Branch organisation and relation to ARM's CMSIS v5 repo

[vincent-chtln]

Hi ST team,

I was wondering about the relation between this repository and ARM's official CMSIS v5 repository (lets call it the base repository). As far as I understand it, this should be a copy of the CMSIS folder from base repository, but there are missing files and folders. How do you choose which files to copy here and which not to copy ?

Moreover, there are currently 6 branches in this repository: 1 master + 5 branches targetting a specific Cortex-M architecture. What is the difference between these dedicated branches, the master branch, and the develop branches in the base repository. Again, dedicated branches miss files that are present in the master branch. How to you choose which files to remove from dedicated branches ?

In the future, do you plan to switch to newer versions of CMSIS v5, or even switch to CMSIS v6 (maybe in cmsis_core_6 repo) ? It has been 5 years since the 5.6.0 release.

Finally, my team is starting a new project on STM32F4 chips and we would like to submodule git repositories for our components. HAL and CMSIS device will be taken from your git repositories, but should we target this repository over the base repository for CMSIS core ?

Thanks !

[ALABSTM]

Hi @vincent-chtln,

Thank you for these questions. Please find my answers below:

• To be more specific, this folder is a subset of the CMSIS_5/CMSIS folder. Some subfolders like ./CMSIS/DAP or ./CMSIS/DoxyGen are not copied as not used in our STM32Cube firmware. Another typical example is the ./CMSIS/Driver subfolder, replaced by our drivers (placed elsewhere in the folder tree).
• Regarding the branches other than the main one, like cm0 and cm33, each one contains a subset of the main branch's. This is to offer size-optimized alternatives.
  • This is mainly about the ./DSP/Lib subfolder, the most voluminous. The one on the main branch contains precompiled libraries for all supported cores while the one on the cm4 branch, for instance, only contains the precompiled libraries for the CM4 core.
  • Note also that the ./Core_A subfolder is not present on any of the cmx branches as applicable to Cortex-A cores not to Cortex-M ones.
• We already upgraded to version 5.9.0 of the CMSIS core but only for some firmware like STM32CubeC0 or STM32CubeH5. This repository will be updated accordingly 😃.
• For the needs of your project, I would suggest the following:
  • target this repository, mainly the cm4 branch, instead of the base repository,
  • consider keeping only the ./Include subfolder to reduce the size of your project's repository if other subfolders like NN or DSP are not needed,
  • if you intend to "submodule" the cmsis_device_f4 repository under path ./Device/ST/STM32F4xx, you may not be able to "submodule" this one as the former should be placed inside the latter (provided you keep the same folder tree as the STM32CubeF4 firmware) and such nested submodules are not possible to implement, as far as I know.

I hope this helps. Do not hesitate otherwise and best of luck for your project.

With regards,

[ALABSTM]

Hi @vincent-chtln,

Version 5.9.0 of the CMSIS Core provided by STMicroelectronics has just been published on this repository. Please allow me to close this thread.

With regards,

[vincent-chtln]

Hi @ALABSTM,

Thank you for the detailled information !

As you suggested we will target the m4 branch to reduce package size (precisely the v5.6.0_cm4 tag for easier version control).

Since we can obiously not place cmsis_device_f4 repository inside another git submodule, we created an ARM/CMSIS_v5 folder for cmsis-core module and a ST/Drivers/CMSIS/Device/ST/STM32F4xx folder for device specific implementation (this architecture mirrors the one in Cube packages), thus splitting submodules according to the external vendor.

We will keep track of the Cube packages' evolution and upgrade to another CMSIS version if needed.

Kind regards,