About how to properly makefile arm stm32

Question

I know this is already a long discussed topic on here, yet I have not been able to fully understand/implement a makefile that suits my folder system and requirements.

here is what my any of my project's folder system looks like:

project_name
|-Inc
|-Src
|-Classes
|-Startup
|-Debug
  Makefile
  |- Src
     subdir_src.mk
  |- Classes
     subdir_class.mk
  |- Startup
     subdir_startup.mk

I want local makefiles for each subfolder(that is subdir_x.mk) for which the source files are one level up (i.e ../Src/file1.cpp) and for that purpose I've built a makefile like this (in the case of subdir_src.mk as an example)

C_SOURCES=$(wildcard ../Src/*.c)
C_OBJECTS=$(patsubst %.c, %.o, $(C_SOURCES))

CXX_SOURCES=$(wildcard ../Src/*.cpp)
CXX_OBJECTS=$(patsubst %.cpp, %.o, $(CXX_SOURCES))


CC=arm-none-eabi-g++ 
MACH=cortex-m4
STD=gnu++14
CFLAGS= -c -mcpu=$(MACH) -mthumb -std=$(STD) -I ../Inc -O0 -g3 -fno-exceptions -ffunction-sections -fdata-sections -fno-exceptions -fno-rtti -fno-use-cxa-atexit -Wall --specs=nano.specs -mfpu=fpv4-sp-d16 -mfloat-abi=hard 


.PHONY: all
.PHONY: objects
.PHONY: clean

objects:$(CXX_OBJECTS) $(C_OBJECTS)

#I want to store the .o files in the /Debug/Src instead of /Src so I think this is the right way to do it  
$(CXX_OBJECTS): /Src/%.o : ../Src/%.cpp
    $(CC) $(CFLAGS) $< -o $@

$(C_OBJECTS): /Src/%.o : ../Src/%.cpp
        $(CC) $(CFLAGS) $< -o $@ 

clean:
    rm -rf *.o *.elf *.dat *.map *.txt

This way does not seem to work as I get the output: make: *** No targets specified and no makefile found. Stop. when I type "make objects" in cmd

I want that when I prompt /Debug/Makefile I want that makefile to make use of each subdir.mk to build the objects and then the "big"makefile link all the objects.

I've Tried to take a look at stm32 build system but I just could not understand quite well... so here I am.

I appreciate the thoughts and comments on how might I make this makefiles since my current way to do it is quite archaic.

Also I need to know how to make make clear to clear the corresponding files in each subfolder.