16 files changed, 669 insertions, 0 deletions
diff --git a/examples/build_system/make/cpu/arm1176.mk b/examples/build_system/make/cpu/arm1176.mk
new file mode 100644
index 000000000..022ccf7ad
--- /dev/null
+++ b/examples/build_system/make/cpu/arm1176.mk
@@ -0,0 +1,9 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mcpu=arm1176jzf-s \
+
+else ifeq ($(TOOLCHAIN),iar)
+	#CFLAGS += --cpu cortex-a53
+	#ASFLAGS += --cpu cortex-a53
+
+endif
diff --git a/examples/build_system/make/cpu/cortex-a53.mk b/examples/build_system/make/cpu/cortex-a53.mk
new file mode 100644
index 000000000..42e522ecf
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-a53.mk
@@ -0,0 +1,12 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mcpu=cortex-a53 \
+
+else ifeq ($(TOOLCHAIN),iar)
+	CFLAGS += \
+		--cpu cortex-a53 \
+
+	ASFLAGS += \
+		--cpu cortex-a53 \
+
+endif
diff --git a/examples/build_system/make/cpu/cortex-a72.mk b/examples/build_system/make/cpu/cortex-a72.mk
new file mode 100644
index 000000000..1b3d8da4a
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-a72.mk
@@ -0,0 +1,12 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mcpu=cortex-a72 \
+
+else ifeq ($(TOOLCHAIN),iar)
+	CFLAGS += \
+		--cpu cortex-a72 \
+
+	ASFLAGS += \
+		--cpu cortex-a72 \
+
+endif
diff --git a/examples/build_system/make/cpu/cortex-m0.mk b/examples/build_system/make/cpu/cortex-m0.mk
new file mode 100644
index 000000000..feb0f395b
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m0.mk
@@ -0,0 +1,14 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m0 \
+    -mfloat-abi=soft \
+
+else ifeq ($(TOOLCHAIN),iar)
+  # IAR Flags
+  CFLAGS += --cpu cortex-m0
+  ASFLAGS += --cpu cortex-m0
+endif
+
+# For freeRTOS port source
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM0
diff --git a/examples/build_system/make/cpu/cortex-m0plus.mk b/examples/build_system/make/cpu/cortex-m0plus.mk
new file mode 100644
index 000000000..b416b7a4a
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m0plus.mk
@@ -0,0 +1,14 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m0plus \
+    -mfloat-abi=soft \
+
+else ifeq ($(TOOLCHAIN),iar)
+  # IAR Flags
+  CFLAGS += --cpu cortex-m0+
+  ASFLAGS += --cpu cortex-m0+
+endif
+
+# For freeRTOS port source
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM0
diff --git a/examples/build_system/make/cpu/cortex-m23.mk b/examples/build_system/make/cpu/cortex-m23.mk
new file mode 100644
index 000000000..29542d8e8
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m23.mk
@@ -0,0 +1,14 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m23 \
+    -mfloat-abi=soft \
+
+else ifeq ($(TOOLCHAIN),iar)
+  # IAR Flags
+  CFLAGS += --cpu cortex-m23
+  ASFLAGS += --cpu cortex-m23
+endif
+
+# For freeRTOS port source
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM23
diff --git a/examples/build_system/make/cpu/cortex-m3.mk b/examples/build_system/make/cpu/cortex-m3.mk
new file mode 100644
index 000000000..7a34b9e04
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m3.mk
@@ -0,0 +1,17 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m3 \
+    -mfloat-abi=soft \
+
+else ifeq ($(TOOLCHAIN),iar)
