file_path := $(build_system_path)/Drivers/CMSIS/Device/ST/$(build_series)/Source/Templates/gcc

	# these are the source directories for the core
	# and variant, normally they stay unchanged
	# if you want to place the core directory somewhere else,
	# define core_root above
	coredir := $(core_root)/$(core_name)/cores/arduino
	coredir += $(core_root)/$(core_name)/libraries/SrcWrapper/src
	#coredir += $(build_system_path)/Drivers/$(build_series)_HAL_Driver/Src
	#coredir += $(build_system_path)/$(build_series)
	#coredir += $(build_system_path)/Middlewares/ST/STM32_USB_Device_Library/Core/Src
	#variantdir := $(core_root)/variants/$(variant)
	#local variannt dir
	#variantdir := $(core_root)/$(core_name)/variants/$(variant)
	#variantdir := $(core_name)/variants/$(build_series)/$(variant)
	variantdir := variants/$(variant)
	#coredir += $(variantdir)

	# source directories
	# these are the initial directories to search for sources
	# relative to this build (root) directory
	# if you use libraries either put them in a sub-directory in src
	srcdir := src
	# or add it here
	#srcdir += library1
	srcdir += $(variantdir)
	srcdir += $(core_name)/libraries/SPI/src

	$(info $(srcdir))

	#this is the ld script in STM32F1/variants/$(variant)/ld to use
	#ldscript := bootloader_20.ld
	ldscript := ldscript.ld
	LD_SCRIPT_PATH := $(variantdir)/$(ldscript)
	#LD_SCRIPT_PATH := variants/Pill_F401CC/$(ldscript)
	#add_ld_script:=src/board.ld

	#this is the startup asm file, mcu specific
	start_mcu_name := stm32f407xx
	start_asm_file := ${start_file_path}/startup_${start_mcu_name}.s

	#the includes i.e. the -Ipath needs to be exlicitly stated
	#no automatic recursive searching
	#if you use libraries you may want to add it here
	includedir := $(srcdir)
	includedir += $(variantdir)
	includedir += $(CMSIS_path)/CMSIS/Core/Include
	includedir += $(build_system_path)/Drivers/CMSIS/Device/ST/$(build_series)/Include/
	#includedir += $(build_system_path)/Drivers/CMSIS/Device/ST/$(build_series)/Source/Templates/gcc/
	includedir += $(CMSIS_path)/CMSIS/DSP/Include
	includedir += $(build_core_path)
	includedir += $(build_core_path)/avr
	includedir += $(build_core_path)/stm32
	includedir += $(build_core_path)/stm32/LL
	includedir += $(build_core_path)/stm32/usb
	includedir += $(build_core_path)/stm32/usb/hid
	includedir += $(build_core_path)/stm32/usb/cdc
	includedir += $(build_system_path)/Drivers/$(build_series)_HAL_Driver/Inc
	includedir += $(build_system_path)/Drivers/$(build_series)_HAL_Driver/Src
	includedir += $(build_system_path)/$(build_series)
	includedir += $(build_system_path)/Middlewares/ST/STM32_USB_Device_Library/Core/Inc
	includedir += $(build_system_path)/Middlewares/ST/STM32_USB_Device_Library/Core/Src


	#if you use core_root, you would need to add that as a prefix
	#includedir := $(addprefix $(core_root)/,$(includedir))

	# update this to match
	# this should be the install base location of ARM_NONE_EABI_GCC toolchain
	ARM_NONE_EABI_PATH := /opt/arduino/gcc-arm-none-eabi-8-2018-q4-major
	# this should be the location of the arm standard libraries c & c++
	# the arm-none-eabi/lib select the folder matching the arch
	# compile options e.g. thumb and v7-m
	LD_TOOLCHAIN_PATH := $(ARM_NONE_EABI_PATH)/arm-none-eabi/lib/thumb/v7e-m+fp


	# recursive wildcard function, call with params:
	# - start directory (finished with /) or empty string for current dir
	# - glob pattern
	# (taken from http://blog.jgc.org/2011/07/gnu-make-recursive-wildcard-function.html)
	rwildcard=$(foreach d,$(wildcard $1),$(call rwildcard,$d/,$2) $(filter $(subst ,%,$2),$d))

	cfiles := $(strip $(foreach s, $(srcdir), $(call rwildcard,$(s),*.c)))
	cxxfiles := $(strip $(foreach s, $(srcdir), $(call rwildcard,$(s),*.cpp)))
	asfiles := $(strip $(foreach s, $(srcdir), $(call rwildcard,$(s),*.s)))
	asfiles += ${start_asm_file}
	$(info $(asfiles))

	core_cfiles += $(subst $(core_root)/,,$(strip $(foreach s, $(coredir), $(call rwildcard,$(s),*.c))))
	core_cxxfiles += $(subst $(core_root)/,,$(strip $(foreach s, $(coredir), $(call rwildcard,$(s),*.cpp))))
	core_asfiles += $(subst $(core_root)/,,$(strip $(foreach s, $(coredir), $(call rwildcard,$(s),*.s))))

