diff --git a/Makefile b/Makefile
index b192f5e6..448c1f2c 100644
--- a/Makefile
+++ b/Makefile
@@ -29,7 +29,7 @@ ifeq ($(OS),Windows_NT)
 		CPP = xtensa-lx106-elf-cpp
 		OBJCOPY = xtensa-lx106-elf-objcopy
 	endif
-	FIRMWAREDIR = ..\\bin\\
+	ESPPORT = com1
     ifeq ($(PROCESSOR_ARCHITECTURE),AMD64)
 # ->AMD64
     endif
@@ -39,13 +39,13 @@ ifeq ($(OS),Windows_NT)
 else
 # We are under other system, may be Linux. Assume using gcc.
 	# Can we use -fdata-sections?
+	ESPPORT = /dev/ttyUSB0
 	CCFLAGS += -Os -ffunction-sections -fno-jump-tables
 	AR = xtensa-lx106-elf-ar
 	CC = xtensa-lx106-elf-gcc
 	NM = xtensa-lx106-elf-nm
 	CPP = xtensa-lx106-elf-cpp
 	OBJCOPY = xtensa-lx106-elf-objcopy
-	FIRMWAREDIR = ../bin/
     UNAME_S := $(shell uname -s)
     ifeq ($(UNAME_S),Linux)
 # LINUX
@@ -65,6 +65,8 @@ else
     endif
 endif
 #############################################################
+ESPTOOL = python ../tools/esptool.py
+FIRMWAREDIR = ../bin/
 
 CSRCS ?= $(wildcard *.c)
 ASRCs ?= $(wildcard *.s)
@@ -137,7 +139,7 @@ endef
 
 $(BINODIR)/%.bin: $(IMAGEODIR)/%.out
 	@mkdir -p $(BINODIR)
-	../tools/esptool.py elf2image $< -o $(FIRMWAREDIR)
+	$(ESPTOOL) elf2image $< -o $(FIRMWAREDIR)/
 
 #############################################################
 # Rules base
@@ -154,6 +156,13 @@ clobber: $(SPECIAL_CLOBBER)
 	$(foreach d, $(SUBDIRS), $(MAKE) -C $(d) clobber;)
 	$(RM) -r $(ODIR)
 
+flash: 
+ifndef PDIR
+	$(MAKE) -C ./app flash
+else
+	$(ESPTOOL) --port $(ESPPORT) write_flash 0x00000 $(FIRMWAREDIR)/0x00000.bin 0x10000 $(FIRMWAREDIR)/0x10000.bin
+endif
+
 .subdirs:
 	@set -e; $(foreach d, $(SUBDIRS), $(MAKE) -C $(d);)
 
diff --git a/app/Makefile b/app/Makefile
index ad9a71c2..753595d6 100644
--- a/app/Makefile
+++ b/app/Makefile
@@ -152,23 +152,6 @@ INCLUDES += -I ./
 PDIR := ../$(PDIR)
 sinclude $(PDIR)Makefile
 
-#########################################################################
-#
-#  generate bin file
-#
-
-ifeq ($(OS),Windows_NT)
-	PORT = com1
-else
-	PORT = /dev/ttyUSB0
-endif
-
-$(BINODIR)/%.bin: $(IMAGEODIR)/%.out
-	@mkdir -p $(BINODIR)
-	../tools/esptool.py elf2image $< -o $(FIRMWAREDIR)
-
-flash:
-	../tools/esptool.py -p $(PORT) write_flash 0x00000 ../bin/0x00000.bin 0x10000 ../bin/0x10000.bin
 
 .PHONY: FORCE
 FORCE: