diff --git a/Makefile b/Makefile
index 3fdf458da4..baff3fae1a 100644
--- a/Makefile
+++ b/Makefile
@@ -58,6 +58,7 @@ FORKNAME      = betaflight
 ROOT            := $(patsubst %/,%,$(dir $(lastword $(MAKEFILE_LIST))))
 PLATFORM_DIR	:= $(ROOT)/src/platform
 SRC_DIR         := $(ROOT)/src/main
+LIB_MAIN_DIR    := $(ROOT)/lib/main
 OBJECT_DIR      := $(ROOT)/obj/main
 BIN_DIR         := $(ROOT)/obj
 CMSIS_DIR       := $(ROOT)/lib/main/CMSIS
@@ -109,7 +110,7 @@ include $(MAKE_SCRIPT_DIR)/$(OSFAMILY).mk
 include $(MAKE_SCRIPT_DIR)/tools.mk
 
 # Search path for sources
-VPATH           := $(SRC_DIR)
+VPATH           := $(SRC_DIR):$(LIB_MAIN_DIR):$(PLATFORM_DIR)
 FATFS_DIR        = $(ROOT)/lib/main/FatFS
 FATFS_SRC        = $(notdir $(wildcard $(FATFS_DIR)/*.c))
 CSOURCES        := $(shell find $(SRC_DIR) -name '*.c')
@@ -126,6 +127,7 @@ include $(MAKE_SCRIPT_DIR)/config.mk
 ifeq ($(CONFIG),)
 ifeq ($(TARGET),)
 TARGET := $(DEFAULT_TARGET)
+SKIPCHECKS := yes
 endif
 endif
 
@@ -138,7 +140,6 @@ CI_TARGETS          := $(filter-out $(CI_EXCLUDED_TARGETS), $(BASE_TARGETS)) $(f
 TARGET_PLATFORM     := $(notdir $(patsubst %/,%,$(subst target/$(TARGET)/,, $(dir $(wildcard $(PLATFORM_DIR)/*/target/$(TARGET)/target.mk)))))
 TARGET_PLATFORM_DIR := $(PLATFORM_DIR)/$(TARGET_PLATFORM)
 LINKER_DIR          := $(TARGET_PLATFORM_DIR)/link
-VPATH               := $(VPATH):$(TARGET_PLATFORM_DIR):$(TARGET_PLATFORM_DIR)/startup:$(PLATFORM_DIR)/common
 
 include $(TARGET_PLATFORM_DIR)/target/$(TARGET)/target.mk
 
@@ -196,8 +197,8 @@ ifneq ($(CONFIG),)
 TARGET_FLAGS := $(TARGET_FLAGS) -DUSE_CONFIG
 endif
 
-SPEED_OPTIMISED_SRC := ""
-SIZE_OPTIMISED_SRC  := ""
+SPEED_OPTIMISED_SRC :=
+SIZE_OPTIMISED_SRC  :=
 
 include $(TARGET_PLATFORM_DIR)/mk/$(TARGET_MCU_FAMILY).mk
 
@@ -233,6 +234,12 @@ VPATH           := $(VPATH):$(TARGET_DIR)
 
 include $(MAKE_SCRIPT_DIR)/source.mk
 
+ifneq ($(SKIPCHECKS),yes)
+ifneq ($(filter-out $(SRC),$(SPEED_OPTIMISED_SRC)),)
+$(error Speed optimised sources not valid: $(strip $(filter-out $(SRC),$(SPEED_OPTIMISED_SRC))))
+endif
+endif
+
 ###############################################################################
 # Things that might need changing to use different tools
 #
@@ -453,6 +460,11 @@ define compile_file
 	$(CROSS_CC) -c -o $@ $(CFLAGS) $(2) $<
 endef
 
+## `paths` is a list of paths that will be replaced for checking of speed, and size optimised sources
+paths := $(SRC_DIR)/ $(LIB_MAIN_DIR)/ $(PLATFORM_DIR)/
+subst_paths_for = $(foreach path,$(paths),$(filter-out $(1),$(subst $(path),,$(1))))
+subst_paths = $(strip $(if $(call subst_paths_for,$(1)), $(call subst_paths_for,$(1)), $(1)))
+
 ifeq ($(DEBUG),GDB)
 $(TARGET_OBJ_DIR)/%.o: %.c
 	$(V1) mkdir -p $(dir $@)
@@ -467,10 +479,10 @@ $(TARGET_OBJ_DIR)/%.o: %.c
 	$(V1) $(if $(findstring $<,$(NOT_OPTIMISED_SRC)), \
 		$(call compile_file,not optimised,$(CC_NO_OPTIMISATION)) \
 	, \
-		$(if $(findstring $(subst ./src/platform/,,$(subst ./src/main/,,$<)),$(SPEED_OPTIMISED_SRC)), \
+		$(if $(findstring $(call subst_paths,$<),$(SPEED_OPTIMISED_SRC)), \
 			$(call compile_file,speed optimised,$(CC_SPEED_OPTIMISATION)) \
 		, \
-			$(if $(findstring $(subst ./src/platform/,,$(subst ./src/main/,,$<)),$(SIZE_OPTIMISED_SRC)), \
+			$(if $(findstring $(call subst_paths,$<),$(SIZE_OPTIMISED_SRC)), \
 				$(call compile_file,size optimised,$(CC_SIZE_OPTIMISATION)) \
 			, \
 				$(call compile_file,optimised,$(CC_DEFAULT_OPTIMISATION)) \
diff --git a/mk/source.mk b/mk/source.mk
index 86b9110502..8129c737b7 100644
--- a/mk/source.mk
+++ b/mk/source.mk
@@ -275,6 +275,8 @@ COMMON_SRC = \
 ifneq ($(SIMULATOR_BUILD),yes)
 
 COMMON_SRC += \
+            drivers/bus_spi.c \
+            drivers/serial_uart.c \
             drivers/accgyro/accgyro_mpu3050.c \
             drivers/accgyro/accgyro_mpu6050.c \
             drivers/accgyro/accgyro_mpu6500.c \
@@ -293,7 +295,7 @@ COMMON_SRC += \
             drivers/accgyro/accgyro_spi_mpu9250.c \
             drivers/accgyro/accgyro_virtual.c \
             drivers/accgyro/gyro_sync.c \
-            $(ROOT)/lib/main/BoschSensortec/BMI270-Sensor-API/bmi270_maximum_fifo.c \
+            BoschSensortec/BMI270-Sensor-API/bmi270_maximum_fifo.c \
             drivers/barometer/barometer_2smpb_02b.c \
             drivers/barometer/barometer_bmp085.c \
             drivers/barometer/barometer_bmp280.c \
@@ -322,13 +324,15 @@ ifneq ($(GYRO_DEFINE),)
 LEGACY_GYRO_DEFINES := USE_GYRO_L3GD20
 ifneq ($(findstring $(GYRO_DEFINE),$(LEGACY_GYRO_DEFINES)),)
 
-COMMON_SRC += \
+LEGACY_SRC := \
             drivers/accgyro/legacy/accgyro_adxl345.c \
             drivers/accgyro/legacy/accgyro_bma280.c \
             drivers/accgyro/legacy/accgyro_l3g4200d.c \
             drivers/accgyro/legacy/accgyro_lsm303dlhc.c \
             drivers/accgyro/legacy/accgyro_mma845x.c
 
+COMMON_SRC += $(LEGACY_SRC)
+SPEED_OPTIMISED_SRC += $(LEGACY_SRC)
 
 endif
 endif
@@ -376,6 +380,26 @@ INCLUDE_DIRS    := $(INCLUDE_DIRS) \
                    $(FATFS_DIR)
 VPATH           := $(VPATH):$(FATFS_DIR)
 
+# Gyro driver files that only contain initialization and configuration code - not runtime code
+SIZE_OPTIMISED_SRC += \
+            drivers/accgyro/accgyro_mpu6050.c \
+            drivers/accgyro/accgyro_mpu6500.c \
+            drivers/accgyro/accgyro_spi_mpu6000.c \
+            drivers/accgyro/accgyro_spi_mpu6500.c \
+            drivers/accgyro/accgyro_spi_mpu9250.c \
+            drivers/accgyro/accgyro_spi_icm20689.c \
+            drivers/accgyro/accgyro_spi_icm426xx.c \
+            drivers/accgyro/accgyro_spi_lsm6dso_init.c
+
+SPEED_OPTIMISED_SRC += \
+            drivers/bus_spi.c \
+            drivers/serial_uart.c \
+            drivers/accgyro/accgyro_mpu.c \
+            drivers/accgyro/accgyro_mpu3050.c \
+            drivers/accgyro/accgyro_spi_bmi160.c \
+            drivers/accgyro/accgyro_spi_bmi270.c \
+            drivers/accgyro/accgyro_spi_lsm6dso.c
+
 endif
 
 COMMON_DEVICE_SRC = \
@@ -405,28 +429,11 @@ SPEED_OPTIMISED_SRC += \
             common/stopwatch.c \
             common/typeconversion.c \
             common/vector.c \
-            drivers/accgyro/accgyro_mpu.c \
-            drivers/accgyro/accgyro_mpu3050.c \
-            drivers/accgyro/accgyro_spi_bmi160.c \
-            drivers/accgyro/accgyro_spi_bmi270.c \
-            drivers/accgyro/accgyro_spi_lsm6dso.c \
-            drivers/accgyro_legacy/accgyro_adxl345.c \
-            drivers/accgyro_legacy/accgyro_bma280.c \
-            drivers/accgyro_legacy/accgyro_l3g4200d.c \
-            drivers/accgyro_legacy/accgyro_l3gd20.c \
-            drivers/accgyro_legacy/accgyro_lsm303dlhc.c \
-            drivers/accgyro_legacy/accgyro_mma845x.c \
             drivers/buf_writer.c \
             drivers/bus.c \
             drivers/bus_quadspi.c \
-            drivers/bus_spi.c \
-            drivers/exti.c \
             drivers/io.c \
-            drivers/pwm_output.c \
-            drivers/rcc.c \
             drivers/serial.c \
-            drivers/serial_uart.c \
-            drivers/timer.c \
             fc/core.c \
             fc/tasks.c \
             fc/rc.c \
@@ -450,6 +457,7 @@ SPEED_OPTIMISED_SRC += \
             rx/sumd.c \
             rx/xbus.c \
             rx/fport.c \
+            rx/frsky_crc.c \
             scheduler/scheduler.c \
             sensors/acceleration.c \
             sensors/boardalignment.c \
@@ -541,28 +549,6 @@ SIZE_OPTIMISED_SRC := $(SIZE_OPTIMISED_SRC) \
             io/vtx_msp.c \
             cms/cms_menu_vtx_msp.c
 
-# Gyro driver files that only contain initialization and configuration code - not runtime code
-SIZE_OPTIMISED_SRC := $(SIZE_OPTIMISED_SRC) \
-            drivers/accgyro/accgyro_mpu6050.c \
-            drivers/accgyro/accgyro_mpu6500.c \
-            drivers/accgyro/accgyro_spi_mpu6000.c \
-            drivers/accgyro/accgyro_spi_mpu6500.c \
-            drivers/accgyro/accgyro_spi_mpu9250.c \
-            drivers/accgyro/accgyro_spi_icm20689.c \
-            drivers/accgyro/accgyro_spi_icm426xx.c \
-            drivers/accgyro/accgyro_spi_lsm6dso_init.c
-
-
-# F4 and F7 optimizations
-SPEED_OPTIMISED_SRC := $(SPEED_OPTIMISED_SRC) \
-            drivers/bus_i2c_hal.c \
-            drivers/bus_spi_ll.c \
-            rx/frsky_crc.c \
-            drivers/max7456.c \
-            drivers/pwm_output_dshot.c \
-            drivers/pwm_output_dshot_shared.c \
-            drivers/pwm_output_dshot_hal.c
-
 SIZE_OPTIMISED_SRC := $(SIZE_OPTIMISED_SRC) \
             drivers/bus_i2c_hal_init.c
 
