RTT Viewer connecting to nrf5340 cpunet core will trigger a mass erase and afterwards one needs to recover the core

[C.Thilo]

Hi all!

I need to see the printks and log messages from the b0n and cpunet app in RTT Viewer.

The problem is, whenever I connect with the SEGGER RTT Viewer to the netcore, I do get the following error message:

CTRL-AP indicates that the device is secured.
For debugger connection the device needs to be unsecured.
Note: Unsecuring will trigger a mass erase of the internal flash, SRAM and UICR of both the application and the network core.

In another ticket, Vidar answered me the following:

Hi Thilo,

It would better if you created a new ticket for this, but I will try to help here.
To troubleshoot this, please disable APPROTECT by using the nrfutil commands below (note: the order matters, netcore needs to be recovered first),
then try to connect the RTT viewer again to see if you get the same error (there will not be any logs).

nrfutil device recover --core network
nrfutil device recover --core application

Cheers

Vidar

Sadly that doesn't change anything. I execute the first command (recover netcore) and then connect via RTT Viewer and the same error message appears and the chip has no fw on it anymore.

Any other idea?

Cheers,
Thilo

[Vidar Berg]

Hi,

Thanks for posting this in a separate thread. I realise now that the FW image loaded by the nrfutil device recover command does not seem to enable the network core, which would explain why AP remains enabled. Just to verify the setup, please try with the attached hex files which I have verified to work here.

2046.merged.hex

3187.merged_CPUNET.hex

Best regards,

Vidar