Which nRF Connect SDK version is compatible with Zephyr 2.7.5 LTS?

[Maverick2k]

Hi All,

I am working on a project that uses Zephyr 2.7.5 Long Term Support. I want to integrate the possibility of having a second image on external flash. I noticed that nRF Connect SDK supports this feature. Currently, I am using the standard (or "vanilla") Zephyr SDK.

I have a couple of questions regarding this migration

1. Which version of the nRF Connect SDK should I install to get this feature? (is there a list of which SDK version is compatible with which version of Zephyr)
2. Can I keep my current toolchain in parallel? For example, is it possible to switch between the two by only changing my environment variables?
3. What are the recommended steps to migrate from one SDK to the Other with an existing project?

If you have any development considerations or recommendations, please feel free to share.

Looking forward to your replies.

Thanks,
Bob

Edit: I think I can go up to 1.9.1 if I am correct: github.com/.../versions.json

[Vidar Berg]

Hi Bob,

1. nRF Connect SDK v1.9.1 will be the closest version to Zephyr 2.7.5, please refer to this link for more details. Your application will likely build without errors against this version.

2. Yes, you can switch between multiple toolchains. This is also supported in our VS code extension if you are using it: https://nrfconnect.github.io/vscode-nrf-connect/guides/extension_migrate_sdk.html?h=toolchain#how-to-change-sdk-and-toolchain-versions.  In SDK v1.9.1, we used the GNU ARM Embedded toolchain for test and verification (Ref. link), but we have transitioned to using the Zephyr SDK in our more recent releases. 

3. I would not expect any breaking changes between these 2 versions. I'd suggest attempting to build your current project with nRF Connect SDK v1.9.1 to see if you encounter any build errors or warnings.

I think another significant benefit of using the nRF Connect SDK is the ability to select the Bluetooth qualified Softdevice controller (Bluetooth QDIDs).

Best regards,

Vidar

[Maverick2k]

Hi Vidar,

Thank you for the insightful information and set of links you refer to. Really helpful, we might go along the same path of moving from the GNU Arm Embedded toolchain to ZephyrSDK when we switch to the new LTS version of Zephyr when it will be available. 

Once again thanks for the support, this really helps

Best Regards,

Bob