@@ -590,10 +576,10 @@ SRC += $(VCP_SRC)
 # end target specific make file checks
 
 # Search path and source files for the Open Location Code library
-OLC_DIR = $(ROOT)/lib/main/google/olc
+OLC_DIR := google/olc
 
 ifneq ($(OLC_DIR),)
-INCLUDE_DIRS += $(OLC_DIR)
+INCLUDE_DIRS += $(LIB_MAIN_DIR)/$(OLC_DIR)
 SRC += $(OLC_DIR)/olc.c
 SIZE_OPTIMISED_SRC += $(OLC_DIR)/olc.c
 endif
diff --git a/src/platform/APM32/mk/APM32F4.mk b/src/platform/APM32/mk/APM32F4.mk
index 9792482a40..1c7d8c42a6 100644
--- a/src/platform/APM32/mk/APM32F4.mk
+++ b/src/platform/APM32/mk/APM32F4.mk
@@ -3,129 +3,126 @@
 #
 
 #CMSIS
-CMSIS_DIR      := $(ROOT)/lib/main/APM32F4/Libraries/Device
-STDPERIPH_DIR   = $(ROOT)/lib/main/APM32F4/Libraries/APM32F4xx_DAL_Driver
+CMSIS_DIR      := $(LIB_MAIN_DIR)/APM32F4/Libraries/Device
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/APM32F4/Libraries/APM32F4xx_DAL_Driver
 STDPERIPH_SRC   = \
-            apm32f4xx_dal_adc.c \
-            apm32f4xx_dal_adc_ex.c \
-            apm32f4xx_dal.c \
-            apm32f4xx_dal_can.c \
-            apm32f4xx_dal_comp.c \
-            apm32f4xx_dal_cortex.c \
-            apm32f4xx_dal_crc.c \
-            apm32f4xx_dal_cryp.c \
-            apm32f4xx_dal_cryp_ex.c \
-            apm32f4xx_dal_dac.c \
-            apm32f4xx_dal_dac_ex.c \
-            apm32f4xx_dal_dci.c \
-            apm32f4xx_dal_dci_ex.c \
-            apm32f4xx_dal_dma.c \
-            apm32f4xx_dal_dma_ex.c \
-            apm32f4xx_dal_eint.c \
-            apm32f4xx_dal_eth.c \
-            apm32f4xx_dal_flash.c \
-            apm32f4xx_dal_flash_ex.c \
-            apm32f4xx_dal_flash_ramfunc.c \
-            apm32f4xx_dal_gpio.c \
-            apm32f4xx_dal_hash.c \
-            apm32f4xx_dal_hash_ex.c \
-            apm32f4xx_dal_hcd.c \
-            apm32f4xx_dal_i2c.c \
-            apm32f4xx_dal_i2c_ex.c \
-            apm32f4xx_dal_i2s.c \
-            apm32f4xx_dal_i2s_ex.c \
-            apm32f4xx_dal_irda.c \
-            apm32f4xx_dal_iwdt.c \
-            apm32f4xx_dal_log.c \
-            apm32f4xx_dal_mmc.c \
-            apm32f4xx_dal_nand.c \
-            apm32f4xx_dal_nor.c \
-            apm32f4xx_dal_pccard.c \
-            apm32f4xx_dal_pcd.c \
-            apm32f4xx_dal_pcd_ex.c \
-            apm32f4xx_dal_pmu.c \
-            apm32f4xx_dal_pmu_ex.c \
-            apm32f4xx_dal_qspi.c \
-            apm32f4xx_dal_rcm.c \
-            apm32f4xx_dal_rcm_ex.c \
-            apm32f4xx_dal_rng.c \
-            apm32f4xx_dal_rtc.c \
-            apm32f4xx_dal_rtc_ex.c \
-            apm32f4xx_dal_sd.c \
-            apm32f4xx_dal_sdram.c \
-            apm32f4xx_dal_smartcard.c \
-            apm32f4xx_dal_smbus.c \
-            apm32f4xx_dal_spi.c \
-            apm32f4xx_dal_sram.c \
-            apm32f4xx_dal_tmr.c \
-            apm32f4xx_dal_tmr_ex.c \
-            apm32f4xx_dal_uart.c \
-            apm32f4xx_dal_usart.c \
-            apm32f4xx_dal_wwdt.c \
-            apm32f4xx_ddl_adc.c \
-            apm32f4xx_ddl_comp.c \
-            apm32f4xx_ddl_crc.c \
-            apm32f4xx_ddl_dac.c \
-            apm32f4xx_ddl_dma.c \
-            apm32f4xx_ddl_dmc.c \
-            apm32f4xx_ddl_eint.c \
-            apm32f4xx_ddl_gpio.c \
-            apm32f4xx_ddl_i2c.c \
-            apm32f4xx_ddl_pmu.c \
-            apm32f4xx_ddl_rcm.c \
-            apm32f4xx_ddl_rng.c \
-            apm32f4xx_ddl_rtc.c \
-            apm32f4xx_ddl_sdmmc.c \
-            apm32f4xx_ddl_smc.c \
-            apm32f4xx_ddl_spi.c \
-            apm32f4xx_ddl_tmr.c \
-            apm32f4xx_ddl_usart.c \
-            apm32f4xx_ddl_usb.c \
-            apm32f4xx_ddl_utils.c
+        apm32f4xx_dal_adc.c \
+        apm32f4xx_dal_adc_ex.c \
+        apm32f4xx_dal.c \
+        apm32f4xx_dal_can.c \
+        apm32f4xx_dal_comp.c \
+        apm32f4xx_dal_cortex.c \
+        apm32f4xx_dal_crc.c \
+        apm32f4xx_dal_cryp.c \
+        apm32f4xx_dal_cryp_ex.c \
+        apm32f4xx_dal_dac.c \
+        apm32f4xx_dal_dac_ex.c \
+        apm32f4xx_dal_dci.c \
+        apm32f4xx_dal_dci_ex.c \
+        apm32f4xx_dal_dma.c \
+        apm32f4xx_dal_dma_ex.c \
+        apm32f4xx_dal_eint.c \
+        apm32f4xx_dal_eth.c \
+        apm32f4xx_dal_flash.c \
+        apm32f4xx_dal_flash_ex.c \
+        apm32f4xx_dal_flash_ramfunc.c \
+        apm32f4xx_dal_gpio.c \
+        apm32f4xx_dal_hash.c \
+        apm32f4xx_dal_hash_ex.c \
+        apm32f4xx_dal_hcd.c \
+        apm32f4xx_dal_i2c.c \
+        apm32f4xx_dal_i2c_ex.c \
+        apm32f4xx_dal_i2s.c \
+        apm32f4xx_dal_i2s_ex.c \
+        apm32f4xx_dal_irda.c \
+        apm32f4xx_dal_iwdt.c \
+        apm32f4xx_dal_log.c \
+        apm32f4xx_dal_mmc.c \
+        apm32f4xx_dal_nand.c \
+        apm32f4xx_dal_nor.c \
+        apm32f4xx_dal_pccard.c \
+        apm32f4xx_dal_pcd.c \
+        apm32f4xx_dal_pcd_ex.c \
+        apm32f4xx_dal_pmu.c \
+        apm32f4xx_dal_pmu_ex.c \
+        apm32f4xx_dal_qspi.c \
+        apm32f4xx_dal_rcm.c \
+        apm32f4xx_dal_rcm_ex.c \
+        apm32f4xx_dal_rng.c \
+        apm32f4xx_dal_rtc.c \
+        apm32f4xx_dal_rtc_ex.c \
+        apm32f4xx_dal_sd.c \
+        apm32f4xx_dal_sdram.c \
+        apm32f4xx_dal_smartcard.c \
+        apm32f4xx_dal_smbus.c \
+        apm32f4xx_dal_spi.c \
+        apm32f4xx_dal_sram.c \
+        apm32f4xx_dal_tmr.c \
+        apm32f4xx_dal_tmr_ex.c \
+        apm32f4xx_dal_uart.c \
+        apm32f4xx_dal_usart.c \
+        apm32f4xx_dal_wwdt.c \
+        apm32f4xx_ddl_adc.c \
+        apm32f4xx_ddl_comp.c \
+        apm32f4xx_ddl_crc.c \
+        apm32f4xx_ddl_dac.c \
+        apm32f4xx_ddl_dma.c \
+        apm32f4xx_ddl_dmc.c \
+        apm32f4xx_ddl_eint.c \
+        apm32f4xx_ddl_gpio.c \
+        apm32f4xx_ddl_i2c.c \
+        apm32f4xx_ddl_pmu.c \
+        apm32f4xx_ddl_rcm.c \
+        apm32f4xx_ddl_rng.c \
+        apm32f4xx_ddl_rtc.c \
+        apm32f4xx_ddl_sdmmc.c \
+        apm32f4xx_ddl_smc.c \
+        apm32f4xx_ddl_spi.c \
+        apm32f4xx_ddl_tmr.c \
+        apm32f4xx_ddl_usart.c \
+        apm32f4xx_ddl_usb.c \
+        apm32f4xx_ddl_utils.c
 
-VPATH       := $(VPATH):$(STDPERIPH_DIR)/Source
+VPATH   := $(VPATH):$(STDPERIPH_DIR)/Source
 
 #USB
-USBCORE_DIR = $(ROOT)/lib/main/APM32F4/Middlewares/APM32_USB_Library/Device/Core
+USBCORE_DIR = APM32F4/Middlewares/APM32_USB_Library/Device/Core
 USBCORE_SRC = \
-        usbd_core.c \
-        usbd_dataXfer.c \
-        usbd_stdReq.c
+        $(USBCORE_DIR)/Src/usbd_core.c \
+        $(USBCORE_DIR)/Src/usbd_dataXfer.c \
+        $(USBCORE_DIR)/Src/usbd_stdReq.c
 
-USBCDC_DIR = $(ROOT)/lib/main/APM32F4/Middlewares/APM32_USB_Library/Device/Class/CDC
-USBCDC_SRC = usbd_cdc.c
+USBCDC_DIR = APM32F4/Middlewares/APM32_USB_Library/Device/Class/CDC
+USBCDC_SRC = \
+        $(USBCDC_DIR)/Src/usbd_cdc.c
 
-USBMSC_DIR = $(ROOT)/lib/main/APM32F4/Middlewares/APM32_USB_Library/Device/Class/MSC
+USBMSC_DIR = APM32F4/Middlewares/APM32_USB_Library/Device/Class/MSC
 USBMSC_SRC = \
-        usbd_msc.c \
-        usbd_msc_bot.c \
-        usbd_msc_scsi.c
+        $(USBMSC_DIR)/Src/usbd_msc.c \
+        $(USBMSC_DIR)/Src/usbd_msc_bot.c \
+        $(USBMSC_DIR)/Src/usbd_msc_scsi.c
 
-VPATH := $(VPATH):$(USBCDC_DIR)/Src:$(USBCORE_DIR)/Src:$(USBMSC_DIR)/Src
-
-DEVICE_STDPERIPH_SRC := $(STDPERIPH_SRC) \
-                        $(USBCORE_SRC) \
-                        $(USBCDC_SRC) \
-                        $(USBMSC_SRC)
+DEVICE_STDPERIPH_SRC := \
+        $(STDPERIPH_SRC) \
+        $(USBCORE_SRC) \
+        $(USBCDC_SRC) \
+        $(USBMSC_SRC)
 #CMSIS
-VPATH           := $(VPATH):$(ROOT)/lib/main/APM32F4/Libraries/Device/Geehy/APM32F4xx
+VPATH := $(VPATH):$(LIB_MAIN_DIR)/APM32F4/Libraries/Device/Geehy/APM32F4xx
 
-INCLUDE_DIRS    := $(INCLUDE_DIRS) \
-                   $(TARGET_PLATFORM_DIR)/startup \
-                   $(TARGET_PLATFORM_DIR)
-
-CMSIS_SRC       :=
-INCLUDE_DIRS    := $(INCLUDE_DIRS) \
-                   $(STDPERIPH_DIR)/Include \
-                   $(USBCORE_DIR)/Inc \
-                   $(USBCDC_DIR)/Inc \
-                   $(USBMSC_DIR)/Inc \
-                   $(CMSIS_DIR)/Geehy/APM32F4xx/Include \
-                   $(TARGET_PLATFORM_DIR)/usb/vcp \
-                   $(TARGET_PLATFORM_DIR)/usb/msc \
-                   $(TARGET_PLATFORM_DIR)/usb \
-                   $(ROOT)/lib/main/CMSIS/Core/Include \
-                   $(SRC_DIR)/msc
+INCLUDE_DIRS += \
+        $(TARGET_PLATFORM_DIR)/startup \
+        $(TARGET_PLATFORM_DIR) \
+        $(STDPERIPH_DIR)/Include \
+        $(LIB_MAIN_DIR)/$(USBCORE_DIR)/Inc \
+        $(LIB_MAIN_DIR)/$(USBCDC_DIR)/Inc \
+        $(LIB_MAIN_DIR)/$(USBMSC_DIR)/Inc \
+        $(CMSIS_DIR)/Geehy/APM32F4xx/Include \
+        $(TARGET_PLATFORM_DIR)/usb/vcp \
+        $(TARGET_PLATFORM_DIR)/usb/msc \
+        $(TARGET_PLATFORM_DIR)/usb \
+        $(LIB_MAIN_DIR)/CMSIS/Core/Include \
+        $(SRC_DIR)/msc
 