+  # IAR Flags
+  CFLAGS += \
+    --cpu cortex-m3 \
+
+  ASFLAGS += \
+     --cpu cortex-m3
+endif
+
+# For freeRTOS port source
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM3
diff --git a/examples/build_system/make/cpu/cortex-m33.mk b/examples/build_system/make/cpu/cortex-m33.mk
new file mode 100644
index 000000000..fe5b7b380
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m33.mk
@@ -0,0 +1,19 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m33 \
+    -mfloat-abi=hard \
+    -mfpu=fpv5-sp-d16 \
+
+else ifeq ($(TOOLCHAIN),iar)
+	CFLAGS += \
+		--cpu cortex-m33 \
+		--fpu VFPv5-SP \
+
+	ASFLAGS += \
+		--cpu cortex-m33 \
+		--fpu VFPv5-SP \
+
+endif
+
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM33_NTZ/non_secure
diff --git a/examples/build_system/make/cpu/cortex-m4.mk b/examples/build_system/make/cpu/cortex-m4.mk
new file mode 100644
index 000000000..d8776b5d8
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m4.mk
@@ -0,0 +1,13 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m4 \
+    -mfloat-abi=hard \
+    -mfpu=fpv4-sp-d16 \
+
+else ifeq ($(TOOLCHAIN),iar)
+  CFLAGS += --cpu cortex-m4 --fpu VFPv4
+  ASFLAGS += --cpu cortex-m4 --fpu VFPv4
+endif
+
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM4F
diff --git a/examples/build_system/make/cpu/cortex-m7.mk b/examples/build_system/make/cpu/cortex-m7.mk
new file mode 100644
index 000000000..0e3461787
--- /dev/null
+++ b/examples/build_system/make/cpu/cortex-m7.mk
@@ -0,0 +1,19 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m7 \
+    -mfloat-abi=hard \
+    -mfpu=fpv5-d16 \
+
+else ifeq ($(TOOLCHAIN),iar)
+  CFLAGS += \
+  	--cpu cortex-m7 \
+  	--fpu VFPv5_D16 \
+
+  ASFLAGS += \
+		--cpu cortex-m7 \
+		--fpu VFPv5_D16 \
+
+endif
+
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM7/r0p1
diff --git a/examples/build_system/make/make.mk b/examples/build_system/make/make.mk
new file mode 100644
index 000000000..e1113aa52
--- /dev/null
+++ b/examples/build_system/make/make.mk
@@ -0,0 +1,144 @@
+# ---------------------------------------
+# Common make definition for all examples
+# ---------------------------------------
+
+#-------------- TOP and CURRENT_PATH ------------
+
+# Set TOP to be the path to get from the current directory (where make was invoked) to the top of the tree.
+# $(lastword $(MAKEFILE_LIST)) returns the name of this makefile relative to where make was invoked.
+THIS_MAKEFILE := $(lastword $(MAKEFILE_LIST))
+
+# strip off /examples/build_system/make to get for example ../../..
+# and Set TOP to an absolute path
+TOP = $(abspath $(subst make.mk,../../..,$(THIS_MAKEFILE)))
+
+# Set CURRENT_PATH to the relative path from TOP to the current directory, ie examples/device/cdc_msc_freertos
+CURRENT_PATH = $(subst $(TOP)/,,$(abspath .))
+
+# Detect whether shell style is windows or not
+# https://stackoverflow.com/questions/714100/os-detecting-makefile/52062069#52062069
+ifeq '$(findstring ;,$(PATH))' ';'
+# PATH contains semicolon - so we're definitely on Windows.
+CMDEXE := 1
+
+# makefile shell commands should use syntax for DOS CMD, not unix sh
+# Force DOS command shell on Windows.
