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

[C.Thilo]

hi vidar

what did you do?!

00> *** Booting nRF Connect SDK v3.3.0-ba167d9f3db4 ***
00> *** Using Zephyr OS v4.3.99-fd9204a02d52 ***
00> Hello world from nrf5340dk/nrf5340/cpunet

That worked for me and please tell me it's just a missing config or such thing

Thanks

Cheers,
Thilo

[Vidar Berg]

Hi Thilo,

I am including the test sample I used below (was built with SDK v3.3.0). I simply added the configurations below to the network core FW. 

CONFIG_LOG=y
CONFIG_USE_SEGGER_RTT=y
CONFIG_RTT_CONSOLE=y

6278.hello_world_multicore.zip

B0n does not enable multithreading by default as I recall, which is required for RTT logging. So you may need to enable CONFIG_MULITHREADING as well. 

I can try with sample that is more close to what you are trying to achieve if you let me know which SDK version you are on.

Cheers,

Vidar

[C.Thilo]

Hi Vidar

Do you think, that it will stop working when I used b0n with SECURE_BOOT enabled?

Perhaps thats the problem?

I downloaded your project and have seen, that it doesn't use mcuboot and b0n, thats why I ask.

Cheers,
Thilo

[Vidar Berg]

Hi Thilo,

It should work with b0n as well. The "CTRL-AP indicates that the device is secured" error indicates that you are facing a different problem unrelated to the logging configuration. But perhaps that is what you are trying to debug? 

To check if the debugger is able to access the network core, please try the command below. 

# Read out CPU registers from the network core
nrfutil device cpu-register-read --core network

Cheers,

Vidar

[C.Thilo]

Hi Vidar

it looks like, that you are on the right track:

(v3.4.0-rc1) cest@simt406:/media/data/projects/pan-ng/nrf-sdk-3.4.0/PAN-NG-PROD_APPCORE$ nrfutil device cpu-register-read --core network
Error: One or more read cpu registers tasks failed:
 * 600104758: Failed to attach to target: The Network core access port is protected (All) (NotAvailableBecauseProtection)


The operation was unavailable for some of the devices because they had readback protection enabled. These devices might be possible to unlock using the `recover` subcommand. See `nrfutil device recover --help` for more information.

How can I it be, that our fw locks theses registers?
I can flash your demo and connect with rtt viewer.
But after I flash our fw, the netcore is protected again.

How can I prevent it, to get protected when flashing our fw?

Cheers,
Thilo