 #Flags
 ARCH_FLAGS      = -mthumb -mcpu=cortex-m4 -march=armv7e-m -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsingle-precision-constant
@@ -135,78 +132,76 @@ DEVICE_FLAGS    = -DUSE_DAL_DRIVER -DHSE_VALUE=$(HSE_VALUE) -DAPM32
 ifeq ($(TARGET_MCU),APM32F405xx)
 DEVICE_FLAGS    += -DAPM32F405xx
 LD_SCRIPT       = $(LINKER_DIR)/apm32_flash_f405.ld
-STARTUP_SRC     = startup/startup_apm32f405xx.S
+STARTUP_SRC     = APM32/startup/startup_apm32f405xx.S
 MCU_FLASH_SIZE  := 1024
 
 else ifeq ($(TARGET_MCU),APM32F407xx)
 DEVICE_FLAGS    += -DAPM32F407xx
 LD_SCRIPT       = $(LINKER_DIR)/apm32_flash_f407.ld
-STARTUP_SRC     = startup/startup_apm32f407xx.S
+STARTUP_SRC     = APM32/startup/startup_apm32f407xx.S
 MCU_FLASH_SIZE  := 1024
 else
 $(error TARGET_MCU [$(TARGET_MCU)] is not supported)
 endif
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
-            startup/system_apm32f4xx.c \
-            drivers/inverter.c \
-            drivers/dshot_bitbang_decode.c \
-            drivers/pwm_output_dshot_shared.c \
-            bus_spi_apm32.c \
-            bus_i2c_apm32.c \
-            bus_i2c_apm32_init.c \
-            camera_control_apm32.c \
-            debug.c \
-            dma_reqmap_mcu.c \
-            dshot_bitbang.c \
-            dshot_bitbang_ddl.c \
-            eint_apm32.c \
-            io_apm32.c \
-            light_ws2811strip_apm32.c \
-            persistent_apm32.c \
-            pwm_output_apm32.c \
-            pwm_output_dshot_apm32.c \
-            rcm_apm32.c \
-            serial_uart_apm32.c \
-            timer_apm32.c \
-            transponder_ir_io_apm32.c \
-            timer_apm32f4xx.c \
-            adc_apm32f4xx.c \
-            dma_apm32f4xx.c \
-            serial_uart_apm32f4xx.c \
-            drivers/adc.c \
-            drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
-            drivers/bus_spi_config.c \
-            drivers/bus_spi_pinconfig.c \
-            drivers/serial_escserial.c \
-            drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
-            drivers/serial_uart_pinconfig.c \
-            system_apm32f4xx.c
+        common/stm32/system.c \
+        APM32/startup/system_apm32f4xx.c \
+        drivers/inverter.c \
+        drivers/dshot_bitbang_decode.c \
+        drivers/pwm_output_dshot_shared.c \
+        APM32/bus_spi_apm32.c \
+        APM32/bus_i2c_apm32.c \
+        APM32/bus_i2c_apm32_init.c \
+        APM32/camera_control_apm32.c \
+        APM32/debug.c \
+        APM32/dma_reqmap_mcu.c \
+        APM32/dshot_bitbang.c \
+        APM32/dshot_bitbang_ddl.c \
+        APM32/eint_apm32.c \
+        APM32/io_apm32.c \
+        APM32/light_ws2811strip_apm32.c \
+        APM32/persistent_apm32.c \
+        APM32/pwm_output_apm32.c \
+        APM32/pwm_output_dshot_apm32.c \
+        APM32/rcm_apm32.c \
+        APM32/serial_uart_apm32.c \
+        APM32/timer_apm32.c \
+        APM32/transponder_ir_io_apm32.c \
+        APM32/timer_apm32f4xx.c \
+        APM32/adc_apm32f4xx.c \
+        APM32/dma_apm32f4xx.c \
+        APM32/serial_uart_apm32f4xx.c \
+        drivers/adc.c \
+        drivers/bus_i2c_config.c \
+        drivers/bus_spi_config.c \
+        drivers/bus_spi_pinconfig.c \
+        drivers/serial_escserial.c \
+        drivers/serial_pinconfig.c \
+        drivers/serial_uart_pinconfig.c \
+        APM32/system_apm32f4xx.c
 
 VCP_SRC = \
-            usb/vcp/usbd_cdc_descriptor.c \
-            usb/usbd_board_apm32f4.c \
-            usb/vcp/usbd_cdc_vcp.c \
-            usb/vcp/serial_usb_vcp.c \
-            drivers/usb_io.c
+        APM32/usb/vcp/usbd_cdc_descriptor.c \
+        APM32/usb/usbd_board_apm32f4.c \
+        APM32/usb/vcp/usbd_cdc_vcp.c \
+        APM32/usb/vcp/serial_usb_vcp.c \
+        drivers/usb_io.c
 
 MSC_SRC = \
-            drivers/usb_msc_common.c \
-            usb/msc/usb_msc_apm32f4xx.c \
-            usb/msc/usbd_memory.c \
-            usb/msc/usbd_msc_descriptor.c \
-            msc/usbd_storage.c \
-            msc/usbd_storage_emfat.c \
-            msc/emfat.c \
-            msc/emfat_file.c \
-            msc/usbd_storage_sd_spi.c \
-            msc/usbd_storage_sdio.c
+        drivers/usb_msc_common.c \
+        APM32/usb/msc/usb_msc_apm32f4xx.c \
+        APM32/usb/msc/usbd_memory.c \
+        APM32/usb/msc/usbd_msc_descriptor.c \
+        msc/usbd_storage.c \
+        msc/usbd_storage_emfat.c \
+        msc/emfat.c \
+        msc/emfat_file.c \
+        msc/usbd_storage_sd_spi.c \
+        msc/usbd_storage_sdio.c
 
 SPEED_OPTIMISED_SRC += \
-            common/stm32/system.c
+        common/stm32/system.c
 
-DSP_LIB := $(ROOT)/lib/main/CMSIS/DSP
+DSP_LIB := $(LIB_MAIN_DIR)/CMSIS/DSP
 DEVICE_FLAGS += -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -DUNALIGNED_SUPPORT_DISABLE -DARM_MATH_CM4 -DUSE_FULL_DDL_DRIVER
diff --git a/src/platform/AT32/mk/AT32F4.mk b/src/platform/AT32/mk/AT32F4.mk
index 89305fe552..dda6847b9c 100644
--- a/src/platform/AT32/mk/AT32F4.mk
+++ b/src/platform/AT32/mk/AT32F4.mk
@@ -2,9 +2,9 @@
 # AT32F4 Make file include
 #
 
-CMSIS_DIR      := $(ROOT)/lib/main/AT32F43x/cmsis
-STDPERIPH_DIR   = $(ROOT)/lib/main/AT32F43x/drivers
-MIDDLEWARES_DIR = $(ROOT)/lib/main/AT32F43x/middlewares
+CMSIS_DIR      := $(LIB_MAIN_DIR)/AT32F43x/cmsis
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/AT32F43x/drivers
+MIDDLEWARES_DIR = $(LIB_MAIN_DIR)/AT32F43x/middlewares
 STDPERIPH_SRC   = \
         at32f435_437_acc.c \
         at32f435_437_adc.c \
@@ -45,9 +45,9 @@ STDPERIPH_SRC   = \
         usbd_class/msc/msc_class.c \
         usbd_class/msc/msc_desc.c
 
-STARTUP_SRC     = startup/startup_at32f435_437.s
+STARTUP_SRC     = AT32/startup/startup_at32f435_437.s
 
-VPATH           := $(VPATH):$(ROOT)/lib/main/AT32F43x/cmsis/cm4/core_support:$(STDPERIPH_DIR)/src:$(MIDDLEWARES_DIR):$(SRC_DIR)/startup/at32
+VPATH           := $(VPATH):$(LIB_MAIN_DIR)/AT32F43x/cmsis/cm4/core_support:$(STDPERIPH_DIR)/src:$(MIDDLEWARES_DIR)
 
 VCP_SRC =  \
             usbd_class/cdc/cdc_class.c \
@@ -80,33 +80,33 @@ ARCH_FLAGS      = -std=c99  -mthumb -mcpu=cortex-m4 -march=armv7e-m -mfloat-abi=
 DEVICE_FLAGS   += -DUSE_ATBSP_DRIVER -DAT32F43x -DHSE_VALUE=$(HSE_VALUE) -DAT32 -DUSE_OTG_HOST_MODE
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
-            startup/at32f435_437_clock.c \
-            startup/system_at32f435_437.c \
-            adc_at32f43x.c \
-            bus_i2c_atbsp.c \
-            bus_i2c_atbsp_init.c \
-            bus_spi_at32bsp.c \
-            camera_control_at32.c \
-            debug.c \
-            dma_at32f43x.c \
-            dma_reqmap_mcu.c \
-            dshot_bitbang.c \
-            dshot_bitbang_stdperiph.c \
-            exti_at32.c \
-            io_at32.c \
-            light_ws2811strip_at32f43x.c \
-            persistent_at32bsp.c \
-            pwm_output_at32bsp.c \
-            pwm_output_dshot.c \
-            rcc_at32.c \
-            serial_uart_at32bsp.c \
-            serial_uart_at32f43x.c \
-            serial_usb_vcp_at32f4.c \
-            system_at32f43x.c \
-            timer_at32bsp.c \
-            timer_at32f43x.c \
-            usb_msc_at32f43x.c \
+            common/stm32/system.c \
+            AT32/startup/at32f435_437_clock.c \
+            AT32/startup/system_at32f435_437.c \
+            AT32/adc_at32f43x.c \
+            AT32/bus_i2c_atbsp.c \
+            AT32/bus_i2c_atbsp_init.c \
+            AT32/bus_spi_at32bsp.c \
+            AT32/camera_control_at32.c \
+            AT32/debug.c \
+            AT32/dma_at32f43x.c \
+            AT32/dma_reqmap_mcu.c \
+            AT32/dshot_bitbang.c \
+            AT32/dshot_bitbang_stdperiph.c \
+            AT32/exti_at32.c \
+            AT32/io_at32.c \
+            AT32/light_ws2811strip_at32f43x.c \
+            AT32/persistent_at32bsp.c \
+            AT32/pwm_output_at32bsp.c \
+            AT32/pwm_output_dshot.c \
+            AT32/rcc_at32.c \
+            AT32/serial_uart_at32bsp.c \
+            AT32/serial_uart_at32f43x.c \
+            AT32/serial_usb_vcp_at32f4.c \
+            AT32/system_at32f43x.c \
+            AT32/timer_at32bsp.c \
+            AT32/timer_at32f43x.c \
+            AT32/usb_msc_at32f43x.c \
             drivers/accgyro/accgyro_mpu.c \
             drivers/dshot_bitbang_decode.c \
             drivers/inverter.c \
@@ -116,12 +116,10 @@ MCU_COMMON_SRC = \
             drivers/usb_msc_common.c \
             drivers/adc.c \
             drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
             drivers/bus_spi_config.c \
             drivers/bus_spi_pinconfig.c \
             drivers/serial_escserial.c \
             drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
             drivers/serial_uart_pinconfig.c \
             msc/usbd_storage.c \
             msc/usbd_storage_emfat.c \
diff --git a/src/platform/PICO/mk/PICO.mk b/src/platform/PICO/mk/PICO.mk
index 84acc3d098..699ee8f0fe 100644
--- a/src/platform/PICO/mk/PICO.mk
+++ b/src/platform/PICO/mk/PICO.mk
@@ -6,7 +6,7 @@ ifeq ($(DEBUG_HARDFAULTS),PICO)
 CFLAGS          += -DDEBUG_HARDFAULTS
 endif
 
-SDK_DIR         = $(ROOT)/lib/main/pico-sdk
+SDK_DIR         = $(LIB_MAIN_DIR)/pico-sdk
 