+SHELL := cmd.exe
+endif
+
+# Handy check parameter function
+check_defined = \
+    $(strip $(foreach 1,$1, \
+    $(call __check_defined,$1,$(strip $(value 2)))))
+__check_defined = \
+    $(if $(value $1),, \
+    $(error Undefined make flag: $1$(if $2, ($2))))
+
+# Build directory
+BUILD := _build/$(BOARD)
+
+PROJECT := $(notdir $(CURDIR))
+BIN := $(TOP)/_bin/$(BOARD)/$(notdir $(CURDIR))
+
+#-------------- Select the board to build for. ------------
+
+# Board without family
+ifneq ($(wildcard $(TOP)/hw/bsp/$(BOARD)/board.mk),)
+BOARD_PATH := hw/bsp/$(BOARD)
+FAMILY :=
+endif
+
+# Board within family
+ifeq ($(BOARD_PATH),)
+  BOARD_PATH := $(subst $(TOP)/,,$(wildcard $(TOP)/hw/bsp/*/boards/$(BOARD)))
+  FAMILY := $(word 3, $(subst /, ,$(BOARD_PATH)))
+  FAMILY_PATH = hw/bsp/$(FAMILY)
+endif
+
+ifeq ($(BOARD_PATH),)
+  $(info You must provide a BOARD parameter with 'BOARD=')
+  $(error Invalid BOARD specified)
+endif
+
+ifeq ($(FAMILY),)
+  include $(TOP)/hw/bsp/$(BOARD)/board.mk
+else
+  # Include Family and Board specific defs
+  include $(TOP)/$(FAMILY_PATH)/family.mk
+  SRC_C += $(subst $(TOP)/,,$(wildcard $(TOP)/$(FAMILY_PATH)/*.c))
+endif
+
+#-------------- Toolchain  ------------
+
+# Supported toolchain: gcc, iar
+TOOLCHAIN ?= gcc
+
+# Can be set by board, default to ARM GCC
+CROSS_COMPILE ?= arm-none-eabi-
+
+ifeq ($(TOOLCHAIN),iar)
+CC := iccarm
+USE_IAR = 1
+endif
+
+ifeq ($(CMDEXE),1)
+  CP = copy
+  RM = del
+  MKDIR = mkdir
+  PYTHON = python
+else
+  CP = cp
+  RM = rm
+  MKDIR = mkdir
+  PYTHON = python3
+endif
+
+#-------------- Source files and compiler flags --------------
+# tinyusb makefile
+include $(TOP)/src/tinyusb.mk
+SRC_C += $(TINYUSB_SRC_C)
+
+# Include all source C in family & board folder
+SRC_C += hw/bsp/board.c
+SRC_C += $(subst $(TOP)/,,$(wildcard $(TOP)/$(BOARD_PATH)/*.c))
+
+INC += \
+  $(TOP)/$(FAMILY_PATH) \
+  $(TOP)/src \
+
+BOARD_UPPER = $(subst a,A,$(subst b,B,$(subst c,C,$(subst d,D,$(subst e,E,$(subst f,F,$(subst g,G,$(subst h,H,$(subst i,I,$(subst j,J,$(subst k,K,$(subst l,L,$(subst m,M,$(subst n,N,$(subst o,O,$(subst p,P,$(subst q,Q,$(subst r,R,$(subst s,S,$(subst t,T,$(subst u,U,$(subst v,V,$(subst w,W,$(subst x,X,$(subst y,Y,$(subst z,Z,$(subst -,_,$(BOARD))))))))))))))))))))))))))))
+CFLAGS += -DBOARD_$(BOARD_UPPER)
+
+# use max3421 as host controller
+ifeq (${MAX3421_HOST},1)
+  SRC_C += src/portable/analog/max3421/hcd_max3421.c
+  CFLAGS += -DCFG_TUH_MAX3421=1
+endif
+
+# Log level is mapped to TUSB DEBUG option
+ifneq ($(LOG),)
+  CMAKE_DEFSYM +=	-DLOG=$(LOG)
+  CFLAGS += -DCFG_TUSB_DEBUG=$(LOG)
+endif
+
+# Logger: default is uart, can be set to rtt or swo
+ifneq ($(LOGGER),)
+	CMAKE_DEFSYM +=	-DLOGGER=$(LOGGER)
