ACL peripheral cannot be used in main processing

[Rockedge]

Hello.

I am trying to write protect the Flash area using nrf52840's ACL peripheral.
I tried to perform the same process on the main processing side by referring to nrf_bootloader_flash_protect() in nrf_bootloader_app_start_final.c, but an exception occurred when writing to the ACL register? will occur and the process will be interrupted.
Is it not possible to use ACL peripherals after finishing startup processing and moving to main processing?
Please note that I understand the following points:
・ACL registers can only be written once
・The only way to cancel the setting is to reset it.

thank you.

[Vidar Berg]

Hello, 

It should not be a problem to use the ACL while running the main app, but it is important to note that you can't access this peripheral directly while the Softdevice is enabled .

Ref. Softdevice reserved peripherals

What kind of exception did you get when you tried to configured the ACL in your app?

Best regards.

Vidar

[Rockedge]

Hello Vidar Berg.
Thank you for your reply.

I understand that access to the ACL register is restricted while SoftDevice is running.
That's right, SoftDevice was working.

Also, after checking the SoftDevice manual, I found that it is possible to write to the ACL register using sd_protected_register_write().

Thank you very much.