 #CMSIS
 CMSIS_DIR      := $(SDK_DIR)/rp2_common/cmsis/stub/CMSIS
diff --git a/src/platform/SITL/dma_reqmap_mcu.h b/src/platform/SIMULATOR/dma_reqmap_mcu.h
similarity index 100%
rename from src/platform/SITL/dma_reqmap_mcu.h
rename to src/platform/SIMULATOR/dma_reqmap_mcu.h
diff --git a/src/platform/SITL/link/sitl.ld b/src/platform/SIMULATOR/link/sitl.ld
similarity index 100%
rename from src/platform/SITL/link/sitl.ld
rename to src/platform/SIMULATOR/link/sitl.ld
diff --git a/src/platform/SIMULATOR/mk/SITL.mk b/src/platform/SIMULATOR/mk/SITL.mk
new file mode 100644
index 0000000000..6a2d8e8b9d
--- /dev/null
+++ b/src/platform/SIMULATOR/mk/SITL.mk
@@ -0,0 +1,57 @@
+
+INCLUDE_DIRS := \
+        $(INCLUDE_DIRS) \
+        $(TARGET_PLATFORM_DIR) \
+        $(LIB_MAIN_DIR)/dyad
+
+MCU_COMMON_SRC  := \
+        $(LIB_MAIN_DIR)/dyad/dyad.c \
+        SIMULATOR/sitl.c \
+        SIMULATOR/udplink.c
+
+#Flags
+ARCH_FLAGS      =
+DEVICE_FLAGS    =
+LD_SCRIPT       = $(LINKER_DIR)/sitl.ld
+STARTUP_SRC     =
+
+MCU_FLASH_SIZE  := 2048
+
+ARM_SDK_PREFIX  =
+
+MCU_EXCLUDES = \
+        drivers/rx/rx_xn297.c \
+        drivers/display_ug2864hsweg01.c \
+        telemetry/crsf.c \
+        telemetry/ghst.c \
+        telemetry/srxl.c \
+        io/displayport_oled.c
+
+TARGET_MAP  = $(OBJECT_DIR)/$(FORKNAME)_$(TARGET).map
+
+LD_FLAGS    := \
+            -lm \
+            -lpthread \
+            -lc \
+            -lrt \
+            $(ARCH_FLAGS) \
+            $(LTO_FLAGS) \
+            $(DEBUG_FLAGS) \
+            -Wl,-gc-sections,-Map,$(TARGET_MAP) \
+            -Wl,-L$(LINKER_DIR) \
+            -Wl,--cref \
+            -T$(LD_SCRIPT)
+
+ifneq ($(filter SITL_STATIC,$(OPTIONS)),)
+LD_FLAGS     += \
+              -static \
+              -static-libgcc
+endif
+
+ifneq ($(DEBUG),GDB)
+OPTIMISE_DEFAULT    := -Ofast
+OPTIMISE_SPEED      := -Ofast
+OPTIMISE_SIZE       := -Os
+
+LTO_FLAGS           := $(OPTIMISATION_BASE) $(OPTIMISE_SPEED)
+endif
diff --git a/src/platform/SITL/platform_mcu.h b/src/platform/SIMULATOR/platform_mcu.h
similarity index 100%
rename from src/platform/SITL/platform_mcu.h
rename to src/platform/SIMULATOR/platform_mcu.h
diff --git a/src/platform/SITL/sitl.c b/src/platform/SIMULATOR/sitl.c
similarity index 100%
rename from src/platform/SITL/sitl.c
rename to src/platform/SIMULATOR/sitl.c
diff --git a/src/platform/SITL/target/SITL/README.md b/src/platform/SIMULATOR/target/SITL/README.md
similarity index 100%
rename from src/platform/SITL/target/SITL/README.md
rename to src/platform/SIMULATOR/target/SITL/README.md
diff --git a/src/platform/SITL/target/SITL/target.h b/src/platform/SIMULATOR/target/SITL/target.h
similarity index 100%
rename from src/platform/SITL/target/SITL/target.h
rename to src/platform/SIMULATOR/target/SITL/target.h
diff --git a/src/platform/SITL/target/SITL/target.mk b/src/platform/SIMULATOR/target/SITL/target.mk
similarity index 88%
rename from src/platform/SITL/target/SITL/target.mk
rename to src/platform/SIMULATOR/target/SITL/target.mk
index 7429467dcb..97a4d2bd2d 100644
--- a/src/platform/SITL/target/SITL/target.mk
+++ b/src/platform/SIMULATOR/target/SITL/target.mk
@@ -1,4 +1,4 @@
-TARGET_MCU        := SITL
+TARGET_MCU        := SIMULATOR
 TARGET_MCU_FAMILY := SITL
 SIMULATOR_BUILD    = yes
 
diff --git a/src/platform/SITL/timer_def.h b/src/platform/SIMULATOR/timer_def.h
similarity index 100%
rename from src/platform/SITL/timer_def.h
rename to src/platform/SIMULATOR/timer_def.h
diff --git a/src/platform/SITL/udplink.c b/src/platform/SIMULATOR/udplink.c
similarity index 100%
rename from src/platform/SITL/udplink.c
rename to src/platform/SIMULATOR/udplink.c
diff --git a/src/platform/SITL/udplink.h b/src/platform/SIMULATOR/udplink.h
similarity index 100%
rename from src/platform/SITL/udplink.h
rename to src/platform/SIMULATOR/udplink.h
diff --git a/src/platform/SITL/mk/SITL.mk b/src/platform/SITL/mk/SITL.mk
deleted file mode 100644
index f9d585d1dd..0000000000
--- a/src/platform/SITL/mk/SITL.mk
+++ /dev/null
@@ -1,55 +0,0 @@
-
-INCLUDE_DIRS    := $(INCLUDE_DIRS) \
-                   $(TARGET_PLATFORM_DIR) \
-                   $(ROOT)/lib/main/dyad
-
-MCU_COMMON_SRC  := $(ROOT)/lib/main/dyad/dyad.c \
-                   sitl.c \
-                   udplink.c
-
-#Flags
-ARCH_FLAGS      =
-DEVICE_FLAGS    =
-LD_SCRIPT       = $(LINKER_DIR)/sitl.ld
-STARTUP_SRC     =
-
-MCU_FLASH_SIZE  := 2048
-
-ARM_SDK_PREFIX  =
-
-MCU_EXCLUDES = \
-            drivers/rx/rx_xn297.c \
-            drivers/display_ug2864hsweg01.c \
-            telemetry/crsf.c \
-            telemetry/ghst.c \
-            telemetry/srxl.c \
-            io/displayport_oled.c
-
-TARGET_MAP  = $(OBJECT_DIR)/$(FORKNAME)_$(TARGET).map
-
-LD_FLAGS    := \
-              -lm \
-              -lpthread \
-              -lc \
-              -lrt \
-              $(ARCH_FLAGS) \
-              $(LTO_FLAGS) \
-              $(DEBUG_FLAGS) \
-              -Wl,-gc-sections,-Map,$(TARGET_MAP) \
-              -Wl,-L$(LINKER_DIR) \
-              -Wl,--cref \
-              -T$(LD_SCRIPT)
-
-ifneq ($(filter SITL_STATIC,$(OPTIONS)),)
-LD_FLAGS     += \
-              -static \
-              -static-libgcc
-endif
-
-ifneq ($(DEBUG),GDB)
-OPTIMISE_DEFAULT    := -Ofast
-OPTIMISE_SPEED      := -Ofast
-OPTIMISE_SIZE       := -Os
-
-LTO_FLAGS           := $(OPTIMISATION_BASE) $(OPTIMISE_SPEED)
-endif
diff --git a/src/platform/STM32/mk/STM32F4.mk b/src/platform/STM32/mk/STM32F4.mk
index ed0274e80a..e9a37cb186 100644
--- a/src/platform/STM32/mk/STM32F4.mk
+++ b/src/platform/STM32/mk/STM32F4.mk
@@ -4,16 +4,16 @@
 
 #CMSIS
 ifeq ($(PERIPH_DRIVER), HAL)
-CMSIS_DIR      := $(ROOT)/lib/main/STM32F4/Drivers/CMSIS
-STDPERIPH_DIR   = $(ROOT)/lib/main/STM32F4/Drivers/STM32F4xx_HAL_Driver
+CMSIS_DIR      := $(LIB_MAIN_DIR)/STM32F4/Drivers/CMSIS
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/STM32F4/Drivers/STM32F4xx_HAL_Driver
 STDPERIPH_SRC   = $(notdir $(wildcard $(STDPERIPH_DIR)/Src/*.c))
 EXCLUDES        =
 
 VPATH       := $(VPATH):$(STDPERIPH_DIR)/Src
 
 else
-CMSIS_DIR      := $(ROOT)/lib/main/CMSIS
-STDPERIPH_DIR   = $(ROOT)/lib/main/STM32F4/Drivers/STM32F4xx_StdPeriph_Driver
+CMSIS_DIR      := $(LIB_MAIN_DIR)/CMSIS
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/STM32F4/Drivers/STM32F4xx_StdPeriph_Driver
 STDPERIPH_SRC   = \
             misc.c \
             stm32f4xx_adc.c \
@@ -48,12 +48,12 @@ endif
 
 ifeq ($(PERIPH_DRIVER), HAL)
 #USB
-USBCORE_DIR = $(ROOT)/lib/main/STM32F4/Middlewares/ST/STM32_USB_Device_Library/Core
+USBCORE_DIR = $(LIB_MAIN_DIR)/STM32F4/Middlewares/ST/STM32_USB_Device_Library/Core
 USBCORE_SRC = $(notdir $(wildcard $(USBCORE_DIR)/Src/*.c))
 EXCLUDES    = usbd_conf_template.c
 USBCORE_SRC := $(filter-out ${EXCLUDES}, $(USBCORE_SRC))
 
-USBCDC_DIR = $(ROOT)/lib/main/STM32F4/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
+USBCDC_DIR = $(LIB_MAIN_DIR)/STM32F4/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
 USBCDC_SRC = $(notdir $(wildcard $(USBCDC_DIR)/Src/*.c))
 EXCLUDES   = usbd_cdc_if_template.c
 USBCDC_SRC := $(filter-out ${EXCLUDES}, $(USBCDC_SRC))
@@ -65,35 +65,37 @@ DEVICE_STDPERIPH_SRC := \
             $(USBCORE_SRC) \
             $(USBCDC_SRC)
 else
-USBCORE_DIR = $(ROOT)/lib/main/STM32_USB_Device_Library/Core
+USBCORE_DIR = STM32_USB_Device_Library/Core
 USBCORE_SRC = \
-            usbd_core.c \
-            usbd_ioreq.c \
-            usbd_req.c
+            $(USBCORE_DIR)/src/usbd_core.c \
+            $(USBCORE_DIR)/src/usbd_ioreq.c \
+            $(USBCORE_DIR)/src/usbd_req.c
 
-USBOTG_DIR  = $(ROOT)/lib/main/STM32_USB_OTG_Driver
+USBOTG_DIR  = STM32_USB_OTG_Driver
 USBOTG_SRC  = \
-            usb_core.c \
-            usb_dcd.c \
-            usb_dcd_int.c
+            $(USBOTG_DIR)/src/usb_core.c \
+            $(USBOTG_DIR)/src/usb_dcd.c \
+            $(USBOTG_DIR)/src/usb_dcd_int.c
 
-USBCDC_DIR  = $(ROOT)/lib/main/STM32_USB_Device_Library/Class/cdc
-USBCDC_SRC  = usbd_cdc_core.c
+USBCDC_DIR  = STM32_USB_Device_Library/Class/cdc
+USBCDC_SRC  = \
+            $(USBCDC_DIR)/src/usbd_cdc_core.c
 
-USBMSC_DIR  = $(ROOT)/lib/main/STM32_USB_Device_Library/Class/msc
+USBMSC_DIR  = STM32_USB_Device_Library/Class/msc
 USBMSC_SRC  = \
-            usbd_msc_bot.c \
-            usbd_msc_core.c \
-            usbd_msc_data.c \
-            usbd_msc_scsi.c
+            $(USBMSC_DIR)/src/usbd_msc_bot.c \
+            $(USBMSC_DIR)/src/usbd_msc_core.c \
+            $(USBMSC_DIR)/src/usbd_msc_data.c \
+            $(USBMSC_DIR)/src/usbd_msc_scsi.c
 