+endif
+
+ifeq ($(LOGGER),rtt)
+  CFLAGS += -DLOGGER_RTT -DSEGGER_RTT_MODE_DEFAULT=SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL
+  RTT_SRC = lib/SEGGER_RTT
+  INC   += $(TOP)/$(RTT_SRC)/RTT
+  SRC_C += $(RTT_SRC)/RTT/SEGGER_RTT.c
+else ifeq ($(LOGGER),swo)
+  CFLAGS += -DLOGGER_SWO
+endif
+
+# CPU specific flags
+ifdef CPU_CORE
+  include ${TOP}/examples/build_system/make/cpu/$(CPU_CORE).mk
+endif
+
+# toolchain specific
+include ${TOP}/examples/build_system/make/toolchain/arm_$(TOOLCHAIN).mk
diff --git a/examples/build_system/make/rules.mk b/examples/build_system/make/rules.mk
new file mode 100644
index 000000000..b02665cdd
--- /dev/null
+++ b/examples/build_system/make/rules.mk
@@ -0,0 +1,173 @@
+# ---------------------------------------
+# Common make rules for all examples
+# ---------------------------------------
+
+# Set all as default goal
+.DEFAULT_GOAL := all
+
+# ---------------- GNU Make Start -----------------------
+# ESP32-Sx and RP2040 has its own CMake build system
+ifeq (,$(findstring $(FAMILY),espressif rp2040))
+
+# ---------------------------------------
+# Compiler Flags
+# ---------------------------------------
+
+CFLAGS += $(addprefix -I,$(INC))
+
+# Verbose mode
+ifeq ("$(V)","1")
+$(info CFLAGS  $(CFLAGS) ) $(info )
+$(info LDFLAGS $(LDFLAGS)) $(info )
+$(info ASFLAGS $(ASFLAGS)) $(info )
+endif
+
+# ---------------------------------------
+# Rules
+# ---------------------------------------
+
+all: $(BUILD)/$(PROJECT).bin $(BUILD)/$(PROJECT).hex size
+
+uf2: $(BUILD)/$(PROJECT).uf2
+
+# We set vpath to point to the top of the tree so that the source files
+# can be located. By following this scheme, it allows a single build rule
+# to be used to compile all .c files.
+vpath %.c . $(TOP)
+vpath %.s . $(TOP)
+vpath %.S . $(TOP)
+
+include ${TOP}/examples/build_system/make/toolchain/arm_$(TOOLCHAIN)_rules.mk
+
+
+OBJ_DIRS = $(sort $(dir $(OBJ)))
+$(OBJ): | $(OBJ_DIRS)
+$(OBJ_DIRS):
+ifeq ($(CMDEXE),1)
+	-@$(MKDIR) $(subst /,\,$@)
+else
+	@$(MKDIR) -p $@
+endif
+
+# UF2 generation, iMXRT need to strip to text only before conversion
+ifneq ($(FAMILY),imxrt)
+$(BUILD)/$(PROJECT).uf2: $(BUILD)/$(PROJECT).hex
+	@echo CREATE $@
+	$(PYTHON) $(TOP)/tools/uf2/utils/uf2conv.py -f $(UF2_FAMILY_ID) -c -o $@ $^
+endif
+
+copy-artifact: $(BUILD)/$(PROJECT).bin $(BUILD)/$(PROJECT).hex $(BUILD)/$(PROJECT).uf2
+
+endif
+# ---------------- GNU Make End -----------------------
+
+.PHONY: clean
+clean:
+ifeq ($(CMDEXE),1)
+	rd /S /Q $(subst /,\,$(BUILD))
+else
+	$(RM) -rf $(BUILD)
+endif
+
+# get depenecies
+.PHONY: get-deps
+get-deps:
+	$(PYTHON) $(TOP)/tools/get_deps.py ${FAMILY}
+
+.PHONY: size
+size: $(BUILD)/$(PROJECT).elf
