Folder description:
./              | Root, contains the Makefile
 + init         | Contains the main.c
 + config       | Configuration files
 + drivers      | Hardware driver layer
 |  + src       | Drivers source code
 |  + interface | Drivers header files. Interface to the HAL layer
 + hal          | Hardware abstaction layer
 |  + src       | HAL source code
 |  + interface | HAL header files. Interface with the other parts of the program
 + modules      | Firmware operating code and headers
 |  + src       | Firmware tasks source code and main.c
 |  + interface | Operating headers. Configure the firmware environement
 + utils        | Utils code. Implement utility block like the console.
 |  + src       | Utils source code
 |  + interface | Utils header files. Interface with the other parts of the program
 + scripts      | Misc. scripts for LD, OpenOCD, make, version control, ...
 |              | *** The two following folders contains the unmodified files ***
 + lib          | Libraries
 |  + FreeRTOS  | Source FreeRTOS folder. Cleaned up from the useless files
 |  + STM32F... | Library folder of the St STM32 peripheral lib
 |  + CMSIS     | Core abstraction layer

Make targets:

all        : Shortcut for build
compile    : Compile cflie.hex. WARNING: Do NOT update version.c
build      : Update version.c and compile cflie.elf/hex
clean_o    : Clean only the Objects files, keep the executables (ie .elf, .hex)
clean      : Clean every compiled files
mrproper   : Clean every compiled files and the classical editors backup files

cload      : If the crazyflie-clients-python is placed on the same directory level and the Crazyradio is inserted
             it will try to flash the firmware using the wireless bootloader.
flash      : Flash cflie.elf using OpenOCD
halt       : Halt the target using OpenOCD
reset      : Reset the target using OpenOCD
openocd    : Launch OpenOCD