	#exclude due to repeat system init
	#core_cfiles := $(filter-out libraries/SrcWrapper/src/stm32/system_stm32yyxx.c,$(core_cfiles))
	#$(info $(core_cfiles))

	src_files := $(cfiles) $(cxxfiles) $(asfiles)
	core_files := $(core_cfiles) $(core_cxxfiles) $(core_asfiles)
	files := $(src_files) $(core_files)
	sdirs := $(sort $(dir $(files)))
	$(info $(sdirs))

	#hfiles := $(foreach s, $(includedir), $(call rwildcard,$(s),*.h))
	#hfiles += $(foreach s, $(srcdir), $(call rwildcard,$(s),*.h))
	#incdirs = $(sort $(dir $(hfiles)))

	TOOLPREFIX := arm-none-eabi-
	CC = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)gcc
	CXX = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)g++
	AS = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)as
	OBJCOPY = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)objcopy
	OBJDUMP = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)objdump
	AR = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)ar
	SIZE = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)size
	NM = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)nm
	LD = $(ARM_NONE_EABI_PATH)/bin/$(TOOLPREFIX)ld
	DFUUTIL = dfu-util


	RM = /usr/bin/rm
	MKDIR = /usr/bin/mkdir -p
	TEST = /usr/bin/test

	DEFINES := $(addprefix -D,$(defines))
	INCLUDES := $(addprefix -I,$(includedir))

	#optimise
	# -O0 - none
	# -Os - optimise size
	# -O1 - optimise
	# -O2 - optimise more
	# -O3 - optimise most
	# -Og - optimise debug
	OFLAG := -Os

	#debug
	# default none
	# -g - debug
	# -g1 - minimal
	# -g3 - maximal
	DFLAG = -g

	COMMON_OFLAGS := -Wl,--gc-sections $(OFLAG) $(DFLAG) \
	-ffunction-sections -fdata-sections \
	-fmessage-length=0 -fsigned-char \
	-ffreestanding -fno-move-loop-invariants \
	--specs=nano.specs -Wall -Wextra

	FPU_FLAGS := -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsingle-precision-constant
	#FPU_FLAGS := -mfloat-abi=softfp -mfpu=fpv4-sp-d16 -fsingle-precision-constant


	TARGET_FLAGS += -mcpu=cortex-m4 -march=armv7e-m+fp -mthumb \
	$(FPU_FLAGS) \
	$(INCLUDES) $(DEFINES)

	GLOBAL_CFLAGS := $(COMMON_OFLAGS) $(TARGET_FLAGS)
	TARGET_CFLAGS :=
	GLOBAL_CXXFLAGS := -fno-rtti -fno-exceptions \
	-fno-use-cxa-atexit -fno-threadsafe-statics \
	$(COMMON_OFLAGS) \
	$(TARGET_FLAGS)
	TARGET_CXXFLAGS :=
	GLOBAL_ASFLAGS := $(TARGET_FLAGS)
	#TARGET_ASFLAGS := -Wl,--gc-sections $(OFLAG) $(DFLAG) -Xassembler -Wall
	TARGET_ASFLAGS := -Wl,--gc-sections $(OFLAG) $(DFLAG)

	# -nostdlib
	# -nodefaultlibs
	# -nostartfiles
	# -Wl,--gc-sections
	GLOBAL_LDFLAGS := --specs=nano.specs \
	-Xlinker --gc-sections

	TARGET_LDFLAGS := $(TARGET_FLAGS) \
	-Xlinker -T$(LD_SCRIPT_PATH) \
	-L $(variantdir)
	# -Xlinker -T$(add_ld_script)

	TARGET_LDFLAGS += -Wl,--defsym,LD_FLASH_OFFSET=$(ld_flash_offset) \
	-Wl,--defsym,LD_MAX_SIZE=$(ld_flash_size) \
	-Wl,--defsym,LD_MAX_DATA_SIZE=$(ld_sram_size)

	CFLAGS = $(GLOBAL_CFLAGS) $(TARGET_CFLAGS)
	CXXFLAGS = $(GLOBAL_CXXFLAGS) $(TARGET_CXXFLAGS)
	CPPFLAGS =
	ASFLAGS = $(GLOBAL_ASFLAGS) $(TARGET_ASFLAGS)

