Question about nrfutil device read behavior on nRF54LM20

[Stanley]

Hi Nordic,

We are developing a PC application for product programming that uses nrfutil to program the nRF54LM20. The programming process involves recovery, programming, code reading, and verification (we need a verification step to confirm that the programmed code has been written correctly). I am using the nrfutil device read command to read the code. If the device does not have a lock function enabled, the entire code can be read successfully. However, if the lock function is enabled, the IC restarts after the first read, causing it to become locked and unreadable. Is there a way to prevent the nrfutil device read command from restarting the IC?

Best regards,

Stanley

[Nissanth]

Hi Stanley, 

You can't prevent it from resetarting the IC after the first read. The lock kicks in after the first reset you set it. Thats why the first read works, but the next doesn't. Once it's active it blocks reading the flash. The only way to reopen the port is to erase the device. I recommend doing the verification before you set the lock.

Regards,

Nissanth Karunanithy

[Stanley]

Hi Nissanth Karunanithy,

A common issue is that customers add protection features to prevent the program from being misused. If the method you proposed is adopted, even if only one device fails to successfully set up the protection feature and is delivered for use, the program code could then be maliciously copied and exploited, resulting in severe commercial losses. Therefore, I believe it is critical that the nrfutil device read function should not automatically restart the MCU. Moreover, the nrfutil device already includes reset and go functions. I sincerely hope your company will consider making this modification.

Regards,

Stanley

[Nissanth]

Hi again, 

I understand your concern, but i don't think making read skip the reset would solve it. You can also confirm the lock took effect with nrfutil device protection-get. You can read more about it here device protection-get | protection-set. 

Regards, 

Nissanth Karunanithy

[Stanley]

Hi Nissanth Karunanithy,

I used the jlink.exe command to read back the code. The problem has been solved. Thank you very much for your reply.

Regards,

Stanley