how to erase MBR?

[Andrej102]

I can't erase MBR via nRF connect v3.7.1 - Programmer. The PCA100056 board.
If I do a full erase and then read, the MBR still stays in flah memory.

[Einar Thorsrud]

Hi,

The nRF52 series devices has just been updated with an improved Access port protection (AP Protection) mechanism that requires code to enable debugging. In order to allow the device to be debugged/programmed after an erase all a small piece of code that does this is added when you do "Erase all". This is similar to when you use "nrfjprog --recover" from the command line using a recent version of nRF Command Line tools.

If you want to fully erase the IC and not write any code back afterwards, you need to use "nrfjprog -e", as that is not supported with nRF Connect Programmer. Note that if you are using the latest revision nRF52 devices (rev 3 for nRF52840) this will make the device non-programmable until you recover again.