added feather nrf52840 sense

hw/bsp/feather_nrf52840_sense/board.mk

@@ -0,0 +1,63 @@
+CFLAGS += \
+  -flto \
+  -mthumb \
+  -mabi=aapcs \
+  -mcpu=cortex-m4 \
+  -mfloat-abi=hard \
+  -mfpu=fpv4-sp-d16 \
+  -DCFG_TUSB_MCU=OPT_MCU_NRF5X \
+  -DNRF52840_XXAA \
+  -DCONFIG_GPIO_AS_PINRESET
+
+# nrfx issue undef _ARMCC_VERSION usage https://github.com/NordicSemiconductor/nrfx/issues/49
+CFLAGS += -Wno-error=undef -Wno-error=unused-parameter
+
+# due to tusb_hal_nrf_power_event
+GCCVERSION = $(firstword $(subst ., ,$(shell arm-none-eabi-gcc -dumpversion)))
+ifeq ($(shell expr $(GCCVERSION) \>= 8), 1)
+CFLAGS += -Wno-error=cast-function-type
+endif
+
+# All source paths should be relative to the top level.
+LD_FILE = hw/bsp/feather_nrf52840_express/nrf52840_s140_v6.ld
+
+LDFLAGS += -L$(TOP)/hw/mcu/nordic/nrfx/mdk
+
+SRC_C += \
+  hw/mcu/nordic/nrfx/drivers/src/nrfx_power.c \
+  hw/mcu/nordic/nrfx/mdk/system_nrf52840.c \
+
+INC += \
+  $(TOP)/hw/mcu/nordic/cmsis/Include \
+  $(TOP)/hw/mcu/nordic \
+  $(TOP)/hw/mcu/nordic/nrfx \
+  $(TOP)/hw/mcu/nordic/nrfx/mdk \
+  $(TOP)/hw/mcu/nordic/nrfx/hal \
+  $(TOP)/hw/mcu/nordic/nrfx/drivers/include \
+  $(TOP)/hw/mcu/nordic/nrfx/drivers/src \
+
+SRC_S += hw/mcu/nordic/nrfx/mdk/gcc_startup_nrf52840.S
+
+ASFLAGS += -D__HEAP_SIZE=0
+
+# For TinyUSB port source
+VENDOR = nordic
+CHIP_FAMILY = nrf5x
+
+# For freeRTOS port source
+FREERTOS_PORT = ARM_CM4F
+
+# For flash-jlink target
+JLINK_DEVICE = nRF52840_xxAA
+JLINK_IF = swd
+
+# For uf2 conversion
+UF2_FAMILY = 0xADA52840
+
+$(BUILD)/$(BOARD)-firmware.zip: $(BUILD)/$(BOARD)-firmware.hex
+	adafruit-nrfutil dfu genpkg --dev-type 0x0052 --sd-req 0xFFFE --application $^ $@
+	
+# flash using adafruit-nrfutil dfu
+flash: $(BUILD)/$(BOARD)-firmware.zip
+	@:$(call check_defined, SERIAL, example: SERIAL=/dev/ttyACM0)
+	adafruit-nrfutil --verbose dfu serial --package $^ -p $(SERIAL) -b 115200 --singlebank --touch 1200