Mbed CLI 2 not configuring project

Mbed CLI
1

Hello! I’m working on a project that requires several MCUs each with a different firmware and in order to save space I want to use a shared instance of the Mbed OS 6 library. Although I couldn’t find it anywhere in the online documentation apparently Mbed CLI 2 (mbed-tools) also has the option to use a shared copy of Mbed OS when the --mbed-os-path option is added to the compile or configure commands.

To test that feature I first imported Mbed OS (v6.9):

C:\Users\Dani\Documents> mbed-tools import mbed-os

Then I created a new project without mbed-os adding the --create-only option.

C:\Users\Dani\Documents> mbed-tools new --create-only  .\test

Next I tried compiling the project with:

C:\Users\Dani\Documents\test> mbed-tools compile -t GCC_ARM -m NUCLEO_F103RB --mbed-os-path "C:/Users/Dani/Documents/mbed-os"

And got the following error:

CMake Error at CMakeLists.txt:10 (include):
include could not find requested file:
    C:/Users/Dani/Documents/test/mbed-os/tools/cmake/app.cmake

Which of course makes sense because that file path is wrong, nevertheless I was expecting the --mbed-os-path to change that automatically.

Next I edited the CMakeLists.txt file in the root of the test project, replacing this line:

set(MBED_PATH ${CMAKE_CURRENT_SOURCE_DIR}/mbed-os CACHE INTERNAL "")

With:

set(MBED_PATH "C:/Users/Dani/Documents/mbed-os" CACHE INTERNAL "")

Trying again the same command to compile I got a new error:

CMake Error at CMakeLists.txt:12 (add_subdirectory):
add_subdirectory not given a binary directory but the given source
directory "C:/Users/Dani/Documents/mbed-os" is not a subdirectory of
"C:/Users/Dani/Documents/test".  When specifying an out-of-tree source a
binary directory must be explicitly specified.

So I provided a build directory to add_subdirectory( ):

add_subdirectory(${MBED_PATH} "C:/Users/Dani/Documents/mbed-os/build")

Only this way I managed to compile successfully the project.

Next I tried to call:

C:\Users\Dani\Documents\test> mbed-tools compile -t GCC_ARM -m NUCLEO_F103RB

And got:

ERROR: Mbed OS was not found due to the following error: The mbed-os directory does not exist.

Very weird, because the argument of --mbed-os-path seems to be ignored and I was overwriting the file anyway, however if not indicated the compiler complains about the missing library.

I tried to configure the project with an apparent success:

C:\Users\Dani\Documents\test> mbed-tools configure -t GCC_ARM -m NUCLEO_F103RB -- mbed-os-path "C:/Users/Dani/Documents/mbed-os"      
mbed_config.cmake has been generated and written to 'C:\Users\Dani\Documents\test\cmake_build\NUCLEO_F103RB\develop\GCC_ARM\mbed_config.cmake'

However typing:

mbed-tools compile

Outputs:

Error: Both --toolchain and --mbed-target arguments are required when using the compile subcommand.

So to sum up, I only managed to compile the project referencing an external copy of mbed-os by overwriting the CMakeLists.txt file. The configure command seems to do nothing (not even in a simple sketch with a local copy of mbed-os). I want to know how to properly configure my project so I can reference an external copy of mbed-os, ideally placing all the compilation objects in the build directory of the project I’m compiling, leaving the mbed-os directory untouched so it can be referenced by other projects.

Thanks in advance.

2

So I found a cleaner way to achieve my initial goal. The CMakeLists.txt has to be modified like so:

...
(-) set(MBED_PATH ${CMAKE_CURRENT_SOURCE_DIR}/mbed-os CACHE INTERNAL "")
(+) set(MBED_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../mbed-os CACHE INTERNAL "")
...
(-) add_subdirectory(${MBED_PATH})
(+) add_subdirectory(${MBED_PATH} ${CMAKE_CURRENT_BINARY_DIR}/mbed-os)

This allows to add an external directory to the main project and place the compiled files in the same place as where they would be placed in a standalone project. The only requirement is that the mbed-os and the mbed program are in the same folder and that the compile command has to include --mbed-os-path "./../mbed-os".

dir
 |-mbed-os
 |-project_folder
    |-cmake_build
        |-NUCLEO_F103RB
            |-develop
                |-GCC_ARM
                   |-mbed-os
                   |-...
                   |-main.bin

Nevertheless, --mbed-os-path seems to be ignored for the build, as I said in my previous post. Mbed CLI 2 requires it when no mbed-os is present in the the project directory, and the argument has to be a folder containing mbed-os otherwise it complains even if that path is not used for the build. For example, editing the CMakeLists.txt as shown above and adding --mbed-os-path "./../mbed-os" or --mbed-os-path "<full_path_to_mbed-os>" to the compile command builds the project just fine.

Probably this is not the best practice, but I think it adds the least modifications to the original files getting the desired result, and can be easily changed back when the functionality is finally added to the Mbed CLI 2 (maybe it is already, but not working for me at least). Again if someone can show me the proper way to configure my project I’ll be very thankful.

3

Your CMake approach for out-of-tree “subdirectories” is the right one.

--mbed-os-path works for when mbed-os is in a subdirectory of the current project, for example ./extern/mbed-os.

4

Hi, thanks for replying. What would be the use case for --mbed-os-path then? Having multiple versions of Mbed OS in the same project?

I think Mbed CLI 1 offers a better way to reference an external copy of Mbed OS (Managing multiple Mbed projects), and as far as I understand it can be even configured locally and globally. Can we expect this feature to be included in Mbed CLI 2?

5

to have mbed-os somewhere that’s not the root of the project, for example we use ./extern/ for external dependencies where mbed-os resides in our case at $root_of_project/extern/mbed-os