+	-@echo ''
+	@$(SIZE) $<
+	-@echo ''
+
+# linkermap must be install previously at https://github.com/hathach/linkermap
+linkermap: $(BUILD)/$(PROJECT).elf
+	@linkermap -v $<.map
+
+# ---------------------------------------
+# Flash Targets
+# ---------------------------------------
+
+# --------------- Jlink -----------------
+ifeq ($(OS),Windows_NT)
+  JLINKEXE = JLink.exe
+else
+  JLINKEXE = JLinkExe
+endif
+
+# Jlink Interface
+JLINK_IF ?= swd
+
+# Jlink script
+$(BUILD)/$(BOARD).jlink: $(BUILD)/$(PROJECT).hex
+	@echo halt > $@
+	@echo loadfile $^ >> $@
+	@echo r >> $@
+	@echo go >> $@
+	@echo exit >> $@
+
+# Flash using jlink
+flash-jlink: $(BUILD)/$(BOARD).jlink
+	$(JLINKEXE) -device $(JLINK_DEVICE) -if $(JLINK_IF) -JTAGConf -1,-1 -speed auto -CommandFile $<
+
+# --------------- stm32 cube programmer -----------------
+# Flash STM32 MCU using stlink with STM32 Cube Programmer CLI
+flash-stlink: $(BUILD)/$(PROJECT).elf
+	STM32_Programmer_CLI --connect port=swd --write $< --go
+
+# --------------- xfel -----------------
+$(BUILD)/$(PROJECT)-sunxi.bin: $(BUILD)/$(PROJECT).bin
+	$(PYTHON) $(TOP)/tools/mksunxi.py $< $@
+
+flash-xfel: $(BUILD)/$(PROJECT)-sunxi.bin
+	xfel spinor write 0 $<
+	xfel reset
+
+# --------------- pyocd -----------------
+PYOCD_OPTION ?=
+flash-pyocd: $(BUILD)/$(PROJECT).hex
+	pyocd flash -t $(PYOCD_TARGET) $(PYOCD_OPTION) $<
+	#pyocd reset -t $(PYOCD_TARGET)
+
+# --------------- openocd -----------------
+OPENOCD_OPTION ?=
+flash-openocd: $(BUILD)/$(PROJECT).elf
+	openocd $(OPENOCD_OPTION) -c "program $< verify reset exit"
+
+# --------------- dfu-util -----------------
+DFU_UTIL_OPTION ?= -a 0
+flash-dfu-util: $(BUILD)/$(PROJECT).bin
+	dfu-util -R $(DFU_UTIL_OPTION) -D $<
+
+# --------------- Black Magic -----------------
+# This symlink is created by https://github.com/blacksphere/blackmagic/blob/master/driver/99-blackmagic.rules
+BMP ?= /dev/ttyBmpGdb
+
+flash-bmp: $(BUILD)/$(PROJECT).elf
+	$(GDB) --batch -ex 'target extended-remote $(BMP)' -ex 'monitor swdp_scan' -ex 'attach 1' -ex load  $<
+
+debug-bmp: $(BUILD)/$(PROJECT).elf
+	$(GDB) -ex 'target extended-remote $(BMP)' -ex 'monitor swdp_scan' -ex 'attach 1' $<
+
+#-------------- Artifacts --------------
+
+# Create binary directory
+$(BIN):
+ifeq ($(CMDEXE),1)
+	@$(MKDIR) $(subst /,\,$@)
+else
+	@$(MKDIR) -p $@
+endif
+
+# Copy binaries .elf, .bin, .hex, .uf2 to BIN for upload
+# due to large size of combined artifacts, only uf2 is uploaded for now
+copy-artifact: $(BIN)
+	@$(CP) $(BUILD)/$(PROJECT).uf2 $(BIN)
+	#@$(CP) $(BUILD)/$(PROJECT).bin $(BIN)
+	#@$(CP) $(BUILD)/$(PROJECT).hex $(BIN)
+	#@$(CP) $(BUILD)/$(PROJECT).elf $(BIN)
+
+# Print out the value of a make variable.
