nrf52833-dk read protection

[Gueston]

Hi,

I bought a second nrf52833-dk. After I program my code on it, I can't debug or read the code because read protection is on. This is strange, because I didn't program it like that. I program the board like this:

nrfjprog -f nrf52 --program [name_of_file].hex --chiperase

Which I also use for the other dk and there no read protection is on.

It makes it even stranger if I program an example from Nordic, that the read protection is not on. Is there something in my code, which triggers a read protection on the new DK and not on the older DK because it has an older chip version or something? And what could cause the read protection in the software code

[Sigurd]

Hi,

You likely have nRF52833 with build code Bxx(or later). Access port protection is enabled by default on these latest revision(s). You can find some more info about this here: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52833%2Fdif.html&cp=4_1_0_3_7_1&anchor=concept_udr_mns_1s

Try to program the chip like this:

nrfjprog -f nrf52 --program [name_of_file].hex --recover

[Gueston]

Oh, I didn't know that has changed. I need to use --sectoranduicrerase because I only want to flash a certain area of the flash.

However, after a reset it's still protected.

I read that I need to disable it in the firmware, but when I type this NRF_UICR->APPROTECT=0x5A; it's still not disabled after reset.

I also read "Firmware must write APPROTECT.DISABLE to SwDisable", but I can't find the APPPROTECT register. How can I write SwDisable to this register?

I already spend a couple hours on this to fix it, I personally don't like this change that nordic made to enable rbp it by default. Would have been better to disable it and the with programming enable it, like I always do.

[Sigurd]

Hi,

Gueston said:

I also read "Firmware must write APPROTECT.DISABLE to SwDisable", but I can't find the APPPROTECT register. How can I write SwDisable to this register?

If you use the latest SDK version, this will be handled for you by the MDK startup code. If you are using an older SDK version, and don't want to update the SDK version, then please update the MDK version instead. We have also have an Informational Notice about the changes here https://infocenter.nordicsemi.com/pdf/in_149_v1.1.pdf?cp=18_13

[Gueston]

I use nRF5_SDK_for_Thread_and_Zigbee_v4.1.0, how can I see which MDK version this uses? And how can I update the MDK?

[Sigurd]

Gueston said:

how can I see which MDK version this uses

You can see that in <sdk root folder>/modules/nrfx/mdk/ in the nrf.h file. E.g.

/* MDK version */
#define MDK_MAJOR_VERSION 8
#define MDK_MINOR_VERSION 40
#define MDK_MICRO_VERSION 3

Gueston said:

And how can I update the MDK?

Take a look at this post  how to update MDK to handle APPROTECT 

[Gueston]

Ok, thanks works now.

But wouldn't it be a good idea to update the SDK of tread and zigbee with this latest mdk?

[Sigurd]

Gueston said:

Ok, thanks works now.

Great!

Gueston said:

But wouldn't it be a good idea to update the SDK of tread and zigbee with this latest mdk?

Ideally, yes, but our main focus is now on nRF Connect SDK. See this post for more information:   nRF Connect SDK and nRF5 SDK statement