The issue where protect is automatically enabled every time the firmware is written

RE: The issue where protect is automatically enabled every time the firmware is written

naya — Tue, 26 Nov 2024 17:13:04 GMT

Thank you very much for answering my inquiry!

RE: The issue where protect is automatically enabled every time the firmware is written

SwRa — Tue, 26 Nov 2024 12:38:20 GMT

Hello,

For the nRF 5 SDK, to disable the access port protection for debugging, follow these steps:

a. Run nrfjprog --recover -f nrf52

b. Compile your code without the ENABLE_APPROTECT define.

c. Write HwDisabled (0x5A) to UICR.APPROTECT. This can be done in your code.

d. Flash the compiled code and perform any reset to run the code. The programmed code will open the access port by writing to APPROTECT.DISABLE during start-up.

If you want to keep the debug interface open across power cycles, you need to add code at the beginning of your application to disable APPROTECT. Here's an example of how to do this:
NRF_APPROTECT->DISABLE = APPROTECT_DISABLE_DISABLE_SwDisable;

By implementing these steps, you should be able to keep the debug interface open and avoid having to perform recovery mode every time you flash new firmware.

How to correctly disable APPPROTECT is also detailed in the following ticket: Unresponsive device when flashing after disabling APPPROTECT

Best Regards,

Swathy

RE: The issue where protect is automatically enabled every time the firmware is written

naya — Wed, 20 Nov 2024 16:59:27 GMT

Hello,

Thank you very much for reviewing the issue. We are also using the nRF Connect SDK, so it will likely be helpful for future use with the 52840. However, the current issue is occurring in a project that uses the nRF52 SDK, version 17.02. I would greatly appreciate it if you could guide me once again on how to resolve this issue within this SDK. Your assistance would be highly appreciated.

Thank you in advance!

RE: The issue where protect is automatically enabled every time the firmware is written

SwRa — Wed, 20 Nov 2024 12:48:32 GMT

Hello,

The nRF52840 Rev 3 has APPROTECT enabled by default after every reset or power cycle. This is a security feature designed to protect the device from unauthorized access.

I assume you are using the nRF Connect SDK.. In your project configuration, add the following Kconfig option to disable APPROTECT:
CONFIG_NRF_APPROTECT_LOCK=n

This configuration will ensure that the firmware doesn't lock the access port on boot: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/security/ap_protect.html#enabling_software_ap-protect_with_confignrfapprotectlock

Best Regards,

Swathy