Implement SHA256 update file checking

stm-firmware/CMakeLists.txt

@@ -136,8 +136,14 @@ add_custom_command(
     )
 
 set(HEX_PATH "${CMAKE_CURRENT_BINARY_DIR}/${HEXFILE}")
-add_custom_target(update-image ALL DEPENDS ${HEX_PATH})
+add_custom_target(update-image ALL DEPENDS ${HEX_PATH} "${HEX_PATH}.sha")
 add_custom_command(
 	DEPENDS ${ELFFILE}
 	OUTPUT ${HEX_PATH}
-	COMMAND ${CMAKE_OBJCOPY} -O ihex ${ELFFILE} ${HEX_PATH})
+	COMMAND ${CMAKE_OBJCOPY} -O ihex ${ELFFILE} ${HEX_PATH}
+	)
+add_custom_command(
+	DEPENDS ${HEX_PATH}
+	OUTPUT "${HEX_PATH}.sha"
+	COMMAND sha256sum "${HEX_PATH}" | cut -d " " -f 1 > "${HEX_PATH}.sha"
+	)