-USBHID_DIR  = $(ROOT)/lib/main/STM32_USB_Device_Library/Class/hid
-USBHID_SRC  = usbd_hid_core.c
+USBHID_DIR  = STM32_USB_Device_Library/Class/hid
+USBHID_SRC  = \
+            $(USBHID_DIR)/src/usbd_hid_core.c
 
-USBWRAPPER_DIR  = $(ROOT)/lib/main/STM32_USB_Device_Library/Class/hid_cdc_wrapper
-USBWRAPPER_SRC  = usbd_hid_cdc_wrapper.c
+USBWRAPPER_DIR  = STM32_USB_Device_Library/Class/hid_cdc_wrapper
+USBWRAPPER_SRC  = \
+            $(USBWRAPPER_DIR)/src/usbd_hid_cdc_wrapper.c
 
-VPATH       := $(VPATH):$(USBOTG_DIR)/src:$(USBCORE_DIR)/src:$(USBCDC_DIR)/src:$(USBMSC_DIR)/src:$(USBHID_DIR)/src:$(USBWRAPPER_DIR)/src
 
 DEVICE_STDPERIPH_SRC := \
             $(STDPERIPH_SRC) \
@@ -106,12 +108,7 @@ DEVICE_STDPERIPH_SRC := \
 endif
 
 #CMSIS
-VPATH        := $(VPATH):$(CMSIS_DIR)/Core/Include:$(ROOT)/lib/main/STM32F4/Drivers/CMSIS/Device/ST/STM32F4xx
-
-INCLUDE_DIRS := \
-            $(INCLUDE_DIRS) \
-            $(SRC_DIR)/startup/stm32 \
-            $(SRC_DIR)/drivers/mcu/stm32
+VPATH        := $(VPATH):$(CMSIS_DIR)/Core/Include:$(LIB_MAIN_DIR)/STM32F4/Drivers/CMSIS/Device/ST/STM32F4xx
 
 ifeq ($(PERIPH_DRIVER), HAL)
 CMSIS_SRC       :=
@@ -120,8 +117,8 @@ INCLUDE_DIRS    := \
             $(TARGET_PLATFORM_DIR) \
             $(TARGET_PLATFORM_DIR)/startup \
             $(STDPERIPH_DIR)/Inc \
-            $(USBCORE_DIR)/Inc \
-            $(USBCDC_DIR)/Inc \
+            $(LIB_MAIN_DIR)/$(USBCORE_DIR)/Inc \
+            $(LIB_MAIN_DIR)/$(USBCDC_DIR)/Inc \
             $(CMSIS_DIR)/Include \
             $(CMSIS_DIR)/Device/ST/STM32F4xx/Include \
             $(TARGET_PLATFORM_DIR)/vcp_hal
@@ -135,14 +132,14 @@ INCLUDE_DIRS    := \
             $(TARGET_PLATFORM_DIR) \
             $(TARGET_PLATFORM_DIR)/startup \
             $(STDPERIPH_DIR)/inc \
-            $(USBOTG_DIR)/inc \
-            $(USBCORE_DIR)/inc \
-            $(USBCDC_DIR)/inc \
-            $(USBHID_DIR)/inc \
-            $(USBWRAPPER_DIR)/inc \
-            $(USBMSC_DIR)/inc \
+            $(LIB_MAIN_DIR)/$(USBOTG_DIR)/inc \
+            $(LIB_MAIN_DIR)/$(USBCORE_DIR)/inc \
+            $(LIB_MAIN_DIR)/$(USBCDC_DIR)/inc \
+            $(LIB_MAIN_DIR)/$(USBHID_DIR)/inc \
+            $(LIB_MAIN_DIR)/$(USBWRAPPER_DIR)/inc \
+            $(LIB_MAIN_DIR)/$(USBMSC_DIR)/inc \
             $(CMSIS_DIR)/Core/Include \
-            $(ROOT)/lib/main/STM32F4/Drivers/CMSIS/Device/ST/STM32F4xx \
+            $(LIB_MAIN_DIR)/STM32F4/Drivers/CMSIS/Device/ST/STM32F4xx \
             $(TARGET_PLATFORM_DIR)/vcpf4
 endif
 
@@ -152,19 +149,19 @@ ARCH_FLAGS      = -mthumb -mcpu=cortex-m4 -march=armv7e-m -mfloat-abi=hard -mfpu
 ifeq ($(TARGET_MCU),STM32F411xE)
 DEVICE_FLAGS    = -DSTM32F411xE -finline-limit=20
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f411.ld
-STARTUP_SRC     = startup/startup_stm32f411xe.s
+STARTUP_SRC     = STM32/startup/startup_stm32f411xe.s
 MCU_FLASH_SIZE  := 512
 
 else ifeq ($(TARGET_MCU),STM32F405xx)
 DEVICE_FLAGS    = -DSTM32F40_41xxx -DSTM32F405xx
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f405.ld
-STARTUP_SRC     = startup/startup_stm32f40xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32f40xx.s
 MCU_FLASH_SIZE  := 1024
 
 else ifeq ($(TARGET_MCU),STM32F446xx)
 DEVICE_FLAGS    = -DSTM32F446xx
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f446.ld
-STARTUP_SRC     = startup/startup_stm32f446xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32f446xx.s
 MCU_FLASH_SIZE  := 512
 
 else
@@ -173,71 +170,70 @@ endif
 DEVICE_FLAGS    += -DHSE_VALUE=$(HSE_VALUE) -DSTM32
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
+            common/stm32/system.c \
             drivers/accgyro/accgyro_mpu.c \
             drivers/dshot_bitbang_decode.c \
             drivers/inverter.c \
             drivers/pwm_output_dshot_shared.c \
-            pwm_output_dshot.c \
-            adc_stm32f4xx.c \
-            bus_i2c_stm32f4xx.c \
-            bus_spi_stdperiph.c \
-            debug.c \
-            dma_reqmap_mcu.c \
-            dma_stm32f4xx.c \
-            dshot_bitbang.c \
-            dshot_bitbang_stdperiph.c \
-            exti.c \
-            io_stm32.c \
-            light_ws2811strip_stdperiph.c \
-            persistent.c \
-            pwm_output.c \
-            rcc_stm32.c \
-            sdio_f4xx.c \
-            serial_uart_stdperiph.c \
-            serial_uart_stm32f4xx.c \
-            system_stm32f4xx.c \
-            timer_stdperiph.c \
-            timer_stm32f4xx.c \
-            transponder_ir_io_stdperiph.c \
-            usbd_msc_desc.c \
-            camera_control_stm32.c \
+            STM32/pwm_output_dshot.c \
+            STM32/adc_stm32f4xx.c \
+            STM32/bus_i2c_stm32f4xx.c \
+            STM32/bus_spi_stdperiph.c \
+            STM32/debug.c \
+            STM32/dma_reqmap_mcu.c \
+            STM32/dma_stm32f4xx.c \
+            STM32/dshot_bitbang.c \
+            STM32/dshot_bitbang_stdperiph.c \
+            STM32/exti.c \
+            STM32/io_stm32.c \
+            STM32/light_ws2811strip_stdperiph.c \
+            STM32/persistent.c \
+            STM32/pwm_output.c \
+            STM32/rcc_stm32.c \
+            STM32/sdio_f4xx.c \
+            STM32/serial_uart_stdperiph.c \
+            STM32/serial_uart_stm32f4xx.c \
+            STM32/system_stm32f4xx.c \
+            STM32/timer_stdperiph.c \
+            STM32/timer_stm32f4xx.c \
+            STM32/transponder_ir_io_stdperiph.c \
+            STM32/usbd_msc_desc.c \
+            STM32/camera_control_stm32.c \
             drivers/adc.c \
             drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
             drivers/bus_spi_config.c \
             drivers/bus_spi_pinconfig.c \
             drivers/serial_escserial.c \
             drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
             drivers/serial_uart_pinconfig.c \
-            startup/system_stm32f4xx.c
+            STM32/startup/system_stm32f4xx.c
 
 SPEED_OPTIMISED_SRC += \
-            common/stm32/system.c
+            common/stm32/system.c \
+            STM32/exti.c
 
 ifeq ($(PERIPH_DRIVER), HAL)
 VCP_SRC = \
-            vcp_hal/usbd_desc.c \
-            vcp_hal/usbd_conf.c \
-            vcp_hal/usbd_cdc_interface.c \
-            serial_usb_vcp.c \
+            STM32/vcp_hal/usbd_desc.c \
+            STM32/vcp_hal/usbd_conf.c \
+            STM32/vcp_hal/usbd_cdc_interface.c \
+            STM32/serial_usb_vcp.c \
             drivers/usb_io.c
 else
 VCP_SRC = \
-            vcpf4/stm32f4xx_it.c \
-            vcpf4/usb_bsp.c \
-            vcpf4/usbd_desc.c \
-            vcpf4/usbd_usr.c \
-            vcpf4/usbd_cdc_vcp.c \
-            vcpf4/usb_cdc_hid.c \
-            serial_usb_vcp.c \
+            STM32/vcpf4/stm32f4xx_it.c \
+            STM32/vcpf4/usb_bsp.c \
+            STM32/vcpf4/usbd_desc.c \
+            STM32/vcpf4/usbd_usr.c \
+            STM32/vcpf4/usbd_cdc_vcp.c \
+            STM32/vcpf4/usb_cdc_hid.c \
+            STM32/serial_usb_vcp.c \
             drivers/usb_io.c
 endif
 
 MSC_SRC = \
             drivers/usb_msc_common.c \
-            usb_msc_f4xx.c \
+            STM32/usb_msc_f4xx.c \
             msc/usbd_storage.c \
             msc/usbd_storage_emfat.c \
             msc/emfat.c \
@@ -245,5 +241,5 @@ MSC_SRC = \
             msc/usbd_storage_sd_spi.c \
             msc/usbd_storage_sdio.c
 
-DSP_LIB := $(ROOT)/lib/main/CMSIS/DSP
+DSP_LIB := $(LIB_MAIN_DIR)/CMSIS/DSP
 DEVICE_FLAGS += -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -D__FPU_PRESENT=1 -DUNALIGNED_SUPPORT_DISABLE -DARM_MATH_CM4
diff --git a/src/platform/STM32/mk/STM32F7.mk b/src/platform/STM32/mk/STM32F7.mk
index 2084b5621a..9c29481815 100644
--- a/src/platform/STM32/mk/STM32F7.mk
+++ b/src/platform/STM32/mk/STM32F7.mk
@@ -7,10 +7,10 @@ CFLAGS               += -DDEBUG_HARDFAULTS
 endif
 
 #CMSIS
-CMSIS_DIR      := $(ROOT)/lib/main/CMSIS
+CMSIS_DIR      := $(LIB_MAIN_DIR)/CMSIS
 
 #STDPERIPH
-STDPERIPH_DIR   = $(ROOT)/lib/main/STM32F7/Drivers/STM32F7xx_HAL_Driver
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/STM32F7/Drivers/STM32F7xx_HAL_Driver
 STDPERIPH_SRC   = \
             stm32f7xx_hal_adc.c \
             stm32f7xx_hal_adc_ex.c \
@@ -51,49 +51,48 @@ STDPERIPH_SRC   = \
             stm32f7xx_ll_utils.c
 
 #USB
-USBCORE_DIR = $(ROOT)/lib/main/STM32F7/Middlewares/ST/STM32_USB_Device_Library/Core
+USBCORE_DIR = STM32F7/Middlewares/ST/STM32_USB_Device_Library/Core
 USBCORE_SRC = \
-            usbd_core.c \
-            usbd_ctlreq.c \
-            usbd_ioreq.c
+            $(USBCORE_DIR)/Src/usbd_core.c \
+            $(USBCORE_DIR)/Src/usbd_ctlreq.c \
+            $(USBCORE_DIR)/Src/usbd_ioreq.c
 
-USBCDC_DIR = $(ROOT)/lib/main/STM32F7/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
-USBCDC_SRC = usbd_cdc.c
+USBCDC_DIR = STM32F7/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
+USBCDC_SRC = \
+            $(USBCDC_DIR)/Src/usbd_cdc.c
 
+USBHID_DIR = STM32F7/Middlewares/ST/STM32_USB_Device_Library/Class/HID
+USBHID_SRC = \
+            $(USBHID_DIR)/Src/usbd_hid.c
 