+# https://stackoverflow.com/questions/16467718/how-to-print-out-a-variable-in-makefile
+print-%:
+	@echo $* = $($*)
diff --git a/examples/build_system/make/toolchain/arm_gcc.mk b/examples/build_system/make/toolchain/arm_gcc.mk
new file mode 100644
index 000000000..b87657f53
--- /dev/null
+++ b/examples/build_system/make/toolchain/arm_gcc.mk
@@ -0,0 +1,79 @@
+# makefile for arm gcc toolchain
+
+CC = $(CROSS_COMPILE)gcc
+CXX = $(CROSS_COMPILE)g++
+AS = $(CC) -x assembler-with-cpp
+LD = $(CC)
+
+GDB = $(CROSS_COMPILE)gdb
+OBJCOPY = $(CROSS_COMPILE)objcopy
+SIZE = $(CROSS_COMPILE)size
+
+CC_VERSION := $(shell $(CC) -dumpversion)
+CC_VERSION_MAJOR = $(firstword $(subst ., ,$(CC_VERSION)))
+
+# ---------------------------------------
+# Compiler Flags
+# ---------------------------------------
+CFLAGS += \
+  -MD \
+  -ggdb \
+  -fdata-sections \
+  -ffunction-sections \
+  -fsingle-precision-constant \
+  -fno-strict-aliasing \
+  -Wall \
+  -Wextra \
+  -Werror \
+  -Wfatal-errors \
+  -Wdouble-promotion \
+  -Wstrict-prototypes \
+  -Wstrict-overflow \
+  -Werror-implicit-function-declaration \
+  -Wfloat-equal \
+  -Wundef \
+  -Wshadow \
+  -Wwrite-strings \
+  -Wsign-compare \
+  -Wmissing-format-attribute \
+  -Wunreachable-code \
+  -Wcast-align \
+  -Wcast-function-type \
+  -Wcast-qual \
+  -Wnull-dereference \
+  -Wuninitialized \
+  -Wunused \
+  -Wreturn-type \
+  -Wredundant-decls \
+
+# conversion is too strict for most mcu driver, may be disable sign/int/arith-conversion
+#  -Wconversion
+
+# Size Optimization as default
+CFLAGS_OPTIMIZED ?= -Os
+
+# Debugging/Optimization
+ifeq ($(DEBUG), 1)
+  CFLAGS += -O0
+  NO_LTO = 1
+else
+  CFLAGS += $(CFLAGS_OPTIMIZED)
+endif
+
+# ---------------------------------------
+# Linker Flags
+# ---------------------------------------
+LDFLAGS += \
+  -Wl,[email protected] \
+  -Wl,-cref \
+  -Wl,-gc-sections \
+
+# renesas rx does not support --print-memory-usage flags
+ifneq ($(FAMILY),rx)
+LDFLAGS += -Wl,--print-memory-usage
+endif
+
+# from version 12
+ifeq ($(shell expr $(CC_VERSION_MAJOR) \>= 12),1)
+LDFLAGS += -Wl,--no-warn-rwx-segment
+endif
diff --git a/examples/build_system/make/toolchain/arm_gcc_rules.mk b/examples/build_system/make/toolchain/arm_gcc_rules.mk
new file mode 100644
index 000000000..d295879d9
--- /dev/null
+++ b/examples/build_system/make/toolchain/arm_gcc_rules.mk
@@ -0,0 +1,75 @@
+SRC_S += $(SRC_S_GCC)
+
+# Assembly files can be name with upper case .S, convert it to .s
+SRC_S := $(SRC_S:.S=.s)
+
+# Due to GCC LTO bug https://bugs.launchpad.net/gcc-arm-embedded/+bug/1747966
+# assembly file should be placed first in linking order
+# '_asm' suffix is added to object of assembly file
+OBJ += $(addprefix $(BUILD)/obj/, $(SRC_S:.s=_asm.o))
+OBJ += $(addprefix $(BUILD)/obj/, $(SRC_C:.c=.o))
+
+CFLAGS += $(CFLAGS_GCC) -MD
+
+# LTO makes it difficult to analyze map file for optimizing size purpose
+# We will run this option in ci
+ifeq ($(NO_LTO),1)
+CFLAGS := $(filter-out -flto,$(CFLAGS))
+endif
+
+ifneq ($(CFLAGS_SKIP),)
