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How to fuse nRF9160 debug port?

Hi,

How do we fuse the debug port on nRF9160? The purpose is to block all access and the ability to erase all from outside. 

This is my understanding:

From debugger as last step in factory:

Set UICR APPROTECT=0 to disable DAP access (non-volatile setting)

Set UICR ERASEPROTECT=0 to disable erase all through CTRL-AP (non-volatile setting)

At each device boot as early as possible:

Set ERASEPROTECT.DISABLE=0 to disable possibilty to enable erase all again

Set ERASEPROTECT.LOCK=1 to disable possibilty to write ERASEPROTECT.DISABLE (strictly not necessary, but a safe guard?)

Is my understanding correct?

 

A related question:

Thingy91 has a nRF52xx SoC. Is it possible to fuse its debug port in the same way?

BR / Björn

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