-USBHID_DIR = $(ROOT)/lib/main/STM32F7/Middlewares/ST/STM32_USB_Device_Library/Class/HID
-USBHID_SRC = usbd_hid.c
-
-USBMSC_DIR = $(ROOT)/lib/main/STM32F7/Middlewares/ST/STM32_USB_Device_Library/Class/MSC
+USBMSC_DIR = STM32F7/Middlewares/ST/STM32_USB_Device_Library/Class/MSC
 USBMSC_SRC = \
-            usbd_msc_bot.c \
-            usbd_msc.c \
-            usbd_msc_data.c \
-            usbd_msc_scsi.c
+            $(USBMSC_DIR)/Src/usbd_msc_bot.c \
+            $(USBMSC_DIR)/Src/usbd_msc.c \
+            $(USBMSC_DIR)/Src/usbd_msc_data.c \
+            $(USBMSC_DIR)/Src/usbd_msc_scsi.c
 
-VPATH := $(VPATH):$(USBCDC_DIR)/Src:$(USBCORE_DIR)/Src:$(USBHID_DIR)/Src:$(USBMSC_DIR)/Src:$(STDPERIPH_DIR)/src
-
-DEVICE_STDPERIPH_SRC := $(STDPERIPH_SRC) \
-                        $(USBCORE_SRC) \
-                        $(USBCDC_SRC) \
-                        $(USBHID_SRC) \
-                        $(USBMSC_SRC)
+DEVICE_STDPERIPH_SRC := \
+            $(STDPERIPH_SRC) \
+            $(USBCORE_SRC) \
+            $(USBCDC_SRC) \
+            $(USBHID_SRC) \
+            $(USBMSC_SRC)
 
 #CMSIS
-VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32F7xx
-VPATH           := $(VPATH):$(STDPERIPH_DIR)/Src
+VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32F7xx:$(STDPERIPH_DIR)/Src
 
 CMSIS_SRC       :=
 INCLUDE_DIRS    := $(INCLUDE_DIRS) \
                    $(TARGET_PLATFORM_DIR) \
                    $(TARGET_PLATFORM_DIR)/startup \
                    $(STDPERIPH_DIR)/Inc \
-                   $(USBCORE_DIR)/Inc \
-                   $(USBCDC_DIR)/Inc \
-                   $(USBHID_DIR)/Inc \
-                   $(USBMSC_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBCORE_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBCDC_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBHID_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBMSC_DIR)/Inc \
                    $(CMSIS_DIR)/Core/Include \
-                   $(ROOT)/lib/main/STM32F7/Drivers/CMSIS/Device/ST/STM32F7xx/Include \
+                   $(LIB_MAIN_DIR)/STM32F7/Drivers/CMSIS/Device/ST/STM32F7xx/Include \
                    $(TARGET_PLATFORM_DIR)/vcp_hal
 
 #Flags
@@ -105,24 +104,24 @@ DEVICE_FLAGS    = -DUSE_HAL_DRIVER -DUSE_FULL_LL_DRIVER
 ifeq ($(TARGET_MCU),STM32F765xx)
 DEVICE_FLAGS   += -DSTM32F765xx
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f765.ld
-STARTUP_SRC     = startup/startup_stm32f765xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32f765xx.s
 MCU_FLASH_SIZE	:= 2048
 else ifeq ($(TARGET_MCU),STM32F745xx)
 DEVICE_FLAGS   += -DSTM32F745xx
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f74x.ld
-STARTUP_SRC     = startup/startup_stm32f745xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32f745xx.s
 MCU_FLASH_SIZE  := 1024
 else ifeq ($(TARGET_MCU),STM32F746xx)
 DEVICE_FLAGS   += -DSTM32F746xx
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f74x.ld
-STARTUP_SRC     = startup/startup_stm32f746xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32f746xx.s
 MCU_FLASH_SIZE  := 1024
 else ifeq ($(TARGET_MCU),STM32F722xx)
 DEVICE_FLAGS   += -DSTM32F722xx
 ifndef LD_SCRIPT
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_f722.ld
 endif
-STARTUP_SRC     = startup/startup_stm32f722xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32f722xx.s
 MCU_FLASH_SIZE  := 512
 # Override the OPTIMISE_SPEED compiler setting to save flash space on these 512KB targets.
 # Performance is only slightly affected but around 50 kB of flash are saved.
@@ -133,58 +132,56 @@ endif
 DEVICE_FLAGS    += -DHSE_VALUE=$(HSE_VALUE) -DSTM32
 
 VCP_SRC = \
-            vcp_hal/usbd_desc.c \
-            vcp_hal/usbd_conf_stm32f7xx.c \
-            vcp_hal/usbd_cdc_hid.c \
-            vcp_hal/usbd_cdc_interface.c \
-            serial_usb_vcp.c \
+            STM32/vcp_hal/usbd_desc.c \
+            STM32/vcp_hal/usbd_conf_stm32f7xx.c \
+            STM32/vcp_hal/usbd_cdc_hid.c \
+            STM32/vcp_hal/usbd_cdc_interface.c \
+            STM32/serial_usb_vcp.c \
             drivers/usb_io.c
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
+            common/stm32/system.c \
             drivers/accgyro/accgyro_mpu.c \
             drivers/bus_i2c_timing.c \
             drivers/dshot_bitbang_decode.c \
             drivers/pwm_output_dshot_shared.c \
-            adc_stm32f7xx.c \
-            audio_stm32f7xx.c \
-            bus_i2c_hal_init.c \
-            bus_i2c_hal.c \
-            bus_spi_ll.c \
-            debug.c \
-            dma_reqmap_mcu.c \
-            dma_stm32f7xx.c \
-            dshot_bitbang_ll.c \
-            dshot_bitbang.c \
-            exti.c \
-            io_stm32.c \
-            light_ws2811strip_hal.c \
-            persistent.c \
-            pwm_output.c \
-            pwm_output_dshot_hal.c \
-            rcc_stm32.c \
-            sdio_f7xx.c \
-            serial_uart_hal.c \
-            serial_uart_stm32f7xx.c \
-            system_stm32f7xx.c \
-            timer_hal.c \
-            timer_stm32f7xx.c \
-            transponder_ir_io_hal.c \
-            camera_control_stm32.c \
+            STM32/adc_stm32f7xx.c \
+            STM32/audio_stm32f7xx.c \
+            STM32/bus_i2c_hal_init.c \
+            STM32/bus_i2c_hal.c \
+            STM32/bus_spi_ll.c \
+            STM32/debug.c \
+            STM32/dma_reqmap_mcu.c \
+            STM32/dma_stm32f7xx.c \
+            STM32/dshot_bitbang_ll.c \
+            STM32/dshot_bitbang.c \
+            STM32/exti.c \
+            STM32/io_stm32.c \
+            STM32/light_ws2811strip_hal.c \
+            STM32/persistent.c \
+            STM32/pwm_output.c \
+            STM32/pwm_output_dshot_hal.c \
+            STM32/rcc_stm32.c \
+            STM32/sdio_f7xx.c \
+            STM32/serial_uart_hal.c \
+            STM32/serial_uart_stm32f7xx.c \
+            STM32/system_stm32f7xx.c \
+            STM32/timer_hal.c \
+            STM32/timer_stm32f7xx.c \
+            STM32/transponder_ir_io_hal.c \
+            STM32/camera_control_stm32.c \
             drivers/adc.c \
             drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
             drivers/bus_spi_config.c \
             drivers/bus_spi_pinconfig.c \
             drivers/serial_escserial.c \
             drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
             drivers/serial_uart_pinconfig.c \
-            startup/system_stm32f7xx.c
+            STM32/startup/system_stm32f7xx.c
 
 MSC_SRC = \
             drivers/usb_msc_common.c \
-            usb_msc_hal.c \
+            STM32/usb_msc_hal.c \
             msc/usbd_storage.c \
             msc/usbd_storage_emfat.c \
             msc/emfat.c \
@@ -193,7 +190,13 @@ MSC_SRC = \
             msc/usbd_storage_sd_spi.c
 
 SPEED_OPTIMISED_SRC += \
-            common/stm32/system.c
+            common/stm32/system.c \
+            STM32/bus_i2c_hal.c \
+            STM32/bus_spi_ll.c \
+            drivers/max7456.c \
+            drivers/pwm_output_dshot_shared.c \
+            STM32/pwm_output_dshot_hal.c \
+            STM32/exti.c
 
-DSP_LIB := $(ROOT)/lib/main/CMSIS/DSP
+DSP_LIB := $(LIB_MAIN_DIR)/CMSIS/DSP
 DEVICE_FLAGS += -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -D__FPU_PRESENT=1 -DUNALIGNED_SUPPORT_DISABLE -DARM_MATH_CM7
diff --git a/src/platform/STM32/mk/STM32G4.mk b/src/platform/STM32/mk/STM32G4.mk
index 923aca727a..4131430398 100644
--- a/src/platform/STM32/mk/STM32G4.mk
+++ b/src/platform/STM32/mk/STM32G4.mk
@@ -7,10 +7,10 @@ CFLAGS          += -DDEBUG_HARDFAULTS
 endif
 
 #CMSIS
-CMSIS_DIR      := $(ROOT)/lib/main/CMSIS
+CMSIS_DIR      := $(LIB_MAIN_DIR)/CMSIS
 
 #STDPERIPH
-STDPERIPH_DIR   = $(ROOT)/lib/main/STM32G4/Drivers/STM32G4xx_HAL_Driver
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/STM32G4/Drivers/STM32G4xx_HAL_Driver
 STDPERIPH_SRC   = \
             stm32g4xx_hal_adc.c \
             stm32g4xx_hal_adc_ex.c \
@@ -44,26 +44,26 @@ STDPERIPH_SRC   = \
             stm32g4xx_ll_usb.c
 
 #USB
-USBCORE_DIR = $(ROOT)/lib/main/STM32G4/Middlewares/ST/STM32_USB_Device_Library/Core
+USBCORE_DIR = STM32G4/Middlewares/ST/STM32_USB_Device_Library/Core
 USBCORE_SRC = \
-            usbd_core.c \
-            usbd_ctlreq.c \
-            usbd_ioreq.c
+            $(USBCORE_DIR)/Src/usbd_core.c \
+            $(USBCORE_DIR)/Src/usbd_ctlreq.c \
+            $(USBCORE_DIR)/Src/usbd_ioreq.c
 
-USBCDC_DIR = $(ROOT)/lib/main/STM32G4/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
-USBCDC_SRC = usbd_cdc.c
+USBCDC_DIR = STM32G4/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
+USBCDC_SRC = \
+            $(USBCDC_DIR)/Src/usbd_cdc.c
 
-USBHID_DIR = $(ROOT)/lib/main/STM32G4/Middlewares/ST/STM32_USB_Device_Library/Class/HID
-USBHID_SRC = usbd_hid.c
+USBHID_DIR = STM32G4/Middlewares/ST/STM32_USB_Device_Library/Class/HID
+USBHID_SRC = \
+            $(USBHID_DIR)/Src/usbd_hid.c
 
-USBMSC_DIR = $(ROOT)/lib/main/STM32G4/Middlewares/ST/STM32_USB_Device_Library/Class/MSC
+USBMSC_DIR = STM32G4/Middlewares/ST/STM32_USB_Device_Library/Class/MSC
 USBMSC_SRC = \
-            usbd_msc_bot.c \
-            usbd_msc.c \
-            usbd_msc_data.c \
-            usbd_msc_scsi.c
-
-VPATH := $(VPATH):$(USBCDC_DIR)/Src:$(USBCORE_DIR)/Src:$(USBHID_DIR)/Src:$(USBMSC_DIR)/Src:$(STDPERIPH_DIR)/src
+            $(USBMSC_DIR)/Src/usbd_msc_bot.c \
+            $(USBMSC_DIR)/Src/usbd_msc.c \
+            $(USBMSC_DIR)/Src/usbd_msc_data.c \
+            $(USBMSC_DIR)/Src/usbd_msc_scsi.c
 
 DEVICE_STDPERIPH_SRC := \
             $(STDPERIPH_SRC) \
@@ -73,20 +73,19 @@ DEVICE_STDPERIPH_SRC := \
             $(USBMSC_SRC)
 
 #CMSIS
-VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32G4xx
-VPATH           := $(VPATH):$(STDPERIPH_DIR)/Src
+VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32G4xx:$(STDPERIPH_DIR)/Src
 CMSIS_SRC       :=
 INCLUDE_DIRS    := \
             $(INCLUDE_DIRS) \
             $(TARGET_PLATFORM_DIR) \
             $(TARGET_PLATFORM_DIR)/startup \
             $(STDPERIPH_DIR)/Inc \
-            $(USBCORE_DIR)/Inc \
-            $(USBCDC_DIR)/Inc \
-            $(USBHID_DIR)/Inc \
-            $(USBMSC_DIR)/Inc \
+            $(LIB_MAIN_DIR)/$(USBCORE_DIR)/Inc \
+            $(LIB_MAIN_DIR)/$(USBCDC_DIR)/Inc \
+            $(LIB_MAIN_DIR)/$(USBHID_DIR)/Inc \
+            $(LIB_MAIN_DIR)/$(USBMSC_DIR)/Inc \
             $(CMSIS_DIR)/Core/Include \
-            $(ROOT)/lib/main/STM32G4/Drivers/CMSIS/Device/ST/STM32G4xx/Include \
+            $(LIB_MAIN_DIR)/STM32G4/Drivers/CMSIS/Device/ST/STM32G4xx/Include \
             $(TARGET_PLATFORM_DIR)/vcp_hal
 
 #Flags
@@ -99,7 +98,7 @@ DEVICE_FLAGS    = -DUSE_HAL_DRIVER -DUSE_FULL_LL_DRIVER -DUSE_DMA_RAM -DMAX_MPU_
 ifeq ($(TARGET_MCU),STM32G474xx)
 DEVICE_FLAGS    += -DSTM32G474xx
 LD_SCRIPT       = $(LINKER_DIR)/stm32_flash_g474.ld
-STARTUP_SRC     = startup/startup_stm32g474xx.s
+STARTUP_SRC     = STM32/startup/startup_stm32g474xx.s
 MCU_FLASH_SIZE  = 512
 # Override the OPTIMISE_SPEED compiler setting to save flash space on these 512KB targets.
 # Performance is only slightly affected but around 50 kB of flash are saved.
@@ -110,59 +109,57 @@ endif
 DEVICE_FLAGS    += -DHSE_VALUE=$(HSE_VALUE) -DSTM32
 
 VCP_SRC = \
-            vcp_hal/usbd_desc.c \
-            vcp_hal/usbd_conf_stm32g4xx.c \
-            vcp_hal/usbd_cdc_hid.c \
-            vcp_hal/usbd_cdc_interface.c \
-            serial_usb_vcp.c \
+            STM32/vcp_hal/usbd_desc.c \
+            STM32/vcp_hal/usbd_conf_stm32g4xx.c \
+            STM32/vcp_hal/usbd_cdc_hid.c \
+            STM32/vcp_hal/usbd_cdc_interface.c \
+            STM32/serial_usb_vcp.c \
             drivers/usb_io.c
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
+            common/stm32/system.c \
             drivers/accgyro/accgyro_mpu.c \
             drivers/bus_i2c_timing.c \
             drivers/dshot_bitbang_decode.c \
             drivers/pwm_output_dshot_shared.c \
-            adc_stm32g4xx.c \
-            bus_i2c_hal_init.c \
-            bus_i2c_hal.c \
-            bus_spi_ll.c \
-            debug.c \
-            dma_reqmap_mcu.c \
-            dma_stm32g4xx.c \
-            dshot_bitbang_ll.c \
-            dshot_bitbang.c \
-            exti.c \
-            io_stm32.c \
-            light_ws2811strip_hal.c \
-            memprot_hal.c \
-            memprot_stm32g4xx.c \
-            persistent.c \
-            pwm_output.c \
-            pwm_output_dshot_hal.c \
-            rcc_stm32.c \
-            serial_uart_hal.c \
-            serial_uart_stm32g4xx.c \
-            system_stm32g4xx.c \
-            timer_hal.c \
-            timer_stm32g4xx.c \
-            transponder_ir_io_hal.c \
-            camera_control_stm32.c \
+            STM32/adc_stm32g4xx.c \
+            STM32/bus_i2c_hal_init.c \
+            STM32/bus_i2c_hal.c \
+            STM32/bus_spi_ll.c \
+            STM32/debug.c \
+            STM32/dma_reqmap_mcu.c \
+            STM32/dma_stm32g4xx.c \
+            STM32/dshot_bitbang_ll.c \
+            STM32/dshot_bitbang.c \
+            STM32/exti.c \
+            STM32/io_stm32.c \
+            STM32/light_ws2811strip_hal.c \
+            STM32/memprot_hal.c \
+            STM32/memprot_stm32g4xx.c \
+            STM32/persistent.c \
+            STM32/pwm_output.c \
+            STM32/pwm_output_dshot_hal.c \
+            STM32/rcc_stm32.c \
+            STM32/serial_uart_hal.c \
+            STM32/serial_uart_stm32g4xx.c \
+            STM32/system_stm32g4xx.c \
+            STM32/timer_hal.c \
+            STM32/timer_stm32g4xx.c \
+            STM32/transponder_ir_io_hal.c \
+            STM32/camera_control_stm32.c \
             drivers/adc.c \
             drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
             drivers/bus_spi_config.c \
             drivers/bus_spi_pinconfig.c \
             drivers/serial_escserial.c \
             drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
             drivers/serial_uart_pinconfig.c \
-            startup/system_stm32g4xx.c
+            STM32/startup/system_stm32g4xx.c
 
 # G4's MSC use the same driver layer file with F7
 MSC_SRC = \
             drivers/usb_msc_common.c \
-            usb_msc_hal.c \
+            STM32/usb_msc_hal.c \
             msc/usbd_storage.c \
             msc/usbd_storage_emfat.c \
             msc/emfat.c \
@@ -171,7 +168,8 @@ MSC_SRC = \
             msc/usbd_storage_sd_spi.c
 
 SPEED_OPTIMISED_SRC += \
-            common/stm32/system.c
+            common/stm32/system.c \
+            STM32/exti.c
 
-DSP_LIB := $(ROOT)/lib/main/CMSIS/DSP
+DSP_LIB := $(LIB_MAIN_DIR)/CMSIS/DSP
 DEVICE_FLAGS += -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -D__FPU_PRESENT=1 -DUNALIGNED_SUPPORT_DISABLE -DARM_MATH_CM4
diff --git a/src/platform/STM32/mk/STM32H5.mk b/src/platform/STM32/mk/STM32H5.mk
index 11cdf5d64c..b6c1682c7b 100644
--- a/src/platform/STM32/mk/STM32H5.mk
+++ b/src/platform/STM32/mk/STM32H5.mk
@@ -7,10 +7,10 @@ CFLAGS          += -DDEBUG_HARDFAULTS
 endif
 
 #CMSIS
-CMSIS_DIR      := $(ROOT)/lib/main/CMSIS
+CMSIS_DIR      := $(LIB_MAIN_DIR)/CMSIS
 
 #STDPERIPH
-STDPERIPH_DIR   = $(ROOT)/lib/main/STM32H5/Drivers/STM32H5xx_HAL_Driver
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/STM32H5/Drivers/STM32H5xx_HAL_Driver
 STDPERIPH_SRC   = \
             stm32h5xx_hal_adc.c \
             stm32h5xx_hal_adc_ex.c \
@@ -69,7 +69,7 @@ STDPERIPH_SRC   = \
             stm32h5xx_util_i3c.c
 
 #USB  ##TODO - need to work through the USB drivers, new directory: USBX
-#USBCORE_DIR = $(ROOT)/lib/main/STM32H5/Middlewares/ST/usbx/Common
+#USBCORE_DIR = $(LIB_MAIN_DIR)/STM32H5/Middlewares/ST/usbx/Common
 #USBCORE_SRC = $(notdir $(wildcard $(USBCORE_DIR)/Src/*.c))
 #EXCLUDES    =
 #USBCORE_SRC := $(filter-out ${EXCLUDES}, $(USBCORE_SRC))
@@ -83,19 +83,18 @@ DEVICE_STDPERIPH_SRC := $(STDPERIPH_SRC) \
                         $(USBMSC_SRC)
 
 #CMSIS
-VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32H5xx
-VPATH           := $(VPATH):$(STDPERIPH_DIR)/Src
+VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32H5xx:$(STDPERIPH_DIR)/Src
 CMSIS_SRC       :=
 INCLUDE_DIRS    := $(INCLUDE_DIRS) \
                    $(TARGET_PLATFORM_DIR) \
                    $(TARGET_PLATFORM_DIR)/startup \
                    $(STDPERIPH_DIR)/Inc \
-                   $(USBCORE_DIR)/Inc \
-                   $(USBCDC_DIR)/Inc \
-                   $(USBHID_DIR)/Inc \
-                   $(USBMSC_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBCORE_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBCDC_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBHID_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBMSC_DIR)/Inc \
                    $(CMSIS_DIR)/Core/Include \
-                   $(ROOT)/lib/main/STM32H5/Drivers/CMSIS/Device/ST/STM32H5xx/Include \
+                   $(LIB_MAIN_DIR)/STM32H5/Drivers/CMSIS/Device/ST/STM32H5xx/Include \
                    $(TARGET_PLATFORM_DIR)/vcp_hal
 
 #Flags
@@ -110,7 +109,7 @@ DEVICE_FLAGS    = -DUSE_HAL_DRIVER -DUSE_FULL_LL_DRIVER
 ifeq ($(TARGET_MCU),STM32H563xx)
 DEVICE_FLAGS       += -DSTM32H563xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h563_2m.ld
-STARTUP_SRC         = startup/startup_stm32h563xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h563xx.s
 MCU_FLASH_SIZE     := 2048
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
@@ -149,41 +148,39 @@ VCP_SRC =
             drivers/usb_io.c
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
+            common/stm32/system.c \
             drivers/bus_i2c_timing.c \
             drivers/bus_quadspi.c \
             drivers/dshot_bitbang_decode.c \
             drivers/pwm_output_dshot_shared.c \
-            bus_i2c_hal_init.c \
-            bus_i2c_hal.c \
-            bus_spi_ll.c \
-            bus_quadspi_hal.c \
-            debug.c \
-            dma_reqmap_mcu.c \
-            dshot_bitbang_ll.c \
-            dshot_bitbang.c \
-            exti.c \
-            io_stm32.c \
-            light_ws2811strip_hal.c \
-            persistent.c \
-            pwm_output.c \
-            pwm_output_dshot_hal.c \
-            rcc_stm32.c \
-            serial_uart_hal.c \
-            timer_hal.c \
-            transponder_ir_io_hal.c \
-            camera_control_stm32.c \
-            system_stm32h5xx.c \
+            STM32/bus_i2c_hal_init.c \
+            STM32/bus_i2c_hal.c \
+            STM32/bus_spi_ll.c \
+            STM32/bus_quadspi_hal.c \
+            STM32/debug.c \
+            STM32/dma_reqmap_mcu.c \
+            STM32/dshot_bitbang_ll.c \
+            STM32/dshot_bitbang.c \
+            STM32/exti.c \
+            STM32/io_stm32.c \
+            STM32/light_ws2811strip_hal.c \
+            STM32/persistent.c \
+            STM32/pwm_output.c \
+            STM32/pwm_output_dshot_hal.c \
+            STM32/rcc_stm32.c \
+            STM32/serial_uart_hal.c \
+            STM32/timer_hal.c \
+            STM32/transponder_ir_io_hal.c \
+            STM32/camera_control_stm32.c \
+            STM32/system_stm32h5xx.c \
             drivers/adc.c \
             drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
             drivers/bus_spi_config.c \
             drivers/bus_spi_pinconfig.c \
             drivers/serial_escserial.c \
             drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
             drivers/serial_uart_pinconfig.c \
-            startup/system_stm32h5xx.c
+            STM32/startup/system_stm32h5xx.c
 
 #            memprot_hal.c \
 #            memprot_stm32h5xx.c \
@@ -205,7 +202,8 @@ MSC_SRC =
             msc/usbd_storage_sdio.c
 
 SPEED_OPTIMISED_SRC += \
-            common/stm32/system.c
+            common/stm32/system.c \
+            STM32/exti.c
 
-DSP_LIB := $(ROOT)/lib/main/CMSIS/DSP
+DSP_LIB := $(LIB_MAIN_DIR)/CMSIS/DSP
 DEVICE_FLAGS += -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -DUNALIGNED_SUPPORT_DISABLE -DARM_MATH_CM7
diff --git a/src/platform/STM32/mk/STM32H7.mk b/src/platform/STM32/mk/STM32H7.mk
index 0639cff249..5651cbd122 100644
--- a/src/platform/STM32/mk/STM32H7.mk
+++ b/src/platform/STM32/mk/STM32H7.mk
@@ -7,10 +7,10 @@ CFLAGS          += -DDEBUG_HARDFAULTS
 endif
 
 #CMSIS
-CMSIS_DIR      := $(ROOT)/lib/main/CMSIS
+CMSIS_DIR      := $(LIB_MAIN_DIR)/CMSIS
 
 #STDPERIPH
-STDPERIPH_DIR   = $(ROOT)/lib/main/STM32H7/Drivers/STM32H7xx_HAL_Driver
+STDPERIPH_DIR   = $(LIB_MAIN_DIR)/STM32H7/Drivers/STM32H7xx_HAL_Driver
 STDPERIPH_SRC   = \
             stm32h7xx_hal_adc.c \
             stm32h7xx_hal_adc_ex.c \
@@ -59,26 +59,26 @@ STDPERIPH_SRC   = \
             stm32h7xx_ll_usb.c
 
 #USB
-USBCORE_DIR = $(ROOT)/lib/main/STM32H7/Middlewares/ST/STM32_USB_Device_Library/Core
+USBCORE_DIR = STM32H7/Middlewares/ST/STM32_USB_Device_Library/Core
 USBCORE_SRC = \
-            usbd_core.c \
-            usbd_ctlreq.c \
-            usbd_ioreq.c
+            $(USBCORE_DIR)/Src/usbd_core.c \
+            $(USBCORE_DIR)/Src/usbd_ctlreq.c \
+            $(USBCORE_DIR)/Src/usbd_ioreq.c
 
-USBCDC_DIR = $(ROOT)/lib/main/STM32H7/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
-USBCDC_SRC = usbd_cdc.c
+USBCDC_DIR = STM32H7/Middlewares/ST/STM32_USB_Device_Library/Class/CDC
+USBCDC_SRC = \
+            $(USBCDC_DIR)/Src/usbd_cdc.c
 
-USBHID_DIR = $(ROOT)/lib/main/STM32H7/Middlewares/ST/STM32_USB_Device_Library/Class/HID
-USBHID_SRC = usbd_hid.c
+USBHID_DIR = STM32H7/Middlewares/ST/STM32_USB_Device_Library/Class/HID
+USBHID_SRC = \
+            $(USBHID_DIR)/Src/usbd_hid.c
 
-USBMSC_DIR = $(ROOT)/lib/main/STM32H7/Middlewares/ST/STM32_USB_Device_Library/Class/MSC
+USBMSC_DIR = STM32H7/Middlewares/ST/STM32_USB_Device_Library/Class/MSC
 USBMSC_SRC = \
-            usbd_msc_bot.c \
-            usbd_msc.c \
-            usbd_msc_data.c \
-            usbd_msc_scsi.c
-
-VPATH := $(VPATH):$(USBCDC_DIR)/Src:$(USBCORE_DIR)/Src:$(USBHID_DIR)/Src:$(USBMSC_DIR)/Src:$(STDPERIPH_DIR)/src
+            $(USBMSC_DIR)/Src/usbd_msc_bot.c \
+            $(USBMSC_DIR)/Src/usbd_msc.c \
+            $(USBMSC_DIR)/Src/usbd_msc_data.c \
+            $(USBMSC_DIR)/Src/usbd_msc_scsi.c
 
 DEVICE_STDPERIPH_SRC := $(STDPERIPH_SRC) \
                         $(USBCORE_SRC) \
@@ -87,19 +87,18 @@ DEVICE_STDPERIPH_SRC := $(STDPERIPH_SRC) \
                         $(USBMSC_SRC)
 
 #CMSIS
-VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32H7xx
-VPATH           := $(VPATH):$(STDPERIPH_DIR)/Src
+VPATH           := $(VPATH):$(CMSIS_DIR)/Include:$(CMSIS_DIR)/Device/ST/STM32H7xx:$(STDPERIPH_DIR)/Src
 CMSIS_SRC       :=
 INCLUDE_DIRS    := $(INCLUDE_DIRS) \
                    $(TARGET_PLATFORM_DIR) \
                    $(TARGET_PLATFORM_DIR)/startup \
                    $(STDPERIPH_DIR)/Inc \
-                   $(USBCORE_DIR)/Inc \
-                   $(USBCDC_DIR)/Inc \
-                   $(USBHID_DIR)/Inc \
-                   $(USBMSC_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBCORE_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBCDC_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBHID_DIR)/Inc \
+                   $(LIB_MAIN_DIR)/$(USBMSC_DIR)/Inc \
                    $(CMSIS_DIR)/Core/Include \
-                   $(ROOT)/lib/main/STM32H7/Drivers/CMSIS/Device/ST/STM32H7xx/Include \
+                   $(LIB_MAIN_DIR)/STM32H7/Drivers/CMSIS/Device/ST/STM32H7xx/Include \
                    $(TARGET_PLATFORM_DIR)/vcp_hal
 
 #Flags
@@ -117,7 +116,7 @@ DEVICE_FLAGS    = -DUSE_HAL_DRIVER -DUSE_FULL_LL_DRIVER
 ifeq ($(TARGET_MCU),STM32H743xx)
 DEVICE_FLAGS       += -DSTM32H743xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h743_2m.ld
-STARTUP_SRC         = startup/startup_stm32h743xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h743xx.s
 MCU_FLASH_SIZE     := 2048
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
@@ -132,7 +131,7 @@ endif
 else ifeq ($(TARGET_MCU),STM32H7A3xxQ)
 DEVICE_FLAGS       += -DSTM32H7A3xxQ
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h7a3_2m.ld
-STARTUP_SRC         = startup/startup_stm32h7a3xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h7a3xx.s
 MCU_FLASH_SIZE     := 2048
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
@@ -147,7 +146,7 @@ endif
 else ifeq ($(TARGET_MCU),STM32H7A3xx)
 DEVICE_FLAGS       += -DSTM32H7A3xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h7a3_2m.ld
-STARTUP_SRC         = startup/startup_stm32h7a3xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h7a3xx.s
 MCU_FLASH_SIZE     := 2048
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
@@ -162,7 +161,7 @@ endif
 else ifeq ($(TARGET_MCU),STM32H723xx)
 DEVICE_FLAGS       += -DSTM32H723xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h723_1m.ld
-STARTUP_SRC         = startup/startup_stm32h723xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h723xx.s
 DEFAULT_TARGET_FLASH := 1024
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
@@ -182,14 +181,14 @@ endif
 else ifeq ($(TARGET_MCU),STM32H725xx)
 DEVICE_FLAGS       += -DSTM32H725xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h723_1m.ld
-STARTUP_SRC         = startup/startup_stm32h723xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h723xx.s
 MCU_FLASH_SIZE     := 1024
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
 else ifeq ($(TARGET_MCU),STM32H730xx)
 DEVICE_FLAGS       += -DSTM32H730xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h730_128m.ld
-STARTUP_SRC         = startup/startup_stm32h730xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h730xx.s
 DEFAULT_TARGET_FLASH := 128
 DEVICE_FLAGS       += -DMAX_MPU_REGIONS=16
 
@@ -211,7 +210,7 @@ endif
 else ifeq ($(TARGET_MCU),STM32H750xx)
 DEVICE_FLAGS       += -DSTM32H750xx
 DEFAULT_LD_SCRIPT   = $(LINKER_DIR)/stm32_flash_h750_128k.ld
-STARTUP_SRC         = startup/startup_stm32h743xx.s
+STARTUP_SRC         = STM32/startup/startup_stm32h743xx.s
 DEFAULT_TARGET_FLASH := 128
 
 ifeq ($(TARGET_FLASH),)
@@ -256,61 +255,59 @@ endif
 DEVICE_FLAGS    += -DHSE_VALUE=$(HSE_VALUE) -DHSE_STARTUP_TIMEOUT=1000 -DSTM32
 
 VCP_SRC = \
-            vcp_hal/usbd_desc.c \
-            vcp_hal/usbd_conf_stm32h7xx.c \
-            vcp_hal/usbd_cdc_hid.c \
-            vcp_hal/usbd_cdc_interface.c \
-            serial_usb_vcp.c \
+            STM32/vcp_hal/usbd_desc.c \
+            STM32/vcp_hal/usbd_conf_stm32h7xx.c \
+            STM32/vcp_hal/usbd_cdc_hid.c \
+            STM32/vcp_hal/usbd_cdc_interface.c \
+            STM32/serial_usb_vcp.c \
             drivers/usb_io.c
 
 MCU_COMMON_SRC = \
-            stm32/system.c \
+            common/stm32/system.c \
             drivers/bus_i2c_timing.c \
             drivers/bus_quadspi.c \
             drivers/dshot_bitbang_decode.c \
             drivers/pwm_output_dshot_shared.c \
-            adc_stm32h7xx.c \
-            audio_stm32h7xx.c \
-            bus_i2c_hal_init.c \
-            bus_i2c_hal.c \
-            bus_spi_ll.c \
-            bus_quadspi_hal.c \
-            bus_octospi_stm32h7xx.c \
-            debug.c \
-            dma_reqmap_mcu.c \
-            dma_stm32h7xx.c \
-            dshot_bitbang_ll.c \
-            dshot_bitbang.c \
-            exti.c \
-            io_stm32.c \
-            light_ws2811strip_hal.c \
-            memprot_hal.c \
-            memprot_stm32h7xx.c \
-            persistent.c \
-            pwm_output.c \
-            pwm_output_dshot_hal.c \
-            rcc_stm32.c \
-            sdio_h7xx.c \
-            serial_uart_hal.c \
-            serial_uart_stm32h7xx.c \
-            system_stm32h7xx.c \
-            timer_hal.c \
-            timer_stm32h7xx.c \
-            transponder_ir_io_hal.c \
-            camera_control_stm32.c \
+            STM32/adc_stm32h7xx.c \
+            STM32/audio_stm32h7xx.c \
+            STM32/bus_i2c_hal_init.c \
+            STM32/bus_i2c_hal.c \
+            STM32/bus_spi_ll.c \
+            STM32/bus_quadspi_hal.c \
+            STM32/bus_octospi_stm32h7xx.c \
+            STM32/debug.c \
+            STM32/dma_reqmap_mcu.c \
+            STM32/dma_stm32h7xx.c \
+            STM32/dshot_bitbang_ll.c \
+            STM32/dshot_bitbang.c \
+            STM32/exti.c \
+            STM32/io_stm32.c \
+            STM32/light_ws2811strip_hal.c \
+            STM32/memprot_hal.c \
+            STM32/memprot_stm32h7xx.c \
+            STM32/persistent.c \
+            STM32/pwm_output.c \
+            STM32/pwm_output_dshot_hal.c \
+            STM32/rcc_stm32.c \
+            STM32/sdio_h7xx.c \
+            STM32/serial_uart_hal.c \
+            STM32/serial_uart_stm32h7xx.c \
+            STM32/system_stm32h7xx.c \
+            STM32/timer_hal.c \
+            STM32/timer_stm32h7xx.c \
+            STM32/transponder_ir_io_hal.c \
+            STM32/camera_control_stm32.c \
             drivers/adc.c \
             drivers/bus_i2c_config.c \
-            drivers/bus_spi.c \
             drivers/bus_spi_config.c \
             drivers/bus_spi_pinconfig.c \
             drivers/serial_escserial.c \
             drivers/serial_pinconfig.c \
-            drivers/serial_uart.c \
             drivers/serial_uart_pinconfig.c \
-            startup/system_stm32h7xx.c
+            STM32/startup/system_stm32h7xx.c
 
 MSC_SRC = \
-            usb_msc_hal.c \
+            STM32/usb_msc_hal.c \
             drivers/usb_msc_common.c \
             msc/usbd_storage.c \
             msc/usbd_storage_emfat.c \
@@ -320,7 +317,8 @@ MSC_SRC = \
             msc/usbd_storage_sdio.c
 
 SPEED_OPTIMISED_SRC += \
-            common/stm32/system.c
+            common/stm32/system.c \
+            STM32/exti.c
 
-DSP_LIB := $(ROOT)/lib/main/CMSIS/DSP
+DSP_LIB := $(LIB_MAIN_DIR)/CMSIS/DSP
 DEVICE_FLAGS += -DARM_MATH_MATRIX_CHECK -DARM_MATH_ROUNDING -D__FPU_PRESENT=1 -DUNALIGNED_SUPPORT_DISABLE -DARM_MATH_CM7