Can I turn on APPROTECT right before we enable softdevice?

[min-ching]

Hi, 

     We would like to protect our product from people accessing the device via J-Link. We build our application with FreeRTOS. Can we follow this to set it before I start the Softdevice thread? Do I still need to reset the device even if I can make the change before I start softdevice?

Thank you,

Min-Ching

[Jørgen Holmefjord]

Hi Min-Ching,

Yes, it is possible to write the UICR registers whenever the softdevice is not enabled. As mentioned in the thread you link, you need to reset the chip before the changes is applied. Any reason you do not want to set APPROTECT register in UICR during production programming? This will make sure the content of the memory can not be read back by the user, as the setting will be applied on first startup. You can find an example of configurating UICR in the SDK peripheral examples.

Best regards,
Jørgen

[min-ching]

Hi Jørgen,

     We may need to re-download the software after it is in the enclosure. We will not have any access to the J-Link. 

     Is it possible to stop softdevice on demand? For instance, if i need to change/erase UICR after SD is up and running, can i stop SD, program UICR, and reset the device? 

Thank you,

Min-Ching

 

[Jørgen Holmefjord]

Yes, you can disable the softdevice at any point in your code by calling the function sd_softdevice_disable().