RE: Debugging on nRF52833 with IAR when using DFU and APPPROTECT

Federico — Tue, 29 Nov 2022 14:55:10 GMT

Thanks! This worked great

RE: Debugging on nRF52833 with IAR when using DFU and APPPROTECT

Vidar Berg — Mon, 31 Oct 2022 10:44:35 GMT

Hi,

The AP protection is supposed to be disabled on startup here: https://github.com/NordicSemiconductor/nrfx/blob/v1.9.0/mdk/system_nrf52_approtect.h#L53. However, due to an unfortunate bug in the MDK version (v8.40.3) bundled with nRF5 SDK 17.1.0, the nrf52_errata_249() function ends up returning false even when it is run on nrf52833 rev.2 with the hardened approtect mechanism ([249] DIF: Access port protection needs software interface configuration)

This issue was addressed in MDK version 8.44.2 (https://www.nordicsemi.com/Products/Development-tools/nRF-MDK ):

So, the fix for this is to download MDK version 8.44.2 or later (https://www.nordicsemi.com/-/media/Software-and-other-downloads/Desktop-software/nRF-MDK/sw/8-51-0/nRF_MDK_8_51_0_GCC_NordicLicense.zip) and replace the files in nRF5_SDK_17.1.0_ddde560/modules/nrfx/mdk with the ones you downloaded and rebuild the application/bootloader.

Before flashing the board for the first time, you should also run "nrfjprog --recover". This will write 0x5A to the non-volatile UICR.APPROTECT register so the readback protection stays disabled across resets.

Best regards,

Vidar