nrf52 DK keeps resecuring itself

RE: nrf52 DK keeps resecuring itself

Vidar Berg — Fri, 17 Jan 2025 07:59:58 GMT

You can try the code snippet I posted here RE: Trying to disable APPROTECT for debugging . This will disable the HW part of the approtect mechanism by writing 0x5A to the UICR.APPROTECT register on first boot.

[quote user="emlynkz"]Our standard production workflow with v2 chips was to perform a eraseall of the flash[/quote]

Note that the ERASEALL must be performed via the CTRL-AP - Control access port on the new revision.

RE: nrf52 DK keeps resecuring itself

emlynkz — Thu, 16 Jan 2025 17:59:47 GMT

I am asking this question for when this project goes into production.

Our standard production workflow with v2 chips was to perform a eraseall of the flash, then flash our .hex with all the firmware on it.

What change in my firmware can I make that will disable APPROTECT? This is to be used with prototypes on which we want debug access, but still run them through the production workflow.

RE: nrf52 DK keeps resecuring itself

Vidar Berg — Thu, 16 Jan 2025 17:57:48 GMT

Hi,

When are you erasing the flash? Performing an eraseall will remove any firmware on the device that can unlock the software part of the approtect during boot. This means that APPROTECT will be enabled again after a power cycle of the board.

RE: nrf52 DK keeps resecuring itself

emlynkz — Thu, 16 Jan 2025 17:18:43 GMT

Hi Vidar,

I have rebuilt my project using the v17.1.0 nRF5 SDK and I keep having the same issue when I do an erase all. Can I have my project set the configuration for the APPPROTECT instead of having nrfjprog --recover do it?

What else do I need to change to my previously working project for it to not secure itself on the new devkit that came with a revision 3 chip?

Thanks.

RE: nrf52 DK keeps resecuring itself

emlynkz — Thu, 16 Jan 2025 14:55:45 GMT

Good, I'll look into that.

Thanks!

RE: nrf52 DK keeps resecuring itself

Vidar Berg — Thu, 16 Jan 2025 14:54:45 GMT

You can update the startup files (part of the MDK package) for you existing projects and rebuild the FW binaries for this revision. We still manufacture and sell the old revision, so another possibility for you may be to use the old ordering code and buy revision 2 chips.

RE: nrf52 DK keeps resecuring itself

emlynkz — Thu, 16 Jan 2025 14:23:57 GMT

Hi Vidar,

thanks for the info.

Upgrading all our projects to nRF5 SDK v17.1.0 is a big endeavour as it breaks a couple of things.

Is there a workaround that can be used with nRF5 SDK v16?

Thanks!

RE: nrf52 DK keeps resecuring itself

Vidar Berg — Thu, 16 Jan 2025 14:21:37 GMT

Hi,

Yes, there is a new silicon revision, please see the IN-142 for more information. The startup files included in nRF5 SDK v16 is not compatible with this HW revision, but those in v17.1.0 are.

RE: nrf52 DK keeps resecuring itself

emlynkz — Thu, 16 Jan 2025 13:59:03 GMT

Hi Vidar,

I usually develop on ANNA-B112 chips and I have never had issues with that. Is it a new hardware revision that changed that?

On my custom boards I can flash the same firmware without an issue of it securing itself.

I'm using nRF5 SDK v16.

RE: nrf52 DK keeps resecuring itself

Vidar Berg — Thu, 16 Jan 2025 12:30:37 GMT

Hi,

The way the APPROTECT mechanism works is that both the non-volatile UICR.APPROTECT register and the volatile APPROTECT.DISABLE register need to be set to the same unlock value (0x5A on the nRF52 series) to disable it (Access port protection controlled by hardware and software). The latter register must be written to by the CPU on boot. This means APPROTECT will be enabled again if you erase and reset the chip.

The nrfjprog --recover operation performs a chip erase, then loads a small firmware binary that writes to the APPROTECT.DISABLE register to ensure APPROTECT remains disabled. This FW will be deleted when you call `nrfjprog --eraseall` after the recover.

Which SDK and SDK version are you using?

[quote user="byte"]This looks very similar to the problem I'm having although I have an nrf5340 project. This started happening to me after I upgraded from nrf connect v2.7.0 to nrf connect v2.9.0. Are you also using nrf connect v2.9.0?[/quote]

Apart from approtect being enabled, does the FW work as expected? Also, do you get the warning about approtect when trying to program the appcore or the netcore?

RE: nrf52 DK keeps resecuring itself

byte — Wed, 15 Jan 2025 17:35:50 GMT

Ah, I just realized what you mean. I am not having that same problem. I only get the error after I flash something from v2.9.0

RE: nrf52 DK keeps resecuring itself

byte — Wed, 15 Jan 2025 17:06:53 GMT

You are not using any version of the sdk? Just directly programming it with what then, an example hex file?

Rob

RE: nrf52 DK keeps resecuring itself

emlynkz — Wed, 15 Jan 2025 17:01:24 GMT

I do not use nRF connect but I use J-Link directly. nRF connect embeds a version of J-Link. Maybe it's that new version that causes this issue.

Étienne

RE: nrf52 DK keeps resecuring itself

byte — Wed, 15 Jan 2025 16:56:17 GMT

Hello Étienne,

This looks very similar to the problem I'm having although I have an nrf5340 project. This started happening to me after I upgraded from nrf connect v2.7.0 to nrf connect v2.9.0. Are you also using nrf connect v2.9.0?

Rob