	# Add toolchain directory to LD search path
	TOOLCHAIN_LDFLAGS := -L $(LD_TOOLCHAIN_PATH) -L $(CMSIS_LD_PATH) -l $(cmsis_lib_gcc)
	LDFLAGS = $(GLOBAL_LDFLAGS) $(TARGET_LDFLAGS) $(TOOLCHAIN_LDFLAGS)

	#build lists of object files relative to $(out_dir)
	COBJS = $(addprefix $(out_dir)/,$(patsubst %.c,%.o,$(cfiles)))
	CXXOBJS = $(addprefix $(out_dir)/,$(patsubst %.cpp,%.o,$(cxxfiles)))
	ASOBJS = $(addprefix $(out_dir)/,$(patsubst %.s,%.o,$(asfiles)))

	CORE_COBJS = $(addprefix $(out_dir)/,$(patsubst %.c,%.o,$(core_cfiles)))
	CORE_CXXOBJS = $(addprefix $(out_dir)/,$(patsubst %.cpp,%.o,$(core_cxxfiles)))
	CORE_ASOBJS = $(addprefix $(out_dir)/,$(patsubst %.s,%.o,$(core_asfiles)))


	variant.ELF = $(out_dir)/$(variant).elf
	variant.BIN = $(out_dir)/$(variant).bin

	.PHONY: all clean mkdir
	all: mkdir $(variant.BIN)
	@echo
	@$(SIZE) $(variant.ELF)
	@echo
	@ls -l $(variant.BIN)
	@echo
	@$(OBJDUMP) --section-headers $(variant.ELF)
	@echo
	@echo Source dirs
	@echo $(srcdir) $(coredir) \| sed 's/ /\n/g'
	@echo
	@echo $(sort $(dir $(src_files))) \| sed 's/ /\n/g'
	@echo $(addprefix $(core_root)/,$(sort $(dir $(core_files)))) \| sed 's/ /\n/g'
	@echo
	@echo Includes
	@echo $(INCLUDES) \| sed 's/ /\n/g'
	@echo
	@echo Defines
	@echo $(DEFINES) \| sed 's/ /\n/g'


	install: all
	$(DFUUTIL) -d 0483:df11 -a 0 -s 0x8000000 -D $(variant.BIN)

	$(variant.BIN): $(variant.ELF)
	$(OBJCOPY) -v -Obinary $(variant.ELF) $@

	$(variant.ELF): $(ASOBJS) $(COBJS) $(CXXOBJS) \
	$(CORE_COBJS) $(CORE_CXXOBJS) $(CORE_ASOBJS)
	$(CXX) $(LDFLAGS) -o $@ -Wl,-Map,$(out_dir)/$(variant).map $+

	# General directory independent build rules, generate dependency information
	$(COBJS): $(out_dir)/%.o: %.c
	$(CC) $(CFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

	$(CXXOBJS): $(out_dir)/%.o: %.cpp
	$(CXX) $(CXXFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

	$(ASOBJS): $(out_dir)/%.o: %.s
	@echo $(ASOBJS)
	$(CC) $(ASFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

	$(CORE_COBJS): $(out_dir)/%.o: $(core_root)/%.c
	$(CC) $(CFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

	$(CORE_CXXOBJS): $(out_dir)/%.o: $(core_root)/%.cpp
	$(CXX) $(CXXFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<

	$(CORE_ASOBJS): $(out_dir)/%.o: $(core_root)/%.s
	$(CC) $(ASFLAGS) -MMD -MP -MF $(@:%.o=%.d) -MT $@ -o $@ -c $<


	# create the build directories
	tgtdirs := $(addsuffix .dir,$(addprefix $(out_dir)/,$(sdirs)))

	mkdir: $(tgtdirs)

	# the .dir file is a marker file that the directory is created
	$(tgtdirs) : $(out_dir)/.dir
	$(MKDIR) $(dir $@)
	@touch $@

	$(out_dir)/.dir:
	$(MKDIR) $(dir $@)
	@touch $@

	clean:
	@echo clean
	$(RM) -r $(out_dir)

	DEPENDS := $(COBJS:%.o=%.d) $(CXXOBJS:%.o=%.d) $(ASOBJS:%.o=%.d)
	DEPENDS += $(CORE_COBJS:%.o=%.d) $(CORE_CXXOBJS:%.o=%.d) $(CORE_ASOBJS:%.o=%.d)

	-include $(DEPENDS)