diff --git a/firmware/Makefile b/firmware/Makefile
index dfc82bc876..582018e448 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -7,13 +7,7 @@ CHIBIOS = ChibiOS4
 RULESPATH = $(CHIBIOS)/os/common/startup/ARMCMx/compilers/GCC
 RULESFILE = $(RULESPATH)/rules.mk
 
-ifeq ("$(wildcard $(RULESFILE))","")
-#
-# todo: someone please figure out the syntax to invoke 'git submodule update --init' from here
-#
-$(error Modules are missing? Did you execute 'git submodule update --init'?)
-endif
-
+include rusefi.mk
 
 # by default EXTRA_PARAMS is empty and we create 'debug' version of the firmware with additional assertions and statistics
 # for 'release' options see 'clean_compile_two_versions.bat' file
@@ -114,27 +108,6 @@ PROJECT_DIR = .
 # Imported source files and paths
 CHIBIOS_CONTRIB = ChibiOS-Contrib
 
-ifeq ($(PROJECT_BOARD),)
-  PROJECT_BOARD = ST_STM32F4
-endif
-DDEFS += -D$(PROJECT_BOARD)
-
-ifeq ($(PROJECT_CPU),)
-  PROJECT_CPU = ST_STM32F4
-endif
-DDEFS += -D$(PROJECT_CPU)
-
-# CPU-dependent defs
-ifeq ($(PROJECT_CPU),ST_STM32F7)
-CPU_STARTUP = startup_stm32f7xx.mk
-CPU_PLATFORM = STM32F7xx/platform.mk
-CPU_HWLAYER = stm32f7
-else # ST_STM32F4
-CPU_STARTUP = startup_stm32f4xx.mk
-CPU_PLATFORM = STM32F4xx/platform.mk
-CPU_HWLAYER = stm32f4
-endif
-
 # Startup files.
 include $(CHIBIOS)/os/common/startup/ARMCMx/compilers/GCC/mk/$(CPU_STARTUP)
 # HAL-OSAL files (optional).
diff --git a/firmware/rusefi.mk b/firmware/rusefi.mk
new file mode 100644
index 0000000000..258d41cc91
--- /dev/null
+++ b/firmware/rusefi.mk
@@ -0,0 +1,28 @@
+
+ifeq ("$(wildcard $(RULESFILE))","")
+#
+# todo: someone please figure out the syntax to invoke 'git submodule update --init' from here
+#
+$(error Modules are missing? Did you execute 'git submodule update --init'?)
+endif
+
+ifeq ($(PROJECT_BOARD),)
+  PROJECT_BOARD = ST_STM32F4
+endif
+DDEFS += -D$(PROJECT_BOARD)
+
+ifeq ($(PROJECT_CPU),)
+  PROJECT_CPU = ST_STM32F4
+endif
+DDEFS += -D$(PROJECT_CPU)
+
+# CPU-dependent defs
+ifeq ($(PROJECT_CPU),ST_STM32F7)
+CPU_STARTUP = startup_stm32f7xx.mk
+CPU_PLATFORM = STM32F7xx/platform.mk
+CPU_HWLAYER = stm32f7
+else # ST_STM32F4
+CPU_STARTUP = startup_stm32f4xx.mk
+CPU_PLATFORM = STM32F4xx/platform.mk
+CPU_HWLAYER = stm32f4
+endif
diff --git a/work_in_progress.md b/work_in_progress.md
index fe70802b0e..4dda320573 100644
--- a/work_in_progress.md
+++ b/work_in_progress.md
@@ -1,2 +1,3 @@
 Dec 2018 status:
-Electronic throttle body https://rusefi.com/forum/viewtopic.php?f=5&t=592
\ No newline at end of file
+* Electronic throttle body https://rusefi.com/forum/viewtopic.php?f=5&t=592
+* Ion Sense https://rusefi.com/forum/viewtopic.php?f=4&t=963
\ No newline at end of file