J-Link issue with nRF21540-DK

[pixbroker]

I am trying to use a nRF21540-DK on macOS and I am having some issue with the J-Link thats on board. 

The J-Link FW reports as: 

Firmware: J-Link OB-nRF5340-NordicSemi compiled Oct 30 2023 12:13:06

However, the DK does not show up in VSCode correctly. Additionally, it shows up in the macOS finder as "J-Link" but only briefly, as it seems to be rebooting and therefore ejecting. This happens in a constant loop.

Disabling the J-Link MSD works (it no longer shows up on finder), but is otherwise still unusable as DK.

I assume there is something wrong with the J-Link FW.

I see there there is a J-Link FW image (.bin) on the nRF21540-DK website. However, im unable to get the DK into boot loader mode. Holding the reset button while powering up the DK never leads to a flashing LED5 nor does it show up in finder as "BOOTLOADER" (msdenabled again).

Does anyone have some trick how to flash the correct (nordic) FW to this DK's J-Link?

[koos]

I think I'm encountering the same issue. 

I connected an nRF52DK (which was working fine on my 2019 Intel Macbook) to my new Macbook Pro M3 and continuously got notifications about "Disk Not Ejected Properly", and the DK was unusable.
So I guess it has to do with the combination of the Apple M3 and Oct 30 2023 J-Link firmware. Other boards with an older J-Link version, and a regular J-Link device have no issues.

As an intermediate solution you could try to remove Segger J-Link 7.94e and downgrade nRF Command Line Tools to 10.23.5 (I was using the latest 10.24.0).
Then open JLinkConfig (note that it should now be J-Link version 7.88j when using nRF Command Line Tools 10.23.5), right-click on the listed device, and click "Replace firmware". 
Following these steps I got it to work again.

[pixbroker]

Thank you koos 

I can't find 7.88j on the Segger download page. The last of the 7.88 versions was "n" and i tried that and my nRF21540DK still does not show up properly in VSCode. (I did this on Windows btw). Where did you get 88j from?

FWIW, the Segger Release notes do mention some change to the macOS "System Tray" (i guess they mean Finder) in version 88h.

I downgraded my nRF Command Line Tools to 10.23.5.

[pixbroker]

Ok, my nRF21540DK now works on macOS. Im not sure what happened to my windows machine, but after the downgrade it is no longer recognizing the DK at all :) but it works now on macOS and the constant eject message is also gone.

Thanks for the help everyone.

Just to clarify, the following JLink OB FW works:

Firmware: J-Link OB-nRF5340-NordicSemi compiled Nov  7 2022 16:22:01