+CFLAGS := $(filter-out $(CFLAGS_SKIP),$(CFLAGS))
+endif
+
+LDFLAGS += $(CFLAGS) $(LDFLAGS_GCC)
+
+ifdef LD_FILE
+LDFLAGS += -Wl,-T,$(TOP)/$(LD_FILE)
+endif
+
+ifdef LD_FILE_GCC
+LDFLAGS += -Wl,-T,$(TOP)/$(LD_FILE_GCC)
+endif
+
+ASFLAGS += $(CFLAGS)
+
+LIBS_GCC ?= -lgcc -lm -lnosys
+
+# libc
+LIBS += $(LIBS_GCC)
+
+ifneq ($(BOARD), spresense)
+LIBS += -lc
+endif
+
+# ---------------------------------------
+# Rules
+# ---------------------------------------
+
+# Compile .c file
+$(BUILD)/obj/%.o: %.c
+	@echo CC $(notdir $@)
+	@$(CC) $(CFLAGS) -c -o $@ $<
+
+# ASM sources lower case .s
+$(BUILD)/obj/%_asm.o: %.s
+	@echo AS $(notdir $@)
+	@$(AS) $(ASFLAGS) -c -o $@ $<
+
+# ASM sources upper case .S
+$(BUILD)/obj/%_asm.o: %.S
+	@echo AS $(notdir $@)
+	@$(AS) $(ASFLAGS) -c -o $@ $<
+
+OBJCOPY_BIN_OPTION ?=
+$(BUILD)/$(PROJECT).bin: $(BUILD)/$(PROJECT).elf
+	@echo CREATE $@
+	$(OBJCOPY) -O binary $(OBJCOPY_BIN_OPTION) $^ $@
+
+$(BUILD)/$(PROJECT).hex: $(BUILD)/$(PROJECT).elf
+	@echo CREATE $@
+	@$(OBJCOPY) -O ihex $^ $@
+
+$(BUILD)/$(PROJECT).elf: $(OBJ)
+	@echo LINK $@
+	@$(LD) -o $@ $(LDFLAGS) $^ -Wl,--start-group $(LIBS) -Wl,--end-group
diff --git a/examples/build_system/make/toolchain/arm_iar.mk b/examples/build_system/make/toolchain/arm_iar.mk
new file mode 100644
index 000000000..04c9f22b3
--- /dev/null
+++ b/examples/build_system/make/toolchain/arm_iar.mk
@@ -0,0 +1,11 @@
+# makefile for arm iar toolchain
+AS = iasmarm
+LD = ilinkarm
+OBJCOPY = ielftool --silent
+SIZE = size
+
+# Enable extension mode (gcc compatible)
+CFLAGS += -e --debug --silent
+
+# silent mode
+ASFLAGS += -S $(addprefix -I,$(INC))
diff --git a/examples/build_system/make/toolchain/arm_iar_rules.mk b/examples/build_system/make/toolchain/arm_iar_rules.mk
new file mode 100644
index 000000000..2c066f6da
--- /dev/null
+++ b/examples/build_system/make/toolchain/arm_iar_rules.mk
@@ -0,0 +1,44 @@
+SRC_S += $(SRC_S_IAR)
+
+# Assembly files can be name with upper case .S, convert it to .s
+SRC_S := $(SRC_S:.S=.s)
+
+# Due to GCC LTO bug https://bugs.launchpad.net/gcc-arm-embedded/+bug/1747966
+# assembly file should be placed first in linking order
+# '_asm' suffix is added to object of assembly file
+OBJ += $(addprefix $(BUILD)/obj/, $(SRC_S:.s=_asm.o))
+OBJ += $(addprefix $(BUILD)/obj/, $(SRC_C:.c=.o))
+
+# Linker script
+LDFLAGS += --config $(TOP)/$(LD_FILE_IAR)
+
+# ---------------------------------------
+# Rules
+# ---------------------------------------
+
+# Compile .c file
+$(BUILD)/obj/%.o: %.c
+	@echo CC $(notdir $@)
+	@$(CC) $(CFLAGS) -c -o $@ $<
+
+# ASM sources lower case .s
+$(BUILD)/obj/%_asm.o: %.s
+	@echo AS $(notdir $@)
+	@$(AS) $(ASFLAGS) -c -o $@ $<
+
+# ASM sources upper case .S
+$(BUILD)/obj/%_asm.o: %.S
+	@echo AS $(notdir $@)
+	@$(AS) $(ASFLAGS) -c -o $@ $<
+
+$(BUILD)/$(PROJECT).bin: $(BUILD)/$(PROJECT).elf
+	@echo CREATE $@
+	@$(OBJCOPY) --bin $^ $@
+
+$(BUILD)/$(PROJECT).hex: $(BUILD)/$(PROJECT).elf
+	@echo CREATE $@
+	@$(OBJCOPY) --ihex $^ $@
+
+$(BUILD)/$(PROJECT).elf: $(OBJ)
+	@echo LINK $@
+	@$(LD) -o $@ $(LDFLAGS) $^