After using the APPROTECT function, complete erasure became impossible.that right?

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Fri, 11 Jul 2025 06:20:54 GMT

I just wanted to erase all mem, and the steps below seem to have done the trick, so I think I'll go ahead with this. Thank you so much for your support.

PS C:\Users\hoko> nrfjprog --recover
Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.
Writing image to disable ap protect.
PS C:\Users\hoko> nrfjprog --eraseall
Erasing user available code and UICR flash areas.
Applying system reset.
PS C:\Users\hoko> nrfjprog --memrd 0x00000000 --n 16
0x00000000: FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF |................|

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Thu, 10 Jul 2025 08:56:41 GMT

OK, I see what I don't understand. Could you please show me a document that explains "This is the beginning of the firmware image that is loaded after the chip is erased here:"? I'll study it.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Vidar Berg — Thu, 10 Jul 2025 08:53:45 GMT

No, you would not have been able to read from the FLASH if readback protection was still enabled.

[quote userid="119152" url="~/f/nordic-q-a/122812/after-using-the-approtect-function-complete-erasure-became-impossible-that-right/542052"]PS C:\Users\hoko> nrfjprog --memrd 0x00000000 --n 16
0x00000000: 20020000 0000057D 000[/quote]

This is the beginning of the firmware image that is loaded after the chip is erased here:

[quote userid="4240" url="~/f/nordic-q-a/122812/after-using-the-approtect-function-complete-erasure-became-impossible-that-right/542012"]

PS C:\Users\hoko> nrfjprog --recover
Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.
Writing image to disable ap protect.
PS C:\Users\hoko> nrfjprog --rbp all --log
Protected the device against read and debug. Only a --recover, --debugreset,
or --pinreset operations will work from now on.

The "recover" command will first erase the chip through the CTRL-AP then it will load a small FW binary which will do the SW unlocking of the approtect mechansim.

[/quote]

Please clarify what you're trying to do or achieve.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Thu, 10 Jul 2025 08:48:18 GMT

OK, I checked again and got the following result:

PS C:\Users\hoko> nrfjprog --deviceversion
483012109 - NRF52833_xxAA_REV2

PS C:\Users\hoko> nrfjprog --recover
Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.
Writing image to disable ap protect.

PS C:\Users\hoko> nrfjprog --memrd 0x00000000 --n 16
0x00000000: 20020000 0000057D 000

I think I may have applied other protection. Is there a way to check?

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Vidar Berg — Thu, 10 Jul 2025 08:21:03 GMT

APPROTECT is referred to as "access port protection" in the linked document. Any existing data on the chip is erased when you run "nrfjprog --recover".

[quote userid="119152" url="~/f/nordic-q-a/122812/after-using-the-approtect-function-complete-erasure-became-impossible-that-right/542042"]I have a feeling that the flash on this device cannot be erased, is that correct?[/quote]

No.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Thu, 10 Jul 2025 08:17:24 GMT

The revision is NRF52833-CJAA-B.

I could not find any mention of APPROTECT in docs.nordicsemi.com/.../in_149_v1.1.pdf.

I have a feeling that the flash on this device cannot be erased, is that correct?

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Vidar Berg — Thu, 10 Jul 2025 07:46:38 GMT

FLASH is erased is a part of the recovery procedure as I mentioned earlier.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Thu, 10 Jul 2025 07:32:20 GMT

I was told that unless I erased the flash I couldn't proceed with the analysis at the factory, so I am currently trying to erase the flash.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Vidar Berg — Thu, 10 Jul 2025 05:48:13 GMT

nRF52833 rev2 has the same approtect mechanism: https://docs.nordicsemi.com/bundle/IN/resource/in_149_v1.1.pdf. But what are you trying to do?

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Thu, 10 Jul 2025 05:43:56 GMT

Sorry. I use NRF52833.

PS C:\Users\hoko> nrfjprog --deviceversion
483012109 - NRF52833_xxAA_REV2

PS C:\Users\hoko> nrfjprog --recover -f NRF52 --log
Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.
Writing image to disable ap protect.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Vidar Berg — Thu, 10 Jul 2025 05:43:18 GMT

Hello,

Sorry, but I'm not sure I understand what you are trying to achieve. It is working as expected here:

The "recover" command will first erase the chip through the CTRL-AP then it will load a small FW binary which will do the SW unlocking of the approtect mechansim.

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Hoko — Thu, 10 Jul 2025 05:16:10 GMT

Thanks　Vidar.

I tried ”nrfjprog --rbp all”,

But.I can't elase flash.

PS C:\Users\hoko> nrfjprog --rbp all
[error] [ Client] - Encountered error -90: Command read_device_info executed for 15 milliseconds with result -90
[error] [ Worker] - Access protection is enabled, can't read device version.
[error] [ Client] - Encountered error -90: Command read_memory_descriptors executed for 15 milliseconds with result -90
[error] [ Worker] - Can't read memory descriptors, ap-protection is enabled.
[error] [ Client] - Encountered error -90: Command readback_protect executed for 15 milliseconds with result -90
[error] [ Worker] - Ap-protection is already enabled, can't enable ap protection.
ERROR: The operation attempted is unavailable due to readback protection in
ERROR: your device. Please use --recover to unlock the device.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

I tried recovering as instructed.

PS C:\Users\hoko> nrfjprog --recover
Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.
Writing image to disable ap protect.
PS C:\Users\hoko> nrfjprog --rbp all --log
Protected the device against read and debug. Only a --recover, --debugreset,
or --pinreset operations will work from now on.

Hiroaki

RE: After using the APPROTECT function, complete erasure became impossible.that right?

Vidar Berg — Wed, 09 Jul 2025 04:44:54 GMT

Hello,

The nRF52832 does not have erase protection like some other nRF chips, but it does have readback protection with the APPROTECT mechanism. After APPROTECT is enabled, it can only be disabled with a full chip erase through the CTRL-AP - Control access port.

You can use the following command to ensure approtect gets enabled:

# Enable APPROTECT
nrfjprog --rbp all

Please also note that the APPROTECT mechanism works differently between revision 2 and 3 as explain in this Informational Notice: IN142 v1.1

Best regards,

Vidar